• 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.

Building new GU-50 stereo amp...

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Here is the PS schematics. Any comments/suggestions?
300 V regulated is to power screen grids and preamps.

pyramidps.gif
 
felixx said:
Hmmm...it looks good ...for now...but where is the main schematics?:D

Later... A bit of patience... (C) :D

Giaime said:
Do I miss something in the face plate? :D

BTW, what are the advantages of a 2 mosfet regulator design, over a Maida regulator with LM317?

Tell me what is Maida regulator with LM317, I will tell you what are the advantages of 2 mosfet regulator. :D

Here 0A2 gas discharge toob is a shunt - regulator of a reference voltage, Q2 is an error amplifier, Q1 is a source follower. Minimun of components and maximum functionality, including nice looking indicator of B+ presence. Here is the previous amp with similar regulator in the darkness:

wavebourntubepp.gif
 
Brian Beck said:


Here's the original Maida HV regulator from National Semiconductor:

Maida HV regulator app note

These days , Q1 and Q2 might be replaced by a single high-voltage transistor, or by a power MOSFET. Simple and effective, if not state-of-the-art.


It is the well known way to utilize low voltage regulator IC for a high voltage. Instead of LM317 may be used as well any 78XX ICs.

Probably I would go this way if I need better voltage regulation instead of nice glow of a gas discharge tube. :)
 
soundbrigade said:
I have both the original article on Priboi and a shortened version in Swedish (my translation), so I don't need a translation.
However Zen-Mod was interested in a translation som Gospodin Welbourne or Gospodin Soundbrigade may give him the necessary points in the article off the list (PM).
Yepp the 6R3S is a tube wellknown for it's poor quality (very unreliable mehanically), so lets stick to the GU50! ;)

I've had my EC52/GU50 singing for some time and I am very happy. Sad the EC52 is such an odd tube, but isn't that half of the fun - to use odd looking tubes.

Next project would possible be a GU50PP., though I have some 6L6 (Russian brands) that would give some power to me. But anyway can anyone a rough idea how such an amp would look like, or could I use an outline for EL34 or 6550/KT88 with slight modifications?


Hi Soundbrigade;

I am answering you in this topic since I feel like it is better for PP GU-50 amp discussion. I've opened the topic when desided to build a prototype of a GU-50 amp I successfully breadboarded.
 
I've opened a thread about group buy of transformers:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=98678

There will be 100 W transformers, 10K CT primary, 30 Hz-20 KHz, secondaries for 4,8,16 Ohm.
I've contacted several manufacturers and hope I'll find good source of OPTs under $70 each.

I'm designing this amps for home audio, sound reinforcement, studio monitoring. However, for guitar amps such trannies will be an overkill, but for bass guitars they will fit more than perfectly!
 
I'll try to follow this thread, though I am leaving for a 5 week visit to mother Russia. Hope to fix my teeth (and that mrs. K will fix her and two passports) and that I will come home with a big heap of nice tubes (GU72).

I'd just say this as I ruined 4 GU50's - if using a tube without the "collar" be careful as the tube can be inserted in several ways. A sort of marker HAS to be made so you know how the tube must go.
This kind of socket/tubeholder is perfect:

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