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Old 17th Jan 2019, 10:54 pm   #64
bikerhifinut
Octode
 
Join Date: Nov 2013
Location: Penrith, Cumbria, UK
Posts: 1,993
Default Re: 120W PP EL34 amplifier re-born.

Just to clarify joe, I was thinking 500V if using 6550/KT88 types. I agree 450V as a maximum HT for EL34 is more sensible and gets you a very decent bang for the buck. The new rework has Ht around the 400V area and I really can't hear the 5 watt difference from the older job with 450V ht. As I'd expect of course. It's still loud enough to make my ears bleed in a normal UK living room.
I don't think any current production output valves are really up to their original versions durability, but that said it isnt so much of an issue on domestic audio amplifiers as we arent looking to squeeze the last milliwatt out.
My feelings are known to you both by now. My take on a lot of the fancy circuitry that gets applied around a valve is merely an attempt to get it to sound like a solid state amp, so in that case I'd buy or build one and do without the supplementary room heating. As no matter how well you getthe circuit working, even the best output transformer is going to compromise the final output?
And you should try and get the best quality OPTs you can afford, again we'd all agree on that.

Well I'm closing the workshop for a fair while now as the building work is about to kick off and there won't be room or time to spread my mess about................
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