Happy holidays!
Guys, I need a little help.
I have a massive channel imbalance, with the right channel being down in output.
Thank you!
Michael
Guys, I need a little help.
I have a massive channel imbalance, with the right channel being down in output.
- I am testing using a 300 ohm Sennheiser HD 600
- I measured using a 440Hz test tone, in one example, 0.36 volts left, while right only has 0.06 volt at the headphone output. Input voltage measured the same.
- The imbalance is not following switching the source input left to right, so that takes the source out of the equation
- Output on the left is ok, goes fairly loud on full volume setting. However, feels also somewhat low-ish. I know the headphones do go louder on another amp (Bottlehead S.E.X.)
- I've built the LED reference power supply option
- I measured all resistors before and after being soldered into the circuit (unfortunately not paying attention to have their value shown on top....)
- The Alps pot has an imbalance in tracking of 500 to 1k ohms.However, the volume difference remains on any volume setting.
- I re-flowed already some of the solder joints and some also from the top to be sure; did not change anything
- I've re-seated the removable op-amp; did not change anything
Thank you!
Michael
There are some solder-pads which are not entirely covered by solder at the backside of the PCB. This could indicate a "cold" solder joint.
An idea could be to measure the bias current of the output stages. It can be done by measure the voltage over the source resistors. The heat sinks should be a bit hot.
An idea could be to measure the bias current of the output stages. It can be done by measure the voltage over the source resistors. The heat sinks should be a bit hot.
yeah, you need to re-solder some pads - The AC connection pads look bad. Be sure to heat the pad and wire
at the same time when you apply solder. You just need to give the pad and wire a bit of time to come up to
temperature. Put a dab on solder the tip of your iron and then touch to pad and wire - it will help with the flow
of heat. The pins of the Volume pot look thin too - redo those. Double check the values of your resistors too.
When placing Dale resistors - it's nice to bend the leads so the resistor value can be seen from the top - helps
with troubleshooting. --if one channel works and the other doesn't it's probably just something simple to fix,
something that's been overlooked or missed.
at the same time when you apply solder. You just need to give the pad and wire a bit of time to come up to
temperature. Put a dab on solder the tip of your iron and then touch to pad and wire - it will help with the flow
of heat. The pins of the Volume pot look thin too - redo those. Double check the values of your resistors too.
When placing Dale resistors - it's nice to bend the leads so the resistor value can be seen from the top - helps
with troubleshooting. --if one channel works and the other doesn't it's probably just something simple to fix,
something that's been overlooked or missed.
And clean the flux. Your board is dirty. As mentioned above...you have very poor solder joints.
What dc offset do you get?
What dc offset do you get?
Here are shown some common solder errors and also how a ok solder joint should look:
https://learn.adafruit.com/adafruit-guide-excellent-soldering/common-problems
And a small solder guide here:
And then best to use solder with low melting point which is the solder that contains lead. Melting point around 185 C or so.
Lower is also possible if it is "eutectic" solder.
https://learn.adafruit.com/adafruit-guide-excellent-soldering/common-problems
And a small solder guide here:
And then best to use solder with low melting point which is the solder that contains lead. Melting point around 185 C or so.
Lower is also possible if it is "eutectic" solder.
I have tried opa627 muses01 ad8610 ad823 ne5532 muses8920 and frankly speaking I did not notice any particular difference with thus amp. However, I do have other amp that clearly shows the difference between those opamps.
I think whammy as wonderful and solid as it is, is bottlenecked by the 10k//22uf signal component. I just got finished with my hv whammy build, +-25v, 4 stages of regulation filtering before the opamp
(Its a 24v ac trafo so 32v dc is knocked down to 15v via cascode regs) and the layout really the best i could hope to make it and... it sounds remarkably similar to my past builds that werent so carefully constructed. That isnt to say its not an excellent amp. The bass is now and always has been some of the best ive heard but the treble always has that bit of a coloration that ive heard absent in some higher performing headphone amps. That being said im still an amateur so any suggestions on how to upgrade the circuit is appreciated. Will post pics later so i can get a feedback on my layout too.
(Its a 24v ac trafo so 32v dc is knocked down to 15v via cascode regs) and the layout really the best i could hope to make it and... it sounds remarkably similar to my past builds that werent so carefully constructed. That isnt to say its not an excellent amp. The bass is now and always has been some of the best ive heard but the treble always has that bit of a coloration that ive heard absent in some higher performing headphone amps. That being said im still an amateur so any suggestions on how to upgrade the circuit is appreciated. Will post pics later so i can get a feedback on my layout too.
