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How many watts will 2 EL84's do ?

#3
Class A will push 10-18 depending on circuit design.

My Budda Superdrive 30 (factory rated at 30W) runs 4 of them in Class AB, but I think that 30W power rating is conservative considering just how loud that amp gets.

The 18W version of the Superdrive is 2 EL84s in Class AB.
 
#5
projectMalamute said:
30 or 35 is about the most I've seen with those. They seem to get used in a lot of class A stuff, putting out more like 10 or 15.
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Whisper said:
60W RMS in a class AB design
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Ok, thanks. I thought something was funny. I just had a guy, a mod actually, on an popular electronics forum tell me there is no way FOUR EL84's will do anywhere close to 58 watts lol.

What is it about TB ? Every time I come here for answers, I get accurate ones, but elsewhere it's a crap shoot ?

Anyhow thanks again. :bassist:


EDIT: in fairness, the thread on the other forum concerns a stereo hi-fi amp, so the guy there might be right. And he's a tech, I'm not.
 
#8
Do the small transformers on this chassis boost the power somehow ?

(click to zoom)
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#13
The big black one is a power transformer. The little ones look like output transformers.

This unit looks like it came out of a console and might do 12 or so watts per channel P/P. This would appear to be a stereo amp so I would expect around 25 total from it. Lots of sound with the right speakers.

I got some pretty inefficient (85db) speakers running on my Dynaco ST-70 and it pushes them just fine with 35 watts per channel. I RARELY push this amp above maybe 10 watts per channel when I am working and need loud music. 5 or 6 when casually listening in the same room. Long story short, it should make a good amp with a decent pre in front of it.

You can look at el84 datasheets here http://www.mif.pg.gda.pl/cgi-bin/vs4.pl

I believe that empty slot on the chassis is for the rectifier.
 
#16
bassmodder said:
The big black one is a power transformer. The little ones look like output transformers.

This unit looks like it came out of a console and might do 12 or so watts per channel P/P. This would appear to be a stereo amp so I would expect around 25 total from it. Lots of sound with the right speakers.

I got some pretty inefficient (85db) speakers running on my Dynaco ST-70 and it pushes them just fine with 35 watts per channel. I RARELY push this amp above maybe 10 watts per channel when I am working and need loud music. 5 or 6 when casually listening in the same room. Long story short, it should make a good amp with a decent pre in front of it.

You can look at el84 datasheets here http://www.mif.pg.gda.pl/cgi-bin/vs4.pl

I believe that empty slot on the chassis is for the rectifier.
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Thanks. You are correct on all counts. The missing tube is an RCA 5AS4A rectifier I already pulled out. And it is in fact a console I got at a yard sale yesterday for 12 bucks lol.

Here is the bottom of the chassis. I haven't pulled the pre amp chassis yet. I didn't power it up because I figured all those caps need replaced

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Super cool emblems and grill


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Stereo-Orthophonic ? Where did they come up with those names ?

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The power tubes are 6BQ5's, but I just said EL84's because they are the same I'm told.

So to use this for guitar, I'd have to use a different preamp right ? The console has 2 10" alnicos in it, and 4 smaller ones I haven't measured yet. btw, it's just a turntable console. No tuner. I also grabbed a Motorola console with a tuner/turntable they has for 5 bucks. It has a 12AX7 I pulled out. And some other tubes I haven't looked up yet.

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#17
metalmariachi said:
Those old stereo chassis make great finds.
They usually never went much higher than 12 watts from a pair of EL-84s, but unlike guitar amps they didn’t want any distortion.
A good tube preamp and some good speakers and your venal will sound amazing and surprisingly loud.
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Aw, ok, I was posting as you did so you answered my question. Yea, I'd love to do that. I just can't see buying these cheap low watt imports that have to be modded anyway, when these things are easy to find, are point to point, and can be had for peanuts.
 
#20
Replace the 2 can caps, Antique electronics probably has the right ones or close enough.
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The ones on the underside are paper & foil in wax, they may still be good. Easy to check with a meter, with power on, carefully check for voltage on both sides, on most designs, there should only be voltage on one side, so voltage on both means bad.
It appears to be cathode biased so no neg voltage on the grids of the EL84s.

It doesn’t look like it got much use at all, no discoloring of the resisters or melting of the wax on those caps.

Oh antique also has those odd tubes in case any are bad.

MM
 

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