USNRET Posted January 19, 2009 Share Posted January 19, 2009 I recently aquired an original Peach and married it up with my MC-2125. Problem is when the amp gain is turned up past 50% I begin hearing a hum which increases as gain is increased. Lz/Hz/HT mode makes no difference. Removed all inputs to preamp, no difference. Changed interconnects and power circuits, no difference. It's in the box headed back to Dr Mark for his healing powers but I was wondering if anyone else had suffered this. Back in the rack where all ladies belong Quote Link to comment Share on other sites More sharing options...
Coytee Posted January 19, 2009 Share Posted January 19, 2009 I might ask the question... where are the gains on the Peach set? As it turns out, if you have them about 12:00, you have them at the maximum noise level the Peach can create. If you turn them down OR (interestingly enough) turn them UP 100%, then the noise will go away. This of course, presumes the noise you are hearing is Peach induced. I've asked Mark about this in the past and he admitted his design had this situation in it. There was a technical reason "drawing on both sides of the tubes" or something that I didn't quite understand. As long as I knew it was ok, I simply maxed my Peach gains and all is well. Quote Link to comment Share on other sites More sharing options...
USNRET Posted January 19, 2009 Author Share Posted January 19, 2009 I might ask the question... where are the gains on the Peach set? As it turns out, if you have them about 12:00, you have them at the maximum noise level the Peach can create. If you turn them down OR (interestingly enough) turn them UP 100%, then the noise will go away. This of course, presumes the noise you are hearing is Peach induced. I've asked Mark about this in the past and he admitted his design had this situation in it. There was a technical reason "drawing on both sides of the tubes" or something that I didn't quite understand. As long as I knew it was ok, I simply maxed my Peach gains and all is well. The Peach gains and volume control has no effect on the hum. At any setting, if the preamp is in play mode, the hum is present. Mark sent me some things to try and then recommended that I send it back to him. Got it boxed up and plan to ship today. On a side note, I ordered the Tercel as well. Quote Link to comment Share on other sites More sharing options...
kuisis Posted January 19, 2009 Share Posted January 19, 2009 I use an original peach and a MC2100. You must like the music loud because on my lascalas I have the amp gains set at noon and can only turn the volume up to about noon on the peach master volume knob. I hope it's something simple. I really love my Mcintosh/Peach combo. Tom Quote Link to comment Share on other sites More sharing options...
USNRET Posted January 19, 2009 Author Share Posted January 19, 2009 I use an original peach and a MC2100. You must like the music loud because on my lascalas I have the amp gains set at noon and can only turn the volume up to about noon on the peach master volume knob. I hope it's something simple. I really love my Mcintosh/Peach combo. Tom Here's my deal, dumb as it may be. I want to use my 2125 as my 2 channel amp and my L&R amp in the HT mode. In order to do that and be able to set the HT levels I need the amp gain knobs at max as my AVR has more wattage (center and sides/rear). With amp gains at 1/2 I dial the AVR to it's max -12db on center and surrounds and just barely equalize SPL. On my Denon this precludes higher volumes as the max volume is reduced by the amount of reduced gain to any speaker. With the amp gains past 1/2 I get the hum. Also, I want to set the L/R levels (balance) equal and my PAA-3 is in the shop (display failed and they are on back order until the 22nd. Now while max gain on either of the preamp or the amp may not be matched exactly at least when I have them maxed I can say "OK brain they are matched" rather than trying to tweak them in as my listening position is several feet away and to the side of the controls. The wife is deaf in one ear so bless her heart, she can't help me and would run away before touching my stereo. Second: Good money for a pre-amp that I don't want to hear a hum from no matter how high I turn up the gain. Third: I guess I could buy more Mc amps to equalize HT Quote Link to comment Share on other sites More sharing options...
mark1101 Posted January 19, 2009 Share Posted January 19, 2009 I bet there is nothing wrong with your Peach. If you hear a hum when you select HT then you probably have a ground loop or mismatched impedances with your other equipment. When you select HT on a Peach there is no audio signal flowing through the Peach..........it is in bypass mode and out of the audio stream. Now that you posted this last information............hence my comments. Mark may install a 3 position ground lift switch which could help the situation. He put this on my Peach and it did help. You could also do the same thing with cheater plugs to try and understand the grounding situation. But............she's already gone. No big deal. You will get it straightened out. Quote Link to comment Share on other sites More sharing options...
