I am going to assume the negative feedback isn't making it back to the op amp or pin 7 is open circuit. Pin 7 is the output of the second op amp, with pin 6 being the negative feedback. If both channels aren't working... I don't really know what the issue would be. Could be a lot of things.
Wow...
So.. uh... turns out I mixed the GND with one of the other channels (TIP/RING) on the jack.
So it would appear that I was actually picking up signal in that channel from the ground - along with the capacitor in line with the GND IEC and maybe that was acting as a filter essentially? I don't have a chassis yet as I'm awaiting the diyAudio chassis.
Not sure exactly why I was hearing a filtered output in that channel when it was wired to GND tho...?
Either way, I feel pretty dumb right now... that's what I get for working on it late one night after some drinks.
I will say, though, that this amp seriously kicks *** (especially for the money)! It's not even broken in yet, and I could still improve things with a chassis and going back over some solder joints, but it's powering my HD650s and Argon Mk3s (known to require some hefty amps for drive to their full potential) with ease.
I'm excited to get the chassis (how's that coming, btw?) and build the remaining two kits for my brothers. They're quite excited now too
Appreciate all of the tips!
So.. uh... turns out I mixed the GND with one of the other channels (TIP/RING) on the jack.
So it would appear that I was actually picking up signal in that channel from the ground - along with the capacitor in line with the GND IEC and maybe that was acting as a filter essentially? I don't have a chassis yet as I'm awaiting the diyAudio chassis.
Not sure exactly why I was hearing a filtered output in that channel when it was wired to GND tho...?
Either way, I feel pretty dumb right now... that's what I get for working on it late one night after some drinks.
I will say, though, that this amp seriously kicks *** (especially for the money)! It's not even broken in yet, and I could still improve things with a chassis and going back over some solder joints, but it's powering my HD650s and Argon Mk3s (known to require some hefty amps for drive to their full potential) with ease.
I'm excited to get the chassis (how's that coming, btw?) and build the remaining two kits for my brothers. They're quite excited now too
Appreciate all of the tips!
Finally replaced my OPA2134PA with an OPA1612AID on an adapter PCB. Needed a bit of grinder work on the sides of that tiny PCB to clear the electrolytic caps. The adapter PCBs came with header pins but I did not look carefully enough at them before I soldered them in place and they were square pins, too large to plug into the main board socket. Ended up soldering the tips of the square pins to the top of a spare 8-pin DIP socket, making a sort of "tower" adapter. Actually, it was easier to plug in when it was built that way.
Soldering the chip to the SMD adapter was a bit easier than I had feared. Tape the chip in place, turn down the iron to a lower temp, and use a small amount of solder with a brief wipe of the tip. And done with a 1/16 tip, as it was all I had. An extra fine tip would have been easier.
The sound is a subtle improvement over the OPA2134PA, but it was well worth the effort. I hear a more extended bottom end and a better overall clarity, without any harshness. Double checked with the scope for oscillation and found none. Nice opamp!
BTW, for preamp use, each channel of the switching headphone jack is fed to a 150 ohm resistor in series with the center pin of the RCA out, along with a 200K resistor connected to the RCA shell ground from the center pin. Can't really see it but a small Keystone terminal lug strip secured to the IEC inlet mounting screw on the RCA output jack side keeps the series resistors from floating around and provides a solid connection for the 22/2 shielded feed from the TRS jack on the front panel.
Attachments
Another Whammy lives... again. I found some spare boards and had half the BOM in my stash so threw one together. Such an easy project.
Works perfectly first time with a pair OPA1641's. Bias is around 88mA with 0.02mV and 0.04mV offset.
I am using EUVL's Danyuk Xfeed module on the 10K pot, the pins of the pot stick out from under the Xfeed PCB to locate in the Whammy pin holes. So no fancy wiring, the signal goes into the Xfeed and out through the existing tracks to the circuit.
The Xfeed steals around 3db of attenuation so I will need to raise the gain substantially, I am at full whack on the pot.
Has anyone raised the gain on the Whammy? should I increase values of R1/R12 or R4/R8?
Works perfectly first time with a pair OPA1641's. Bias is around 88mA with 0.02mV and 0.04mV offset.
I am using EUVL's Danyuk Xfeed module on the 10K pot, the pins of the pot stick out from under the Xfeed PCB to locate in the Whammy pin holes. So no fancy wiring, the signal goes into the Xfeed and out through the existing tracks to the circuit.
The Xfeed steals around 3db of attenuation so I will need to raise the gain substantially, I am at full whack on the pot.
Has anyone raised the gain on the Whammy? should I increase values of R1/R12 or R4/R8?
Attachments
OPA1612AID
The more I listen to the OPA1612AID the more I'm impressed. Larger sound stage, greater immersion in the music, a more overall exciting experience. There are details in the background I've never heard before. All this with no fatigue, no stress, very smooth.