Do you run the high bias using the 10 ohm source resistors (60mA)?
From memory I went for 6.8 ohm. The heatsinks get a little hot......but not too hot. Maybe a change of bias can change the sound a bit.
Burson V6 opamp works well. I use the Classic version. I modified a resistor a bit so I don't exceed the max. voltage rating of the Burson.
For the regulator I use the red LED as voltage reference. Therefor I needed a bit less voltage for the op amp to be on the safe side for the Burson.
I also covered the transformer with mu-metal to reduce 50 Hz noise. It is very silent.
I like the short mains wires and also short wires to input/output.
The relative long wires to the ALPS seems not to pick up noise. I tried to put the wires as far away from mains wires as possible.
I the moment I use the Whammy as preamp for the VFET kit-amp. The sound is a bit more "monitor like" than using the Staving Student II pre-amp.
Both gives very nice sound. The SSII is easy to build if you want to have another amp to compare with.
From memory I went for 6.8 ohm. The heatsinks get a little hot......but not too hot. Maybe a change of bias can change the sound a bit.
Burson V6 opamp works well. I use the Classic version. I modified a resistor a bit so I don't exceed the max. voltage rating of the Burson.
For the regulator I use the red LED as voltage reference. Therefor I needed a bit less voltage for the op amp to be on the safe side for the Burson.
I also covered the transformer with mu-metal to reduce 50 Hz noise. It is very silent.
I like the short mains wires and also short wires to input/output.
The relative long wires to the ALPS seems not to pick up noise. I tried to put the wires as far away from mains wires as possible.
I the moment I use the Whammy as preamp for the VFET kit-amp. The sound is a bit more "monitor like" than using the Staving Student II pre-amp.
Both gives very nice sound. The SSII is easy to build if you want to have another amp to compare with.
very nice, MEPER. A solid build. youll want to twist all 3 pairs of wires belonging to the volume pot together to minimize the hum. better would be to wrap the bundle in an alum foil tape and ground one end of it
somewhere.
here's my build. its a very ambitious project actually. started as a plaything during pandemic and been polishing it for 2 years until now its probably better than a lot of commercial products out there. i look at their layouts sometimes and scoff. bryston? please.
30va 24v trafos with enough juice to probably turn the whole thing into a mini speaker amp. 1st filter is capmx then pre-regged lm317/337, then RC passive shunt to the opamp. lm317 is outputting 25v directly to the mosfet buffer. i haven't measured it but the psrr must be insanely high by the time opamp gets the psu juice and you can hear it. the sound is verrrrry detailed and calm.
as you can see the module has key components on the bottom side of the board for optimal layout. placing them that way was actually an afterthought cuz i didnt build the psu around whammy but rather the other way around.
ive tried tl071 and 5534 so far. its 0v dc offset with the former and 3mv with the latter.
id like to know how much degradation im introducing with the passive shunt reg. 500ohm>15v zener//330uf. i figured 500ohm was a pretty good filtering to have but i hear the zener itself is a lot of noise. ive been recommended ic regs instead.
somewhere.
here's my build. its a very ambitious project actually. started as a plaything during pandemic and been polishing it for 2 years until now its probably better than a lot of commercial products out there. i look at their layouts sometimes and scoff. bryston? please.
30va 24v trafos with enough juice to probably turn the whole thing into a mini speaker amp. 1st filter is capmx then pre-regged lm317/337, then RC passive shunt to the opamp. lm317 is outputting 25v directly to the mosfet buffer. i haven't measured it but the psrr must be insanely high by the time opamp gets the psu juice and you can hear it. the sound is verrrrry detailed and calm.
as you can see the module has key components on the bottom side of the board for optimal layout. placing them that way was actually an afterthought cuz i didnt build the psu around whammy but rather the other way around.
ive tried tl071 and 5534 so far. its 0v dc offset with the former and 3mv with the latter.
id like to know how much degradation im introducing with the passive shunt reg. 500ohm>15v zener//330uf. i figured 500ohm was a pretty good filtering to have but i hear the zener itself is a lot of noise. ive been recommended ic regs instead.
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I see........that is a new amp built around the "Whammy schematic"?
The split from dual to single opamp is quite nice. Then it is more like a dual-mono construction.
