Cambridge Audio A1 mk3 upgrade mods

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i once replaced the power supply caps with two DNM (BHC) slit foils (not the t-network, the normal ones). I'm sure they could be had quite a bit cheaper there since they are UK company i believe. And the opamps in the preamp to burr brown opa2604's and let me tell you the amp turned into a monster while retaining all of it's typical strengths. It made it super punchy and sent heaps of energy out the speakrs. In fact i'm on the lookout for a used one here in Canada so I can do that mod to it. Best amp i've had. I do'nt know why you wanna take out the tone controls.. they are useful and sound great.
 
Thanks for the reply, do you happen to know the cap and op amp ID's on the PCB?

It is a cracking amp even in it's standard form and well built, too much HiFi snobbery around if you ask me.

Generally I don't use the tone controls so would like to bypass them and maybe fit a switch so I have the option.

Best Wishes
Tom
 
Well when you open the case, the board closest to the front plate is the preamp circuit. There are two gold rectangular covers which will have to be removed to get to the opamps. These covers don't really serve any purpose other than looking cool. I think i cut mine off with some heavy duty wire cutters. There is one opamp under each cover.. you cannot miss them. They are ne5532's.

As for the power supply caps, you cannot miss them either. They'll be the biggest in the amp. I have to mention though that I've had two of these amps at different times and one of them had two large filter caps (around 5000 to 10000 uf each) and the other had two banks of four 2200 uf caps. I hope for you it's just the two caps as it'll make it easier to wire up.

You will have to take out both the circuit boards (the amp and preamp) to work on them. Which in this amp involves taking the knobs off, severing the power wires, taking out quite a few screws and i'm sure other things i cna't think of now.. but if you do it all in order and keep it neat it's not that difficult at all. Well worth it.

I actually remember wanting to do the same as you with the first amp i had.. to bypass the tone controls but i never got to it. You may be able to bypass the preamp board altogether by rearranging the jumper cables that connect the boards. But I'm really not sure of that, so do that at your own risk!
 
Had a look last night my amp has two groups of 4 caps all 2200uf 35V.

Had a look at BHC slit foil caps and they don't appear to do anything less than 10,000uf (excluding the large 200v + ones).

I suppose I should look for low or ultra low ESR caps as BHC slit foil are aprox 0.06m'ohms and low ESR are aprox 0.1m'ohms, so anyhting less than 0.1m'ohms should be almost as good unless you know of anything.

I haven't removed covers from op amps as they look soldered from underside but I assume they are DIP and not surface mount??

Tom
 
Hey.. that's unfortunate.. I don't know of any caps that fit that bill. I'm actually not sure what's so special about the DNM ones. I just know they sounded great. Here at the parts connexion they call them premium power supply caps. And I don't recall any DNM markings on them either.. just BHC. I also am not sure if you could somehow just use two 10,000 uf ones and somehow rewire into the existing places.. a circuit diagram and someone more knowledgeable in electronics might be able to help.

The covers are indeed soldered from underneath and yes the opamps are DIP not surface mount. I just installed adapters so you can plug in different chips easily. If i could get this amp here in Canada I would. But now you got me thinking i might have to damage my bank account and get the one i can get cheapest here which is the azur350 now. It has lm3886's i believe not tda1514's. It worries me a little.. i think the lm3886s are mosfet output and the tda1514s are bipolar output which may have something to do with its gutsy sound. I could be wrong though.

Mind you.. i did both these mods at once and i always assumed that it was the caps that made the amp sound bigger but now that i'm actually recommending it to someone maybe i should suggest that if you are going to do a mod that you do the op-amps first as it's the cheaper and easier mod. I suppose it is possible that they were responsible for the majority of the difference. Let me know how it goes if you go ahead with it... Mladen
 
Thanks, I'll leave at the op amps which I hopefully will be ordering today as I'm also ordering parts to make a Kwak Clock 7 (low jitter clock) for my CD player.

I'm also going to fit a schaffner mains filter to the rear of the amp.

Fitted one to my cd player, seemed to help wiht the sound but not sure could have been placebo effect.

I have one lying round so it's not going to cost me anything to fit it.

Will let you know when done.

Thanks,
 
Cool.. I'd still install a DIP adapter so you can swap opams easily. That way you're not heating the opamp with your soldering gun too. If you're referring to THD, in my experience it doesn't correlate to sound quality. I have a preamp, a Morrison elad, which has (had) two AD797's in it, which may still be the lowest noise opamp out there. But it still tends to sound hard and unmusical. So i took them out and put opa627's in there. And while you can tell that it probably has a color to it, to me it sounds waaay better. There probably aint that much difference between it and and the opa2604. Except the price. But i'm curious about the LM4562. I haven't got any new opamps since the companies were still sending out free samples! That's how i got my 627's!
 
Just spent the morning fitting a schaffner mains filter and replacing all the left and right channel screened cables with some very high quality silver coax, also replaced the left and right speaker out wires with same coax (inner and outer twisted togther for each) and ran direct route under PCB.

Will fit the op amps when they arrive from Canada (it was a LOT cheaper than ordering from Farnell)

Tom
 
Well just changing the cables and adding the filter has brought the mid range right forward, really surprised at the difference has taken some getting used to (not sure if I liked it at first). Seems to have cleaned the treble ever so slightly too, not sure how replacing such short cable could make this much difference.

Will have to see what changing the opamps does when I get them.

Tom
 
I use LM4562 on my cd upgrades now and I reckon it's a superb op-amp for the price. Of course you could fit dogs and go upmarket with 2 single op-amps per channel but it's costly and i'm not sure it's worth it. I think if you can fit two 10,000uf caps in place of those four 2200ufs you will get get great results but you might have to mess around to get them in. Barry
 
Base is tighter and a tad more of it, mids and highs a bit cleaner with a bit more detail or may be that's because they're cleaner, at first my impression was the sound is harder but then I realised it's because the sound is more natural.

I suppose the sound will improve slightly as the op amps get run in but so far very impressed and pleased with my little project.

Will be fitting more of same op amps in my cd payer tomorrow.

Tom
 
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