are you running the outputs fully balanced via XLR? Those outputs will give 6 db higher than the single ended outputs.
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No, I was using the single ended outputs. I am not sure about the 6 dB more gain beacuse it depends on how the line pre-amp handles balanced inputs. Uncertain about the JC2, but some pre-amps I know of divide back the 6 dB gain when they convert back to single ended internally, so they match the same levels of other singel ended inputs.
Since my original posting I had a chance to make some measurements on a spectrum analyzer. I thought I might have a defective unit. Although PS Audio does not publish noise specifications, I thought I might compare it's performance with some other products (such as the Cambridge Audio 651, which has some pretty good noise specs).
What I found was the noise performance is pretty good. At the x48 dB gain position, I got a noise level of -105 (200 Hz) to -110 (20 KHz) dBV (ref to 1 V RMS output) at the 1:30 volume positition, or 40 dB actual gain. Moving the front volume control to MAX CW position, gain is x48 dB, and noise increases to -90@200 to -100@20K dBV, which tends to indicate you are picking up a bit more noise than you are gaining in gain. These measurements were made with the internal 1 K source resistance (not shorted), which is more realistic source impedance of a MM cart. These are raw measurements, with no weighting (A or C). The range of about -10 dBV indicates the drop in noise with frequency from about 200 Hz to 20 KHz.
At the 66 dB gain position, I measured noise levels at the 1:30 volume position (actual gain of 60 dB) to be essentially the same as the x48 dB gain setting; -90 to -100 dBV. But increasing the volume to MAX, noise increased to -75 dB (200 Hz) to -90 dB @ 20KHz. Source resistance was 100 ohms. Here you lose a wopping 15 dB SN for an increase in gain of only 6 dB.
So at x66 dB, MAX volume, you get a worse case noise level of -75 dB, un weighted, which is pretty good. Weighting and shorted inputs always improve the numbers somewhat. But -75 db is pretty audible based on my earlier criteria of listening to the drivers directly. The SN in my system is worse than -75 dB because my gain is set for a listening level ref to 300 mV, not 1 VRMS (which is now actually -65 dB ref 300 mV RMS).
So with the GCPH, if you need gain use the main gain switches at the back, and try to keep the volume control at 1:30 or below.
Interesting findings. I know ps recommends keeping the gain between 12 to 3 on the dial. I run mine at around 1:30-2 for my lomc (dyna xx2 mk2) which has .28 MV output. I use the 66 db setting and run xlr out to my pass xp10 but also have to set the pass to the higher gain setting. I know it's the weak link in my system but it works pretty well for now. What other phono pres have you used? Swanny
I dont know about the difference in gain settings, but I do know my GCPH sounds best when the volume knob is at 1:30 or less. For the $500 I paid new for the unit, I think it is exceptional. I run the GCPH straight into my amp, using the volume control on the GCPH and the result is very satisfactory. Remote control for volume, phase and mono is nice too. Also, you can really hear the differences in cartridge loading, which is external and doesnt require opening the box and flipping DIP switches. Much easier to set up the system than most.
I'm just getting back into vinyl (after 30+ years), so this is a "starter" phono preamp for me. I use Parasound line (JC2) and power (JC1) amps and up till now have only had CD sources (CA 840C with a Bryston BDA-1 D/A).
I considered the Parasound JC3 phono, but its 2.5x the cost of the PS Audio and I did not want to commit to that much cash at the beginning. The Parasound is also quite inflexible in cart loading choices, and gain is fixed as well.
My only beef with the GCPH so far is the cap loading (it is fixed at each resistance loading position); also it is too high for some MM carts (like the AT 150 MXL), forcing you to buy very expensive phono interconnects. Some of these cost as much as the GCPH itself. With MCs, this is much less of an issue.
My other concern was I thought this was an all class A discrete design, which it is not. Not to say that having an IC amp input circuit is a bad thing (in fact it is quite common in phono pre-amps under $1000), but their advertising implies otherwise.
I also considered the CA 650/651 products, but they need considerable modification for best sound quality. They are considerably cheaper however.
