The Peerless Tone 18 Watt Resource Page

LATEST UPDATE_11/27/08

I have a complete pic collection of the amp detailing every aspect of the build. Very comprehensive and detailed. I will have that up soon.

Then I shall rewrite this page transforming it from the data dump that it is not into a Peerless Tone 18 watt resource center.

The amp is finished. It sounds great. I was impressed as to how quite it is. No issues at all. Well, actually, my tone pot for the normal channels volume is dead. I either have a lead shorting out the pot or the pot itself is bad. I feel like it is the latter since all the other wiring is good.

As good as it does sound you can tell there is some breaking in to do. The caps and transfomers at least need time to break in. This is something I would like to further and more completely discuss in the final version of this page. As the amp breaks in, basicaly, the detial will improve. Less bluriness. I am hearing some of this at high volumes.

The JJ tubes sound okay. Fine for pedal use but to get really good overdrive tones from this amp better tubes will be required. The volume and gain work on this amp so that turning the gain up lets me overdrive the the preamp tubes whereas increasing the volume overdrives the power tubes. The phase inverter tube overdrives some with increasing the volume knob and this is a phenomenon that has been poorly described and "mythed" on the internet. At least I have seen quite a few people try to set "everybody straight" and then they get it all wrong. I want to clarify this simply using the facts presented on how these DIFFERENT circuits work from the Dave Hunter Book.

I have been so satisfied and content playing the plexi channel that I have been slow to correct the normal channel. I have the trouble shooting done I just need to remove and rebuild the compoment connections to the normal channels vol pot.

In the meantime here is more data dumping. The description for the Trinity siii Plexi 18 watt Marshall clone from Trinity Amps:

ENJOY THE THANKSGIVING HOLIDAYS
the sIII Plexi which THUMPS and grinds with a little less compressed tone than the others. The normal Channel provides way more overdrive than most 18 watt normal channels. The TMB channel is capable of some of the best clean sound out of an 18 watter. Crank up the gain and you are in crunch tone heaven. And it has this THUMP that the other variants don't. It's that frequency that moves pant legs! The Plexi sIII is much more like the '69 plexi where you get great cleans low on the volume knob and full bore distortion as you get above 2 or 3.
Sounds very much like a great 50 watt plexi, it has way more girth than most other 18 watters. The clean boost adds another dimension and it nails all those old AC-DC tones dead on and has way more gain on tap if needed.

Siii TO PLEXI
--------------
what I [Stephen of Trinity amps] did to the sIII to make it sound like a Plexi:

*all coupling caps changed to .02uf from .01uf; normal channel cathode bypass changed to 220uf from 47uf and coupling cap change to .02uf; added a 500pf bright cap to the normal channel.

YOU ARE VIEWING A WORK IN PROGRESS. WE ARE JUST DUMPING INFO INTO THIS PAGE AND IT WILL BE FURTHER EDITED AND INTEGRATED LATER. THE BASIC TIME LINE AND STORY LINE ARE INTACT.

http://www.peerlesstone.com/images/18watt/18watt.html

We have taken a great interest in these tone-full little amps. The original Marshall 18 watt amp was produced long ago and only for a couple of years as a combo. It was replaced by the Marshall 20 watt combo which many players now consider to be an inferior sounding amp. Recently Marshall reissued the original watt in all its glory. However, word on the street is that this amp does not sound as good as the original or many of the 18 watt clones available.

We at Peerless Tone recently went on a tone quest to build one of these brilliant little amps. Our ultimate goal was to end up with the best sounding 18 watt variant we could muster. To that end we concluded that one of the kits would be the best way to go. Several good kits are available and we chose what we felt like would be the best one based on it components used and its reputation among other players. Unfortunately, I must admit that for once, price also entered into our final decision. All this will be discussed more below.

Basically the contents of this page are the resources we uncovered and used to purchase an 18 watt head. We are going to reveal what we learned and how arrived at any conclusions. Rather than point you two a series of sites and discussion forums (and we are going to do that here) we are also going to pull out a lot of the coolest resources and information and do our best to narrate out 18 watt learning process.

If this page is not completed after the first chassis pictures go up then I probably electrocuted myself. Be sure and read our links on safety and safe amp building.

If you are reading this NOW, then what you are reading is a work in progress. Come back in a few hours and more will be up. We have a lot of information on 18 watts to share and we are going to reveal the Peerless learning process as well as put some Peerless Tone fundamentals into practice.

18 Watt Kits
http://www.trinityamps.com/Product_Trin18.htm
http://www.ceriatone.com/
http://gdsamps.com/
--
Like the Fender 5E3 tweed Deluxe the Marshall 1974xx 18 Watt amp is commonly available as a kit that the DIY enthusiast can build himself at a much lower cost than the Marshall reissue or any of the boutique clones. You can source all the parts yourself or you can buy a complete kit that contains all you need to build the head or combo chassis. From there you can buy an enclosure already covered or you can tolex it yourself. From our understanding, based on the results of countless players and test results, the kits sound just as good, if not better, than at least some the boutique builds. This is arguable of course and we will show you why below.

