Cambridge Audio 640C v1 Mods

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#123
Mike if you order another pair of opamps i'll not charge you delivery if that helps. The gains will be loads better than changing just the 2 final ones.
Click to expand...

Hi Brent.

I ordered another pair of opamps. Thanks.

I'll be following your mods in the latest pic you posted.

I also have a bunch of BG's coming soon. Thanks Lee.

I have 12 x 10uF Bg's for the opamps. 2 x 470uF for the power supply. and another pair of 220uF for the DAC's.

Where should I look next? Maybe an Spower for the clock?

GF is pissed about me spending money so I'll have to do mods a little bit at a time!

Thanks to all here for your help so far.
 
#124
Mike, one of the things you should do is replace the voltage regulators with 12v versions, 15v is very close to the 16v caps limit. In the past I have accidentally run a 16v BG at ~16.7v for months and it was ok, but it's best not to take the risk.

Lee
 
#125
neda said:
Brent,

When you "fit the SPower regs onto the opamps" will you use
a 12v or 15v regulator?

Ned
Click to expand...

I have been testing with 12V and 15V SPowers and the caps are ok with the 15V. The main thing though is the sound quality and there is no difference between the two voltages so I think the 12V will be used.

Using 16V Black gate caps over 25V saves quite a few £££

Brent
 
#126
mikesnowdon said:
Nice one Brent.

Could you discribe how you did the psu caps? I noticed there is an additional pair?

Cheers, Mike
Click to expand...

I had to drill 8 new holes in the pcb to fit these caps and link them underneath. I may have a go @ using some BHC Aerovox (like Naim) on the next one I do and mounting these next to the pcb. The main smoothers are rubbish and very small in the CA and makes it difficult to do a simple upgrade.

Brent
 
#127
mikesnowdon said:


Hi Brent.

I ordered another pair of opamps. Thanks.

I'll be following your mods in the latest pic you posted.

I also have a bunch of BG's coming soon. Thanks Lee.

I have 12 x 10uF Bg's for the opamps. 2 x 470uF for the power supply. and another pair of 220uF for the DAC's.

Where should I look next? Maybe an Spower for the clock?

GF is pissed about me spending money so I'll have to do mods a little bit at a time!

Thanks to all here for your help so far.
Click to expand...

Got your order thanks, I have instructed Sarah in admin to credit you back your postage as promised.

Your best areas for SPower are either 2X reg for opamp supply or 2X reg for Dac analogue. Or all 4 😀 😉 Opamp supply is quite critical in these players due to the poor supply and the gains are big.

P.S Best not to tell her anything - or take a note of all the clothes , hand bags , shoes and magazines she buys etc etc. A bit of ammo is always good

Brent
 
#128
I had to drill 8 new holes in the pcb to fit these caps and link them underneath. I may have a go @ using some BHC Aerovox (like Naim) on the next one I do and mounting these next to the pcb. The main smoothers are rubbish and very small in the CA and makes it difficult to do a simple upgrade.
Click to expand...

Did you use an additional pair due to the increased size over the standard caps? eg: 1x2000uF replaced by 2x1000uF?

Im thinking of going for Panasonic FC'c if I can get them in.
 
#130
Hi Brent.

I noticed theres a large resistor next to the PSU Caps. I found these and thought it might be worth a try. Do you know if they are suitable?

I also noticed a few resistors around the main opamps, and near the coupling caps. What about replacing them with the Kiwame?

Thanks in advance.
 
#134
Understood.

Im expecting my bits any time soon. Im going to hold back on the install. I have Jantzen Cross caps and new resistors on order for my speakers. I'm going to change them first so that when I do the mods on the CDP /i'll be able to hear the difference better.

Does anyonme know if Kiwame resistors would be suitable for crossover networks?
 
#139
Brent,
Did you decide against the 12v regs for any particular reason?


Mike,
I've used the Kiwame resistors in my "Curcio" Dynaco MK3
with very good results. Nice sounding and very close tolerance,
But I believe they come in only 2 & 5 watts.

Ned
 
#140
Hi Ned.

Do you know if 5w is ok for crossover networks? My amp gives 45w p/ch is if its relevant.

Brent,

I have 4 x 220uf bg's. I see in your pic there are 2 near the digital supply regs. I'll put 2 there as in your picture. Thing is, im not sure what to do with the other 2? I was thinking of putting one on the clock supply? What do you advise.

Thanks in advance!
 
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