Did you try the R12 modification Jack suggested earlier?:
https://www.diyaudio.com/forums/pass-labs/204336-building-pearl-2-a-204.html#post6193843
https://www.diyaudio.com/forums/pass-labs/204336-building-pearl-2-a-204.html#post6193843
Got mine together last night, but it doesn't sound right. The symptoms sound similar to what others have diagnosed as a bad Q2--distortion and clipping. How can I test to confirm that this is the problem before I break out the solder sucker and replace those MOSFETs?
What's the stated output of your cartridge?
Listening again, I'm not sure if there's really a lot of clipping. It just sounds very tinny.
If you short the inputs, is there much noise when you turn up the volume?
Yeah, it makes about the most terrifying noise in the world.
Listening again, I'm not sure if there's really a lot of clipping. It just sounds very tinny.
check that you didn't put the caps in the wrong positions.
check that you didn't put the caps in the wrong positions.
Anything look out of place? First pic shows both boards before I got them in. Both boards seem to have the same issue. Second pic is one board in its current state. I'm only messing with one until I get it right. Sorry about the lighting, it's the best I can do at this time of day.
Attachments
Yeah, it makes about the most terrifying noise in the world.
Ok, something is very wrong.
It should be quiet with inputs shorted. Can we see photos of the back panel (inside) as well as a couple of the PSU.
Can you post a recording of that noise? I can imagine some white noise if your
preamp is cranked all the way up, but your description seems to be something else.
preamp is cranked all the way up, but your description seems to be something else.
There are a few variables here, I can't say for sure why yours would be noisier.
To start, we both may have different "normal listening levels", so our baseline to inspect the level of hiss could be different.
Mine is built with 55dB, so the extra gain could contribute as well. If you have sufficient range in your volume put with 65dB (say, if you are at mid-level with your preamp at normal listening levels), then it would be worth a shot bringing the Pearl down to 55dB.
Lastly, the RN55D resistors mentioned in the PDF and in the sample BOM are 100ppm.
Wanye wrote in the Pearl documentation:
Trying to address this, I went with RN55E (25ppm) resistors, and RN55C (50ppm) where "E" was not available.
Now, I wouldn't recommend replacing your resistors and I have no idea if this actually makes a difference, but I thought it would be worth pointing out for future builders when starting from scratch.
Thanks for replying back to me. I looked again at my Mouser order and the build guide, and I ordered mostly 100ppm. I was also reading in Audio Karma about people on that forum's Pearl 2 builds and one mentioned to be aware that it inverts phase, and the light bulb went off! I totally forgot about that and Wayne even wrote about it in the manual and Jim mentioned in the guide. I switched the leads at the cartridge, played a record and the difference was substantial; imaging got focused, bass got tighter, the noise floor dropped and I am not getting the loud screech any longer when I switch inputs. I am not sure if this is because of inverting phase or if it's just coincidence. All around, the Pearl sounds like what people have been talking about. I think now instead of loading at 150ohms, I might drop it to 100ohm because now it's a bit brighter once the phase was inverted. Am I imaging things?!
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Thanks for replying back to me. I looked again at my Mouser order and the build guide, and I ordered mostly 100ppm. I was also reading in Audio Karma about people on that forum's Pearl 2 builds and one mentioned to be aware that it inverts phase, and the light bulb went off! I totally forgot about that and Wayne even wrote about it in the manual and Jim mentioned in the guide. I switched the leads at the cartridge, played a record and the difference was substantial; imaging got focused, bass got tighter, the noise floor dropped and I am not getting the loud screech any longer when I switch inputs. I am not sure if this is because of inverting phase or if it's just coincidence. All around the Pearl sounds like what people have been talking about. I think now instead of loading at 150ohms, I might drop it to 100ohm because now it's a bit brighter once the phase was inverted. Am I imaging things?!
Most people can't tell the difference when phase is inverted or not.
Is the chassis actually attached to ground? (At ground post is the best place)
Does the metal outside of the umbilical jack connect to ground?
Does the metal outside of the umbilical jack connect to ground?
Most people can't tell the difference when phase is inverted or not.
When something is out of phase, you lose center image focus. I can hear it after a lot of years of using the sure phono test record and the jbl speakers test record. Also, familiar records from the 60's and 70's will have the tracks bussed to one channel now reversed and that will be unacceptable if you like the song.
Is the chassis actually attached to ground? (At ground post is the best place)
Does the metal outside of the umbilical jack connect to ground?
The chassis is not attached to ground. The frame of the umbilical plug does not connect to ground.
Attach the ground lug to chassis.
Make sure all the panels on the chassis have the anodizing scraped away in spots so all the panels are electrically connected.
This is most likely not the source of your issue, but it’s going to need to be addressed at some time so you might as well do it now.
🙂
Make sure all the panels on the chassis have the anodizing scraped away in spots so all the panels are electrically connected.
This is most likely not the source of your issue, but it’s going to need to be addressed at some time so you might as well do it now.

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