The beautiful thing about the Marshall 1974x is that it is a small Marshall cousin to its larger 50 and 100 watt counter parts. It is a simple circuit amendable to modification. It is a great sounding amp on its own--un-modded. The Marshall 1974x does have the basic Marshall sound due to its tone stack, transformers, power tubes (EL84s are essentially smaller wattage EL34s, they are similar yet not exact. This view is a bit simplistic. Many audiophiles regard the EL84 as a more toneful tube. My favorite amps are the vintage Fenders using 6v6s or 6L6s but I do agree that an EL84 is a very musical sounding tube. It performance properties make it wonderful for using in small wattage amps. This is a great power tube to push hard and distort.) Everything about the 1974x 18 watt in its design and components is strictly Marshall and lends itself to the Marshall tone. Its just a smaller package. Some purist allow this point to travel only so far. I do agree that the quintessential Marshall stack tone of a cranked full blast Marshall (usually ONLY heard on recordings or a 1970'sLed Zeppelin stadium concert due to the massive volume required)is not in the 18 watts range. But let me say this about the loud volume required to get this tone. A vintage Marshall Plexi is much louder at full up than any 100 watt Mesa Boogie of today. These Plexi's had "the sound" only full up and not many circumstances can support this volume. So whats the point of anyone short of Jimmy Page even having one? Most of your weekend warriors or guitar enthusiasts can't reach these volumes in their typical playing environments. Most Marshall stacks in existence are doomed to sit between 2 and 6 and will never really sound as good as they possibly could. They may sound great at these lower volumes (and I bet you use a pedal) but there is another level.

Enter the 18 watt. A sensible solution. Modifying the 18 watt to more closely resemble the tones of the Marshall Stacks or JTM-45 era amps is a really sensible thing to do.

Given this point we at Peerless Tone have chosen the Trinity 18 watt clone as our amp kit to work with. We started with the above list of 18 watt kits and decided to go with the Trinity for several reasons. First, the parts are top shelf. GDS also has high end components in their kits but we liked the mojo of the Trintity's more. We think that SoZo caps are superior to the orange drops of the GDS kit. We were highly impressed with the GDS documentation but Trintity's was the second runner up. Both amps have a great reputation for sounding very good. The GDS reputation is very strong and this is the top choice of amp kit for an 18 watt among the discussion forums. However, the Trintity is newer and at this time less known but their amps have a strong following and buzz about them. They are defiantly doing something right. We were really impressed by the Trintity transformers and considered them a serious alternative to the Mercury Magnetics. Pretty much the same goes with GDS but the GDS kit is a bit overpriced considering the prices of the other 18 watt amp kits we looked at. I guess they can do this given their reputation and documentation. Trinity offered a great price for their kit (especially bundled with transformers!) and the components were slightly better.

Hats off to Ceriatone though as we consider it a serious runner up. Their kit wins the bang for the buck if you just want to cheaply buy a preassembled 18 watt clone. They sell various kits but they do not come with instructions, you have to actually know what you are doing. They have a great reputation and although nothing boutique is used they do have a solid reputation for sounding great. They too are doing something right. We were not impressed with the Weber kit. We noticed that the Weber kit is used often by more experienced builders to source the parts but they often do their own thing in regard to the layout. The Weber layout is not as good as the others and documentation is strictly for the experts.

BACKGROUND READING

Ok, so you have an amp kit on the way and while the parts are in the mail and your soldering iron is heating up I suggest you make the most out of the effort by actually reading up on [guitar] amp theory
and building practices. I wanted to make the building of my first guitar amp as educational as possible. I wanted to take this opportunity to solidify all the theoretical concepts and guru insights I have read about over the years. I wanted to know the purpose and nature of each components as I soldered it in place and I wanted a handle on why I would make any possible modifications. I wanted this be amp building 101 and 102.

I think with the 4 books summarized below, you would be off to a good running start. These are the 4 books I wanted after distilling all that it out there. I am not including the old texts like the essential Mullard Amp building book. Those books are better left for the initiated. Here are the 4 books that will bring one up to speed. They are paired, so really its two intense studies with 2 complementary books each (I could not have planned it better, this is great.)

BELOW I HAVE LISTED THE BOOKS AND EDITED REVIEWS FROM AMAZON CUSTOMERS IN ORDER TO SUMMARIZE EACH BOOK.

Valve Amplifiers, Third Edition (Paperback)

Morgan Jones covers just about every tube related subject, not hesitating to offer his opinions along the way. He doesn't hide his dislike for some current tube audio trends, such as tube power supply regulators and single ended amplifiers. There's a single ended amplifier project in the book, and while it's not a 300B amp project (he rightly says there are enough of those around), he goes through the project with all the thoroughness and care we've come to expect. There are several other projects, including a tube headphone amp, the author's original EL84 amp, a more powerful push-pull amp using 13E1 output tubes, his original "practical pre amplifier" from his first edition, plus a balanced preamp and a new line preamp and phono stage.

The wonderful thing about the projects in this book is that the author doesn't just present the schematic and say "build this", he goes through every step from tube and component selection to each design choice along the way. This isn't just a project book, this is a book that teaches you how to actually design an amp. I haven't built any of the designs in the book (yet), but I have no doubt that they sound very, very good indeed. And for vinyl enthusiasts, the amount of time spent explaining phono preamps is an absolute treasure. You won't find this information anywhere else!