Regarding the twisting of wires I like to keep L and R separate to keep the channel separation as good as possible.
The Burson V6 also comes as 2 x single opamp so you can try it out.
I think the dual V6 is built like 2 x single in one case. In original whammy they just share the same power supply.
The split from dual to single opamp is quite nice. Then it is more like a dual-mono construction.
Regarding the twisting of wires I like to keep L and R separate to keep the channel separation as good as possible.
The Burson V6 also comes as 2 x single opamp so you can try it out.
I think the dual V6 is built like 2 x single in one case. In original whammy they just share the same power supply.
Yup its dual mono. The only non compromising solution there is.
Ive tried burson before and liked it. I didnt think it was higher perfoming than a 5534 tho. But it had that certain magic that i liked
Ive tried burson before and liked it. I didnt think it was higher perfoming than a 5534 tho. But it had that certain magic that i liked
Dual mono is nice. Once I had an idea of making a preamp as two mono blocks which requires 2 x mono pots (click type would be most practical for equal settings).
It should be possible also as a headphone amp. It would require 2 x mono jack. I have a headphone where each earcup has one small jack connector. So with this it would be possible. Another headphone I have has integrated wires which ends op in one. For this the headphone would need a modification. Two separate wire for L and R earcup will give best possible separation.
Did you do any objective noise measurements on original Whammy and the modified version to check if the dual mono with enhanced PSUs gives you lower measured noise/distortion?
It should be possible also as a headphone amp. It would require 2 x mono jack. I have a headphone where each earcup has one small jack connector. So with this it would be possible. Another headphone I have has integrated wires which ends op in one. For this the headphone would need a modification. Two separate wire for L and R earcup will give best possible separation.
Did you do any objective noise measurements on original Whammy and the modified version to check if the dual mono with enhanced PSUs gives you lower measured noise/distortion?
Thanks again. I re-flowed all joints and cleaned the board. All sorted now and playing sweet music. This is a nice HP amp!
So I built this amp kit for someone yesterday, works and sounds great but just find something a little strange: with my HD800 plugged in it produces a loud short burst of noise on both channels thru the headphones a couple seconds or so after turning off the power switch.
While I do understand some amps without output relay and such they will do this probably due to capacitor discharging at turnoff, the strangest thing is it only happens with my HD800, I also tried HD600 and SRH1440 (lowest nominal impedance and highest sensitivity among the 3) and it doesn't happen with these two.
My build is with LED reference in PSU regulators and only changes made were jumping input caps C1 and C5 and replacing the opamps with OPA627 and I can confirm it has nothing to do with the source and the position of the pot.
I'm not too concerned about this (or should I?) but would really appreciate if someone can shine a light, thanks!
While I do understand some amps without output relay and such they will do this probably due to capacitor discharging at turnoff, the strangest thing is it only happens with my HD800, I also tried HD600 and SRH1440 (lowest nominal impedance and highest sensitivity among the 3) and it doesn't happen with these two.
My build is with LED reference in PSU regulators and only changes made were jumping input caps C1 and C5 and replacing the opamps with OPA627 and I can confirm it has nothing to do with the source and the position of the pot.
I'm not too concerned about this (or should I?) but would really appreciate if someone can shine a light, thanks!
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I had a pretty similar issue with my R70X (470 ohms) when using a LME49720NA op amp. I switched to a OPA2134PA and the problem went away. Not a peep now. TBH the stock op amp was quiet too (from memory), so maybe try that popping that back in and compare. Couldn't tell you the technical reason for any of this, but I'm sure someone here could
Thanks for the advice! I will check with the stock op amp. Curious if you also found it to be headphone dependent as in my case? Based on you observation with different op amps I suspect if it's the particular complex impedance of the headphones interact with it at turnoff, tho I know nothing about what exactly can be happening neither...
I honestly can't be 100% that it didn't happen with other headphones, just that it definitely happened with the R70X and hasn't happened with other op amps I tried. Basically I stopped playing with it when I got to the OPA2134 because it did everything perfectly. I have 6 other op amps I haven't even taken out of the packaging. 😂
The only other thing that might be worth looking at is, does your Whammy have any resistors on the output RCAs? As per a recommendation on this thread I put some 20 something ohm resistors in line with the signal on the outputs. Not sure if not having them could exacerbate the issue or not, just can't see any on your build from that photo. Apologies if I'm just not seeing them.