Push-Pull KT88 poweramp

[Steve Conner]

The 6550 etc. aren't so much replacements for the EL34, as upgrades. You can put 6550s into an EL34 amp, and it'll work fine (they were used often in Marshalls imported to the USA, and I've done the swap to one of my own amps) but you'll only get 10-20 watts more than you'd have got with the EL34s. To get the extra power you need to beef up the power supply so it can deliver more voltage and more current.

The Ampeg SVT is a complex, dangerous beast, and not at all the kind of thing a beginner should be messing with. Forget you ever saw the schematic for it.

The difference between 60 watts and 90 watts isn't really that audible.

That preamp looks reasonable if you're after that high-gain kind of sound. Most of these preamps are ultimately based on the Soldano SLO100, so you should probably clone that in the first instance.

[JacksonRR]

Yeah, it looked scary... Forgotten. Yeah, the more I think about it, I'm not so concerned on wattage. I just really want the KT88 characteristics in the power section.

I'm gonna wait this out a little further until I get those Merlin Blencowe books. I'll be able to ask better questions or find them there once I get the basics down a little better. I read a bit of his writing on designing a 12ax7 gain stage to produce different amounts of harmonics. I was seriously impressed. You guys sure are in the know. I like this forum compared to the amp sections at the guitar sites. There seems to be much less guessing and fooling around. I'm keeping the Antec power tranny in mind, as it sounds good. Do you guys have a preference on OTs? Mercury Magnetics, Weber and Hammond are all I know of. I don't wanna spend for Mercury on this though.

[Steve Conner]

Merlin's books are great, from what I've seen. He hangs out here, too.

The Hammond transformers are great too. My hi-fi amp runs off two of their Marshall replacement PTs.

Antek make OTs too, but they're toroidal, and musical instrument amp guys seem to prefer regular shaped OTs.

[überfuzz]

Wow... It's a nice scheme and all, but you might wanna go for something slightly simpler, for a first build.

I take it you're going to build a guitar amplifier. Do you have any preferences regarding sound? Go for a preamp that muster this sound. You're mentioning European tubes, or should I say valves. Are you looking for a English, Marshall, sound? I think the EL34 gives a more rugged distortion. (Not sure!) Well, try to figure out what you want. To keep it very simple, or to narrow it down for you. Start with this:

1. Tone - You could probably get an idea of what preamp you want searching youtube.
2. Break up - What kind of distortion are you looking for? - The power section plays a big part. Clean -> überdistortion?

(You find that a lot of the voice sits in the speakers.) The 2 questions above can help you getting an idea of where to start. What transformers to get etc.

[JacksonRR]

Yes, my preferences are set in stone on the resulting tone. My original plan was to make a simple power section for an ENGL E530. I finally found a decent(and built) schematic for the ENGL screamer, so I think that's my ticket for distortion. The power section needs to be clean and wide, with a lot of headroom.

[JacksonRR]

The edcors. Woweewawa. I never knew they existed. I read a little review site where the guy was comparing his to Hammonds and some others. I'm very very impressed with that. The high-end response was extended beyond that of the expensive unit he was using and was more efficient at the same time. Anyone else giving the thumbs up to these Edcors?

[Steve Conner]

He posted a link to the Engl Screamer preamp above. Looks good in a Mesa/Soldano kind of way.

The Edcor transformers seem to be well spoken of, and they're quite cheap.

[überfuzz]

He posted a link to the Engl Screamer preamp above. Looks good in a Mesa/Soldano kind of way.

The Edcor transformers seem to be well spoken of, and they're quite cheap.

Thanks, it looks crowded...