I am also considering a modification to the GCPH to remove the torrodial transformer and relocate it in an outside chassis, perhaps even building a DC supply with it and running seperate power into the GCPH. This would do a lot to reduce the noise floor even further, as I could easily see the 60/120/240 Hz power artifacts in the spectrum analysis.
Had more time to investigate the noise issues and found that the large filter caps in the power supply were not soldered well to the PCB. PS Audio uses plated through holes as part of the signal path and the copper in these holes (that mount the filter caps) seemed to be defective, as the signal was not connecting well from the lower traces to the upper traces. I soldered a heavy jumper wire to enhance the connection and what will you know, the 120 Hz noise level dropped dramatically.
I am looking next into relocating the torroidal transformer to an external chassis.
I've experienced no noise problems at all with the GCPH. That's set at it's highest gains, inputting a Dynavector 17D3(.3mV output), with SR's Tricon Analog phono leads. I run my TacT 2.2X at 99.9 and use the GCPH volume control, which is generally close to maxed(the 2.2 contributes very little gain), or maxed with some albums, recorded at lower levels. Only after 2:00 on the volume knob, do I start to hear a slight 60Hz hum(none- with the phono leads disconnected, and I am extremely sensitive to extraneous noise). I've simply been experimenting with the unit, not expecting much from one so inexpensive, to find what loading and gain I needed, with my system and low output cartridges(17D3 and Denon 103D). I intended to install FREDs, but found fairly fast diodes in the unit already. A HI-FI Tuning Supreme and Zu Mother PC, made a marked difference in the presentation. Defects do occur, regardless of manufacturing procedures(especially when humans are involved). I'd have sent the unit back, and let them find the problem, once I eliminated every other possible noise source. I was dismayed, to find that the thing was manufactured in China. A fact NOT mentioned in ANY of PS Audio's ads, or in any articles written on the piece. No surprise that your problems were not caught by Quality Control(AS IF that existed there)!
Thanks for your comments. After re-soldering the caps the audible noise (60-120 Hz) was reduced considerably, although my measurements were made prior to this. So I doubt if PS Audio would would say there is anything wrong, as the specifications were pretty good as measured, and I have no published specs to compare (and I don't know what internal specs PS Audio uses). So you may have a unit that was soldered well from the getgo.
I still cannot use the volume control past about 1:30, but that is OK because I can get all the gain I need with the rear gain control. I am planning on using an AT 150 xlm MM cartridge, but attenuated by 5:1 (see my post under Analog). With this setup at 66 dB gain, AND the phono interconnects/tonearm/cart connected, the noise level is extremely low, with little to no hum detectable with my ear at the speakers, and my normal max gain settings.
The made in China issue is a fact of life today, but what frosted me to some extent is the comment I made previously, where PS Audio claims the GCPH contains "all balanced class A circuitry" which it does not. It uses an IC pre-amp which is neither balanced or class A. I'm sure they were refering to the Gain Cells, but they should know better when trying to market to audiophiles.
I do not know where in China the GCPH is made, but if it's Taiwan (as opposed to Mainland) that's about as good as it gets. The most sophisticated electronic products (such as motherboards and video cards for PCs) are made there. Quality issues (or lack thereof) are typically produced by corporate bean counters looking to cut costs, as opposed to where something is manufactured.
And regarding the relocation of the transformer, I cannot see how this would not reduce hum levels even further. Mounting that torrodial transformer within INCHES of the low level circuitry, without any shielding, seems to be too much of a design/cost compromise to me. I know the noise can be minimized by rotating the transformer, but come on, why not get the thing out of the chassis altogether? I asked this question of the PS Audio marketing folks and the answer was a simple one word "cost".
