Talked too fast... High pitch hum... Grrrrr!
Hi ticknpop,
I'm using 25K R2R ladder but Zload is set to 1M to match JC-80 input impedance.
I think I talked to fast yesterday and I realized I am getting a high pitch hum. Cannot be heard from woofer, just tweeters... It is not loud but there nonetheless...
I also have the Borbely Super Shunt but using the onboard rectifier for now. One super shunt per JC-80 and they both have their dedicated 28V 50VA transfos.
The JC-80 has 0V, +30V and -30V. I'm wondering what is the possible cause of the hum... On the JC-80, there's a ground solder point just on top of the 0V and below the signal out. Did you connect this or you're just using the signal out ground?
Do you have a connection diagram of your PSU (From AC power line to DC on JC-80)?
I've already tried using a single AMB o22 to power both JC-80 but the same high pitch hum can be heard.
Thanks
Do
Hi ticknpop,
I'm using 25K R2R ladder but Zload is set to 1M to match JC-80 input impedance.
I think I talked to fast yesterday and I realized I am getting a high pitch hum. Cannot be heard from woofer, just tweeters... It is not loud but there nonetheless...
I also have the Borbely Super Shunt but using the onboard rectifier for now. One super shunt per JC-80 and they both have their dedicated 28V 50VA transfos.
The JC-80 has 0V, +30V and -30V. I'm wondering what is the possible cause of the hum... On the JC-80, there's a ground solder point just on top of the 0V and below the signal out. Did you connect this or you're just using the signal out ground?
Do you have a connection diagram of your PSU (From AC power line to DC on JC-80)?
I've already tried using a single AMB o22 to power both JC-80 but the same high pitch hum can be heard.
Thanks
Do
Hi Sean,
Are you planning a GB on your new PCB? If not, can you let us know where to buy once completed?
Ah, yes, as a suggestion and purely aesthetically, can you make the board black?
For best performance, what would be your recommended mA per rail. I believe I had adjusted the Bias on mine around 230mA - 270mA per rail.
Thanks
Do
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Pinnichio,
I don't understand hum from tweeters. Do you mean high frquency osscilation or buzz in the tweeter?
Hum is:.
A) poorly filtered DC - not likely in this case,
B) magnetic radiation - If your transformer is in seperate chassis located a distance away then not likely,
C) Grounding ? Is your AC transformer secondary center tap chassis ground referenced ( reason to use seperate full wave bridge for each power supply polarity is to avoid tying power supply grounds to AC line ground) The Borbely supper shunt board does create this seperate ground. Do not connect the Borbely shunt output ground to chassis ground. I found this to be very good at keeping my system dead silent.
D) Is your input and output balanced?
E) did you ever see Borbely preamp wiring drawing - i used same for jC 80 / Blowtorch and it worked well for me. I can email if you want it.
I don't understand hum from tweeters. Do you mean high frquency osscilation or buzz in the tweeter?
Hum is:.
A) poorly filtered DC - not likely in this case,
B) magnetic radiation - If your transformer is in seperate chassis located a distance away then not likely,
C) Grounding ? Is your AC transformer secondary center tap chassis ground referenced ( reason to use seperate full wave bridge for each power supply polarity is to avoid tying power supply grounds to AC line ground) The Borbely supper shunt board does create this seperate ground. Do not connect the Borbely shunt output ground to chassis ground. I found this to be very good at keeping my system dead silent.
D) Is your input and output balanced?
E) did you ever see Borbely preamp wiring drawing - i used same for jC 80 / Blowtorch and it worked well for me. I can email if you want it.
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Sorry for the lack of words... Must be my French...
It is a buzz sound.
I'm using two α10 boards from AMB with their δ1, δ2 and LCDuino-1 installed on the backplane. I have stacked them on top of each other
This is my build so far
The backplace was initially designed to receive the o22 PSU and o25 regulator. Since I have retrofitted the JC-80 where the 022 Reg is supposed to be, I'm using the AC traces (3 of them) to bring the necessary DC to the JC-80 board. I guess I should be connecting the ground from that trace to the backplace analog ground (where the o22 reg output was supposed to be)?