USNRET Posted January 19, 2009 Author Share Posted January 19, 2009 If you hear a hum when you select HT then you probably have a ground loop or mismatched impedances with your other equipment. No matter what was selected Lz/Hz or HT the hum was there. See first post. Additionally all grounds were tried lifted, all grounds were taken to earth (8' buried copper), normal household circuit, Monster HTS 5100SS or the normal 20 amp hospital circuit dedicated to amp and pre-amp. Basically these: anytime Peach was connected to amp it hummed with amp gains past 50% no matter what selection was made to any pot or switch on the Peach (except of course OFF or Standby). I tried all Mark's troubleshooting and sent it back on his recommendation. I am hoping there is something wrong with the preamp as nothing here worked and no other combinations of equipment on my circuit has done this in the 4 years that the mancave has been operational. If the preamp has an issue I am sure Mark will get it worked out. If not, then I have had an expensive lesson that I don't need to be 'tubing'. Apologies: I don't mean to come across as an a**hat and I truly appreciate the help and suggestions! Bring them on I'll try them all. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted January 19, 2009 Share Posted January 19, 2009 Extraneous noise is a major pet peave of mine also. That kind of stuff bugs me a lot. If there is something wrong with your Peach Mark will address it. I had issues when I tried matching my Peach with certain pro amps.....and got into these "clean boxes" to stop the noise.........but degraded the sound. It was all just not meant to be and I went back to home audio equipment where the Peach is much happier. Another situation was caused by a less than smart placement in the rack and the Peach picked up noise from other equipment and from my cell phone. Remember, it is not in a metal box and lacks shielding. Mine is on top of the rack now and away from TVs, big transformers and magnets and I have no noise issues at all. I recently had the 6H30 upgrade installed and THAT was well worth having done. I had been told by a forum member who came to visit that my Peach was "one of the quieter" ones he had heard. It is definitely even more quiet now. These things have personalities...........get to know your Peach. [] Quote Link to comment Share on other sites More sharing options...
USNRET Posted January 19, 2009 Author Share Posted January 19, 2009 UhOh, what pray tell is the 6H30, I might need one of those [^o)] OK, google is my friend. I assume you are talking about the 6H30 tubes. You installed 3? Matched set? Obtained from? Cost? Quote Link to comment Share on other sites More sharing options...
mark1101 Posted January 20, 2009 Share Posted January 20, 2009 Talk to Mark about the 6H30 upgrade. The V1 position can be changed from 6dj8/6922 to 6H30. With this upgrade V2 and V3 remain 6dj8/6922. Quote Link to comment Share on other sites More sharing options...
USNRET Posted January 20, 2009 Author Share Posted January 20, 2009 Thanks, I check in with him after he looks at the Peach. I've been doing some heavy duty searching and reading on many topics regarding the original Peach from many sources. Best I can tell, while there may be some noise issues (mostly hiss and not the preamp's fault) I have not found hum problems. As stated before, this is my first tube experience (except for the Jolida CD) and I just can not imagine you guys with mega dollar systems putting up with the hum I heard. Hard time decribing it but at 3-4 feet from speaker it was clearly audible above my DLP fan noise and computer fans. From sitting position 12-13' away I knew it was there. We'll see what's up. Quote Link to comment Share on other sites More sharing options...
Bill H. Posted January 20, 2009 Share Posted January 20, 2009 I don't know tube gear, but on my regular Receiver I had Humming and this did the trick. Don't know if It would work for you case. Ground Loop Isolator $16.99 Model: 270-054 Catalog #: 270-054 Online: In stockUsually ships in 1 - 2 business days Quote Link to comment Share on other sites More sharing options...
USNRET Posted January 20, 2009 Author Share Posted January 20, 2009 Just wanted to add a note that although I seem to be having issues with my setup and this Peach, Heritagebob (the forum member I bought it from) has contacted me regarding this issue. I did not want to give any impression that he is not a standup guy. We are awaiting Mark's diagnosis to see if it is a preamp or my setup problem. Mike Quote Link to comment Share on other sites More sharing options...
Coytee Posted January 20, 2009 Share Posted January 20, 2009 I think it's all of those Heritage speakers you have..... when should I show up to take them off your hands? Quote Link to comment Share on other sites More sharing options...
USNRET Posted January 20, 2009 Author Share Posted January 20, 2009 I think it's all of those Heritage speakers you have..... when should I show up to take them off your hands?Yep, that's it and you can come tonight to get any of these:For Sale: Quartets, Chorus IIs, Academy, McIntosh C-28, MR-74 & MAC-1700; Pioneer SX650 and 727, Meridian DAC, Denon EQ, Carver Dolby Processor, Niles Ac and speaker switchers, Klipsch AB networks, K-77 tweeters, K-55-Ms When's the shindig at your place??? Quote Link to comment Share on other sites More sharing options...
HeritageBob Posted January 20, 2009 Share Posted January 20, 2009 I had it dead quiet through VRD's and into Chorus II's which are pretty sensitive before I wrapped her up to ship her out, I mean absolutely no noise at all. I just hope FedEx didnt abuse her in the shipping. Either way I will stand by and take care of any issues that I need to. I just wanted her to have a good home as I have to downsize. Bob Quote Link to comment Share on other sites More sharing options...