I agree, regarding the X-former location. Ideally; the entire power supply would be in a separate chassis, but- we ARE talking about a sub-K unit here. I know that discrete use of TI's EMI/RFI shielding can make a marked difference, within the unit. PS Audio makes this statement about their gain stages: "The GCPH is built around two discrete and fully class A balanced gain stages: a high gain, low noise input stage and a Gain Cell for the output stage, with the passive RIAA curve between the two stages." They DO say that the unit is a, "true balanced design from input to output", but don't claim it to be Class A, all the way: (http://www.psaudio.com/products/audio/perfectwave-accessories/gcph-phono/). I believe PS recently moved all their manufacturing back to this side of the pond. I'm certain yours was not the only problem unit produced over there. As far as marketing to them: Given the technical ignorance of the average, "audiophile".....Well, have you ever read the crap/hype printed in an 'Audio Advisor' brochure? Happy listening!
The GCPH description "built around two discrete and fully class A balanced gain stages: a high gain, low noise input stage and a Gain Cell for the output stage, with the passive RIAA curve between the two stages" is what is no longer true. The "low noise" input stage is an Analog Devices SSM2019 "Self contained Audio Preamplifier", not discrete circuitry. Maybe the GCPH was at one time, when the marketing hype was written, but not in the one I received. Like most IC OP amps, its biasing state (Class A or otherwise) for all the internal gain stages is unknown. So to claim it's "Class A" is stretching the truth somewhat. And, the SSM2019 is not "fully balanced", its single ended, as a quick review of the AD data sheet will reveal.
I have no issue with PS Audio improving their products and maybe the SSM2019 is an improvement over discrete stages (or maybe discrete low noise transistors are becoming impossible to find any longer), but their literature should be updated to reflect what they are currently selling, not what they designed 10 years ago. Did you also realize the photos of the product in the manual and online are not of the GCPH, but the GCHA (the headphone amplifier)?
There are a number of sub 1K phono preamps that have outboard transformers (maybe not full DC supplies). I agree that these mostly are cheesy wall warts and not the beefy 50W torodial transformer PS uses. I am putting together a kit to relocate the PS transformer and build a remote DC supply for the GCPH.
Yes, I have received "advice" from Audio Advisor. Not all that accurate and we can leave it at that.
I purchased a new PS GCPH a while ago for MC cartridge usage and just used it in my system, which consist of a Mcintosh Mx-135, Denon Dp-A100 TT, Mcintosh MC402 and B&W 804d.
1. When I use ps gcph+amplifier, without another pre-amp, the sound is fine, but the MX135 with its MM is much better!
2. In connection mode without PS gcph, Denon DP-A100 (TT)->MX-135->MC402, the whole system sounds wonderful with MM cartridge (AT440ML). However when I put PS GCPH into the chain such as, Denon DP-A100 -> PS GCPH ->MX-135->MC402, the sound quality degrades enormously and gets lean where I loose some details such as imaging, staging, edges on Bass and midrange frqs. I still didnt try MC cartridges with PS gcph+preamp but I guess I will have the same effect.
As a matter of practicality of using one main cable set with my amp and not switch it between Ps gcpj and pre-amp, I was wondering why using PS gcph+preamp degrades the sound enormously and what should I do to gain the sound quality that I would expect from ps gcph?
As for input level informations on MX135, here is the data:
Phono: 47k Ohms, 65pf
High Level: 22k Ohms Unbalanced
50k Ohms Balanced
Sensitivity for inout
High Level: 400mV Unbalanced
Maximum Input Signal
High Level: 5V Unbalanced
I would appreciate your feedback. I tried PS audio support desk and so far there is no result!?!
Since a few days ago I left GCPH on and connected to the system, for break-in purposes. I tried again this morning and I was amazed how sound quality was improved. Perhaps after more break-in process the sound quality will improve. I read somewhere it would takes about 300 hours!. As for gain/sound adjustment, I use 48db knob and switched to 66 db where I put volume on 1:30-2 at GCPH, as it is recommended in the web sites. the result is much better in this case.
perhaps with more break-in process, the sounds will improve further. As a comment the PS audio has been very supportive ... thanks ...
I suspect the input capacitance of the GCPH plus your phono cables is too high for that cartridge, but that is just a guess. Its not published, but PS told me the input capacitance for the MM/47K input is 100 pF. I have an AT 150 MLX that requires a max of 150-200 pF, and is reported to sound bright and edgy with higher capacitance. 150 pF is reported to be the optimum, but with the GCPH 47K input of 100 pF and an arm wiring capacitance of 30 pF, it leaves only 20 pF for the cables. Almost impossible to obtain (unless you want to pay thousands for the interconnects).
