it is a bummer, Dodo Jfet ...... most likely even 2 and most likely in top section
proceed with amp, you can use it that way and observe is there sonic difference between proper channel and that crippled one
then buzz me, so we'll see ... in case that you're in mood for some SMD re-work, I'll send you triplet of JFets
if not, I'll send you one pcb pre-assembled with JFets
proceed with amp, you can use it that way and observe is there sonic difference between proper channel and that crippled one
then buzz me, so we'll see ... in case that you're in mood for some SMD re-work, I'll send you triplet of JFets
if not, I'll send you one pcb pre-assembled with JFets
Definitely a bummer. Glad it wasn't more catastrophic though. I have another 80-ish JFets I can match a new set from, should the mood strike. My mistake is not on you. I appreciate the gesture ZM. For now I will try it as-is and see how the sound is compared to my fully functioning channel. Either way, looking forward to listening in stereo.
Stay tuned and thanks, as always, for your guidance.
Stay tuned and thanks, as always, for your guidance.
or - you can remove SMD completely and put 2SK170
matched pair up, matched pair down
considering that they're not having heavy load, hardly you'll hear difference between channel with smd and channel with TO92
pair with higher Idss down, pair with lower Idss up
Iq set to smidge bellow sum of Idss of upper pair
matched pair up, matched pair down
considering that they're not having heavy load, hardly you'll hear difference between channel with smd and channel with TO92
pair with higher Idss down, pair with lower Idss up
Iq set to smidge bellow sum of Idss of upper pair
Listening! Hooked up to Papa B1Korg and Schiit Bifrost 2, through Lii Audio Crystal 10’s over GRS PF8’s.
Even with the injured jfets in the left channel it’s sounding very good. I believe in the power of the SIT! 😁
I do have equal buzz in both channels. Wiring in right channel is much longer than left, so wire length does not seem to be the issue. I’ll take a look at my grounding scheme as well as shortening the input wires as much as possible when I get around to it. Chassis are not quite done yet either, so that may help as well.
Thank you Mighty ZM!
I see some twisted fat wires going close to twisted tiny ( signal) wires
first thing to re-dress
first thing to re-dress
Thanks ZM!
Wiring definitely needs some tweaking. Just fiddled with inputs and buzz is much better. Final button up should do the trick.
Wiring definitely needs some tweaking. Just fiddled with inputs and buzz is much better. Final button up should do the trick.
My replacement THF-51 just arrived.
This one is well traveled.
Somehow it was returned to pras and she sent it out again.
Ordered first week of December so others waiting - be patient - your devices will arrive eventually and the delay has nothing to do with pras.
Wish it was a Friday since I do not feel like doing this on a weekday evening.
Now to see if this is the cause of the buzz. I sure hope it is,
This one is well traveled.
Somehow it was returned to pras and she sent it out again.
Ordered first week of December so others waiting - be patient - your devices will arrive eventually and the delay has nothing to do with pras.
Wish it was a Friday since I do not feel like doing this on a weekday evening.
Now to see if this is the cause of the buzz. I sure hope it is,
jwjarch - I have always been told that the noise of a toroid power transformer is emitted from the center and flows from there.
It could be that this is a cause of your noise. I know plenty of time I have been tempted to try what you did for packaging reasons but have not for fear of noise problems.
It could be that this is a cause of your noise. I know plenty of time I have been tempted to try what you did for packaging reasons but have not for fear of noise problems.
Hi Rick. I seemed to have toroid noise issues in several of my amp builds but with more care of shortening transformer wires and signal input wires it usually takes care of things. My main issue on this amp was that my input connectors seem to have been creating a ground loop. I've since changed their position through trial and error and everything is completely silent now. I still have to fabricate the rear panel and give them a solid home in some aluminum. Hoping to get to that soon. Thanks for the tip on the transformer mounting. I've also heard from Ben Mah and others, that rotating/clocking these toroids can help in reducing noise. I might give that a try at some point to see what if any effect there is.
My toroid transformer experience has been with Anteks, and they definitely leak electromagnetic fields at the wire lead exit locations, so rotating them to find the orientation of least EMI is worthwhile.
