Hi, I just bought a a Pass Labs Pearl 1 from a very nice guy on this forum. Im using a MM 5.0mv cartridge. With CD I can only turn volume up to 9 or 10 o'clock and it is very loud. With Pearl/turntable I can turn it to 5 o'clock/ full blast and you can barely hear it. Previous owner had this problem when he switched from 150 watt solid state amp to a class D amp and thought class D didn't have enough juice to run phono pre. We talked on phone this afternoon and he experienced what I am. I know it's not the power of my amp it is something in the Pearl and previous owner agrees now looking back on it. Has anyone experienced this before while owning the Pearl. Previous owner is very willing to refund money or I send it back to him and see if he can fix it and then ship it back to me. If it's possible to fix it without shipping it back I would prefer to do that. I'm not the best diy guy but I do have friends that may be able to help if I could point them in the right direction, thank you for any help or guidance, Paul
Sorry, Pearl phono stage, I talked to Kent at Pass Labs he said i might want to post on here due to so may people built these phono Preamp. When I play the Pearl both speakers are at matched volume you can hear the detail from cymbals so it's not a muted dead sound it is just very very low in volume or seriously lacking gain. The person I bought it from is original owner and built it many years ago. At one time played very loud I was told so something must have gone wrong lately.
Cartridge is Azden YM-P50-VL or also known as a Emire 875 XLT, Azden made it for Empire in its day it is a moving magnet 4.0mv so it is high out put. I do have a Soundsmith 2.5mv and tried that thinking maybe Azden went bad while sitting in a drawer but not the case no volume with Soundsmith either. I have flipped interconnects checked polarity all is well, it has to be something faulty in Pearl phono Preamp, any help would be appreciated, thanks
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Dirk, the parts you marked in red read the same on both boards. The 11.7 marked on board reads 8.8, 24.6 on board reads 21.5, 29.0 Volts reads 26.5. Please understand I am not a skilled diy guy I learned to solder a couple years ago so I can change out caps to better quality in preamps, speakers ,cd players, phono stages and to add resistors in a dual volume pot that had to much gain per step. I am willing to learn and reason I joined DIY forum was to maybe learn to build a Pass Preamp. I thought buying the Pearl would give me an idea what a DIY amp is capable of. That is why I don't want to have to return the Pearl and was hoping to get it up and running. Thanks everyone for your help
to creed2/Paul
Hello Paul,
I think your main problem are the pretty low voltages. A voltage sag of 2.5 - 3 volts can be a lot.
Wayne Colburn wrote in his documentation about the Pearl 1 that it has 29dB
gain in the first stage and 30dB of gain in the second stage.
You are using MM - cartridges with an output voltage of 2.5mV (Soundsmith)
and 4.5mV (Empire 875 XLT). With both cartridges the Pearl 1 should drive
your Pre-/Poweramp to pretty loud levels. My Pearl1 does!
It is pretty normal that a CD player (output voltage often between 1 - 2 Vrms) is louder than your signal from a phono pre.
As codyt wrote in his post #14 you should adjust your input resistors on the Pearl 1 - pcb to the requirements of your cartridge.
The Empire 875XLT has following requirements (datas from internet):
it puts out 4.5 mV at 47kOhm and recommended 150pF capacitance.
From the pics of your boards I can see that resistor R1 is in. Rx is in, but not jumpered / C14 and C16 stuffed, but also not jumpered.
If I realize the colourcode on the resistor R1 right:
1. ring: yellow = 4
2. ring: violet= 7
3. ring: black= 0
4. ring: red= 100 or brown= 10 Ohm
(5. ring: green is tolerance 0.5% / 6. ring: yellow is 25ppm/K)
If the 4. ring is red your input impedance would be 47kOhm.
On the pics it looks like brown - then it would be 4.7 kOhm (too low).
But I think the loading of your cartridge is not the main problem.
Could you measure the resistance of R1? Pearl 1 switched off!!!
DMM set at 200KOhm - One probe of DMM to the upper leg of R1 -
other probe of DMM to lower leg of R1.
Greets
Dirk
Hello Paul,
I think your main problem are the pretty low voltages. A voltage sag of 2.5 - 3 volts can be a lot.
Wayne Colburn wrote in his documentation about the Pearl 1 that it has 29dB
gain in the first stage and 30dB of gain in the second stage.
You are using MM - cartridges with an output voltage of 2.5mV (Soundsmith)
and 4.5mV (Empire 875 XLT). With both cartridges the Pearl 1 should drive
your Pre-/Poweramp to pretty loud levels. My Pearl1 does!
It is pretty normal that a CD player (output voltage often between 1 - 2 Vrms) is louder than your signal from a phono pre.
As codyt wrote in his post #14 you should adjust your input resistors on the Pearl 1 - pcb to the requirements of your cartridge.
The Empire 875XLT has following requirements (datas from internet):
it puts out 4.5 mV at 47kOhm and recommended 150pF capacitance.
From the pics of your boards I can see that resistor R1 is in. Rx is in, but not jumpered / C14 and C16 stuffed, but also not jumpered.
If I realize the colourcode on the resistor R1 right:
1. ring: yellow = 4
2. ring: violet= 7
3. ring: black= 0
4. ring: red= 100 or brown= 10 Ohm
(5. ring: green is tolerance 0.5% / 6. ring: yellow is 25ppm/K)
If the 4. ring is red your input impedance would be 47kOhm.
On the pics it looks like brown - then it would be 4.7 kOhm (too low).
But I think the loading of your cartridge is not the main problem.
Could you measure the resistance of R1? Pearl 1 switched off!!!
DMM set at 200KOhm - One probe of DMM to the upper leg of R1 -
other probe of DMM to lower leg of R1.
Greets
Dirk
Attachments
Sorry, meant the inclusion of a resistor at Rx. Like Dirk mentioned, measure the resistance of R1. If It does in fact measure at 47k, you could simply remove the resistor at Rx. Assuming that you’ll be sticking with MM...
I want to thank everybody for there help. I'm a going to send amp back to the original owner after talking to him tonight and he is going to go through it. I'm a little concerned I may damage something I may have to return anyway. If it is repairable it will be returned to me. It was very nice how you guys put all your time and effort to help me out. I think if we would have keep going we may have had this thing running. Thanks again everyone.
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