Sound of Output Transformers

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Sound of Output Transformers

Postby RS DeLuxe » Thu Oct 23, 2008 3:38 pm

Would appreciate comments on the sound, size, etc. on the various different Output Trannies that have been used in Marshall 45-100 and 100 watt amps, how they stacked up against one another, etc.;
Specifically these trannies:

1202-84
1202-119
1202-132
C1998

(I'm planning on building a 100 watt Marshall clone using Marstran transformers)
RS DeLuxe
 
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Re: Sound of Output Transformers

Postby neikeel » Fri Oct 24, 2008 3:32 pm

Asking that question ( I saw it on Metroamp) and started a reply and stopped thinking that someone else with more experience than me will answer.

My problem is that the transformer is only part of the equation, the amp is the sum of its parts. I can tell you what my 1202-84 clone sounds like compared with my 1202-132 clone vs my C1998 clone but that is in my amps which I have made and which are the nearest I can get to how the factory turned them out. I only use Mullard/GEC valves of new or testing new spec. The amps are very different animals there is some overlap between them.

Unless you find someone who has built an amp and tried all the above trannies in a rig without changing anything but the tranny your question will be very hard to answer properly.

Start off and help us by telling us what tone you are after, what ground you want to cover, what you want to nail, what you are happy with approximations of etc.

Sorry not to be able to tell you what you want to hear but I doubt anyone but Brian or a select few others can 8)
Neil
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Re: Sound of Output Transformers

Postby RS DeLuxe » Fri Oct 24, 2008 4:31 pm

Yeah, I guess I kind of phrased the question wrong.
I've built 6 or 7 JTM45's with Marstran trannies, and there are differences depending upon types of caps & resistors used,
wiring layout, etc. etc. not to mention how different tubes greatly affect sound.
I'm looking to build a 100 watt Marshall clone, using Marstran trannies of course, but have no idea which ones have what sound in general. I guess I should say rather, I'm not familiar with the overall character of the sound of the various 100
watt Marshalls. So...
I'd like to build a non-master volume (did a 2203 already) 100 watter that has that same wide range of tone as a JTM45.
I'm inclined to do a JTM45-100, as I love the harmonics from KT66's, but on the other hand the EL34 can also be a great sounding tube in the right amp.
My experience has been that GZ34 rectifier amps have that special something, but I would also consider a diode rectifier circuit. Same goes for power supply filter capacitance: less can be better, say as in the first JMP100's with just a single above chassis filter cap...
Any comments or observations of your experiences with various NMV Marshall 100 watters, especially if you know what iron was in them, greatly appreciated.
RS DeLuxe
 
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Re: Sound of Output Transformers

Postby neikeel » Tue Dec 02, 2008 1:31 pm

Sorry just saw this, so very belated response.

My favourite 100watter, so far is my Metro 12xxx series build. I really like the 45/100 with its KT66s and the JTM100 with EL34S and low filtering, but the 12 series just rocks out with a range of clean(ish) to downright dirty if I juggle the PPIMV and guitar knob.

I have to use a Hotplate with the other two, although I have placed an order with Rick for a Motherload elemental, I hope that will strangle the tone less.

If I had to have just one amp I am really not sure what I would have. The 45/100 is very flexible and great with a strat (as is the JTM100) but I use a humbucker guitar most of the time so the 12series nails it (for now :wink: )

Have you decided yet?
Neil
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Re: Sound of Output Transformers

Postby RS DeLuxe » Tue Dec 02, 2008 1:55 pm

Thanks for your observations & input.
Well... I decided that I haven't heard enough different Marshalls, so I just started building a "Black Flag" JTM50.
Ordered Brian's 1202-118 massive JTM50 power transformer of course.
I had a spare O/P tranny laying around, a MM custom 60 watt version of the original Radio Spares iron. It will give me 3.4k
input impedance with a single 16 ohm speaker O/P. The amp circuit will be the early one with a GZ34 Rectifier, 10H Choke, and the dual 32uf on-board cap with two chassis mount 32uf filter caps. Since this is very similar to a JTM45, I'll see if I prefer the EL34 tube to the KT66.
The PTP board came out pretty good:Image
RS DeLuxe
 
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