The Singing Bush is single ended so it does not benefit from noise cancellation the way push-pull circuits do. That makes minimizing noise more important, especially if you have very sensitive speakers. Power supply ripple, proximity of power transformer and AC wires to signal wiring and circuitry, loop areas (routing and twisting of wires and their returns), all make a difference.
The Singing Bush is single ended so it does not benefit from noise cancellation the way push-pull circuits do. That makes minimizing noise more important, especially if you have very sensitive speakers. Power supply ripple, proximity of power transformer and AC wires to signal wiring and circuitry, loop areas (routing and twisting of wires and their returns), all make a difference.
jwjarch,
Glad you found the best place. I have one, of four, amplifier with a buzz. I have changed everything except the SIT and hope that is the case. All were made the same way yet one buzzes.
Anything is possible in DIY audio which is why it is good we know our amps intimately.
Every evening I continue to be amazed by what these amplifiers can do. If there is something significantly better it does not matter to me since I could not afford it. i would love to be proved wrong but I sincerely doubt there is anything significantly better. Even with one having a slight buzz
Gratification beyond words to Mr Pass and ZM.
Glad you found the best place. I have one, of four, amplifier with a buzz. I have changed everything except the SIT and hope that is the case. All were made the same way yet one buzzes.
Anything is possible in DIY audio which is why it is good we know our amps intimately.
Every evening I continue to be amazed by what these amplifiers can do. If there is something significantly better it does not matter to me since I could not afford it. i would love to be proved wrong but I sincerely doubt there is anything significantly better. Even with one having a slight buzz
Gratification beyond words to Mr Pass and ZM.
No doubt Rick. The utmost respect for Nelson and ZM. Without them, where would we be?
Another area to check for noise pickup are your interconnects. I literally just finished soldering together new interconnects for my system from Mogami 2524 cable with Neutrik Rean NYS373-2 RCA connectors. I heard an immediate difference and further reduction in noise coming through the speakers. Prior to that I had a really horrible mix of “free” interconnects. You know, the ones that came with your VCR back in the day. I also had a pair of Audioquest cables which ended up getting broken ground wires and seemed to amplify noise. So that’s another great improvement to the system. Listening to Jazz at the Pawnshop Vol. 1 right now. The marimba is crystal clear. Amazing. These amps are truly special.
Another area to check for noise pickup are your interconnects. I literally just finished soldering together new interconnects for my system from Mogami 2524 cable with Neutrik Rean NYS373-2 RCA connectors. I heard an immediate difference and further reduction in noise coming through the speakers. Prior to that I had a really horrible mix of “free” interconnects. You know, the ones that came with your VCR back in the day. I also had a pair of Audioquest cables which ended up getting broken ground wires and seemed to amplify noise. So that’s another great improvement to the system. Listening to Jazz at the Pawnshop Vol. 1 right now. The marimba is crystal clear. Amazing. These amps are truly special.
Attachments
I am an interconnect DIYer. I have the wires directly soldered into the input board. Bare XLR connector (only the core, none of that other stuff) at the output of the DSP processor.
The XLRs are silver plated tubular conductors that are almost free compared to silly audiophile RCAs and are as close to no connector as I have heard.
I continue to think Allen Wright's book on interconnects is all one needs to know. To the late great Allen the best approach is having the wires completely separate from each other dangling in the air. The same advice given by a fellow from Malaysia who used to contribute to AUDIO DIMENSIONS' (of San Diego) little update publication of the late seventies and early eighties. Where I first learned of the ROGERS LS3/5a- the first good loudspeaker I ever owned.
Having four amps allows you to know if something is wrong or right. Where I live shielding is not necessary so I use high purity copper magnet wire. If only one of the four makes a noise i feel certain it is not the interconnects.
I will know Saturday afternoon if it was the SIT or something I have done.
The XLRs are silver plated tubular conductors that are almost free compared to silly audiophile RCAs and are as close to no connector as I have heard.
I continue to think Allen Wright's book on interconnects is all one needs to know. To the late great Allen the best approach is having the wires completely separate from each other dangling in the air. The same advice given by a fellow from Malaysia who used to contribute to AUDIO DIMENSIONS' (of San Diego) little update publication of the late seventies and early eighties. Where I first learned of the ROGERS LS3/5a- the first good loudspeaker I ever owned.
Having four amps allows you to know if something is wrong or right. Where I live shielding is not necessary so I use high purity copper magnet wire. If only one of the four makes a noise i feel certain it is not the interconnects.
