Pearl Two

So today I decided to play around with cartridge loading and gain. I am running a Denon DL-103R. I do have enough gain stock, but the inputs are mismatched when switching between CD and vinyl, so I thought I'd try the 65dB setting. I soldered a 470 ohm in parallel to the 1K R14 and I get a terrible distortion. I remove it and it sounds great again. I doubt I'd be overloading it with a 0.25mV cartridge???

Any ideas?
 
So today I decided to play around with cartridge loading and gain. I am running a Denon DL-103R. I do have enough gain stock, but the inputs are mismatched when switching between CD and vinyl, so I thought I'd try the 65dB setting. I soldered a 470 ohm in parallel to the 1K R14 and I get a terrible distortion. I remove it and it sounds great again. I doubt I'd be overloading it with a 0.25mV cartridge???

Any ideas?

I installed sockets in mine and routinely change out R14 depending on the cartridge. No issues, although if the gain is too much it overloads my headphone amp.
 
I agree do not mess with the phono stage gain,
make it up else where,
you are trying to level match a signal source that for one is in the uV to low mV range with something that puts out 2V full scale(CD).
If anything, attenuate the CD input to better match the phono stage. It is called a resistive pad or attenuation, look it up easy to put together or buy one.
 
FWIW, I had some reservations about this preamp being enough gain for my DL-103R. I am running it in stock configuration (50dB) and I have PLENTY of gain with no need for a SUT!

Just thought I'd share for those concerned running low output MC's.

You must have a LOT of gain in your pre-amp. I've never been able to run any of my LOMC's into my Pearl Mk1 without a step-up of some kind. I can run a 1:20 SUT with my DL-103R, and not overload anything.

jeff
 
what is the source of distortion when upping PEARL II gain to the max?
The non-linearity of the devices.
The design has a fixed amount of open loop gain, it is not run open open, nor do you want to, so it uses feedback to reduce distortion, stabilize, increase BW etc. The distortion is a factor of the feedback ratio.
A rule of them, it is better to have more gain stages than less, as it easier to control the non-linearities.
In an old japanese stereo, they basically had 4 gain stages
MC head amp(40-60dB), feed to MM phono stage(35-40dB),pre-amp(10dB), power amp (25-35dB). Add it up, there is lots of gain to distribute around.
Problem here is a CD will overload a power amp with 25-35dB gain, it is the odd ball in the equation.
 
I have plenty of gain for my DL-103R in the stock configuration (55dB). I run the Pearl 2 into a DCB1 into Aleph J and then some 102dB Cornwalls.

I was just looking to do some volume balancing and saw many others on here use a 300 ohm R14 (also in the PDF per Wayne) to up the gain to 65dB. For some reason I get a lot of distortion. I understand what causes distortion, but why would my Pearl 2 be distorted when others can run at 65dB just fine?
 
I have plenty of gain for my DL-103R in the stock configuration (55dB). I run the Pearl 2 into a DCB1 into Aleph J and then some 102dB Cornwalls.

I was just looking to do some volume balancing and saw many others on here use a 300 ohm R14 (also in the PDF per Wayne) to up the gain to 65dB. For some reason I get a lot of distortion. I understand what causes distortion, but why would my Pearl 2 be distorted when others can run at 65dB just fine?

Did you re-adjust P1 after changing R14?
 
I decided to live with it the way it is. With my Cornwalls, the Aleph J provides enough volume. It is only a handful of vinyl that gives me this issue anyway.

I got the Pearl 2 wired into it's permanent home last night and it looks great and sounds even better! What an incredible phono stage!

Now just waiting on the faceplate back from the machine shop for the Mezmerize (getting an LCD window opening).
 

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Question for the gurus ... I added a mono switch to my build. You can see it to the left of the input jacks in the pic above. When I switch it to mono, I get an out-of-phase hum. Since these boards are mono, should I also be switching the signal negative leads and shorting them as well?

Mine hums as well in mono mode, I hope you find a solution to this.