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-   -   Has anyone on this forum heard a gainclone? (http://www.diyaudio.com/forums/tubes-valves/23687-has-anyone-forum-heard-gainclone.html)

Saurav 4th December 2003 06:20 PM

Has anyone on this forum heard a gainclone?
 
How good are they, really? I'm looking for something to drive a woofer in a bi-amped setup, and want more power than my 2A3 SET can provide (my tweeters are about 10dB more sensitive, so I can use that amp there). My other option would be to build one of the simpler EL34 PP designs, I'm sure I can find many to choose from. Budget is a concern, I don't have too much to spend on iron. I have One Electron OPTs in the SET, and I could try to match that, but it'll probably end up being something cheaper on the new amp.

So... just curious. People on the chip amp forums rave about these amps, but I'm hoping to get an opinion from someone who's familiar with good tube amps. The gainclone is attractive because I think it'll be cheaper and simpler/quicker to build.

Thanks,
Saurav

Morse 5th December 2003 04:18 AM

Hi Saurav;

Why not try an EL34 or KT88 SET to drive those woofers? You should be able to get 10 or more watts out and you'll have less investment than with a PP amp. Or you could go really wild and try your hand at a pair of Fostex FE207E in BR cabs - about 96-97dB SPL IIRC; more than plenty for a 2A3.

On gainclones:

I've built chipamps before, though mostly for headphone or subwoofer duty, so a comparison is not really fair. That said, the OPA134/OPA2134 based headphone amps tend to be a little less resolving than my better valve efforts, but at least they do not annoy. And they can be run from a single 9V battery!

Some time in the next 3 weeks I should have a small TDA2030 and/or LM4766 based chipamp ready for general purpose listening and I'll post my results and comparisons then. Frankly I'd rather be building up one of my valve projects (please don't grass on me over at the chipamp forum! ;) ) but $$ prevents it at the moment. Anyway it should be a fun project, and illustrative of what can be done on a (VERY) small budget.

Good luck with your projects!
Morse

Saurav 5th December 2003 04:43 AM

My current speakers *are* 97dB :) I just want to try out active XOs and biamping. I guess an EL34 SE would be an option too, I hadn't thought about that. And yes, less parts needed.

analog_sa 5th December 2003 05:46 AM

For what its worth i recently compared a nicely built GC (BG standard, dual mono, tantalum resistors, Cardas connectors) to a stock Quad II. There is not a single aspect in which the GC sounds better. To my ears of course.

Morse 5th December 2003 07:23 AM

Hi Saurav;

Whoops! I'd forgotten that you had high efficiency speakers - sorry!

Anyway, if you go with an EL34 SET, you could try either Hammond 125ESE or Hammond 1627SE. If money's a concern, I personally think the answer's a no-brainer, since most everyone who's tried the 125ESE likes it - for the money. Only thing I'd warn about on cost cutting with Hammonds is to go with the 3xx series PS trafos or use a voltage dropping autotransformer to make sure that the primary of a 2xx series Hammond's not being saturated. They hum like heck when they saturate! :(

All the best,
Morse

Saurav 5th December 2003 08:21 AM

Morse,

I had the 125ESEs on my 2A3 amp before I went to the One Electrons. I think I'll want something better than that. Maybe something in the 16xx line. That's a good tip about the PS transformer, I'll remember that. I think I have a 272something in my current amp. It's being run quite a bit under max capacity though (barely gets warm), which is probably why it doesn't hum too much.

analog_sa,

Thanks, that's useful information.

Saurav

Morse 5th December 2003 09:29 AM

Hi Saurav;

I've got the 1627's now and they're really sweet performers. Good everywhere with no weaknesses in their audio range that I can detect with my current system. Great deal for the $$.

The easiest way I've found to rig an autotransformer for my 2A3's mains in is as part of my power filter. I'm using a 25.2VCT Radio Shack $10 special as an autoformer and it works fine - doesn't heat up too much or any of that nonsense. Only things I have to do now are to wire in a switch to allow for no drop, 6.3V drop, or 12.6V drop, and add an AC volts meter to the case of my filter. Depending on time of day and season here, I have measured 128VAC down to 113VAC - and even with my 272JX run way below Imax ratings, it hums pretty badly when the line AC is at the high end of that range....OTOH, around 119VAC it starts to quiet down, and by 115VAC it's very quiet indeed.

One last thought on the 'varying line voltage' theme is that your valve's filaments will be run hot or cold depending on how far from "normal" your AC provider allows things to slip. Without voltage regulation, you could well have diminished lifespans on some valves.

All the best,
Morse

Pjotr 5th December 2003 05:14 PM

Hi, just came across this:

http://www.vonschweikert.com/db100.html

I am working on a 40W UL PP amp for my VR-1s. Funny enough, when I bought my VR-1s a year ago, I was thinking of something similar: To build an active corrected and SS-amplified bas system to accompany the VR-1s and doubling as a stand for the VR-1s. The idea is to use the 3 x 6 long throw bas units each box and each speaker unit powered by its own LM chip.

Cheers ;)

Magnetmaz 5th December 2003 05:19 PM

I previously was using a 300b SE amp, but i've switched to my 4ch gainclone in the last week because of grounding issues i need to work out.

The gainclone sounds great on my Klipsch cornwalls, ..i'm really enjoying it.

-Maz

James D. 5th December 2003 08:09 PM

Hi Saurav,

Doede Douma has a very nice simple mosfet amplifier design on his website that seems to work very well with valve amps. Try TUMOS , it might be just what you need.

ciao

james


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