Building Valve Amplifiers (Paperback)

This book goes into great detail on how to build a chassis, wiring techniques, PCB's, metalwork and assembly using only hand tools. Examples are given of tools to be used (often with more than one choice for a given job) and how to use them properly. The book then goes on to explain the use of oscilloscopes, distortion measurements and troubleshooting, completely illustrated with pictures and drawings needed to do these things. There are also useful tricks, such as using a discarded radio tuning capacitor to find the optimum capacitance for feedback compensation.

This, along with Valve Amplifiers, are the definitive modern works for the amateur on how to design and build tube amplifiers. If you're interested in tube DIY audio, there just aren't any substitutes for these books, they're simply the best currently available, period.

Vacuum Tube Circuit Design: Guitar Amplifier Preamps (Paperback)

Kuehnel's volume manages to avoid becoming mired in theoretical detail yet remains analytically rigorous. The reader is expected to have a firm grasp of basic electronics and electronic components but explanations do not extend into the realm of system-function in frequency domain, laplace and fourier analysis. This contrasts with Kuehnel's seminal volume on the Fender Bassman 5F6-A, which is mathematically much more demanding.

The reader here is led quickly through basic triode operation and resistive divider networks. A reasonably comprehensive chapter on guitar pickup characteristics is included, this is extremely welcome as many works on similar subject neglect this topic, which is of fundamental importance. Further chapters cover topics of Miller capacitance, pentode operation, headroom, distortion, noise, cathode degeneration and parallel operation of triodes. The Ampeg B42X pre-amp is analyzed, chosen because it does differ somewhat from the more familiar Fender Marshall circuits.

In keeping with the desire to use an engineering approach rather than that of a 'guru', Kuehnel includes data on real-world capacitor and resistor performance. He resists the temptation to pontificate on the vintage-component-tone-mojo debate and leaves it to the reader to assess the implications.

Circuit Analysis of a Legendary Tube Amplifier: The Fender Bassman 5F6-A, Second Edition (Paperback)

Each stage of the 5F6-A circuit is rigorously considered as a separate subsystem and the results are eventually integrated and summarized. This allows one to skip around and explore the book in the order of topics that interest them.

As engineering books go this one is very readable, but it might be difficult for anyone that does not have formal training in electrical engineering (or the like) or is not otherwise a serious student of analytic techniques.

Digest what you can from these and use them for reference material.

ALRIGHT.....So, that should cover about what you need to know. Read them, cross reference them, and use them for reference material. The first pair seem really comprehensive. They are not just for guitar amps though and that's a plus and a minus depending on how you look at it. These books cover the back ground to make you a guru--to bring you up to the tube amp basics and everything you missed since America turned away from this audiophile technology. It also would teach you a lot about guitar amps. Its great that there is an entire book just on the subject of building and getting hands on.

The 2nd pair are more exciting. Instead of an old guru waxing and waning about what he thinks sounds good we have something more along the lines of a engineering textbook made friendly. Here all the theory is considered and its all specific to guitar amps! A lot of the some info will be presented from a different point of view and frame of reference. One important thing about this book is that the author puts a lot of emphasis on analytics and looking at the data--He also shows how to use these technics , stuff like Fourier analysis. This may be the pair I start with. About $85 per pair at Amazon.

The original two Gerald Weber books are also very good general reading. A lot of people rag on Kendrick or Mr. Weber but this is silly and a bit naive. Weber is a student of Ken Fischer. If you do not know why this significant then I hope your not one of the people who turn their nose up at Gerald Weber. Weber is not a scientist or anything and he has own way of relating to some of the science behind all this stuff that is not always 'theoretically correct'. I think this is where the problem comes in. However, he has a LOT of experience with vintage amps and this experience is priceless and can't be gleaned from any book on electrical engineering. Further, his own amp designs are pushing the envelope. He knows tone. His amps are some of the best sounding in the world. His first two books are not perfect but they read fast. Read them then move on.

Two other great general reading books on amps are 'The complete guide to Guitar and AMp maintenance' by Ritchie Fliegler and "The Guitar Amp Handbook: Understanding Tube Amplifiers and Getting Great Sounds"
by Dave Hunter. <= This book is wonderful and should probably be at the top of the list with more devoted to it.
--

--

DISCHARGING THE AMP FOR SERVICING
-----------------------------------
Here is what I’m basically going to do after researching and talking with an amp tech.

1. Unplug Amp. It is protocol to put the plug/cord in the floor in open view.

2. Wear my work boots that are electrically insulated (or rubber mat with tennis shoes or something)

3. Turn amp on standby. (wait a bit… 30 sec? not sure)

4. Alligator clip to chassis and short out pin 1 on preamp tube the input runs to. (30 secs or so) (HAND IN POCKET)

5. Set multimeter to DC range of 500V and touch ground to chassis and RED to that same pin 1. (PUT HAND IN POCKET)

6. Adjust meter till clear reading and get it AT LEAST below 10V. Discharging more as needed.

7. If clear at pin 1 go ahead and hit the positive side of the filter cap just to be sure.

Anyways that was my summary for easy reference. Though read this and double check it.

http://studentweb.eku.edu/justin_holton/caps.html

Drain Power Caps
http://www.peerlesstone.com/node/120

--
I have also heard that you can turn the amp on with the switch and then unplug the amp from the wall. If your amp has a standby then you must turn it 'off' so that electricity is not shunted from the tubes. I have read these methods so many times now that they are running together. Drain power at the preamp tube socket @ p1 then again at the filter caps. I think that's the average method I have in my head after reading all this stuff. I read that you can measure your b+ voltage to confirm the results of the drain.

