I have just completed construction of the pearl phono amp. I have found the sound to be quite detailed but a bit bright, flat and fatiguing. At this point, I am hoping that I did something wrong.
I built the unit following the instructions closely. I decided to try using batteries to power the amp. I used three 12 V sealed lead acid batteries (5Ah) per channel.
I used the following equipment for my listening tests: VPI Aries Basic turntable, VPI JMW 10 tonearm, Grado Reference Sonata cartridge (47 kohms, 320 pF loading), NAD integrated amp, Definitive Technology BP2002 speakers. All comparisons were made versus my old NAD PP1 phono stage.
I enjoy a lush, warm midrange. The midrange of the my pearl is thin. Could this be due to my power supply? Do I need to load my Grado down with a bit more capacitance?
Any suggestions would be appreciated.
I built the unit following the instructions closely. I decided to try using batteries to power the amp. I used three 12 V sealed lead acid batteries (5Ah) per channel.
I used the following equipment for my listening tests: VPI Aries Basic turntable, VPI JMW 10 tonearm, Grado Reference Sonata cartridge (47 kohms, 320 pF loading), NAD integrated amp, Definitive Technology BP2002 speakers. All comparisons were made versus my old NAD PP1 phono stage.
I enjoy a lush, warm midrange. The midrange of the my pearl is thin. Could this be due to my power supply? Do I need to load my Grado down with a bit more capacitance?
Any suggestions would be appreciated.
emillam
yes, the batteries may contribute to your problem. all bateries have different tonal qualities, so even if i don't normally associate thin tonal balance with lead acid batteries, your particular brand may be to blame. Minimalist circuits usually have great transparency but could easily sound thin, unless of course they're minimalist but with valves. You may wish to play around with resistor types and use carbon instead of metal film. What are your filter caps? I don't personally subscribe much to the burn-in theories unless you're using black gates. Not much more you can do before you pronounce the NAD a winner. I have long lost touch with NADs but years ago they had pretty nice phono stages in their better integrateds and i wouldn't describe them as thin.
peter
yes, the batteries may contribute to your problem. all bateries have different tonal qualities, so even if i don't normally associate thin tonal balance with lead acid batteries, your particular brand may be to blame. Minimalist circuits usually have great transparency but could easily sound thin, unless of course they're minimalist but with valves. You may wish to play around with resistor types and use carbon instead of metal film. What are your filter caps? I don't personally subscribe much to the burn-in theories unless you're using black gates. Not much more you can do before you pronounce the NAD a winner. I have long lost touch with NADs but years ago they had pretty nice phono stages in their better integrateds and i wouldn't describe them as thin.
peter
Thanks for the input.
I am experimenting with reducing the value of the input resistor. It has helped a great deal. I still wouldn't call the midrange warm or lush, but it not as thin as it once was. At the moment I have installed a pot so that I can play with this vlaue. How low do I dare go? Right now I have found that 30 kohms sounds fairly good.
My output capacitor is an XEON polypropylene type.
I have increased my tracking force as far as I feel comfortable going. I am running the Grado at 1.6 g (the reccomendation is 1.5 g).
My cartridge is well broken in, I will give my phono amp more time.
I would like to thank everyone for all of the suggestions. They have been very helpful.
Evan
I am experimenting with reducing the value of the input resistor. It has helped a great deal. I still wouldn't call the midrange warm or lush, but it not as thin as it once was. At the moment I have installed a pot so that I can play with this vlaue. How low do I dare go? Right now I have found that 30 kohms sounds fairly good.
My output capacitor is an XEON polypropylene type.
I have increased my tracking force as far as I feel comfortable going. I am running the Grado at 1.6 g (the reccomendation is 1.5 g).
My cartridge is well broken in, I will give my phono amp more time.
I would like to thank everyone for all of the suggestions. They have been very helpful.
Evan
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