Some problems with Death Of Zen

[bezobraznia]

First of all sorr for my bad English, but i never learn this language at school (I'm Bulgarian)
I've built DoZ and it's play, but i have little problems with it:
Power supply is aobut 54V DC and i've made it capacitance multipler and use two of 2N3055 for make my output voltage when amp is turned on it about 40V DC , so far so good
i adjust my center point of voltage with voltagemeter and after with osciloscope for better sinus , then i gain ampers to 1.6A for chanel and all is good and after 10 hours of work consumation is 1.85~1.95A on channel with ~39,5V DC. First i use 2N3055 (Tungsram) , but after i've changed with KD503 (Tesla) and result is better , but this my move rise temperature on heatsinks with 20C. and i use bigest heatsinks and result is ~70C on each heatsink, but i have problem - my transformator have temperature about 100 degres C. and in the beginning when i turn on the amp, resistor on my zobel network star smoking and this is (i don't know word) stir up on high level !#$$ , after this things go ok (i don't know how) but i know that my amp is still possible for stiring up , and my big problem is that on the high frequences i hear some woolly , not noise, but high frequencies is not that clear that i want , one friend of mine told me that i have to put some small inductors on my KD503 , but i don't know what capacitance because i'm afraid of reject some high frequencies
please help for all of my problems
thank you
Niki
Bulgaria

[eLarson]

Interesting question, but probably better asked on Rod Elliot's forum.

Actually he does post over on the Solid-State forum. I've not ever seen him post here, though.

[corbato]

Consider adding 100uf + .1uf (ceramic preferably) decoupling capacitors to each channel’s PCB. Try also to roll off the HF gain at the input stage. Your amp is probably having HF oscillation. I’m assuming you have built it as per designer’s schema.

Are you having a sufficiently large transformer? Long and/or thin powers leads may cause problems. 54volts unloaded sounds too high for 3055 running at Class A.

Try removing the zobel network. Usually you shouldn’t not have any problems by doing that. What kind of loudspeakers you are using?

What is the url of Rod Eliot forum?

[Nelson Pass]

I think it's the bad Karma that comes from calling it the
Death of Zen

[ultrachrome]

Originally posted by Nelson Pass
I think it's the bad Karma that comes from calling it the
Death of Zen

He he.

Rod's forum is here: http://www.instantboard.com/users/rode/

[bezobraznia]

I'll make some voodoo magic to remove that bad carma
hi again ...
yes (that is word) i have HF Oscilation. I think that remove Zobel network form output is not good because this is the most importand point that i know about that HF Oscilation... my transformer is 54Volt but after i use my Capacitance multypler then i get exactly 40V on the amp. running in 1.65~1.90A. I use 2n3055 only in capacitance multipler but on my amp i use KD503 that are more slow , but sounds more good, or you mean that i have to change my 2n3055 on Capacitance multipler?
With amp I use pair of Russian speaker boxes 2x40W that sounds very good, but not perfect, and they capacitance is 6.4Ohm , but i have pair of Visaton BG20 speakers, but i don't make boxes yet ... they are at 8ohm full range , and even in my vacuumcleaner box they sounds very good

[joensd]

Sorry to get offtopic here...
Niki, do you have a proper design for your BG20´s
or will you just experiment with them?
I´m thinking about buying some as they´re quite cheap for a nice fullrange.

Cheers
Jens

[Nelson Pass]

Originally posted by ultrachrome
Rod's forum is here:

I much prefer this forum - much less work for me.

By the way, Jason, you have forgotten to hit PL up for a
contribution for server costs.

[SY]

Nelson: Make the check out to the Committee Against Special Help (just use the acronym), and mail it directly to me.

[ultrachrome]

Who's Jason? Who's PL?