Here's an odd one

[Pieoftheday]

I have recently added a Cambridge audio power amp to my set up,I'm using a novafidelity x40 server as pre. When the volume shows 50 it's a nice level but when I go over 50, the volume reduces, any ideas? Cheers jim BTW, I'm not talking neighbour annoying levels

[sumday]

ANY chance you can put up the model number.
a possible problem could be a builtin distortion sensing circuit...this was, is fitted to the 540/640 series integrated amps and was prone to throwing a hissy.

my son went through THREE 640s purchased new from richer sounds...all developed the same fault before he gave up and swapped for a NAD.

I hope your power amp is not suffering the same problem!!

p.s., in the integrated amps, upon premature activation the motorised volume control would lower the output.

NIGE.

[sumday]

DOH....just noticed the mod number is in yer kit list!!!

NIGE.

[Pieoftheday]

Hi nigel, it's a 651w power amp

[Pieoftheday]

ANY chance you can put up the model number.
a possible problem could be a builtin distortion sensing circuit...this was, is fitted to the 540/640 series integrated amps and was prone to throwing a hissy.

my son went through THREE 640s purchased new from richer sounds...all developed the same fault before he gave up and swapped for a NAD.

I hope your power amp is not suffering the same problem!!

p.s., in the integrated amps, upon premature activation the motorised volume control would lower the output.

NIGE.

Cheers Nigel, thanks for your reply,I've emailed Cambridge audio due to your answer ,thanks Jim

[sumday]

a quick look online tells me your amp is fitted with CAP....the same type of sensing/protection circuit.
assuming all your cables/conections are in good shape, I would look in this direction.

fingers crossed.....NIGE.

[TazSob]

Hi James, have you checked the speaker connections to see if they've not been crossed or have the polarity swapped? Reminds me of a issue a customer had years ago in his car audio install... Once he would go higher than 16 on his cd player it would do what you described, it was as if the amp was getting some feed back from drivers and reducing the volume as a result. Once we re-wired his system the problem was no more

[Pieoftheday]

a quick look online tells me your amp is fitted with CAP....the same type of sensing/protection circuit.
assuming all your cables/conections are in good shape, I would look in this direction.

fingers crossed.....NIGE.

Ta Nige, cables are all good, quite new,though I'll make sure everything is hooked up proper tomorrow,thank you

[Pieoftheday]

Hi James, have you checked the speaker connections to see if they've not been crossed or have the polarity swapped? Reminds me of a issue a customer had years ago in his car audio install... Once he would go higher than 16 on his cd player it would do what you described, it was as if the amp was getting some feed back from drivers and reducing the volume as a result. Once we re-wired his system the problem was no more

Hi Taz, Im going to pull everything apart tomorrow, I'll feel a rite tit if that's all it is, cheers Jim

[Pieoftheday]

Well I've reconnected everything and the odd behavior remains, hmm

[struth]

The distortion sensing circuit sounds like the culprit. how loud is it before it goes into meltdown?

[Pieoftheday]

The distortion sensing circuit sounds like the culprit. how loud is it before it goes into meltdown?

good morning Grant,it really isnt very loud, on a scale of 1 to ten, 3 being normal tv listening id say 5. there are protection indicators on the front,but they arnt doing owt:scratch: it does seem that the cap5 is at fault as you say.

[struth]

certainly seems that way James. if its not even getting loud enough to distort then the thing must be faulty. does it have its own amp or is it just a pre. if it does you could see if it happens when under its own power only. might give you a clue

[Pieoftheday]

certainly seems that way James. if its not even getting loud enough to distort then the thing must be faulty. does it have its own amp or is it just a pre. if it does you could see if it happens when under its own power only. might give you a clue

its a power amp Grant, i using my novafidelty x40 server as pre, no problems using my previous quad 306

[Pieoftheday]

ive just noticed the ebay vendor i bought it from, AUDIO PARTNERSHIP, is Cambridge Audio's online sale shop, fingers crossed theyre ont ball

[Macca]

its a power amp Grant, i using my novafidelty x40 server as pre, no problems using my previous quad 306

Got to be a fault on the power amp then surely?

