What sets the power amp section of a Friedman, Metropolis etc apart from a JCM800?

[Nickerz]

What mods would you have to do to the power section specifically to provide a platform for a steller JCM style preamp? Is it really just good tube selection and nice transformers? I understand that at this level there's some small touches that make it nicer, but if you wanted to get 85% there, what would you do? What about 95%?

Glad I finally found a forum of true amp nutjobs! The Marshall Poweramps (100\100 or 9005) aren't going to hack it and this is the place I'm hoping can have the answers! Because I got to find a way out of slaving two Friedmans which is a $7000 power amp

[M Fowler]

Nothing special with a Friedman he uses Heyboer transformers while Metro amps use special transformers such as Merrin.

I use Magnetic Components or Heyboer in mine.

Friedman has DC heaters in the preamp, not sure about Metro.

Mark

[Nickerz]

Are DC heaters relevant to the power amp section?

I'm only asking because the question I have can't be sufficiently answered on a normal gear forum. More or less, I want to rackmount a hotrod JCM800 poweramp section 100W on both sides. So I'm trying to figure out what would be involved in that and how far the Marshall 9005 deviates from an actual JCM800 power section and whether I can have a qualified tech bring it up to Friedman esc specs and increase it to 100W per side.

Consensus seems to be the 100\100 is a lesser animal to the 9005.

So my preamp will 100% be "out of the box" but you included it in your answer so I assume it has some relevance I don't yet know as a guy that doesn't yet build amps.

[pompeiisneaks]

I'm not going to have intimate knowledge of the Friedman, I've not seen the guts of one, but I did find someone that had hand drawn a horrible schematic of it showing how it differed from stock marshall, and it didn't include any of the power section, which to me hints that the power section isn't different in components.
Maybe it's power filtering? Maybe the transformers as mentioned? But really the marshalls push the preamp in a way that causes the power tubes to drive hard as well, so I think, in my limited knowledge, that it's more likely they've tweaked the preamp stages to be able to do more of what they want into the PI to make that power stage drive harder. I am far from a marshall expert, though, and am only building my first marshall based amp right now, so most of this is from reading schematics and forums, and could be WAY up in the night

~Phil

[Nickerz]

You bring up a very interesting meta point. Can a line level preamp ever achieve the results of a hotrodded head?

E.g. can an ADA-MP1\JMP modded with a JCM800 power section ever be on the same level? I think that's the question that is arising here.

[pompeiisneaks]

I don't think so, because line level is, by definition, lower output so that the next stage of common equipment won't be overloaded. That's not what you want for a power section of a great sounding overdriven tube amp Unless you add some kind of level that has a 'danger this goes to eleven' on it so people don't roast their solid state equipment

~Phil

[Reeltarded]

You sounds like someone trying to put stereo effects in a loop.

Meh.

I do what you want your thing to do but I do it for 2200 watts whole rig. Put good amps on loads, a mixer with loops outs and returns everywhere, whatever my rack is, a stupid 6lb class D stereo power amp and a quad of cabinets.

You cant drive the power section of a tube amp with effects that aren't distored by that oitput. You make the sounds you want, they get mixed, they get treated, it comes out of two holes in the mixer the way you thought it should sound, and then you can play 4 hundred watt amps that all switch through the same cabinets... right.

[Nickerz]

All my effects are generated from the preamp. So I'm just slaving. I have quad outs from the preamp section to power two stereo cabinets. But since I'm actually slaving, I need to be cognisant of the flavor of the power amp being that I'm not interested in using it as a neutral part of the equation. I'm not doing this for volume, but for tone. I want my power amp section to drip in Marshall and JCM800 hotrod tone. El34s are 50% of that. I'm sorting out the rest, which seems to be transformers and some other flavor I'm waiting on.

[Reeltarded]

So run one head into a good load and a power amp..

I could tell you ten thousand reasons not to break out a preamp into a bunch of slaved tube amps. I fell in all these pits 30 years ago.

[Reeltarded]

What is your preamp?

[romberg]

I'm not interested in using it as a neutral part of the equation. I'm not doing this for volume, but for tone. I want my power amp section to drip in Marshall and JCM800 hotrod tone.

In order for a power amp to have any significant contribution to the "tone" you need to be playing loud. Really, really loud. The power tubes themselves need to start clipping. Otherwise, the vast majority of your tone is what happens in the preamp. How loud do you expect to be playing?

The jcm800 series were all mostly master volume amps. Have you ever played a 2203 (100 watt version) or 2204 (50 watt version)? Most players crank up the volume and turn down the master to avoid sound pressure levels that put them at serious risk for permanent hearing damage. To get power amp distortion you do the opposite. You crank the master volume all the way up. Then increase the volume until the amp distorts. This way the power amp is clipping. The only way to make the power amp clip is volume. Do, you really play at these sorts of volume levels? Two 100 watt tube amps running full bore into power amp clipping is WHO territory .

If your master is normally set at 3 or less, you probably are not really getting much of your "tone" from a power amp. It just is not being pushed hard enough.

Mike

[Roe]

Nothing special with a Friedman he uses Heyboer transformers while Metro amps use special transformers such as Merrin.

I use Magnetic Components or Heyboer in mine.

Friedman has DC heaters in the preamp, not sure about Metro.

Mark

Metro never uses Merren transformer - "Merren" is even blocked on the metro forum. The metro transformers are made by heyboer to george's specs

[M Fowler]

Nothing special with a Friedman he uses Heyboer transformers while Metro amps use special transformers such as Merrin.

I use Magnetic Components or Heyboer in mine.

Friedman has DC heaters in the preamp, not sure about Metro.

Mark

Metro never uses Merren transformer - "Merren" is even blocked on the metro forum. The metro transformers are made by heyboer to george's specs

It doesn't matter what George uses. If I felt it was really important I would have looked up facts. Why not just build an amp and find out for yourself how to build like whatever amp you think you need to copy. It's faster and you learn so much more then guys typing on internet forums.

Mark

[Reeltarded]

I want to know what the preamp that makes all the effects is. If any of the effects are reverb, then there are zero reasons not to use an off the shelf stereo mosfet or whatever. Never clip after the ambient stuff. My 2.2kW Peavey thing sounds great for 5 years so far and cost less than a quad of nice tubes that would hardly ever do anything but idle. Used to use Crests or Crowns. All fine.

[norburybrook]

EVH still uses HH v800 mosfet power amps for the very same purpose

One great amp for center dry and then stereo power amps as miles said for FX. If EVH still uses that method you can guarantee it's the best way, he could have what ever he wanted, doesn't have to carry them, pay for them, set them up but

Listen to uncle Reeltarded….he's right


M