The backplane has two a20 line stage spots (where you see JISBOS buffer) on each side of the R2R ladder. This is where I'm picking up my signal source and destination for the JC-80.
Right now the only reference ground on the backplane is the one from the JC80 line out ground. Should I connect the Borbely 0V gnd to the analog gnd on the backplane first them connect it to the JC-80 0V?
When I was using a single JC-80 (when my second backplane was not yet completed) and using SE as input (- phase shorted to gnd) and SE output using the same source, PSU and amplifier, it was dead silent...
Thanks
Do
So I disconnected one of the JC-80 SE output going to my amp and shorted it to GND on the amp side.
The left channel was totally dead silent. I could not even tell the amp was on or off. Then played music and it was all good. Did the same thing with the right channel (second JC-80) and same results.
Wondering of the left and right signal GND going to the amp are somehow looping...
Any thoughts?
Do
The left channel was totally dead silent. I could not even tell the amp was on or off. Then played music and it was all good. Did the same thing with the right channel (second JC-80) and same results.
Wondering of the left and right signal GND going to the amp are somehow looping...
Any thoughts?
Do
Yeah, I had quite a shock when I went through the BOM for the Borbley shunt regulator. I mean, did I really have to buy NOS parts for this? and really good ones too? It's just a freaking regulator! Kind of a waste of an SK389... and the p channel compliment.
Fortunately, I don't need to build it any time soon.
Well, for those hearing buzzing sounds after reading my posts...
What I did is to try and isolate if it was one of the JC-80 causing the buzzing by connecting them one at a time to the amplifier and doing so, both of them were all good, no buzzing when ran separately (mono).
So I'm trying to figure out what to try next, aside trying an output transformer to terminate any possible GND loop.
Anyways, I only have input transfos so I wouldn't be able to test one...
Do
What I did is to try and isolate if it was one of the JC-80 causing the buzzing by connecting them one at a time to the amplifier and doing so, both of them were all good, no buzzing when ran separately (mono).
So I'm trying to figure out what to try next, aside trying an output transformer to terminate any possible GND loop.
Anyways, I only have input transfos so I wouldn't be able to test one...
Do
This is my build so far
Do
Are you going to make a really big box to put it all in, or what? That's a lot of stuff there!
After rereading your posts three times I hear a buzzing too. Try visiting an audiologist and letting Wolfsin know what he tells you to do so Wolfsin can clear it up as well
Heck, I've had buzzing for years....
Wolfsin had been warned by ticknpop re the Borbely BOM so he opted for the Kubota. Easy, cheap, but so little to complain about he felt deflated. Perhaps four years ago the Borbely made more sense.
It will be very interesting to note the changes Sean makes to the JC-80 pcb, other than painting it black with racing stripes for Do
It will be very interesting to note the changes Sean makes to the JC-80 pcb, other than painting it black with racing stripes for Do
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Wolfsin had been warned by ticknpop so he opted for the Kubota. Easy, cheap, but so little to complain about he felt deflated. Perhaps four years ago the Borbely made more sense.
It will be very interesting to note the changes Sean makes to the JC-80 pcb, other than painting it black with racing stripes for Do
I have two of the Kubota kits. I was impressed the they included current regulating diodes. They are much more expensive than ordinary parts. Mine also has the LM329 which is a precision part from what I have read. One improvement that I can see is to replace the resistors in the tails of the differential amplifiers with CRD's. The noise can be lowered by replacing the zener diode with a resistor. There's a CRD feeding the zener now, but it's not needed.
Inches! Unless I have this new zap gun that can get my stuff smaller!
Do
OK, that's a big box.
