CA 640A volume

[admin_exported]

Maybe one for Mathewpiano or other CA owners....

I've just noticed that at very low volume my CA 640A has more output through the right hand speaker. As I increase the volume from zero the sound gradually balances to both speakers. At normal listening level and above it is fine and you would never know until I turn it way down again.

Is this the same fault which is mentioned in the CA34A thread?

Is it fairly common place?....Somewhere recently on WHF I read someone with a NAD amp was having the same problem.

Is it a problem which could become worse?

Any info appreciated.

 

[obithius]

Hi,I have the same amp,and the same issue at very low volume.As I turn up the volume from zero it comes from the right first,then left.

All I have found to work is to turn it up a little too loud, and then back down to where I want it,seems to level off.

 

[matthewpiano]

This is a common issue on the CA A5, 340A, 340A SE, 540A, and 640A. I also experienced it particularly severely in a short daliance with their Topaz AM1.

It is down to the volume control and the way in which it is designed. Basically, it doesn't track channel balance properly at low levels. It is the main reason why I gave up on CA amps.

Newer models which have the Alps Black Box pentiometer (350A, 550A and 650A) and higher-range models (740A and 840A) don't have this problem.

There is no reason why it should get any worse. I couldn't cope with it because I sometimes listen at fairly low levels and I seem to be particularly sensitive to balance and soundstaging problems, but if it sounds fine at your normal listening levels I wouldn't worry too much.

I have had several NAD amps (C325BEE, C326BEE and a couple of older models) and never found a problem with those but I tried a Denon PMA-510AE for a couple of weeks and found it a big problem on that amp.

 

[Big Chris]

If it's a problem, why not purchase some attenuators?

Rothwell attenuators can be bought for around £40. These are fitted on the end of the interconnects (amp end is preferred), and drop the input level by 10db. This means you have to turn the volume knob up further to get the same volume levels from the speakers.

Sounds like just the ticket to get your volume out of the mismatched channels zone. Also helps if you find that turning the volume knob means you go from a fraction too quiet to a fraction too loud.

Only issue is you'll need a pair for each input on the amp you're using (CD, Tuner, etc, etc)

 

[Anonymous]

Agree with Big chris, I had the 340A and noticed the same thing at low volume's (late at night).

The attenuators solved the problem. Didn't want to blow £40 tho so I bought some from Ebay for £10. They looked and worked great.

It really only effected the CDp the tuner and TT seemed to be ok for some reason.

Eventually upgraded to the 740A and at low volume's the problem wasn't there.

Regards

 

[SteveR750]

GWindy:Agree with Big chris, I had the 340A and noticed the same thing at low volume's (late at night). The attenuators solved the problem. Didn't want to blow £40 tho so I bought some from Ebay for £10. They looked and worked great. It really only effected the CDp the tuner and TT seemed to be ok for some reason. Eventually upgraded to the 740A and at low volume's the problem wasn't there. Regards

I wonder if stuffing a £10 ebay item in the signal path really has no effect, if only that there is a reason why amp and i/c designers spend so much time developing their products in the first place!

 

[Anonymous]

Last week I had to return my CA 650 V2 to Richer sounds as the motorised volume control stopped working. The returned 650A and the replacement unit both have the same unbalance at very low volume.

 

[Anonymous]

just to clarify I bought the Rothwell items from ebay. In the back of my mind I didnt see how they could fix problem - had searched the net and come across lots of people with similar issue's. i didnt want to waste £40 in case they didnt work, so i lived with it till I could try some cheaper. The 340A was always just an experiment, I'd often wondered if a 'proper' hifi would sound differet to what I had. Figured it wasnt too much money to spend on amp (and matching CD) as my old system (15yrs old) had just died. needless to say I was blown away and then the path to selling on and moving up began. Would have saved a lot of money if I had just stopped with the attunators!!

 

[Anonymous]

This feedback is interesting and also disappointing as it suggests a fundamental design and manufacturing issue. I've come to enjoy my 640A on a 'bang for buck' basis but obviously not at low volume.

I can't understand how such an issue can find it's way through to market. Maybe someone from RS would like to explain/comment?

I have spoken to customer service at RS and they were receptive to my complaint but as expected "knew nothing" of this problem

Yeah and Right spring to mind.