The proof for me is, do I break out in a surprised grin when I listen to the music? The answer with this opamp is a big yes!
Congrats to Wayne for an output circuit and power supply that totally and accurately reproduces everything that the front end opamp provides, regardless of the headphone load. And congrats to TI for proving how good a bipolar front end can sound.
The more I listen to the OPA1612AID the more I'm impressed. Larger sound stage, greater immersion in the music, a more overall exciting experience. There are details in the background I've never heard before. All this with no fatigue, no stress, very smooth.
The proof for me is, do I break out in a surprised grin when I listen to the music? The answer with this opamp is a big yes!
Congrats to Wayne for an output circuit and power supply that totally and accurately reproduces everything that the front end opamp provides, regardless of the headphone load. And congrats to TI for proving how good a bipolar front end can sound.
Hi. Burson Audio sent me a couple of their opamps to test (unsolicited) in exchange for posting a picture. They sent me a classic V6 and a vivid. Here's the picture. I had to use a couple of extra sockets to extend the pins and allow a fit.
How do they sound? Honestly, I really can't hear a difference between them, or other opamps. I even have two WHAMMYs and did a/b testing. Maybe, possibly, there is a subtle difference, but I could not really identify it, and my ears would adjust so fast, it wouldn't make a difference to me.
Thanks to Burson for the opamps.
How do they sound? Honestly, I really can't hear a difference between them, or other opamps. I even have two WHAMMYs and did a/b testing. Maybe, possibly, there is a subtle difference, but I could not really identify it, and my ears would adjust so fast, it wouldn't make a difference to me.
Thanks to Burson for the opamps.
I also got Burson Audio V6 Classics from Charles at Burson Audio.
Burson Audio has spotted my thread about ESS9018 DAC at theartofsound forum and offered their opamps free of charge provided I post pictures and write my impressions (good or bad) about the sound. Due to some misunderstanding I have got Dual V6 which I cannot use in the DAC. I proposed I would use them in the Whammy and write about it. So here it is.
I started with opa2134. I was using it in my C'Moy and expected somewhat bright sound. Indeed it turned out quite bright. Then there was LM4562 which I kind of liked but I missed some body. I tried also NE5532 but was not impressed. Then somebody in this forum suggested LM833. I was told that I would be positively surprised. And indeed I was. Not great but it kind of had nice tonal balance. Maybe not too much detail. I did not like the offset though: almost 20mV. Finally, I settled with AD823 which ticked all my boxes: nice tonal balance, fantastically low offset (sub 1mV) and pretty musical. Later I got so called "reclaimed" opa627 from *bay (I can't say whether they were fake or not, but I haven't paid much, but I figured it would be fair for a reclaimed part). The signature was close to AD823 which I preferred after all.
Still, Whammy was my second choice after Pellerano's ZEN, which gave me more musicality and more organic sound. However I have some hum with Zen using sensitive cans (HD595). My main cans HD600 are less sensitive, the hum is not there anymore and the sound can be pretty seductive.
Then there came Burson. I find Whammy much more musical with Burson. I really enjoy it now. It makes me listen more to music than the sound quality.
I started tapping with my feet which is always a good sign.
I can't say there is more bass or treble or whatever compared to AD823. There is certainly more music. The quality of treble is very, very good. The soprano's are very good, the tenors are good as well. The offset is sub 10mV.
I think I still prefer Zen, but now just by a small margin. Having said that it is like comparing oranges and pears as Zen is biased so much higher than Whammy. I might change my mind if the output transistors in Whammy were running as hot as Zen's. Unfortunately my heatsinks would not take that.
As mentioned above I did most of my listening with Senn HD600, some with HD595. The source was my ES9018 DAC fed from foobar2000 and CD played with Musical Fidelity E601 and and old Philips player with TDA1541 (no A, no crown just plain) with separate PS for the digital filter and kind of Pass D1 IV converter - very non fatiguing, liquid sound.
Anyway happy camper here. I will be even more happy when I get V6's for the DAC!
And to make me more happy I just ordered PCB set for SL HPA from EUVL!
Burson Audio has spotted my thread about ESS9018 DAC at theartofsound forum and offered their opamps free of charge provided I post pictures and write my impressions (good or bad) about the sound. Due to some misunderstanding I have got Dual V6 which I cannot use in the DAC. I proposed I would use them in the Whammy and write about it. So here it is.
I started with opa2134. I was using it in my C'Moy and expected somewhat bright sound. Indeed it turned out quite bright. Then there was LM4562 which I kind of liked but I missed some body. I tried also NE5532 but was not impressed. Then somebody in this forum suggested LM833. I was told that I would be positively surprised. And indeed I was. Not great but it kind of had nice tonal balance. Maybe not too much detail. I did not like the offset though: almost 20mV. Finally, I settled with AD823 which ticked all my boxes: nice tonal balance, fantastically low offset (sub 1mV) and pretty musical. Later I got so called "reclaimed" opa627 from *bay (I can't say whether they were fake or not, but I haven't paid much, but I figured it would be fair for a reclaimed part). The signature was close to AD823 which I preferred after all.
