Impressions of PS Audio GCPH

I have completed my project to relocate (or actually disable) the power transformer for the GCPH.

I built an outboard power supply with a similar torroidal transformer and 132,000 mfd of power supply capacitance, and disconnected the stock torroidal transformer. The DC inputs go into the bridge diodes via the same connector the original transformer was connected to. I left the original in place in case I want to go back to stock.

The results are amazing. All audible hum components in the output are GONE. No hum whatsoever. On any gain setting, all the way up to max volume. I am very pleased with these results.

Sorry for these 2-3 weeks of delay on reply, I was out of country for a conference back in EU.

DHL93449, Glad to hear that you did successfully relocate power transformer outside of the Box and you are happy with results. BTW I do appreciate that you took time time to look at MX135 Manuel, thanks a lot.

To answer you question, yes, earlier I did try to use BAL1 of MX135 input (used for CD player) for GCPH and still had the same problem of sound degradation. I used other type of cables too, but not a big improvement!

I also looked at the internal circuitry of MX135, to find out how to bypass pre-amp stage and lead gcph signal directly toward MX135 output. In schematic MM phono goes through a first stage pre-amp, along with other inputs (RCA), it gets buffered before switching stage with Balance inputs. Selected input after another amplification stage goes to the processor where as an option one could choose external inputs too, without these pre-amp stages fed to the processor. Output of processor gets treated for Bass/TREB boosting options before final stage. Therefore, I tried different configurations to ameliorate sound quality of GCPH+MX135 and the result was not really encouraging!

This last weekend, I took my GCPH with some selected LPs to a friend’s house and tried to test it on his hi-fi system (Roksan Xerxes, AQVOX phono, Krell 280, krell PFB250s, Focal Diva speakers). We made some experiments with Krell-280 pre-amp, ps-Audio GCPH, AQVOX phono and different cartridges (MM/MC). Issue concerning gcph+preamp sound degradations was present but a little bit less audible; I mean Krell 280 compared with MX135. Again, GCPH + AMP were much better in sound quality. I have to say AQVOX phono was phenomenal! AQVOX phono+pre-amp were excellent and AQVOX+AMP were even better! There were some differences but not really very audible. We also tried different phono cartridges and compared related quality of GCPH and AQVOX phono. AQVOX outperforms GCPH in details especially in fastness and imaging aspects, as well as different range of frequency, better midrange, and higher freqs with a bass deeper than gcph.

I brought home for a couple of days the AQVOX and made some test with my MX135 and my new JA MICHELLE Gyro turntable. AQVOX+MX135 present an excellent sound, much better than GCPH+MX135. In case of AQVOX+AMP I got same sound quality with deeper bass. With AQVOX, I got much more details in sound compared to GCPH. The MM phono stage of AQVOX is as good as MX135 phono stage where I got a little bit more forward sound with MX135.

As for different cartridges, MM cartridges in GCPH present reasonable sound quality but with LO MC GCPH couldn’t handle it properly. I used MC cartridges too, where I found out MCs with an output of >0.45mv should be fine but with very LO MCs the degradation is really audible. Contrary to PS-audio GCPH, AQVOX is perfectly capable to handle even very LO MCs. Unfortunately, in PS-audio manual/specification it doesn’t provide any information on min/max input sensitivity for MM or MC cartridges!!???! It is bizarre …

Once again, I checked reviews on GCPH, nobody mentioned quality differences between GCPH W/Wo external pre-amp because they didn’t perform these sorts of tests. I also asked a ps–audio dealer in SF area and they didn’t have any experience on this regard!?

Based on my experience with both AQVOX phono and ps-audio gcph, I would certainly recommend AQVOX phono with a price tag of 998.00 Euro~$1250. It could handle very LO MC (>0.15mv) and it is totally configurable for different phono cartridges. It could be purchased only online from Germany website which might be inconvenient for some people!!? I wish I had purchased AQVOX instead of GCPH.

Being frustrated with GCPH experience, I decided to disconnect my ps-audio gcph from the system and will use only MX135 with its MM phono which is excellent, until I purchase a MCintosh MC2300, having both MC/MM phono stages. It is sad but that’s my fault to not have tested gcph before, and just trusted the reviews …

Mr D.,

Yes, It is a new device!!! 4 weeks ago I contacted PS-audio and someone named MArk, after a few exchange messages , suggested that he will find a dealer that I could take my GCPH there and eventually use different cables or loan me some cables and ... since then I didn't have any feedback from them!!?!

If there is an internal circuitry issue with my ps-audio it would be so shameful for Ps-audo that they don't have a quality check line on their products!

My guess is that the problem is the overall quality of GCPH which is on question, some people find it perhaps reasonalbe quality for $1000! I am not sure ... Honestly speaking that is a lot of money! that's why I expected a high quality sound out of it ... and that's why I am disappointed ...

Michel:

With all fairness to PS Audio, how can you blame them when the product sounds much better directly connected to the power amp? Adding any amp in between is most likely to reduce the quality of the sound, but that is not the fault of the GCPH.
As for the comparison with the AQVOX, perhaps the GCPH is inferior to that product, I don't know. I took a look at the 6moons review of this product, and it looks quite interesting. But remember Stereophile also gave the GCPH a rave review as well. So you cannot tell much about the sonic -preferences of a product from reviews. Sometimes when you make comparisons you get surprised, but you can only chalk that up to learning. The AQVOX appears to be more expensive (1000 euros list which is $1200-1300 US) and you can typically get a new/demo GCPH for $750 (as I got mine from Parts Express). But cost is another parameter that may not be all that relavent. Some folks like the CA products (if modified) and they are considerably cheaper than the GCPH. If you like the AVQOX that much, then sell the GCPH and move on. Life is too short to fret over how the GCPH should sound versus how it actually sounds.

You have nothing to lose by having PS Audio check it out. I cannot imagine anything about the circuitry in the GCPH that would degrade the sound through pre-amps that would not also be heard through a power amp. Unless you have the gain of the GCPH too high and you are overloading the pre-amp which would degrade the sound. But again, that is not the fault of the GCPH but how you are using it. I think I suggested you run your tests with the gain on the GCPH as low as possible if you are feeding a pre-amp.