I decided to build my headphone amp in a 1U rack mount box. I put a photo up in the headphone amplifier forum. I spent most of my spare time today working on the box. It has two Kubota regulators in it. I had to replace the tall electrolytics with shorties and I have to bend over the TO-220 power transistors and mount them on aluminum bars for heat sinks. The supplied heatsinks were too tall.
There's a great thread about building a box, in this case for a computer:
Cygnus X1. - Overclockers Australia Forums
You have to go to page 36 to see the finished product.
Cygnus X1. - Overclockers Australia Forums
You have to go to page 36 to see the finished product.
You need 2U chassis for JC 80 and Borbely shunt because of heatsink height. Lots of bias needs lots of heatsink.
Pinnochio - Your build is more ambitious. I run stepped attenuator now and have some balanced Twisted Pear Joshua Trees , but not installed yet - waiting for thier remote control system controller. But i don't know if i like the number of relay contacts they use in series.
I have some 2SJ109's /2SK389 left, but not for regulators - there I use matched 2SJ 74 with Evul's special dual heatsink to improve their thermal tracking. I'll email the Borbely preamp wiring diagram tomorrow morning to those who asked.
Borbely shunts can still be built if you look around . I was lucky and bought extras of all the original devices before they started to disappear. The Chinese version doesn't use the E102/ E202 CRDs and 2Sj148 /2SK 982 and 2Sj313 / 2SK2013 that Erno's original design used.
Not sure what the benifit of a surface mount JC 80 would be. The resistors arent as good , the input devices are'nt available as surface mount. I didn't even like the servo being surface mount becasue i use MIT RTX polystryrene for servo caps and caddocks - Vishay bulk foil for signal path.
Seems you go to a lesser quality of active devices and passive components on better layout with a ground plane or better power supply distribution. The outputs and cap multipliers still need a decent heatsink (unless the layout uses the chassis as heatsink like the Blowtorch did - that would be a good step). But that seems to be where the electronics industry is going and why Constellation, Nelson, Charles, Parasound etc all stocked up on 2SJ109 and 2SJ74 for a decade or mores future production because nothing else currently available is quite as good.
Pinnochio - Your build is more ambitious. I run stepped attenuator now and have some balanced Twisted Pear Joshua Trees , but not installed yet - waiting for thier remote control system controller. But i don't know if i like the number of relay contacts they use in series.
I have some 2SJ109's /2SK389 left, but not for regulators - there I use matched 2SJ 74 with Evul's special dual heatsink to improve their thermal tracking. I'll email the Borbely preamp wiring diagram tomorrow morning to those who asked.
Borbely shunts can still be built if you look around . I was lucky and bought extras of all the original devices before they started to disappear. The Chinese version doesn't use the E102/ E202 CRDs and 2Sj148 /2SK 982 and 2Sj313 / 2SK2013 that Erno's original design used.
Not sure what the benifit of a surface mount JC 80 would be. The resistors arent as good , the input devices are'nt available as surface mount. I didn't even like the servo being surface mount becasue i use MIT RTX polystryrene for servo caps and caddocks - Vishay bulk foil for signal path.
Seems you go to a lesser quality of active devices and passive components on better layout with a ground plane or better power supply distribution. The outputs and cap multipliers still need a decent heatsink (unless the layout uses the chassis as heatsink like the Blowtorch did - that would be a good step). But that seems to be where the electronics industry is going and why Constellation, Nelson, Charles, Parasound etc all stocked up on 2SJ109 and 2SJ74 for a decade or mores future production because nothing else currently available is quite as good.
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Hi ticknpop,
On my Super Shunt I'm using 2SJ109 / 2SK389, 2SJ148 / 2SK982 and 2SJ313 / 2SK2013 instead of the IRF replacement for the last one.
What have the E102 / E202 CRDs been substituted by on the Chinese version or have they been omitted?
BTW, do you have Blowtorch schematics to share? How do you like the sound of it compared to JC-80?
Also, do you have the mods you did to the Kubota? I have two of them that I can use if needed.
Thanks
Do
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