I will know Saturday afternoon if it was the SIT or something I have done.
Installed the new SIT and there is still the noise.
Ever heard of a noisy heat sink? That and the switches are the only things that have not been substituted.
I will try that just to eliminate the possibility.
Luckily the noise is easily lived with. Still a beautiful sounding amplifier.
Oh, well ... Three out of four is not bad.
Ever heard of a noisy heat sink? That and the switches are the only things that have not been substituted.
I will try that just to eliminate the possibility.
Luckily the noise is easily lived with. Still a beautiful sounding amplifier.
Oh, well ... Three out of four is not bad.
^ I cannot remember if you said you had an oscilloscope or not. Do you?
If not, and if you want to give something a try, you can consider building one of devices linked below (or similar). I haven't, but it looks pretty slick.
With either tool (or perhaps others) you can possibly better narrow down where the noise originates.
If not, and if you want to give something a try, you can consider building one of devices linked below (or similar). I haven't, but it looks pretty slick.
With either tool (or perhaps others) you can possibly better narrow down where the noise originates.
I do have an oscilloscope but next to no skills. Something like this should give me the inspiration to gain.
If the amp sounded bad, if it sounded less than glorious, it would be easier to get motivated but only rarely is the noise noticeable. I could live with it forever.
I had convinced myself the problem was the SIT since that is what I really wanted it to be. Now I have a spare.
No computer speakers at home so I will look at this tomorrow at work.
That guy has almost as much gear as Zen Mod.
If the amp sounded bad, if it sounded less than glorious, it would be easier to get motivated but only rarely is the noise noticeable. I could live with it forever.
I had convinced myself the problem was the SIT since that is what I really wanted it to be. Now I have a spare.
No computer speakers at home so I will look at this tomorrow at work.
That guy has almost as much gear as Zen Mod.
Well, there is silence.
I am sure ZM will get a well deserved chuckle at my problem - a bad cable.
I had measured the bad cable and it measured zero ohms in both legs so I dismissed the cable as the problem.
Yesterday, with very few possibilities remaining, I decided to make a new cable - nothing more than 24 gauge magnet wire of good quality - soldered to a new/old connector. And dangling - no twisting.
I wire directly to the PCB and the ground hole is such a pain to get to I tucked the wire under the 200K resistor's lead and there was absolute silence. (I used a larger than specified capacitor and it crowds the space near the hole)
I thought I had re-soldered the old connector - I must not have or the connector has problems - the bad solder joint that acts like a diode? The fact this is the woofer amplifier must have disguised the sonic effects. Of course, I think it sounds better now but cannot swear to it.
I do not ground my amplifiers since there is not a metal chassis. I did try grounding with the bad cable and the noise became worse.
What a convoluted way to have an excuse for a spare device.
Sorry to have made such a big deal out of what was a simple problem. Should have made another cable months ago. Nothing as dangerous as being overly sure of oneself.
Nothing more satisfying than The Singing Bush.
I am sure ZM will get a well deserved chuckle at my problem - a bad cable.
I had measured the bad cable and it measured zero ohms in both legs so I dismissed the cable as the problem.
Yesterday, with very few possibilities remaining, I decided to make a new cable - nothing more than 24 gauge magnet wire of good quality - soldered to a new/old connector. And dangling - no twisting.
I wire directly to the PCB and the ground hole is such a pain to get to I tucked the wire under the 200K resistor's lead and there was absolute silence. (I used a larger than specified capacitor and it crowds the space near the hole)
I thought I had re-soldered the old connector - I must not have or the connector has problems - the bad solder joint that acts like a diode? The fact this is the woofer amplifier must have disguised the sonic effects. Of course, I think it sounds better now but cannot swear to it.
I do not ground my amplifiers since there is not a metal chassis. I did try grounding with the bad cable and the noise became worse.
What a convoluted way to have an excuse for a spare device.
Sorry to have made such a big deal out of what was a simple problem. Should have made another cable months ago. Nothing as dangerous as being overly sure of oneself.
Nothing more satisfying than The Singing Bush.
Awesome news!!! Heck, I think we've all had some 'very simple' things that drove us nuts.
😀 😀 😀 😀 😀
😀 😀 😀 😀 😀