• 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.

The sound of... tubes !

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S

stroop

Member
Joined 2005
Hi everyone,

I'm new in this neck of the woods, so first of hello!

I am looking at another project altogether but have found somewhere in my travels that might be of interest, it is in German but it is pretty easy to follow. www.welter-electronic.de

and also

www.thel.de

They have lots of kits and the iron is relatively inexpensive. They have alot of experience and get good reviews on the German fora apparently.

Cheers Stroop
 
jane

jane

Member
Joined 2004
veiset.net/
EC8010 said:
I just looked at the pictures! I'm a little uneasy about global feedback around so many stages of AC coupling, but driving the output valves directly from cathode followers is definitely worthwhile.
Click to expand...

I ended up with a mix of local and global feedback in that amplifier. About 10dB local feedback (from the plates of the output tubes back to the drivers) and ~14dB gNFB. This gave me the best sonic and technical results (frequency response, distortion, Zo, etc).

An externally hosted image should be here but it was not working when we last tested it.


http://www.veiset.net/valhalla/04MAR2006.html


Jan E Veiset
 
knubie

knubie

Member
Joined 2005
I'm putting my money on this, half a fortune in transformers though....
http://www.audiodesignguide.com/my/pp3.html

Simple design, 20W class-A, HT increase to 400-450 for <40W power, but drops out of class-A.

To get more power than KT88, 6550, EL34, 300B... will do in P-P is a pain in the ***....
So paralleling output tubes or using transmitter tubes (845, 211) requires a third driver stage and sometimes even a cathode follower + a beast of a power supply.... So were looking for more than twice the complexity and component count...
Most of use give up or keep on dreaming....

SE - Interstage - PP in classA, I've heard credible reports from several that they sound like sunshine on a spring moring...
:D
 
J

JAMESBOS

Member
Joined 2007
I am using a universal SEAmp, triode, push pull, driving a full range planar speaker of my own design, 21" x 24" x 2.5". Using neodynium magnets. The amplifier uses2 x 6J5GT's, and 2 x EL38's and a GZ 37 RECTIFIER. I use variable bias so the amplifier can use any of the following valves :-7581A,KT88,KT66,EL35,EL38,EL34,12E1,12E14,S11E12,6550,TT21,5881,6L6. Which makes it truly a universal amp. It sounds great with the planar speakers much better than any other speaker I have made in the past.
 
J

JAMESBOS

Member
Joined 2007
You know a lot more about valves than I do!! All I DO IS FOLLOW SCHEMATICS. If it doesn't work , bad luck on to the next amp!! I also build speakers and I have built about 6 pairs of planar full range speakers from 21" to about 3 mtrs. I must say that these speakers sound wonderfully airy and clear, better than any box.
 
EC8010

EC8010

Ex-Moderator
Joined 2003
Cobra2 said:
How do I check if an amp is running in class A?
Click to expand...

If you can warm your hands from a distance of 300mm, it's Class A. :D

Seriously, you need a current probe and an oscilloscope. You measure the current going into the anode, and if it drops to zero at any point, you're entering Class B. It's easier to look at valve data sheets and draw loadlines to predict it...
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
vinylkid58 said:


Or maybe something like this ARC VT60, reminded me visually of the old Dynaco. Couldn't find a schematic, just pics.

http://www.6v6gt.com/VT60/index.html
http://www.arcdb.ws/VT60/VT60.html

Jeff
Click to expand...


I like VT60. Its just so well and logically and err... honestly executed. And Manley is almost like that. Good sound, clean and forceful, only that 6922 & 6550 signature is always present. I would like it so much if it was based on 6SN7 & KT88.
 
Cobra2

Cobra2

Member
Joined 2002
Paid Member
Why not 200W?
1) cost
2) heat
3) by experience, I know that most(?) tube-amps have more usable headroom.

But I could stretch to a 100-120+W ;-)

I have been looking at these...(links) any comments?

http://cgi.ebay.com/ws/eBayISAPI.dl...MEWA:IT&viewitem=&item=170075401952&rd=1&rd=1

http://cgi.ebay.com/ws/eBayISAPI.dl...MEWA:IT&viewitem=&item=170075403784&rd=1&rd=1

Arne K

Why not tube-sound? What I think of tube-sound, is only good for jazz & classical...not talking guitar-amps and fuzz boxes here...
 
A

Audio_idiot

Member
Joined 2006
Hi Arne,

Maybe they would be better with electric guitar when tube power exceeded the 200Watt per channel? and have a better control over the speaker cones:cool:

I can't comment as I do not have the means to build >200W tube amp without breaking the bank...

Anyone tried this apple to apple comparison?

Cheers
 
J

JAMESBOS

Member
Joined 2007
Hi Cobra 2, If I can drive my small planar speakers with only 20watts why do you need 100 watts. 30 watts is more than enough and you could get it with SEAmp, which would sound better than a P/P Amp and be cheaper to build , especially if you use normal speakers which are more sensitive than planars or ribbons. Yours Henry.
 
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