The Mac may sound better because it has a much lower input capacitance at 65 pF.
In my case (see my post under analog on the AT 150) I solved my problem but using a 5:1 attenuator ahead of the MM input on the GCPH. This isolates the 100 pF input cap from the cartridge, and now I can use 100-120 pF cables without exceeding the 150 pF loading on the cartridge.
I use a gain setting on the GCPH of 60 dB to compensate for the attenuator.
The attenuator is easy to build. Its located in an inline RCA adapter that plugs into the GCPH inputs.
Forgot to ask, what inputs are you plugging the GCPH into when you use TT>GCPH>MX135? A high level Aux input, right? The same one you use when you use a MC cartridge with the GCPH?
You of course cannot connect the GCPH into the phono stage of your MAC pre-amp. That would be disasterous (you are double RIAA EQing!)
If you are going into an AUX input on the MAC, perhaps therein lies the problem. Maybe you are overloading the inputs with the output from the GCPH. Does the sonic degradation stay the same if you turn the level control of the GCPH way down and use the MAC for volume adjustment?
Thank you DHL93449 for your comments.
for this purpose, I used balanced or (one of 11)unbalanced inputs of MX135. In either cases, the sounds degrades and looses a lot of details once signal goes through GCPH+Mx135. There has been some improvement with break-in process and perhaps it will get better but maybe not too much! I need to add GCPH+AMP sounds very good better than SIM-LP5. Of course it doesn't have the same deep bass and mid-range quality offered by MX135 but it still be decent.
Your comments on input capacitor stage seems to be a good explanation of this problem. It requires some knowledge/experience before getting into the GCPH box. Since my undergraduate degree on EE, I haven't touch measurement instruments which is a shame! In the other hand, I wouldn't spend too much money like twice of $gcph for cables. Unfortunately I am not as handy as you are to make changes as you did.
Right now I use AT440 and Shelter-201 which are not bad at all, maybe it is not as good as AT150 but the details and bass is pretty good. I thought instead of spending on more expensive cables just purchase more sophisticated MM cartridge. An alternative is to use only MM cartridges with MX135 where its quality is fantastic. and sell my MC cartridges+GCPH that I received as birthday presents!
Besides I am so tempted to replace MX135+gcph with a MC2300 which its quality is far superior. I need to think more seriously about this last option ...however I still hope to resolve the gcph problem ...
I set it first at 54db and volume knob to 3:00 - 4:00, the sound with MX135 was too compressed and not too much details. As a test I changed it to 66db @1:30-2 and sounds was much more open.
Without MX135, I used also the same combination and found more details on mid to high-frequency ranges compared to 54db @2:00.
If you ask me why? I am not sure about it...
Hello again Mr D- I checked both the manual that came with my unit, and the site(url) that I posted. Both have pics of the GCPH. My manual(15-044-11-1) does not mention anything about discrete or Class A anything. I suppose the blurbsheet(url) I posted is out of date, and should be refreshed, as you mentioned. HOPEFULLY- that's simply an oversight, on their part. The issue of how much to spend on cables came up earlier. As I said; I'm using the GCPH experimentally, but- even my power cord(Zu Mother) cost me more than the unit itself. The Kimber KS-1030's and Synergistic Tricon Analogs both cost over twice the unit's price. I can't afford anything stratospheric, regarding cables, but I learned, long ago, how much difference carefully selected cables can make in a resolving system. That's especially true, if one gets to hear a lot of live music, and has for decades. I wonder what Mr M is using, with regards to cabling, and whether he might realize an improvement, with an upgrade.
48-54 dB sound more reasonable. Remember that gain is only as registered on the gain setting when the volume control is full CW. If used at 1:30 - 2:00, its about 6 dB lower.