See the Trin18 docs faq section, look at the 'tips' at the end and then read the first entry of the faq.

You need to develop a good understanding of b+ voltage. To do this read the Rectifier Demystified article in a recent issue of Guitar Player/World [I thought it was Guitar Player but I searched all through my mags and I can't find this great article again HELP!], then read what Stephen says about it in the faq, and also read some other sources. B+ voltage is the voltage that the rectifier has converted from AC and is sending to the power transformer. It is a very important number.

Also read 'Complete Guide to Guitar and Amp Maint.' p.60 to really see an example of DIY bias measurement
that will really advance your understanding and knowledge of amp circuitry.

DO you have the G Weber book called 'Hip Desktop Ref to Vintage Amps', or something like that. Its his first book and not the one with a picture of a rectifier tube on beige carpet. There is a awesome chapter on vintage transformers in that book. It is very short but it gives you the lowdown on transformers. This was written well before companies like Mercury Magnetics were formed. At the time (you heard me say this before) if you lost your transformer, you were sunk or had a vintage amp without its mojo (like Austin Powers). This chapter explains why. It clearly explains what a lot of people still want to argue about when it comes to vintage transformers.

Did you know that the first Marshall transformers were from a company called Radio Spheres? Probably, as everybody on the 'net runs around wanting a absolute vintage replica of a RS transformer in their amp. Did you know that Radio Spheres was a mail order company selling these "general purpose stock " transformers as clearance surplus. They were made by HyGrade and mostly sold for P.A. Amps. Fender, Marshall, and Vox just bought and used surplus transformers because custom transformers were too expensive. In the old days it did not cost a lot of money to build a good transformers. So even these stock, general purpose transformers far exceed what we have today. Similarly, this is the same trend with guitars and why a guitar from Sears built in the 1950s will smoke a modern imported budget guitar from Asia. Since America was leading the production of iron and steel these metals were cheap and of a high quality. Now that America farms out this work it is more expensive and quality is poorer (because we have to pay so much for good iron and steel). A company like Fender or Marshall could not "start up" in todays modern market and make products of any significant quality. The vintage market of today can be more about economics than mojo. How very sad.

Check out some ideas on attenuation:

The 18 watt amps (he better ones at least) sound a lot louder than 18 watts. They are a lot louder than a 22-watt Fender Deluxe Reverb.

This is promising, LeeMo says it works well:
http://www.trinityamps.com/phpbb/viewtopic.php?t=827&highlight=attenuato...

Made one and it works decent & is external:
http://www.trinityamps.com/phpbb/viewtopic.php?t=783&highlight=attenuato...

Other options:
http://www.trinityamps.com/phpbb/viewtopic.php?t=340&highlight=attenuato...
-----------------------------------------------------
10/12/08
WELL MY AMP KIT HAS ARRIVED. The directions are less idiot proof than I hoped for. Good thing I read all those books, huh? LOL.

This link has been essential in learning how to put the amp together. http://www.ampmaker.com/pp18guide/pp18kc.asp

I'll get some pics up soon.

[INSERT CAP POLARITY DOC HERE]

[INSERT LINK TO siiiv6 BUILD NOTES by jcny HERE]

Transformers are critical to the performance of an amp. Ten years ago, the DIY amp scene and the idea of building a decent clone amp were limited do to the availability of vintage era transformers. Even vintage amps without a stock transformers were basically worthless and these amps were often parted out. After market transformers were just too modern in design. No transformer company was going to build a vintage accurate transformers because, technically, these designs are severely limited and are only good for one thing: guitar amps. It all goes back to the idea of creating an amp to distort the input signal is just a backwards idea from a technological point of view. Today, companies like Mercury Magnetics and Heyboar have changed all this. Is is now possible to get vintage accurate transformers or even better (Mercury Magnetics). Clone amp designs are now worthwhile and can just as toneful as their vintage counterparts. Even more so if you add modern twists in the right places and in the right amounts. Mercury Magnetics is an especially forward thinking company in regard to preserving vintage tone. They have intensely studied the transformers from vintage amps one by one and have made careful notes on the idiosyncrasies of these transformers. Simply correlate this data with which amps in your sample sound the best and you can truly reverse engineer transformers from two perspectives. The first being vintage accurate in specs. The second being due to the nature of these original vintage specs, there was room for variance and tolerances were not so great. Couple this with drift over time and you get the true secrete recipe of a good sounding amp transformer. For instance the number of windings on a transformer may vary from one to another with the same model. Also rust can also change the number of functional windings a transformer possesses. Mercury Magnetics has simply recreated the specs for the best sounding transformers for various vintage amp models. Also, there research has made them very knowledgeable in this area and they have great expertise in designing modern transformers or updating original designs. You can take either route with Mercury Magnetics. Word on the street is that these are indeed the best sounding transformers available today. They are also probably the most expensive.

