Mercury Magnetics mods: worth it?

[Jax]

^bump^

[rob S]

cant really offer you anything specific to the peavey MM xfrmer set.
i can only say i did the valve jr mod and it definitely made a difference.
in spite of the hype for that amp, i didnt think much of it before hand.
now its a little one trick pony and i like its trick.
it made me want to do a similiar mod to my fender pro jr.
there seemed to be some magic with the choke.
i called mercury magnetics and they recommended one.
it was a simple mod and i really liked what it did to the amp.
it brought a 3D quality that didnt exist previously.

[Tim Greer]

It can improve the sound. The transformers play a large part in the tone and characteristics of an amp. MM's are far better than the junk they toss into the Peavey amps. I think it's a lot to invest into a Peavey, but if you like the sound and want to improve it, go for it. The main transformer you should care about, is the output transformer. MM's aren't bad at all, and I've got maybe a dozen for amp projects I'm working on, if that tells you how much I think they'd make a difference in sound quality (albeit, I do have more vintage transformers from old Marshalls I use more). But, everyone has their own ear and you might like the stock stuff for your sound better, it's hard to say. You probably will notice a marked improvement though.

[Jax]

Thanks for the ideas. Good to know that upgrading the IT might not yield a big change in sound. I'll skip it, but the choke and OT seem to be worth doing.

Tim, what do you hear that changes or sounds better when you put in MM parts? Rob S mentioned a more 3d sound from just changing the choke. That's what I'm trying to get out of this thread.

[Tim Greer]

While many components play a part in this, a big part is the Output Transformer, in that it offers a tighter, punchier low end, more definition (not as squashed or muddy), a better, fuller body (sounds like I'm describing beer here), which explains that 3-D sound. The notes stand out more. However, a lot of that depends on a lot of components, and the design of the amp circuit itself, but the transformers play a huge part in that. You also need to consider the purpose of the transformers, and how the tubes will run with the MM mod. I've not used an MM mod, I just use some of their transformers in projects, among other companies, and it might need to draw more power, with the tubes and how hot they run, the combination of the tubes, OT, etc, where you might need the power transformer with a different rating for it to run properly and sound right.

[rob S]

in both cases the mod involving the choke was not a parts upgrade.
originally there wasnt a choke, there was a resistor.
so you swap it out and replace it with the choke.

[sloper]

The upgrades are worth it, hands down the best thing i ever did to my bassman. It removed a boxy and sort of hard sound that i didn't like in the amp. I can use my treble control much more freely now with the new transformer. It didn't change the amps character so much, but it made it sound a lot better if that makes any sense.

I would say if you like your amp but you're not quite there with your tone that this would be worth looking into before any other mods or upgrades are made. The difference for me was quite big.

-slope

[Wes Kuhnley]

I would be inclined to say that changing your output transformer will likely make a difference, but don't expect a mind-blowing change. It will be on par with a new set of tubes or breaking in your speakers.

Don't waste you money on a new power transformer and choke. MM iron is already expensive enough, why buy parts you don't need that won't make a difference?

[kafka]

I suppose the question is how different is the replacement transformer from your current one? The size of a transformer definitely makes a difference. I have an older 30/60 watt switchable (boutique) amp, and the stock output transformer is easily bigger than in any 100 watt amp I've seen. It's definitely a factor in this amp.

If your OT is just able to carry the expected load, you may not be getting the response out of it you could. Significantly oversizing the transformer can make a big difference. On the other hand, if the replacement is fairly similar to your current transformer, you may not notice much of a change at all. Try to find someone who has already done the exact change you're looking to do. That's the only way to tell for sure.

[rob S]

after swapping our the output transformer and listening and then replacing R32 with a suitable choke from MM the difference was noticeable in the pro jr.
it was not an intellectual exercise.
it definitely made a nice easy to hear improvement.
these steps were taken after retubing and upgrading the speaker.
both of which were helpful but it still ws kinda grainy.
the iron and the choke made for nicer bottom end and a bit more bloom.
so its not a useless endeavor.
but MMs is definitely pricey.

[rob S]

two other mods worth noting
bypass the cathode resistor on the first stage with 25uf cap.
and 100k pot in place of the neg feedback resistor.
oh and replaced cerimac caps with silver mica.
and tone section with mallory's.
this thing is done.
sounds really good.

[drbob1]

I've replaced OTs in a few amps with generally good results. Not night and day but useful. That said, I'd play the amp first. They're pretty decent sounding out of the box and my main problem with the 5150 line (noise in high gain mode) isn't going to be fixed with a new OT.