[Pieoftheday]

Got to be a fault on the power amp then surely?

I've just been driving the volume up and down around the 50 mark on my pre, when I get to 51 the volume reduces about 20%, but then I can continue to increase the volume up to party levels with no problem, other than the fact that I'm having to use more if the pre amps range to get there. The clipping and protection indicators show no issue?:scratch:

[Macca]

But it didn't do that with the 306? It is weird but if the only thing that has changed is the power amp then there's your culprit.

[Pieoftheday]

But it didn't do that with the 306? It is weird but if the only thing that has changed is the power amp then there's your culprit.

hi Martin, no prob when using the 306, i suppose the 306 will go in the' gear i wish i hadnt sold' thread:doh: to be fair other than this annoying problem the cambridge is very good i think

[struth]

some sort of impedence mismatch maybe causing it

[Arkless Electronics]

some sort of impedence mismatch maybe causing it

No. It can only be a faulty power amp if it doesn't do this with other power amps. There is no fault which could cause this in a typical power amp and so I guess it must be to do with this overload protector or some such. This will be specific to Cambridge Audio so that's the end of the line as far as fault diagnosis goes I'm afraid.

[Pieoftheday]

No. It can only be a faulty power amp if it doesn't do this with other power amps. There is no fault which could cause this in a typical power amp and so I guess it must be to do with this overload protector or some such. This will be specific to Cambridge Audio so that's the end of the line as far as fault diagnosis goes I'm afraid.

Hi Jez, apparently it was an issue with some older Cambridge amps so I think your right, no response from Cambridge audio or Audio partnership as yet:steam:

[Pieoftheday]

At the risk of going on a bit, playing music via the x40 hard drive things are louder given the same volume shown on the x40's pre display, so 50 shown is quite loud,going over 50 still reduces the volume almost like introducing an attenuator, I can then go loud without any harshness or distortion, I wish I had the technical know how to explain better. Incidently, when I then reduce the volume to the point at which the amp reduced volume itself, the volume increases!!!

[sumday]

further to my son's experience with his Cambridge amps fault, I was given the distinct impression that the staff were at least aware of a possible problem with the protection curcit.
they were reluctant on all occasions to replace the errant amp, amps and offered the usual "send it off to the repair dept"

I strongly suggest you stand your ground and if nessesary offer to show them the fault....DEMAND a refund.....its your right!!

good hunting....NIGE.

[Pieoftheday]

further to my son's experience with his Cambridge amps fault, I was given the distinct impression that the staff were at least aware of a possible problem with the protection curcit.
they were reluctant on all occasions to replace the errant amp, amps and offered the usual "send it off to the repair dept"

I strongly suggest you stand your ground and if nessesary offer to show them the fault....DEMAND a refund.....its your right!!

good hunting....NIGE.

Nige, still awaiting a response from the vendor which is Cambridge audios online shop and Cambridge audio themselves, it's an odd thing, like having 2 amps in one, up to a certain volume it's great but it's almost like it's reaching the point where it's not going to be comfortable soon and then someone sticks a 10db attenuator in and all is well, very well infact, it never sounds anything but good, just the strange reduction In Volume, all replies are most appreciated, jim

[Pieoftheday]

Still no reply from the seller or Cambridge audio, they must take the weekend off:steam:

[Barry]

Still no reply from the seller or Cambridge audio, they must take the weekend off:steam:

In my experience Cambridge Audio are very poor at replying to technical enquiries - in other words they don't reply at all! :(

[walpurgis]

In my experience Cambridge Audio are very poor at replying to technical enquiries - in other words they don't reply at all! :(

Pay budget prices and you get budget aftercare.

[Barry]

Pay budget prices and you get budget aftercare.

It was in connection with a friend's CD player, which was bought used at £800. Not quite budget price.

[TazSob]

Sorry to hear about CA messing you about. Try sending them a message on their Twitter page https://mobile.twitter.com/CambridgeAudio , some customers who have had issues with companies have had success making a public complaint on Twitter. I would link this page to it too to share with them your frustration about the whole incident.