While I used MM transformers in my Lil Dawg with great success (best sounding 5E3 on the block) I decided this time to go with the Trinity transformer. Stephen at Trinity is an expert on the 18 watt amp and his hybrid designs recreate the classic sounds of the larger 100 watt Marshall variants. Given this and the GREAT PRICE of these transformers it just made sense to go with his design.

Here is Trinity press release on their 18 watt transformer:

We are pleased to offer a new Custom built 18 Watt Transformer set for $140 USD + shipping.

We worked with Heyboer Transformers to put together an excellent sounding and looking transformer set. Blind sound tests with our sIII amp, have consistently proven that the new Output Transformer, based on the Original Radio Spares Deluxe design, has the Quintessential Marshall sound.

The output transformer is an almost identical clone of the original 18 watt Radio Spares Deluxe Output Transformer - and with a paper bobbin, vintage steel, additional interleaves and splits, it should sound like it!

The Power transformer sports a beautiful Vintage Marshall Hammertone Gray bell, comes with 120/240 V and has an extra 5V tap.

This is a premium sounding set, made in the USA that you are guaranteed to be thrilled with.

email: stephen@trinityamps.com

Trinity Amps RS18 Output Transformer Specifications
---------------------------------------------------------------
> Radio Spares Deluxe Design - Quintessential Marshall sound.
> Impedance taps: 8K AND 5K
> Secondaries: 4 ohm, 8 ohm, 16 ohm
> Lamination: M-27 steel
> Bobbin: Paper
> Interleaves: 5
> Primary layers: 18
> Secondary Layers: 5
> Current Capacity: 1.2 Amps maximum.
> Core: 1"x1" EI core
> Mylar between windings or interleaves. Nomax wrap over bobbin; Glassine paper between layers
> Flying leads

Trinity Amps Power Transformer Specifications
-----------------------------------------------------
> Primary: 115/240 V 60/50 Hz.
> Secondaries:
> > 290-0-290 120 mA
> > 5V 2A Rectifier tap
> > 6.3 V 1A Rectifier tap;
> > 6.3 VCT 3.25A Filament tap;
> Bell Cover Finish: Vintage Marshall Hammertone Gray
> Flying leads

Trinity Transformer Schematic Hook-Up

http://www.trinityamps.com/ForumGallery/trinity/TrinityCustomTransformer...
_________________
Stephen
www.trinityamps.com

I also talked with Stephen a bit about this transformer and this is what he said:

Jason,

The Output Transformer is the most critical element of the build so we worked with Heyboer Transformers to put together an excellent sounding transformer. Our objective was primarily to get a Radio Spares Deluxe clone that was versatile, vintage sounding and able to be use it in many amps with variations. So in addition, to the 8K primary designed for two EL84/6BQ5, we took the Ultra linear taps from the original design and changed the ratio ever-so-slightly to provide 5K taps for other concept amps.

This output transformer is wound the same as the original Radio Spares transformer used in the early Marshall 18 watt amplifiers. Because the M-6 grade today is a better quality than early 60's M-6, we decided to use M-27 vintage grade steel, low efficiency lamination material. This was done to
capture the tone of the original 18 watt amplifier.

The design has more interleaves than other 18 watt transformers and this iswhat gives it the extended frequency response and complexity. We also used a
paper bobbin, not a plastic, modern one. The clone is very close to the original 18 watt in construction electrically and mechanically has a stand-up channel mount. The OT is oversized for this application and is
almost as large as some 50 watt modern amps in the market today. More iron in the core increases the low frequency response and the transformer core
will saturate a little less.

All of the details of this design adds to the quality of the sound.

To validate the design, we took the original prototype and spent hours doing
blind sound tests with other designs and suppliers. Using our sIII amp, we
consistently chose the transformer based on the Original Radio Spares Deluxe
design, as having the Quintessential Marshall sound.

Test Method
------------
We used a transformer jig and with four (4) transformers to listen to. I
changed the transformers while 2 players played and we all listened -
closely. This was a blind test, only I knew which one was plugged in at any
given time and he recorded the results / comments. (see below) Amp controls
were not changed once testing started.
Some results were recorded.

It took a long time to settle in on the two best and then we focused on only
them. It took some really serious picking and listening to get there but
when we did it was a clear difference!!

HERE IS THE TRINITY TEST REPORT:

Some of you may know, we have been using and promoting the excellent s2 transformers with our kits and built into all of our amps. We are currently testing two custom output transformers built specifically for us by Heyboer Transformers*. One was a Radio Spares Clone and the other was the 'standard 18 Watt construction, with changes. We received the two models a week ago.

We recently started to comparison test the three brand new OTs. All three were mounted on a board and sequentially plugged into the output circuit of an sIII. Our first impressions are very encouraging.

Right off the bat, the Radio Spares Clone has a broader frequency response, especially in the high end. The clone exhibited clean high ends with no extra ‘fur’ on the high notes. This provided a full, rich complex and smooth tone. First impressions were that with the full but not overly hyped bass and clearer highs than all samples. It was smoother and slightly more compressed.

