Very nice RCruz.
Initial impressions. I came home with a RIAA. It wasnt the Simplistic😀 HAving been around the block with the Salas Shunt, I was not surprised by the black as night background, but he was. We had some hum, but I believe it was layout and trafo related. The 50Va hammonds I bought hummed from the very beginning. The shunt reg was set for 38V and 175mA. They should not be working that hard. Dissapointed to say the least. Hum was not bad, but noticeable playing classical and with volume cranked, naturally. You could tell the caps had not been broken in, having that compressed new cap sound. Not worried at all, as I am sure that will go away. As for the sound, It was wonderful. Punchy and dynamic. Clean with good overall presentation of the soundstage. Brother could not get over the fact that he was enjoying a SS RIAA so much. He said it was the only other SS RIAA he had heard the he liked, with one exception being the XOno. Not bad company. I look forward t more listening, as I know the caps will continue ti develop and losen up. IF this thing decompresses like I expect, I will have a big hats off to Salas. I do trust his ears.
Brother told me to get the best componenets I could. I will be looking at Auricap or Multicap, leaning toward Auricap. I am considering going with Rush's DCB1 output, As we want to use Vcap in the output and 2uF Vcap is borderline crazy. I have not put it on test bench officially, but It is very quiet. It is my hope that we are reaping the rewards of the SMD parts and excellent design of Salas in both the Shunt and Riaa stages. I want to try to find the 369, as I want the lowest noise option. Any help here is appreciated.
What can I say, Salas. Another winner. I may pick your brain about layout to make sure it is not an issue in terms of noise. Thid thing deserves a concentrated layout attempt. It will only get better.
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See to sort out the hum issues first, box it up in metal and use coax for signal. Tx & rectification in separate box. Even with new lytics its the hum that adds low freq harmonics and sounded kinda squat. Good start nonetheless. 60dB totally quiet phono ain't easy in the open, so far so good. Congrats.
I mat try using big Antek tomorrow and running both shunts off one trafo. IT is 400VA. I will haev to kill some voltage with resistor, but no big deal.
Salas,
Any way to use 12 mA idss 369? I have a pair at 12 I would like Buzzforb to use, if you could make the circuit work for that high idss. Is it a whole new design?
Rush
No worries. Amps lab has some. I'll just get the there, although I do have a question. I believe you said a single 369 beat dual 170's. what about distortion? I would think dual 170's would have better linearity than single 369.
About the violin..... No.. not really..
I gave up Contrabaixo years ago and violin is even more difficult.
Sometimes I hit the flute and the piano, but I do not have enough fluidity with strings.
I gave up Contrabaixo years ago and violin is even more difficult.
Sometimes I hit the flute and the piano, but I do not have enough fluidity with strings.
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Hi buzz... this folded version picks up like an antena.... enclosure is a must.... I use copper case but iron is also very good.
My builds are totally silent.
My builds are totally silent.
.I knew it would be susceptable to hum. I am taking big donut over there today. It may not help much, but the hammonds hummed right out of the box.
Not in our test, it was the same like the telescopic with open lid in same box, psu and grounding arrangement. Had no hum or buzz. It will pick up from a contaminated ground as much as a telescopic from a contaminated rail. There is no high gain phono we can afford to roughly test unpackaged and expect no hum nonetheless.
The 369 will beat them below 300Hz only. Gate capacitance is roughly the same for one 369 and two K170. You will lose 1.5dB gain with the single 369 in this circuit.
P.S. Having two positions already its easy to check one or the other config.
Thanks for the comments Salas. Degeneration is an option, but i have discivered i like as little as possiblle. Have you tried with none?
I had double and triple matched 369s without any Rs and they had instability tendencies due to capacitance and gain. Small Rs tamed them. Lends some more linearity also. Although the swings in first stage aren't anything that demanding.
I am going to be getting some TX2575 resistors for the 47K signal path spot as well as some 220R for the DCB1. Anyone interested, PM me Sorry Salas, not trying to turn this into buying thread, just thought RCruz and others might like a shot.
Salas,
redesigining everything and working on the PSU. I am going to have the Toroid in a seperate case, with shielded umbilical bringing the secondary voltage into the main case. I am unsure of how to ground the main case to earth. I will bring earth in the umbilical so the case can be grounded. Just wandering if I just run a wire from the prereg ground to earth ground, sperated by dual diodes. Any suggestions on wire up for quiet ground?
redesigining everything and working on the PSU. I am going to have the Toroid in a seperate case, with shielded umbilical bringing the secondary voltage into the main case. I am unsure of how to ground the main case to earth. I will bring earth in the umbilical so the case can be grounded. Just wandering if I just run a wire from the prereg ground to earth ground, sperated by dual diodes. Any suggestions on wire up for quiet ground?
No don't run AC umbilical, run DC only to the phono box to achieve best results. Move the bridge diodes in the Tx box and connect to the filter cap remotely as it will be left alone on the reg board.
Connect PSU ground and reg ground, and reserve one cable in the umbilical to connect chassis to chassis.