Still, Whammy was my second choice after Pellerano's ZEN, which gave me more musicality and more organic sound. However I have some hum with Zen using sensitive cans (HD595). My main cans HD600 are less sensitive, the hum is not there anymore and the sound can be pretty seductive.
Then there came Burson. I find Whammy much more musical with Burson. I really enjoy it now. It makes me listen more to music than the sound quality.
I started tapping with my feet which is always a good sign.
I can't say there is more bass or treble or whatever compared to AD823. There is certainly more music. The quality of treble is very, very good. The soprano's are very good, the tenors are good as well. The offset is sub 10mV.
I think I still prefer Zen, but now just by a small margin. Having said that it is like comparing oranges and pears as Zen is biased so much higher than Whammy. I might change my mind if the output transistors in Whammy were running as hot as Zen's. Unfortunately my heatsinks would not take that.
As mentioned above I did most of my listening with Senn HD600, some with HD595. The source was my ES9018 DAC fed from foobar2000 and CD played with Musical Fidelity E601 and and old Philips player with TDA1541 (no A, no crown just plain) with separate PS for the digital filter and kind of Pass D1 IV converter - very non fatiguing, liquid sound.
Anyway happy camper here. I will be even more happy when I get V6's for the DAC!
And to make me more happy I just ordered PCB set for SL HPA from EUVL!
Attachments
Hi. Burson Audio sent me a couple of their opamps to test (unsolicited) in exchange for posting a picture. They sent me a classic V6 and a vivid. Here's the picture. I had to use a couple of extra sockets to extend the pins and allow a fit.
How do they sound? Honestly, I really can't hear a difference between them, or other opamps. I even have two WHAMMYs and did a/b testing. Maybe, possibly, there is a subtle difference, but I could not really identify it, and my ears would adjust so fast, it wouldn't make a difference to me.
Thanks to Burson for the opamps.
Theoretically, this would increase the capacitance from all that extra socketing wouldn't it?
I doubt it is audible, but I would feel compelled to have a properly soldered riser if I did something like that.
Also, distance is a very important thing regarding the bypass capacitor for the op amp power rail, so the distance as well may effect things.
Like I said, I doubt it would be audible, but both things are things you typically try to avoid with op amps.
Can someone advise how to double the gain? Tried 10K in R4/R8 and it it introduced a lot of squelch and noise when using the pot.
I read that gain factor is R4/R1 + 1 so assumed 10K would give a gain of around 10.
Need to order some more resistor values to play with and wanted an idea of what to use.
I read that gain factor is R4/R1 + 1 so assumed 10K would give a gain of around 10.
Need to order some more resistor values to play with and wanted an idea of what to use.
Thanks ZM, the pot is good I think, 10K alps RK27 with Danyuk passive Xfeed. Until I changed R4/R8 to 10K it was working just fine.
The 100pF C2/C7 in parallel have been omitted, should these be in place do you think at 50pF?
Since yesterday, I have an issue on my Whammy that was otherwise sounding great and rock solid:
After testing different Op Amps, left channel seems to be about 12dB lower than right channel. Only connecting the left RCA and increasing the volume seems to give proper performance.
This happens with different Op Amps, and I see the corresponding DC of each Op Amps on the output.
I tried on a different headphone amp, and got proper channel balance.
I noticed that some 0.7v remains for a very long time (2mins+) across the Vcc+/Vcc- of the Op Amp after shutting it down. I only noticed this now, meaning that I swapped Op Amps with this voltage. Maybe some surrounding components got damaged in the process?
Any idea on where to start troubleshooting?
After testing different Op Amps, left channel seems to be about 12dB lower than right channel. Only connecting the left RCA and increasing the volume seems to give proper performance.
This happens with different Op Amps, and I see the corresponding DC of each Op Amps on the output.
I tried on a different headphone amp, and got proper channel balance.
I noticed that some 0.7v remains for a very long time (2mins+) across the Vcc+/Vcc- of the Op Amp after shutting it down. I only noticed this now, meaning that I swapped Op Amps with this voltage. Maybe some surrounding components got damaged in the process?
Any idea on where to start troubleshooting?
considering quantity of pins soldered on daily basis of regular Greedy Boy , no harm and no time wasted, if - whenever you see dull looking pins of part , use exacto knife and scrape them in soldering area
being new or NOS or whatever
and , Zen is greater ..... greater chance of actually thinking how circuit actually works
being new or NOS or whatever
and , Zen is greater ..... greater chance of actually thinking how circuit actually works