My comment about the input capacitance value of 100 pF comes from a direct inquiry with PS Audio. I did not confirm the actual value myself. Even if you open the unit, you cannot read the component values because they are all surface mount chip components. You need a magnifiying lupe just to see them!
I should have been clearer about the photos. The photo of the interior is not of the GCPH, it is the GCHA (page 4 of the manual, under "Questions and answers"). The same photo shows up if you Google the GCPH, and here:
All the photos of the exterior views are correct.
The photo of the interior shows only two large filter caps, the GCPH has four clustered together. Look at the rear panel. There are only two RCAs, the GCPH has four. In the photo there are no range selection pots (because the GCHA does not have them) nor are there any balanced line out XLRs. The regulators with the heat sinks are not mounted in the same location either.This is clearly not the GCPH.
If we could post photos in the forum, I'd post the ones of my GCPH.
Looks like they removed language of Class A on the website, but they still speak of "balanced" construction throughout. Unless you listen to the video review on Audio Advisor by Ryan Conway:
The IC pre-amp (SSM2019) is cited to be "true differential input" by Analog Devices (TI), but it's not truly balanced, because it's output is single ended (not differential). So sorry, the circuit is not fully balanced throughout.
Re cables, anything that cost twice what the GCPH is worth IS stratospheric in my mind, but I have always been one to build my own stuff, including interconnects.
There is no reason for a MM input to have such a high capacitance (100 pF), given the range of what most MM cartridges need. I think they should have made it 20-30 pF to give the user more flexibility in cable selection. I think one main reason it is so high is the concern of the PS engineers for input RF rejection, and they may consider this more important than cartridge loading. I think I have read some comments relavent to this on the Graham Slee forums.
Regarding Cables used in my system, I initially used AQ king Cobra, and switched to AQ Columbia, AQ Niagara and Nordost Heimdall. Of course there has been some improvement on sound quality when signal goes directly to AMP. The sound is pretty good and I like it very much so. This scenario is kind of not practical because when I want to listen to CDs I need to disconnect cables from GCPH-AMP and reconnect it again to my pre-amp(MX135)!
Unfortunately, the problem of sound degradation is being present once I use GCPH+pre-AMP+AMP. Even though using my AT33 cartridge, it sounds worse than a cheap cartridge as $20, no details at all on output sound ... I guess there is a mismatch (capacitor/impedance) between these two and I am very curious to find how?
Mr Rodman, I totally agree that cables play a huge role on sound quality, but I am afraid this case is not directly associated to cable issue. In case of upgrading cables to $4k cables only on phono stage, I would rather to buy a Manley Steelhead phono pre-amp, or the most practical option would be to upgrade to MC2300 where its phono stage is so phenomenal.
I read in these comments that you guy use gcph with some other pre-amps like parasound, TAcT and ... I was wondering whether how was your experience on using GCPH with pre-amp and how would you compare sound quality on GCPH+AMP and GCPH+pre-amp+AMP?
In most of the research I did before purchasing the GCPH, I found no sources that really found the sound quality unpleasant or unsatisfactory. Noise/hum were common complaints in earlier reviews, but never sound quality. I am still in the process of building my phono setup, so I have no direct audio performance to report other than the noise issues mentioned above.
I do find it strange that the GCPH in your system sounds good when connected directly to your power amp, but not to the same power amp thru the MAC line amp (pre-amp). That would indicate to me that there is an issue with the line stages in the Mac pre-amp, either a voltage overload issue or maybe an impedance issue (as you suggest). I doubt if it's cables, as I would assume you use the same cables to connect to the power amp. I am also assuming the power amp has similar impedance/voltage requirements as the Mac pre-amp.
I would try backing off the gain in the GCPH and see if that does not improve things. Also, try different Aux line inputs if they are available. I know my Parasound P3 had different quality amplifiers connected to the different inputs. Maybe that's the case with yours as well. If not, maybe you need to move on to another product.
I took a look at the specs for your Mac pre-amp. I did not realize it was a large and complex AV pre-amp.
