lol. I will take some pics when I "finalize". It looks horrendous at the moment, i've just been experimenting.
Lee.
Lee.
Thomo said:
No problem always good to help.
It was interesting how the implementation of the discrete on both the V1 and V2 was the same but with differing output levels which we sorted with different input attenution before the fets.
Brent
It's not +/- voltage. There as most dacs are +5V digital supply and +5V analogue supply.
Realistically both on each dac need replacing. But I always find replacing dac analogue brings the biggest gains so therefore is always changed first.
With regard to your other question I cannot answer from home, I would need to see the cdp and sch.
Brent
Realistically both on each dac need replacing. But I always find replacing dac analogue brings the biggest gains so therefore is always changed first.
With regard to your other question I cannot answer from home, I would need to see the cdp and sch.
Brent
Just another update...
I just finished removing all the regs etc from my (broken) Marantz.
I have fitted my Superclock4 now, whilst fitting this I also removed the Sch(m)itt Inverter 74HC14 Chip, which was used to split & buffer the clock signal. The clock is now direct to the dac and also feeds the servo direct. This has improved things no-end. Treble is much cleaner (still not good enough though).
The discrete output stage is just a buffer with no filtering at the moment. Whether this is a good thing I don't know, but it certainly sounds far better than the opamps.
Adding more tx's has made quite a difference, Cambridge's original design is awful with all those regs supplied by one voltage rail.
Sounding very nice now, but still not near the Marantz CD67 yet!
Going to look into whether or not the Servo board can be re-clocked a-la cd63.
Lee.
edit: I think that the clock buffer bypass can also be implemented in the 740 too.
I just finished removing all the regs etc from my (broken) Marantz.
I have fitted my Superclock4 now, whilst fitting this I also removed the Sch(m)itt Inverter 74HC14 Chip, which was used to split & buffer the clock signal. The clock is now direct to the dac and also feeds the servo direct. This has improved things no-end. Treble is much cleaner (still not good enough though).
The discrete output stage is just a buffer with no filtering at the moment. Whether this is a good thing I don't know, but it certainly sounds far better than the opamps.
Adding more tx's has made quite a difference, Cambridge's original design is awful with all those regs supplied by one voltage rail.
Sounding very nice now, but still not near the Marantz CD67 yet!
Going to look into whether or not the Servo board can be re-clocked a-la cd63.
Lee.
edit: I think that the clock buffer bypass can also be implemented in the 740 too.
Very interesting, Im considering a seperate power supply for the digital side, clock and DAC's.
I would get a good quality reg on the dac analog and/or fit a good clock before fitting extra power supplies, Mike. This will give you the best bang for your buck and what you've done so far will let those mods shine.
Lee.
Lee.
Yes of course.
Plan is to upgrade the opamp regs, then the clock, followed by better DAC regs. Then a dedicated supply to the DAC's and clock.
Plan is to upgrade the opamp regs, then the clock, followed by better DAC regs. Then a dedicated supply to the DAC's and clock.
So these caps are 100pf ceramics, do they needto be ceramic for a reason or can I put something better in there? Obviously they are right in the signal path (C32.C34) so they will have an effect on the sound.
Anyone able to enlighten me here?
I found out that these smaal ceramic caps are not in the signal path but shunt the output to ground when the mute relays are closed, I think.
I read on another forum that adding film caps across the -/+ pins on the opamp can give a smoother sound and a little more bass. These are slight issues I have at the moment so I'd like to try it. Can anyone comment or advise here?
I read on another forum that adding film caps across the -/+ pins on the opamp can give a smoother sound and a little more bass. These are slight issues I have at the moment so I'd like to try it. Can anyone comment or advise here?
Did you fit the Black Gates right next to the opamps? If you did then the small bypass cap on the opamp pins may not be a good idea, as it will essentially be bypassing the BG's. As in all things audio, try it and see. 220nF PPS caps are very good for using under the opamps.
Lee
Lee
Yes, I fitted the 10uf as Brent recommended. Do you think adding a larger cap there might have the same effect, smoother, more bass?
PS. Did you get my emails on the BG Nx,s and rubycon ZLH?
PS. Did you get my emails on the BG Nx,s and rubycon ZLH?
Brent.
