Silver Mica
I compensated the amp with Russian surplus silver mica. It takes 2X360p = 720p parallel to the 1K feedback resistor for the given OPT. The silver mica kills easier the edges on the scope (10kHz sq wave) compared to the handy ceramics that I initially used. Subjectively the 3D and mellowness improves noticeably. I know, I have done it before and it was planed so, but its a steady reminder. Don't skimp there.
P.S. This amp makes 20W triode for 0dBV input. The gain is 26dB. The FB=18dB. Those readings are for 8 Ohm load on the respective OPT tap.
I compensated the amp with Russian surplus silver mica. It takes 2X360p = 720p parallel to the 1K feedback resistor for the given OPT. The silver mica kills easier the edges on the scope (10kHz sq wave) compared to the handy ceramics that I initially used. Subjectively the 3D and mellowness improves noticeably. I know, I have done it before and it was planed so, but its a steady reminder. Don't skimp there.
P.S. This amp makes 20W triode for 0dBV input. The gain is 26dB. The FB=18dB. Those readings are for 8 Ohm load on the respective OPT tap.
Some sound check.
I have a neighbor, he owns a Jadis DA30 (Euro 5600). He brought it around to compare, because he liked the sound of the ugly one.
He preferred the ugly one's sonics by large.
My opinion is that the Jadis is very respectable for sonics and has real value construction, but its tuned for classical.
Anyway, the ugly one proved potent in exalted company and that is good news.
In the photo, the ugly one lurks below the beautiful French waiting for the lights to dim out. 🤐
I have a neighbor, he owns a Jadis DA30 (Euro 5600). He brought it around to compare, because he liked the sound of the ugly one.
He preferred the ugly one's sonics by large.
My opinion is that the Jadis is very respectable for sonics and has real value construction, but its tuned for classical.
Anyway, the ugly one proved potent in exalted company and that is good news.
In the photo, the ugly one lurks below the beautiful French waiting for the lights to dim out. 🤐
I have it on good authority that the French word "Jadis" translates, roughly, to the English phrase "don't bother us with engineering; we're artists". You've probably got the better amp there Salas, and I'll bet that you spent a good bit less than 5600 Euros on it. Still the Jadis is kind of pretty, but then so are Renaults and Peugeots.
Actually a confirmed Francophile...
Actually a confirmed Francophile...
Re: Silver Mica
Just a small notice. I have settled on a 1K2 feedback resistor without changing the silver mica values. It noticeably locks better for sonics with that value. Of course if someone ever attempts to copy this amp but using different OPTs must see for optimal values by measuring square waves. With 1K2 the gain is 28dB, the feedback is 16dB for 8 Ohm. What I do is using the 8 ohm tap for 4 Ohm load, so I make the 6k OPT to go under 5k, and the feedback 10dB.
salas said:
Just a small notice. I have settled on a 1K2 feedback resistor without changing the silver mica values. It noticeably locks better for sonics with that value. Of course if someone ever attempts to copy this amp but using different OPTs must see for optimal values by measuring square waves. With 1K2 the gain is 28dB, the feedback is 16dB for 8 Ohm. What I do is using the 8 ohm tap for 4 Ohm load, so I make the 6k OPT to go under 5k, and the feedback 10dB.
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