Marantz output misbalance

siderealxxx

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I've just purchased a Marantz PM6005 and CD6005 to go with my new B&W 685 S2's for the lounge hifi system. However, as soon as I wired up the amp and CD player I noticed the left/right output levels seem subtly but noticably different to each other (in this instance the left ouput is quieter). This was more noticable at lower volumes and in fact you could fade the volume down and the music would appear to track across to the right hand side.

I set about testing the system thoroughly in order to identify the problem. This involved placing a matched pair of microphones directly in front of each speaker and playing a test oscillator (sine wave) through the amp and recording the result back (photo in link below). What this showed up was a difference of around 6db between the two outputs - a significant amount.

I made a video of these tests (links at bottom) where I ruled out any other components by swapping speakers, cables, outputs A & B, and even speaker placement (to eliminate any room resonance). The problem was consistent and the culprit definitely seemed to by the PM6005 amp. Consequently I contacted the vendor and arranged to take the unit in to look at. They informed me that "this is a common problem in various amps, particularly at low volumes". Sure enough we tested it in store with other speakers and against another PM6005 and the problem seems to be inherent in the amp.

This is not a problem I've encountered before and I'm now unsure what to do as this undermines its very basic function in my opinion and is hugely disappointing. Equally I'm surpised this is apparently a 'common problem' and that people just live with it. I fully expect a £279 amp to be able to output on the left and right side equally! So what are peoples experience of this? What do you advise?

I would greatly appreciate any advice on the matter whilst I decide how to resolve it. Thanks in advance, Sidx

Photo:
https://dl.dropboxusercontent.com/u/74474385/Temporary/Hifi%20Test.JPG

Videos:
https://dl.dropboxusercontent.com/u/74474385/Temporary/Hifi%20Test%201.mov
https://dl.dropboxusercontent.com/u/74474385/Temporary/Hifi%20Test%202.mov
https://dl.dropboxusercontent.com/u/74474385/Temporary/Hifi%20Test%203.mov
https://dl.dropboxusercontent.com/u/74474385/Temporary/Hifi%20Test%204.mov
https://dl.dropboxusercontent.com/u/74474385/Temporary/Hifi%20Test%205.mov
 
Hi Sid

I've not watched all your videos but I 'get' your problem. Poorly matched channels tend to be much more obvious at lower levels. 6dB is too much in my book, and I think below satisfactory quality. Can you get a replacement?

If it is intrinsic, as your dealer implies, and you otherwise like the amp (which is after all well awarded and a big seller) you could consider a line attenuator to give you a greater use of the volume control, and minimise the problem zone at low levels. Snag is, last time i looked these were upwards of thirty quid, which is ten percent of the price! Rothwell is the brand i recall.

Please note, I am assuming this is mainly when using CD as source, but if LP too then I'd have to consider trying a different amp. The NAD D3020 or Arcam FMJ A19 are both costlier, but the speakers deserve the Arcam or similar.

i hope that helps.
 

siderealxxx

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Thanks for your reply. 6db is very audible to me and not reasonable as you say. I can get a replacement, but it's thrown the whole system into question now. I have these nice speakers and I need to find the right amp/cd within my budget. The Marantz looked too good to be true, so I'm disappointed it's proved problematic.

A line attenuator wouldn't work for me because the issue relates to all inputs and I'm using cd, phono, dvd, aux and digital. I like the Arcam sound but that and the CD player would cost £1300, nearly 3 times the Marantz and still no digital!

I dont one know what to do now. I'm waiting to hear from Marantz with any wisdom, but I already checked another PM6005 and it didn't seem any better to me.
 
The NAD would be worth a try then. Of course you don't 'need' a matching CDP, the CD6005 will be fine.

Don't be put off by the lower nominal power; they've been tested at around 60wpc. Cannot vouch for the sound match with B&W, however. Alternatively, at a budget price, the remote-free Rotel RA-10, imported by B&W. Should be available at around £300.
 

siderealxxx

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Will check the source direct in the morning.

the other optic I just found is the Rotel RA11 which has digital and I think a remote. Should pair well with the B&Ws but the reviews are hot/cold/lukewarm... Its a jump up in price too.
 

Covenanter

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Without in any way disputing what you have observed I find it hard to believe that a reputable manufacturer would be selling kit with a consistent major flaw. (I would take as much notice of most dealers as I would of the Daily Mail.) I would speak directly to Marantz on this.

Chris
 

siderealxxx

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My thoughts exactly Chris! I'm surprised this issue is so apparent and appears to be across more than just my amp. Admittedly I couldn't test the other amp in store as thoroughly, but I wasn't convinced by the result. I'm waiting a response from Marantz, but as a customer I have to exchange/swap sooner than later and my faith is quite dented.
 

Thompsonuxb

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I'm in the swap the amp out asap camp.

If you can hear the difference it's a fault.

Do make sure the 'balance' is centred though.

Marantz usually come with tone/balance control.

But start researching options - May be worth considering a receiver looking at your requirements.

Prepare to start auditioning.
 

Frank Harvey

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We sell a lot of these (in store and online), and I don't recall anyone having brought this issue up before, and that includes its predecessor, the PM6004. So either most people don't play at low enough volumes to notice, or it's not a consistent issue - I've certainly not noticed anything that major during demos. You could possibly come across a batch issue which might have faulty volume pots, which would of course be sorted out by the manufacturer.
 

friendly_ghost

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FWIW, I have now owned the amp for several months and have not noticed anything similar, even at lower volumes. So I don't think it's a general problem either...
 

Tannoyed

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Assuming it has a conventional volume control pot I would put it down to a mismatch in the linearity (logarity really, human hearing is logarithmic with regard to volume level) of the pots used in the two channels. A new pot should sort it, or indeed a new amp although these problems can be batch related. They must have had a dodgy batch of potentiometers. Get a replacement with a serial number substantially different to the one you have!

I have the same problem with a Cambridge Audio amp but just live with it-it is only a cheap one.
 

matthewpiano

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Must be faulty. I had a PM6005 for a while and never had any issues with balance, even at very low volumes. I am very sensitive to such issues and have come across them on other amps. Some Cambridge Audio models have terrible problems in this respect - the Topaz ones are every bit as bad as the old A-series models and the older Azur models. Only the more recent Azur ranges have rectified the issue by using quality ALPs volume pots. However I have never come across such issues on Marantz so I would say you need to get your amp changed as others have suggested above.
 

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