The other transformer was similar in construction to several 18 watt transformers you can purchase from various dealers. Again, as with the clone, this sample exhibited clean high ends with no extra ‘fur’ on the high notes. There seemed to be slightly less bass response than the s2. First impressions were equal to the s2 standard we have been using but with a clean high end and marginally less bass. The clean high end is inherent to the transformer.

We expect it will take some time to ‘burn in’ all of them as all 3 test samples are brand new. That may result in some smoothing of tone – we’ll have to see. Another week perhaps less.

Lawrence and I plan to do a QA test on all 3, and provide comparison sound clips for people to 'vote' for their favorite – and getting feedback on it. That will be interesting. We'll do that on our forum soon.
--
*Heyboer Transformers has been designing and building the highest quality transformers for the electronics industry since 1958, serving customers worldwide. They have two West Michigan manufacturing locations.

Here's a picture of the jig we made with the transformers mounted and ready to test. The amp is hooked up to the jig by way of 3 wires coming out from the inside. Then we plug in whichever transformer we want to listen to.

This give us the advantage of being able to A-B-C every easilty and make valid comparisons.

Here are the comments on the Transformer testing we have done to date. This time we had Lawrence and Martin who has 35 years of Strats and Marshalls. Martin also makes a wicked JTM45.

It was a pleasure for me to listen to both of them play and in the end we had a clear, unanimous winner!

Method:
We used the transformer jig and with four (4) transformers to listen to.
Stephen changed the transformers while Martin and Lawrence played and we all listened - closely.
This was a blind test, only Stephen knew which one was plugged in at any given time and he recorded the results / comments. (see below) Amp controls were not changed once testing started.
Some results were recorded. Hope to post them if they come out OK.

It took a long time to settle in on the two best and then we focused on only them. It took some really serious picking and listening to get there but when we did it was - Wow - what a clear difference!!

All transformers sounded good, this was about picking the 'crème de la crème'!

Used:
> Guitars - Fender Stratocaster with rosewood neck; Historic Les Paul
> Speakers - Marshall 4 x12 cab loaded with 2 X Celestion Greenbacks and 2 x Tone Tubbies
> Amp - Trinity sIII with bridged inputs Power
> Transformer s2
> Pedals - none
> Trinity Amps transformer jig with 3 custom Heyboers and our standard s2

Conclusion (written independently by Martin Newall):

Of the 4 output trannies that were switched in and out of the jig there was one that stood head and shoulders above the rest. The resulting tone from this amp was without doubt THE quintessential early Marshall cranked tone to die for but with an added sweet, compressed, focused and beautiful complexity to the sound that will nail Stevie Ray, Mark Knopfler, Angus Young, Dave Gilmour, Vince Gill and beyond. (It's just a matter of guitar choice and where you set the vol pot...it's all there to explore!!)

Increasing pick pressure on the strings will accentuate the natural compression of the amp while still maintaining outstanding tone with no added fuzzies or buzzy artifacts riding on the signal. Rolling back on the vol pot will bring out the bell like qualities of the EL84 output tubes.

EDIT NOTE - the one that stood out was the Radio Spares Clone custom.

----------------------------------------------------------------------------
Detailed Results and Comments:

Transformer - Radio Spares Clone custom made for Trinity Amps
> Full frequency response / bandwidth
> Nice midrange tone
> More Marshall sounding
> Responsive
> Does not 'fight' the player
> Transparent - clear - doesn’t add tone
> Could cut through a stage mix
> Natural compression
> Good sustain / clear
> Higher bandwidth
> Woody sounding with a Strat
> More musical
> Even sounding
> Easier to play - you hear what you're expecting to hear
> Quintessential Marshall sound
> Broader frequency response, especially in the high end.
> Clean high ends with no extra ‘fur’ on the high notes.
> Full, rich complex and smooth tone.
> Not overly emphasized bass and clear highs

Transformer - Heyboer 18 W Custom
> High frequency roll-off
> Not as responsive as RS Clone - not as "quick"
> Bassy
> Woofyness in bass
> Crunchy - but not sure "I like it"
> Not as clear as RS Clone
> Had to fight a bit to play this one.

Transformer - Heyboer 18W Custom for Trinity Amps
> Clean high ends with no extra ‘fur’ on the high notes.
> Bass is marginally less bold than the s2.

Transformer - s2 Amps 18 W
> Bit of an edge on the high end
> Extended Bass response
> Accentuated bass
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BUILD JOURNAL
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ENTRY - 10-17-08 - FINISHING THE TAG BOARD

T am posting my pics online as I go just in the hopes that someone will spot a mistake. Now I have to do the hardware mounting. Once that is done I do think I can do the heater wiring. A big unknown for me right now is the input jack wiring. I have read over the docs once and I am still a little cloudy but the 2 sets of instruction I have are pretty good. I also worry about doing the wiring from the vol and the input to v1. If I were you I would check your carbon comp resistor values. They are all over the place but I think most are within spec. I think the carbon comps can drift up to 10%. Anyway, I suggest using your tightest resistors in the phase inverter stage on the tag board. This is because the phase inverter needs to have everything matched perfectly. The phase inverter wiring has pairs of resistors in x formations so it is easy to identify on the board. I would match these resistors as closely as possible and also as close to spec as possible so your phase inverter can properly do its job (it will split your signal into two halves, you want each split signal to be the same.) I am working off an assumption here since the phase inverter tube needs to be a matched triode and the balance of your phase inverter triode is critical. Seems logical that the circuit the tube is plugged into would be balanced as well.

http://www.sozoamplification.com/
http://www.soundclick.com/bands/default.cfm?bandID=839081&content=music

Trinity 18 Watt Overview

The Trinity 18 uses a pair or EL-84 output tubes, 3 12AX7 preamps, and an EZ-81 rectifier. It is a Cathode Bias, Class AB all-tube design.