USNRET Posted January 20, 2009 Author Share Posted January 20, 2009 I had it dead quiet through VRD's and into Chorus II's which are pretty sensitive before I wrapped her up to ship her out, I mean absolutely no noise at all. I just hope FedEx didnt abuse her in the shipping. Either way I will stand by and take care of any issues that I need to. I just wanted her to have a good home as I have to downsize. Bob Your girl will get used to her new home but needed to visit for a checkup before her adopted Dad gets to enjoy! You know kids, they get cranky when removed from familiar surroundings. We just wanted to make sure she was properly nourished and any preventative innoculations were administered. No problem at all (well it actually stinks as I wanted to hear it like that) but I know that we'll be 'all good" with a little delay. You know, like my kids at Christmas. Not a bad anology as my son had to wait 2 weeks to play his Rock Band 2 guitar from Santa as it was dead on arrivial. Difference is EASPORTS customer service is dismal. Thanks Bob. Retired Squid PS: Have you spoken with a friend of mine here in Atlanta about a Sony ES preamp you may or may not have been selling. We were talking today and he wondered if it was you based on nothing except state of residence. Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted January 20, 2009 Share Posted January 20, 2009 Guys, I continue to read posts about noisy JMA preamps and must think that the problem is some spooky anomaly. We understand that many 6922's are known to be noisy, but not all of them. So let's say that all of us have good tubes. It is understandable that some inline pro devices (amps, EQ's, active networks) could be a mismatch and cause hum. So is it IC's, or something weird like the power grid or house wiring? The reason I say this(ask and wonder) is because I have used two JMA preamps without an issue. With little Merlin and volume at two o'clock I could hear a faint hiss from one foot away. Nothing more. With Peach ll and volume at two o'clock I must remove the grills and put my ear against the 2404's to hear much of anything at all. Now a bit of HF hiss is one thing but HUMMMM at six feet is another. I must agree with Mark Fragnito, I can't live with that. I use a tube CDP, the Peach ll, in to 20 year old bridged SS power amps. All connected with (cheap) 18 year old Audioquest Turquoise IC's. With that mix and match combo, I feel that I haven have given the JMA's ample oppertunity to misbehave. ?? Now if I have been lucky,......it would be the first time. I think your noise must be a spook...........[:|] tc Quote Link to comment Share on other sites More sharing options...
fenderbender Posted January 20, 2009 Share Posted January 20, 2009 I Bet good money that Mark1101 hit the nail on the head, and it's a grounding loop......I have everything in my system except for the power amp un-grounded via home made power strip ....with NO line conditioners, surge protection, fuses, nothing...and that took care of all my hum .... just for the hell of it.....is the hum equal in both speakers? and did you double check all your interconnects.......One thing I found out the hard way with JMA products is the RCA jacks used do not take kindly to higher end interconnects......and the cheapo's make much better contact.........I was having fit's with my BBX ...had it boxed up and ready to ship back when I read somewhere about the rca's.......figured WTH and hooked it back up with $3 cheepo's and Viola!!!!! As always I'm talking out both sides of my a$$ and my technical comments should be taken at face value.......but I hope this can be of some help..... Quote Link to comment Share on other sites More sharing options...
USNRET Posted January 21, 2009 Author Share Posted January 21, 2009 Below is what Mark had me try: Try this:Connect ONLY the preamp and power amp. No other components whatsoever. DoneUse the MOST GENERIC rca cables you have. No special cables. DonePlug preamp and power amp into SAME electrical circuit. No filters, conditioners, generators, or other AC gadgets. DoneConnect amp to speakers only. No subwoofers, or other gadgets. DoneSet preamp left and right level controls to 12:00 o'clock position. Set volume to zero. Pre-amp level control and volume changes make no difference. On my MC-2125 and Klipsch Belles there is a distinct hum and some hiss detectable from 50% gain on amp and increases as the gain is increased. Both channels. This noise is not there when I use the C-28 or Denon AVR-4306 AVR as preamp or disconnect the Peach. When I go from standby to play there is definite click/pop approx 3-5 seconds before the 45 sec timeout (enough to swing the amp meters 20% deflection) and then the hiss/hum comes on. Sometimes during this check I heard pre-amp volume pot noise (click/pop) at about 1100 but it was not consistent. I perceive slightly less hum but definitely still there following removal of the Verastarr cables and disconnecting the Jolida CD, not a major difference.Is there hum?Move volume up...is there hum? If yes, there may be something wrong with the preamp and I will have to get it here to fix. Quote Link to comment Share on other sites More sharing options...
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