It very likely uses operational amplifiers (IC op amps) for those miriad of inputs. The spec I saw showed it did not have a phono pre-amp input, but maybe yours is different. It would not surprise me that the GCPH directly into the power amp will sound much better than going into the line inputs of this AV pre-amp and then into the power amp. You are cutting out a lot of intermediate processing and amplifier stages. Perhaps the phono input stage of this AV pre-amp is designed to bypass some of that processing as well. Also, if op amps are being used, you definitely want to keep your input voltages as low as possible, as the distortion performance of many types of op-amps increases dramatically once you get near 1 volt (even though their spec sheets won't indicate this).
Are you using the balanced inputs or single ended? In some amps, they sound different so try both.
Also, if your CD sounds good to you, I would try inputing the GCPH into the same CD input for comparison. Adjust the volume on the GCPH so that it matches the volume of the CD deck and make the comparison.
But in general, I would not expect you will get sonic parity by putting the AV pre-amp between the GCPH and the power amp.
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 friends 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 couldnt 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 doesnt 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 didnt perform these sorts of tests. I also asked a psaudio dealer in SF area and they didnt 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 thats my fault to not have tested gcph before, and just trusted the reviews
Maybe you have a problem in the GCPH? If it's still under a warranty (and even if not, PS Audio is very liberal with potential warranty issues), I would contact PS Audio and explain your situation. I would think that maybe you have a problem in those gain cells. Can't hurt to send to PS Audio for a check up. If they say it's OK, then just consider selling it.
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 ...
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.
To me GCPH issue is a closed case which is a worse pre-amp for $1000 as I mentioned in my previous message! Thats why I removed it from my system.
The answer to last part of your e-mail was already given in previous messages. It is not an issue of low/high gain...
The sound quality differences between phono preamp W/WO line pre-amp are normal at certain extent! However when I compare sound quality of GCPH with other ones in almost same price range , you may find GCPH is not well placed at all in the ranking ... this is when you realize the sound degradation between GCPH W/Wo extra line preamp is much worse than other phono preamps. That should be something wrong with its circuitry design for this price range ($1000) there is a lack of honesty too! When they dont mention min/max input sensitivity, or make believe you it is made in USA where it is made in china, where there is no any serious product quality check. Two days a go with a friend, I visited a hifi store (turntable guru store) in San Jose having an excellent reputation, during discussions the owner mentioned they used to be ps-audio dealer of GCPH, he got too many complains from customer and he is not caring any more gcph because of that! He was saying even Music Hall phone line ~$150 is better than gcph.
As for Stereophile review that you mentioned, Robert Deutch says it is a preview and not a review he is not an expert for phono stages or turntables related devices he quoted: my listening to LPs is rather sporadic, and not so much for sound quality as for content: much of my LP collection is sufficiently obscure that it has not beenand is unlikely to bereleased on CD, let alone SACD or DVD-Audio. By the end he says it is a good match for ps-audio GCC-100 integrated amp . Actually I wouldnt consider it as a good review Of course for analog components if this was come from Michael Farmer of stereophile I would have given more credit to the review !!! BTW look at Michael Farmer review in ST about AQVOX phono, it is a very good review . Besides other reviews on GCPH, use only integrated amps rather separate devices, which changes the usage context
I dont have any intention to make publicity for any band like AQVOX or any other one! I presented my experiences on GCPH, AQVOX with different systems in order to be shared with other fellows in Audiogon my previous comments would perhaps present a sense of reality in GCPH quality, testing in different circumstances, devices, cables and phono cartridges BTW I dont push the idea that GCPH is the best because I bought it Regarding pricing, there is always a price degradation on second hand devices even demos or used ones, I think there is always a way to find an AQVOX phono as used (~$700-$800 instead of $1250) like the one your gcph that you bought at $750 instead of $1000+tax
I got GCPH (HUGE mistake) as a temporary solution for using with my MC cartridges before moving toward a robust phono line like C2300. This unpleasant experience just motivated me more to move toward a good integrated phono stage If you use CD player and other sources in the system, it seems for a >$25K whole hifi system, it is better to have an integrated phono stage in a preamplifier even with a higher price tag ... other wise one should invest in extra cables, power cables and not having the same sound quality as expected