The Trinity 18 TMB is a dual channel amp with Channel 1 - Tone and Volume, 2 inputs and Channel 2 - Treble, Midrange, Bass, Volume and Gain, 2 inputs. The tone controls are of standard Marshall “Tone Stack” design.

Channels can be jumpered for even more complex sounds.

Voiced to sound period correct for a Marshall Plexi Lead. Screaming guitar lead tones at a much lower volume. The amp can thump and grind with less compressed tone than the other 18 watt variants. The normal Channel provides way more overdrive than most 18 watt normal channels while the Plexi channel is capable of the best clean sound we have ever heard come out of an 18 watter. With a pair of greenbacks, you'll be shocked how period correct it sounds. Crank up the gain and you are in crunch tone heaven. The clean boost just adds another dimension, it nails all those old AC-DC tones dead on and has way more gain on tap if needed.

Trinity 18 amplifiers are built using point-to-point wiring utilizing turret board construction for service and reliability.

SOZO coupling, Carbon Composition resistors; CLIFF jacks, ALPHA pots.

JJ 32/32uf filter cap

GP-03 material 1/8" thick Boards;

-A fiberglass reinforced polymer laminate. This material is the industry standard for flame & arc/track resistant electrical components. GP03 also offers an excellent combination of high strength, flame resistance, and low smoke, flame, & toxicity generation. GP03 is a NEMA approved material per NEMA procedure NEMA LI-1.
-Impact Strength: 8-9 ft-lbs/in

-Flex Strength: 22,100 PSI

-Tensile Strength: 7,800 PSI

-Compressive Strength: 33,100 PSI

Laser Cut 0.08” bare Aluminum Chassis.
-small box Plexi-style design.

Belton Micalex tube sockets

large size KEYSTONE Turrets;

CARLING switches

LORLIN impedance switches;

Below are a few key general build features. These features are common to many of today's boutique amps and many vintage amps. Most kits have most or all of these features as well. There is nothing too exciting here, these are just features found in any well built amp in order to achieve good tone and long lasting performance. The only reason to point out these features is because they are scarcely present on any of the big name amps you will pay top dollar for at the guitar super store (Marshall hand wired and Fender Custom Shop amps included; will not contain but maybe 1-2 of these at the most (Aluminum chassis, ceramic tube sockets).

Building a guitar amplifier on an Aluminum chassis has several key benefits. The first of these benefits is that Aluminum exhibits a non-magnetic behavior. Power transformers create magnetic fields, and because of its inherent properties the Aluminum chassis will not interact with these fields, thereby reducing 60Hz hum. In addition, Aluminum cannot rust like steel and is many times lighter than steel.

Terminal board construction is extremely reliable because of superior mechanical contact between the parts and the connecting wires. Mechanical strength is achieved when the leads from the parts are fed directly into the turrets themselves and then soldered for guaranteed electrical bonding. Terminal board construction provides ease in changing circuitry as ongoing development occurs.

?Teflon insulated wire will not burn like plastic coated wire. Teflon insulated wiring also resists heat, preventing cracking of the wiring insulation. In addition, silver-plated copper wire is an excellent conductor.?

Central point grounding reduces ground loops while also improving conductive points for each area requiring ground connection. Power amps are better served when grounds are brought together to their respective points and not just made in different points across the chassis.

If the contact between the input jack and chassis corrodes and the ground is poor and you will become an antenna when you plug your guitar cord into the amp. To prevent this action, rather than a mechanical ground made at the input jack, the amplifier has a solid ground made with a soldered connection directly to the input jacks.

Ceramic Tube sockets are also a part of a high grade component makeup. Ceramic sockets do not burn and are less likely to arc with the high voltage present at the tube pins. Lower grade tube sockets such as phenolic or plastic can burn and cause a carbon resistance to form, which in turn will increase arcing between the high voltage tube pins.

INITIAL POWER UP PROCEDURE

INITIAL VOLTAGE READINGS
AC Mains Voltage: 122
B+ NO TUBES: 439
B+ ALL TUBES: 357

Tube Voltages [LOCATION: EXPECTED/MEASURED]

V1P1: 155/150
V1P3 1.00/0.93
V1P6 155/143
V1P8 1.00/0.97

V2P1 180/171
V2P3 1.5/1.72
V2P6 272/263
V2P8 180/171

V3P1 220/205
V3P2 50/51
V3/P3 75/74
V3P6 217/210
V3P7 62/51
V3P8 75/74

V4P3 12/11
V4P7 345/341
V4P9 340/330

V5P7 345/339
V5P9 340/328

V6P1 292/300
V6P3 350/357
V6P7 292/300

TROUBLE SHOOTING THE AMP
PROBLEM: NO SOUND FROM NORMAL CHANNEL

Here are the suggestions [Stephen] outlined for troubleshooting my normal channel:

1. make sure the jacks are wired correctly. I think they are, so check
continuity from a plugged in cable to the back of the jack and then from there to the 68K resistor. Since both inputs aren't working, I suspect a problem at of after V1.