[Pieoftheday]

Sorry to hear about CA messing you about. Try sending them a message on their Twitter page https://mobile.twitter.com/CambridgeAudio , some customers who have had issues with companies have had success making a public complaint on Twitter. I would link this page to it too to share with them your frustration about the whole incident.

Im not on twitter but i might be if i dont get anywhere! Ta jim

[Pieoftheday]

Pay budget prices and you get budget aftercare.

Ive bought much cheaper stuff and had great aftercare

[spendorman]

If bought on-line, I believe that gives some extra rights to you, like returning the item for a refund if within a certain time. Also paying by credit card, debit card, or Paypal, you should also have some protection.

I was going to offer to buy the 306, but see that you sold it. I have Quad II's 303's and a 405-2.

[struth]

They used to at least reply when i had a cambridge. Werent interested in fixing it mind as it was basically unfixable. Apparently they all went this way and repair was silly money.
Put me off them i have to say. But they are not alone in this. Good customer service from manufacturers is getting thin on ground.

[Pieoftheday]

If bought on-line, I believe that gives some extra rights to you, like returning the item for a refund if within a certain time. Also paying by credit card, debit card, or Paypal, you should also have some protection.

I was going to offer to buy the 306, but see that you sold it. I have Quad II's 303's and a 405-2.

i bought via ebay seller HIFI Specialist/Audio partnership which seems to be cambridge audio's online shop and parent company, the seller asked me to contact cambridge audio customer services which i did, who asked me to take it to richer sounds to be serviced!! which clearly i wont be doing, i have asked them to arrange to collect the amp, watch this space...........

[spendorman]

Yes, whoever you paid money to is responsible. I believe you can demand a refund within 30 days as it's faulty.

[Pieoftheday]

Yes, whoever you paid money too is responsible. I believe you can demand a refund within 30 days as it's faulty.
I'd happy for it to be repaired if possible as it's an otherwise cracking amp

[spendorman]

I'm not sure, but once you allow them to repair it and they get it wrong, you have to allow them another chance to fix it again rather than getting a refund. Perhaps someone knows definitely.

[Pieoftheday]

well, after a few emails Cambridge Audio are going to collect the amp, i suppose these things are best done face to face or at least over the phone,but fair play theyre on it now:)

[spendorman]

Excellent, I would take photos of it's condition as it is now, and get a receipt from whoever collects the amp.

[Pieoftheday]

Excellent, I would take photos of it's condition as it is now, and get a receipt from whoever collects the amp.

You read my mind Alex, photos taken!!!

[Pieoftheday]

Well Cambridge Audio have been very good and I have a new replacement amp:) without even checking the one I sent back,it's a really good amp, however, the issue is still present. Of course it could be a second 'faulty' amp but I now doubt the first was faulty.could it be a compatibility issue with my digital pre?

[spendorman]

Sorry to hear that you still have the same problem, what speakers are you using? Had a quick look back and didn't see.

[Arkless Electronics]

Almost certainly there is no fault then. It seems they do that...

[Pieoftheday]

Sorry to hear that you still have the same problem, what speakers are you using? Had a quick look back and didn't see.

At the mo some cheap n cheerful wharfedale diamond 10.1, but swapped in my usher s520's just to see

[Pieoftheday]

Almost certainly there is no fault then. It seems they do that...

Hi Jez, when you say it seems they do that, do you mean you've heard of it before or it's just one of those things? BTW, how's your new power amp coming along? Jim

[spendorman]

I see that the Wharfedale's nominal impedance is 6 Ohms, this is a bit lower than a normal nominal 8 Ohm load, perhaps this is triggering the protection. Not so good if this is so.

[walpurgis]

I see that the Wharfedale's nominal impedance is 6 Ohms, this is a bit lower than a normal nominal 8 Ohm load, perhaps this is triggering the protection. Not so good if this is so.

Seems likely.

Try another amp or higher impedance speakers perhaps.

[Arkless Electronics]

Hi Jez, when you say it seems they do that, do you mean you've heard of it before or it's just one of those things? BTW, how's your new power amp coming along? Jim

I mean it would appear to be "just one of those things".... If two samples do exactly the same thing and if it sounds great then I wouldn't worry about it ;)

The power amp is sounding good ("petrat" of this parish has heard it at my place, but not commented as far as I know... maybe he didn't like it!? gawd knows.. probably as both the entire system and the room acoustics are unfamiliar to him he's understandably chosen to say nowt) and has had quite a few changes to it so far.