Can you confirm which caps your using for the main smoothers and on the dac's - the ones to the left of the 'digital' regs. Its a ZLH but not sure what value's?
Can you confirm which caps your using for the main smoothers and on the dac's - the ones to the left of the 'digital' regs. Its a ZLH but not sure what value's?
On the unit @ work I used 470uF ZLH for dac digital and BG std for the dac analogue.
Also using the 10uF BG on all the opamps does not suffer the player in any way. Don't get yourself too bogged down in all the values. The biggest difference is always found in the quality of the parts.
Brent
Also using the 10uF BG on all the opamps does not suffer the player in any way. Don't get yourself too bogged down in all the values. The biggest difference is always found in the quality of the parts.
Brent
Cheers Brent.
I have an old 'Opus' multiroom controller upstairs and a couple of local amp modules. The main unit has the same casework that CA use on the Azur range although its branded 'Mordaunt short' I couldnt resist a peep inside it as I am plannig an amp build soon and need some bits.
I wasnt suprised to see the name 'audio partnership' on all the boards. Theres lots of usefull stuff in there, A huge tx and another smaller one. Heatsik, NE5532 opamps, etc. not to mention the case itself. Its simmlar to the case on the 740/840 range.
The biggest suprise I found was the poweramps using 2 x 50v 4700uf Rubycons per channel. Im going to borrow 2 for the PSU of my 640C, if they'll fit that is.
All the other components were the usual cheap stuff I think, a trained eye might spot some other goodies though.
Wondering if I can use the amp modules for my old Missions, had a look inside, going by the markings on the pcb it needs 24v. Not sure where to feed it though, the module has one of those multipin colour coded computer sockets. If I can get them working then I have something decent for the PC. Great for playing CMR2!
I have an old 'Opus' multiroom controller upstairs and a couple of local amp modules. The main unit has the same casework that CA use on the Azur range although its branded 'Mordaunt short' I couldnt resist a peep inside it as I am plannig an amp build soon and need some bits.
I wasnt suprised to see the name 'audio partnership' on all the boards. Theres lots of usefull stuff in there, A huge tx and another smaller one. Heatsik, NE5532 opamps, etc. not to mention the case itself. Its simmlar to the case on the 740/840 range.
The biggest suprise I found was the poweramps using 2 x 50v 4700uf Rubycons per channel. Im going to borrow 2 for the PSU of my 640C, if they'll fit that is.
All the other components were the usual cheap stuff I think, a trained eye might spot some other goodies though.
Wondering if I can use the amp modules for my old Missions, had a look inside, going by the markings on the pcb it needs 24v. Not sure where to feed it though, the module has one of those multipin colour coded computer sockets. If I can get them working then I have something decent for the PC. Great for playing CMR2!
Brent.
I would like to place an order today but need your advice beforehand.
Im not sure if I should get the C1 clock or the Spower for the opamps first. (I'll be ordering some BG Nx for the DAC's from Lee once he confirms what values I need for decoupling and
smoothing)
If get the clock and the regs It will probably be too much to afford this month so which should I get first?
Also can you tell me if the 4700uf 50v Rubycons I found will be ok for the main PSU. (theyre not ZLH and I found them in a power amp)
PS. Im doing the attenuation you reccomended also. Do you have the resistors I need and if so, can I buy some from you?
I would like to place an order today but need your advice beforehand.
Im not sure if I should get the C1 clock or the Spower for the opamps first. (I'll be ordering some BG Nx for the DAC's from Lee once he confirms what values I need for decoupling and
smoothing)
If get the clock and the regs It will probably be too much to afford this month so which should I get first?
Also can you tell me if the 4700uf 50v Rubycons I found will be ok for the main PSU. (theyre not ZLH and I found them in a power amp)
PS. Im doing the attenuation you reccomended also. Do you have the resistors I need and if so, can I buy some from you?
Hi Mike
I would get the 2 SPowers on the opamps first to finalise the work you have already put in.
Those caps will be fine also.
I have 2 used 10K and 2 new 6K8 in my draw. I'll chuck em in FOC with your order.
cheers
Brent
I would get the 2 SPowers on the opamps first to finalise the work you have already put in.
Those caps will be fine also.
I have 2 used 10K and 2 new 6K8 in my draw. I'll chuck em in FOC with your order.
cheers
Brent
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