2. So confirm all your connections match the layout. Measure from component lead to component lead, e.g. not from pin to turret. Test the connection from board 0.022 cap/470K intersection point turret to the volume control .

(1) I rechecked the input jack wiring and I think its good. Continuity checks out from the instrument cable tip to the hot lead of the jack and then on to the 68k resistor lead. This is true for both normal input jacks. I could get continuity up to the resistor. I could not get continuity on the resistor lead on the other side of the resistor or from the V1P7 pin itself.

(2) Not complete. QUESTION: When measuring from component lead to lead and testing the 0.022 cap/470K intersection, do I just do continuity tests or is there something else? If so exactly how do I test using the meter (all this is new to me)?

Should I be able to measure 500k resistance for the normal volume pot after its wired up in the amp? It measures 0.0. The other pots measures their appropriate values but some were more difficult than others to get stable readings from. Whats supposed to be going on with this pot?

[Stephen]Check that the lead from the .022cap /470K intersection turret, goes directly to the volume control. and the lead from the .01 on the board goes to the middle lead of the pot.

[Stephen]Check the pot value from one lug to the center lug. It should change as you rotate it.

[Stephen]Also, touch pin 7 with a small screwdriver and see if you get a noise/pop with the volume about 1/4 way up.
--I get noise when touching these pins but can't make any judgment on the quality of the noise. I am not sure if it is loud enough. I MAY

GO BACK AND REPEAT TEST WHILE ALSO TESTING THE PLEXI INPUT--DO THEY SOUND THE SAME OR IS THE NORMAL CHANNEL LESS LOUD. THIS WOULD BE THE PROPER WAY TO TROUBLE SHOOT THIS.

First, I measured continuity through the instrument cable. If I plug into the normal hi input and clip a probe where the belkin shielded cable attaches to the solder tag at VI, and then touch the other probe to the instrument cable tip I get continuity. I do not get continuity if I touch the cable shield. If I then plug into any of the other amp inputs put stay clipped at this same point at the solder tag (the hi input for channel 1) I get no continuity for tip but I do for the shield. I can repeat this procedure with the same results for any and all the other inputs. That is, continuity from instrument cable tip to its appropriate input at V1. Changing the input that the instrument cable is plugged into abolishes continuity at the tip but gets continuity from cable shield. I wish I could explain it better but I have no experience with this stuff. However, it does appear that the shielded cable inputs to V1 are ok.

Now I have returned my attention back to the pots. Remember I told you that my normal channel pot measures 0 resistance and all the other pots measures their appropriate value when probing the two outer lugs. However it was sometimes hard to get stable readings and this seemed to be associated with how much stuff was soldered to a given lug. Therefore I redid the experiment with alligator clips and I took several measurements for each pot.

For each pot I clipped a probe to the two outer lugs and took readings with the pot at 0 and at 10. Then I repeated this with the rightmost clip now cliped to the wiper of the pot.

Here all my results:

MEASURING RESISTANCE ACROSS TWO OUTER LUGS

PLEXI CHANNEL
BASS (0) .496 (10) .275
MIDDLE (0) .025 (10) .024
TREBLE (0) .242 (10) .163
GAIN (0) .489 (10).085
VOLUME (0) .025 (10) .025

NORMAL CHANNEL
TONE (0).520 (10) .522
VOLUME (0) 0 (10) 0

For instance, with the BASS at O the reading across the two outer lugs was .496, approximate for the value of that pot, and it dropped to .275 as the pot was turned to (10). This trend occurred for all the other pots except for the 25k pots. They did not change much. I do not recall which pots were nonlinear. Interesting, for the normal input tone, the pots did approximatly measure it 500k value but their was no drop. Most of the pots dropped to half their value. The NORMAL pot measured 0 at any setting.

MEASURING RESISTANCE BETWEEN OUTER LUG AND WIPER

PLEXI CHANNEL
BASS (0) 0 (10)272
MIDDLE (0) 0 (10) .025
TREBLE (0) 0 (10) .162
GAIN (0) .489 (10) .085
VOLUME (0) 0 (10) .025

NORMAL CHANNEL
TONE (0) 0 (10) .500
VOLUME (0) 0 (8) .100 (10) 0

For the PLEXI channel the results are as expected. The ranged from 0 to the approximate value at 10 as seen when measuring across the outer lugs. The TONE pot for the NORMAL channel measures fine but the VOLUME pot for the NORMAL channel does not behave like the other pots. It gave values of 0.0 except for around 8 where it measures approximately .100 but then immediate dropped to 0.

Let me stress that the pots were measured hooked up to everything else in circuit. A friend of mine who has built several amps tells me that the pot may not be bad. A lead may be shorting to ground and causing the pots failure. He didn't say to much more other than to truly test the pot I will have to remove everything connected to it. At this point I am more interested in looking for something that may be shorting out the pot than I am totally unhooking it.