• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Vacuum Tube OTL power amp!!

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Joined 2010
Yup--Need to make something that at least Looks half tidy.

Currently (And this is why there's no pics) the current version looks nothing much more than a breadboard-in-a-box.--ie, a Pile 'o scrap...
--Sounds nice though!

Ive been messing round since I first built it, so many variations and alterations, a 'nice' build wouldn't have got modded much, so would have limited 'research'....

Only one thing more I would like to try, and thats to MOSFET load the second gain stage,--See if its worth the effort...

--I tried MOSFET followers driving the 6C33C, but no huge leap forward in sound for the extra parts etc, so has returned to the scheme as you have it....

I think its great,

Looking forward to the results.

Regards
M. Gregg
 
Right now it´s indeed a VERY transformerless ampbuild LOL

Filreg finished HT is tomorrows challenge.

filreg.jpg


Good to hear you testing it full throttle M Gregg.

Airlink told me toroid is finished and on the road.

Waiting for the :snail: mail to arrive.
 
Disabled Account
Joined 2010
I reckon those tubes should be pretty well matured by now, with what you've been feeding 'em!....

How's it sounding?:)

Sounds great!:)
It sounds smooth and detailed loads of very deep bass. It is very natural sounding no hiss or spit. One of the things I notice is that all the "sounds" on the recording seem to be at the correct level. What I mean is that on some amps you seem to get selective frequency attenuation. So some of the details are lost. I guess this is the O/P Tx.

Regards
M. Gregg
 
Ah--Thats great! I'm happy that after all the effort you have put into it and your excellent construction has paid off....

Superb build I must add....

I only ask your impressions, on its sound, as those who listen to mine,--while impressed, are not what you may call 'audiophiles' and have little idea of the more technical aspects of amplification....

--To some of them, a boom-box sounds good!

Nice to have a good ear check it out--all be it by 'proxy' as it were!

Without going into audiophile gobbledegook, I find the sound extremely Clear,--Defined-- Things you cant sometimes hear are audible, and those things are usually pretty subtle--Sorta you can easily understand what the backing-singers are singing, without having to conciously listen to them...
Hard to describe.....

Maybe it is as you say--a selective attenuation by combos of amps/speakers, who knows....
 
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Disabled Account
Joined 2010
I find that the volume is more than I need with one heater running!

Only thing is once on it sort of stays on..LOL :)

Listening to female vocals shows lots of detail, you can hear them breath as they sing!
Also you can hear room acoustics. "Echo" ect.
Also accents of singers are easy to pick out!
You can hear the skin on drums /tom tom etc

This kind of information is normaly linked to Higher end SS equipment.

Regards
M. Gregg
 
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Over the last year or so, and as you know--many mods ad updates, I usually play the TV sound through the amp...

While in a lot of cases TV sound--even digital-- Isnt good, over time you can get a pretty good impression of an amps deficiencies and other issues.

Some things transmitted, just show distortions so clearly--even though on a good source, everything sounded just fine,--I have no idea why, but wasn't happy until I sorted that completely etc...

Guess thats why I havent up until now made a Proper finished build,-- Too busy getting it as Right as I could...
Pretty happy now with it,--Just that last thing to try.....
 
Disabled Account
Joined 2010
Over the last year or so, and as you know--many mods ad updates, I usually play the TV sound through the amp...

While in a lot of cases TV sound--even digital-- Isnt good, over time you can get a pretty good impression of an amps deficiencies and other issues.

Some things transmitted, just show distortions so clearly--even though on a good source, everything sounded just fine,--I have no idea why, but wasn't happy until I sorted that completely etc...

Guess thats why I havent up until now made a Proper finished build,-- Too busy getting it as Right as I could...
Pretty happy now with it,--Just that last thing to try.....


The problem with tweaking is you can end up with something that tends to favour a particular type of music ie great for solo singers rubbish for rock, Good for soul rubbish for acoustic.

By using the source TV you have not favored a particular type of music or sound.
This shows all types of music I have played have sounded good! No one type favored over another!

Regards
M. Gregg
 
The good impressions from M Gregg make me really look forward to getting this one working.

Only disadvantage with nice looking amps is that they have a bad habit of wondering out the door with some friend that likes them to.

Right now it´s very quite with only a PCL82 SEPP contraption supplying the music.
 
PCL 82 is a very nice tube used it every way around SE PP SEPP and it performs well.

A local surplus dealer sells Siemens PCL82 in boxes of 100 for lunchmoney :).

Together with 9/18v toroid and salvaged computer PSU it´s the nr 1 givaway amp.

pcl82sepp.jpg


No toroids and itch for building has made me dig out some humming sins from the past that needs attention.

Next in line is a 6aq5/ecc81 compactliving humplifier that need major resomething .
 
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Joined 2010
Just FWIW- over the years I've seen many of those with leakage problems... IMO its the worst 6SN7 ever made. If you are on a budget try the Chinese 6SN7, it sounds better and is a lot more reliable.

Well yes you are correct,

I have the replacement tube for the original 6H8C.

The sound is way better. So their you go. Tung Sol's on order. :)

Regards
M. Gregg
 
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