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previous: Mark Buckingham I've got a Zoom gf8 multifx process... -- 7/20/2000 6:50 PM View Thread

Re: 6550 SE Stereo

7/21/2000 2:31 PM
Steve M.
Re: 6550 SE Stereo
Sounds like you have some good ideas here.  
I want to get something that sounds like the ac-4 clone, but louder. (The ac-4 clone is just an ef86, a volume pot, and a el84. I have no tone controls or anything else on it.)  
I would like to get close to 20 watts per side, so I thought the 6550 would be a good choice...
I would think that the EL34 would be closer in tone to what you want. You might have to parallel two in SE operation to get close to 20 watts, though.  
So I've got a couple of questions-  
1) does this sound like a good idea?
Sounds like a good idea to me :)  
2) will a 6550 be too sterile or should I go with en el34 or 5881?  
I think it depends on which 6550 you use. I heard some say that the GE 6550A sounds sterile for guitar amps and the Tung-Sol 6550 sounds great for guitar amps, but they will cost you. I've heard varying reports about the Svetlana 6550s.  
3) would the ef86 have enough power to drive the bigger tube. It seems to do well with the el84, especially if the zoom is putting out a decent signal to begin with.  
Don't know on this one, I'll let someone with more knowledge tackle this one.  
4) The whole thing is problably going to be mounted into a 2-space rack, with nothing hanging out. Is this likely to work out?  
I think this will be your biggest challenge. There are very few suitable SE transformers that can be used for a 20 watt SE circuit. Take the Hammond 1627SE or 1640SE, I think either one could be used, but the dimensions are 3.75" x 5.00" x 4.56". Would this fit in your rack case? Also they weigh 11 lbs and you need two for stereo, also something to consider. Also, if you paralleled two EL34s, you'd still need to use comparable iron to the Hammonds to handle the current.  
5) Am I barking up the wrong tree with SE idea? Maybe I should just use push-pull el84's or 6v6's?  
A 20 watt circuit using 6V6s is possible, and two OTs would fit the rack case. On the plus side the 6V6 circuit would be lighter and most likely cheaper (the aforementioned Hammond 16XX series are around $100 each, repro Fender Deluxe Reverb OTs can be had for considerably less). On the downside, a push pull circuit won't sound like an SE circuit.  
(I'm just thinking that some of the reason why the ac-4 clone sounds good is because it's SE.)  
SE does have a different sound, you're right on that count.  
I think the 20 SE circuit is possible, but you might have to go to a 3 space rack case. Also, you're going to have to put in a *big* power transformer to handle the current draw of the tubes. A fan would not be a bad idea if you are enclosing the tubes in a rack case.  
Just my $.02, YMMV.  
Hope this helps,  

Mark Buckingham Thanks Steve-I thin... -- 7/21/2000 8:08 PM