 

[Anonymous]

Nooby, Matthew and others,

Firstly I am really to sorry to hear of your problems with the volume controls at low level on some of our now discontinued amplifiers.

This did affect some of our *40 amplifiers and as others have said is not uncommon across many brands due to the potentiometer manufacturing process and the high cost of tighter tolerence parts from manufacturers such as Alps. over the past few years we have sold many tens of thousands of *40 series amps and I can assure you we have not had complaints of an epidemic nature (although from time to time people have for sure raised the issue on their product).

When designing our *50 series amps we took the decision to specify expensive Alps potentiometers to eliminate completely any future complaints. And since launch I have not heard of any customer having a channel balance issue. Bladesmith, if you be kind enough to contact me via the Customer Care web interface I'd like to arrange a replacement 650A so we can investigate the issue you report on your amp.

Thanks,

James Johnson-Flint, CEO, Cambridge Audio

 

[Anonymous]

Hi James

Thank you for your input here.... I will write to the email addy you have provided about my 640A.

Best wishes

Mike

 

[Anonymous]

Is this resolved? Is there a problem with the 650A volume as well as the 640A? CA say it was 'designed out' yet this one poster on this thread says he DID have the same low volume issue as that noted on the 640A with his 650A. This is putting me off a 650A purchase, as is the report of motorised volume knob problems

 

[Anonymous]

Hi Hawkmoon,

Yes, this was 'designed out'. As James mentions in his earlier post, this did affect some of the 640 amplifiers. He also points out, with the 550 and 650 series amps we took the decision to use expensive Alps potentiometers to eliminate completely any future complaints about this.

Since launch we have not heard of a single customer having a channel balance issue with the 550A or 650A amplifiers. We have also not had any customer with a 650A contact us through our support centre to report this.

I would urge anyone thinking of purchasing a 550A or 650A to contact their local dealer and audition the unit if they are concerned, and they will hear that this is no longer an issue.

Thanks

 

[Anonymous]

Thanks for your reply - but are you suggesting Bladesmith is imagining that he had a balance problem on his 650A ?

BenBeaumont:

Hi Hawkmoon,

Yes, this was 'designed out'. As James mentions in his earlier post, this did affect some of the 640 amplifiers. He also points out, with the 550 and 650 series amps we took the decision to use expensive Alps potentiometers to eliminate completely any future complaints about this.

Since launch we have not heard of a single customer having a channel balance issue with the 550A or 650A amplifiers. We have also not had any customer with a 650A contact us through our support centre to report this.

I would urge anyone thinking of purchasing a 550A or 650A to contact their local dealer and audition the unit if they are concerned, and they will hear that this is no longer an issue.

Thanks

 

[Anonymous]

Not at all, but Bladesmith has stated his/her model as being a CA 650 V2, which doesn't exhist. I'm suggesting that perhaps this was a typo, and he meant 640A v2.

Additionally, no customer/forum member has contacted us about a problem with a 650A, as per James' invitation.

 

[Anonymous]

Any comment on the motorised volume control being faulty on two brand new units, as reported by Bladesmith? Have you no reports of this on the 640 or 650?

BenBeaumont:

Not at all, but Bladesmith has stated his/her model as being a CA 650 V2, which doesn't exhist. I'm suggesting that perhaps this was a typo, and he meant 640A v2.

Additionally, no customer/forum member has contacted us about a problem with a 650A, as per James' invitation.

 

[Anonymous]

This certainly isn't something I've ever seen or heard about on a 650A.

I'd simply recommend auditioning the 650A to see and hear it for yourself if you are in any way curious about it.

 

[Anonymous]

Yes I will do - it has received a lot of praise and it is on my shortlist.

Don't suppose you might comment on whether it is a poor match though, for my KEF iQ5Se speakers? The speakers have been described as bright and some say the 650A is as well...

BenBeaumont:

This certainly isn't something I've ever seen or heard about on a 650A.

I'd simply recommend auditioning the 650A to see and hear it for yourself if you are in any way curious about it.

 

[Anonymous]

I'm afraid that I have never heard the Kef iQ5 SE speakers, and would be unable to comment on their sound and system matching requirements. Again, I would recommend an audition of these and the amplifier to hear them for yourself.