I'm currently working on 3 different avenues of investigation (yes 3 amps) which are completely different from each other and I'll report in my trade area when I feel I've made a major breakthrough... or not! The major issue is the old, old story.... although we can measure all sorts of parameters, beyond the point where the measurements confirm that an amp is at least fairly competent, they say pretty much nothing about how it will sound. This means that in spite of all the computer simulation and doing measurements on a lashed up single channel of the amp, ultimately one has to build an actual working stereo prototype and audition it! All very time consuming and also most frustrating when , after maybe 20 hours of work to build something solid enough to properly audition it... it sounds not much different to the last amp... or a bit worse... or maybe slightly better but you've listened to so many changes in a short time you no longer trust your own ears to be right and need a break from it.... All good fun :scratch::D:doh:

[Pieoftheday]

I mean it would appear to be "just one of those things".... If two samples do exactly the same thing and if it sounds great then I wouldn't worry about it ;)

The power amp is sounding good ("petrat" of this parish has heard it at my place, but not commented as far as I know... maybe he didn't like it!? gawd knows.. probably as both the entire system and the room acoustics are unfamiliar to him he's understandably chosen to say nowt) and has had quite a few changes to it so far.

I'm currently working on 3 different avenues of investigation (yes 3 amps) which are completely different from each other and I'll report in my trade area when I feel I've made a major breakthrough... or not! The major issue is the old, old story.... although we can measure all sorts of parameters, beyond the point where the measurements confirm that an amp is at least fairly competent, they say pretty much nothing about how it will sound. This means that in spite of all the computer simulation and doing measurements on a lashed up single channel of the amp, ultimately one has to build an actual working stereo prototype and audition it! All very time consuming and also most frustrating when , after maybe 20 hours of work to build something solid enough to properly audition it... it sounds not much different to the last amp... or a bit worse... or maybe slightly better but you've listened to so many changes in a short time you no longer trust your own ears to be right and need a break from it.... All good fun :scratch::D:doh:

Cheers Jez, i have chosen not to worry about it:) good look with your endeavour!!

[spendorman]

You might try connecting your speakers in series so as to increase the impedance, just to see if this changes the situation.

[Pieoftheday]

I see that the Wharfedale's nominal impedance is 6 Ohms, this is a bit lower than a normal nominal 8 Ohm load, perhaps this is triggering the protection. Not so good if this is so.

Apparently wharfedale recommend amps from 20w to 100w so the Cambridge should have no problem

[Pieoftheday]

Well just on the off chance I contacted Novatron Korea, designers of my preamp/server, and explained the issue,I got a simple one sentence reply, we will clear this bug via the next firmware update at the end if the month. Thanks for all your replies:cool:

[struth]

A suggestion its not first complaint then, and that its a software problem reducing the output

[Pieoftheday]

A suggestion its not first complaint then, and that its a software problem reducing the output
So it would seem Grant,a problem they must have been aware of if they're preparing a fix,it's odd the issue didn't show up whilst using my quad 306 which is why I thought it must be the Cambridge 651w, you live n learn eh

[walpurgis]

The Quad 306 has pretty high input sensitivity. You probably didn't have the levels as high for the same volume.

[Pieoftheday]

The Quad 306 has pretty high input sensitivity. You probably didn't have the levels as high for the same volume.

Very possibly,at least it's another one of life's niggles I'll be able to cross off the list:)

[Pieoftheday]

New firmware released and installed,:cool:

[TazSob]

New firmware released and installed,:cool:

How you finding the update, has it sorted the cut out James?

[Pieoftheday]

How you finding the update, has it sorted the cut out James?

Hi Taz, yes all sorted, took about 5 minutes, cocktail audio in Korea were very helpful:)

[TazSob]

Hi Taz, yes all sorted, took about 5 minutes, cocktail audio in Korea were very helpful:)

Nice one, it's good to know what fixed it and even better that it was sorted by an software update. You can go back to enjoying your kit without having to send it out for repair. :cool: