philpoole said:
Do you own shares in Veroboard???
and to think I was worried about breadboarding some stuff when I get home !!!!!!
Andy
I'm sure PCB is far more elegant and more suitable for high frequency work. But so far, so good. I'm sure absolute perfection would require PCB, but no major complaints at the moment.
Yes, it's deliberately modular. My first NOS DAC was all on one board, which made it tricky to extend, so I started again, and deliberately did in modules. That's been handy for swapping out the SAA7220 for a PMD100 for instance, and I can revert back if I want to (not sure why I'd want to at the moment).
Another part I want to change one day is the analogue stage, so its good to swap it out.
It would be nice to have it so the DAC board doesn't overhang the front of the box... ...one day😉
Yes, it's deliberately modular. My first NOS DAC was all on one board, which made it tricky to extend, so I started again, and deliberately did in modules. That's been handy for swapping out the SAA7220 for a PMD100 for instance, and I can revert back if I want to (not sure why I'd want to at the moment).
Another part I want to change one day is the analogue stage, so its good to swap it out.
It would be nice to have it so the DAC board doesn't overhang the front of the box... ...one day😉
with simple DACs like the TDA's - I find it is often easier to just use bare matrix board and hardwire underneath using solid core insulated wires. - gives you the best of all worlds - you can kind of 'design' the board better - it looks neat (ish!) from above - and it is also very easy to swap things around when you need to.
Well it works for me 😀
Mind you, I started with a NOS DAC intentionally because, at 2 and a bit MHz, you shouldn't have any serious trouble with stripboard. Then I eventually managed to get the 7220 working without any problems (with regard to board type, I obviously had problems with lethargy 🙂 ), so never worried about exotic PCBs.
Besides how many Kwak Clocks are there out there in point to point?
It's currently a bit untidy as I tacked an extra 1541 on the DAC module, with 4 wires in air to the second chip - so not ideal layout. Now I know what I like, I think there's merit to do a new board populated with the 2 DACs (or maybe more 😀) and digital filter.
I'm always distracted by other things though.
Mind you, I started with a NOS DAC intentionally because, at 2 and a bit MHz, you shouldn't have any serious trouble with stripboard. Then I eventually managed to get the 7220 working without any problems (with regard to board type, I obviously had problems with lethargy 🙂 ), so never worried about exotic PCBs.
Besides how many Kwak Clocks are there out there in point to point?
It's currently a bit untidy as I tacked an extra 1541 on the DAC module, with 4 wires in air to the second chip - so not ideal layout. Now I know what I like, I think there's merit to do a new board populated with the 2 DACs (or maybe more 😀) and digital filter.
I'm always distracted by other things though.
James,
Your points were so many and interesting I'll reply to each separately.
I'm rather hoping he will share with us what he's found, I don't know much except that it's really, really simple.
How so? The big cap is smoothing before the regulator, the small caps are local decoupling next to the supplied chips. The regulators have their own output caps on-board. I thought this was pretty much textbook.
C-R-C - I don't like this idea, it's big and won't deliver the transient demands as well, will it? The S Power is a gooood regulator so I feel these supplies are sorted. I will be changing the bridge to HEXFREDs though. I may try alternative decouplers, although I like ZAs. I might try and find some BGs for it, as they are worth it.
I'll have to do a search to find out what a Hagerman snubber is. Thanks for the tips.
Wonderful, this is pretty clear. It will be done, just give me a month 😀
Question for you, as you seem to be very clued up on your parts choice.. I have one Black Gate Standard 1000uF/25V lying around. Should I put it on DAC +5, -5V or -15V? Currently all pins are on ZA 220uF/35V.
Cheers,
Simon
Your points were so many and interesting I'll reply to each separately.
jameshillj said:
I'm rather hoping he will share with us what he's found, I don't know much except that it's really, really simple.
How so? The big cap is smoothing before the regulator, the small caps are local decoupling next to the supplied chips. The regulators have their own output caps on-board. I thought this was pretty much textbook.
C-R-C - I don't like this idea, it's big and won't deliver the transient demands as well, will it? The S Power is a gooood regulator so I feel these supplies are sorted. I will be changing the bridge to HEXFREDs though. I may try alternative decouplers, although I like ZAs. I might try and find some BGs for it, as they are worth it.
I'll have to do a search to find out what a Hagerman snubber is. Thanks for the tips.
Wonderful, this is pretty clear. It will be done, just give me a month 😀
Question for you, as you seem to be very clued up on your parts choice.. I have one Black Gate Standard 1000uF/25V lying around. Should I put it on DAC +5, -5V or -15V? Currently all pins are on ZA 220uF/35V.
Cheers,
Simon
Well, last time, when it was SAA7220 and single 1541, I was at least pleased that I didn't embarass myself.
I think I've made some big improvements though. Having said that, Martin's Naim is very nice. Flea regulation and Single Crown DAC. Hard to come close in many respects. Soundstage and detail is the stuff it lacked most last time, in comparison to Martin's Naim.
Once more, I'd be more than pleased not to embarass myself.
I think I've made some big improvements though. Having said that, Martin's Naim is very nice. Flea regulation and Single Crown DAC. Hard to come close in many respects. Soundstage and detail is the stuff it lacked most last time, in comparison to Martin's Naim.
Once more, I'd be more than pleased not to embarass myself.
Good stuff, I hope you post about it on here.
With a couple more tweaks I'd happily put mine against any reasonable player and expect it to do fine. It could use more bass, but I'll get working on that.
Simon
With a couple more tweaks I'd happily put mine against any reasonable player and expect it to do fine. It could use more bass, but I'll get working on that.
Simon
back to standard - almost
OK - I've spent most of the day listening carefully - and then not so carefully - (you know - just letting it wash over me kind of listening!😉 ....................... and I have just put all the caps back to standard
the only thing I've left is the 5v reg feeding the 7220.
You know what - I've finally decided that I really don't like OScons!! - each and every time I use them i find myself wondering at the slightly metallic thing going on - I mean you can almost HEAR the solid aluminium ringing away!!🙁
lots of different audio projects have seen me flirt with them - only to take most if not all of them out and opt for something else.
So - I'm back to the little 47u Nichicons again - and the MUSIC is back too - with bounce and rhythm - much better. It could be argued that I didn't leave them long enough - but I was relying here on previous exp. as much as anything - the OScons had much more detail going on (none of it very nice though) - esp. in the HF but at the expense of the LF and the rhythm.
The good thing is - the main board in this Mission (CD650) is so quick to remove and replace that you can make these quick component changes - from that point of view it's a great player.
I'd like to make just 1 more comment - and that is the use of large values of capacitance around a predominantly digital circuit. Some of you guys are routinely using 220-1000u to decouple supply pins on receivers and DAC
There is some thinking that such values are likely to be counter-productive - and may slow things down and possibly rob the music of life and dynamics - think about it, Philips, & Marantz only use small values on these supply pins - like 33-47u - my Mission was I guess a CD650 supposedly breathed on by the Brits to some extent - yet still only 47u was used to local decouple the main IC's.
From a simple perspective - do you need that kind of 'headroom' when you are dealing with digital? - I don't reckon so fellas - infact I'm going resist the temptatio in future to simply increase the local caps -
any thoughts guys? .........😉
OK - I've spent most of the day listening carefully - and then not so carefully - (you know - just letting it wash over me kind of listening!😉 ....................... and I have just put all the caps back to standard
the only thing I've left is the 5v reg feeding the 7220.
You know what - I've finally decided that I really don't like OScons!! - each and every time I use them i find myself wondering at the slightly metallic thing going on - I mean you can almost HEAR the solid aluminium ringing away!!🙁
lots of different audio projects have seen me flirt with them - only to take most if not all of them out and opt for something else.
So - I'm back to the little 47u Nichicons again - and the MUSIC is back too - with bounce and rhythm - much better. It could be argued that I didn't leave them long enough - but I was relying here on previous exp. as much as anything - the OScons had much more detail going on (none of it very nice though) - esp. in the HF but at the expense of the LF and the rhythm.
The good thing is - the main board in this Mission (CD650) is so quick to remove and replace that you can make these quick component changes - from that point of view it's a great player.
I'd like to make just 1 more comment - and that is the use of large values of capacitance around a predominantly digital circuit. Some of you guys are routinely using 220-1000u to decouple supply pins on receivers and DAC
There is some thinking that such values are likely to be counter-productive - and may slow things down and possibly rob the music of life and dynamics - think about it, Philips, & Marantz only use small values on these supply pins - like 33-47u - my Mission was I guess a CD650 supposedly breathed on by the Brits to some extent - yet still only 47u was used to local decouple the main IC's.
From a simple perspective - do you need that kind of 'headroom' when you are dealing with digital? - I don't reckon so fellas - infact I'm going resist the temptatio in future to simply increase the local caps -
any thoughts guys? .........😉
I dunno, some have claimed you can tune the sound to your preferred tastes by altering the sizes. I've used 100uF and 220uF mostly so far. I think for the chips pulling big current (SAA7210 and 220 pull 200mA each!) it might make some sense to use fairly "large" values. I'm going to try some os-cons on those chips soon...
Simon
Simon
I replaced the decoupling for my 7220 with 47uF ZA, BG nx and oscon. They sounded very clean, but very lean. I quickly placed a 220uF ZA and things got FAR better. Bass in particular became full-bodied once again, and the whole sound was just better integrated.
I don't think this was necessarily down to the larger capacitance, but I suspect down the the better esr, ripple ratings etc of this cap compared to the others. The 220uF 35v ZA is the best cap in that range for those reasons.
Discrete IV almost ready for a proper test.
Cheers, Lee.
I don't think this was necessarily down to the larger capacitance, but I suspect down the the better esr, ripple ratings etc of this cap compared to the others. The 220uF 35v ZA is the best cap in that range for those reasons.
Discrete IV almost ready for a proper test.
Cheers, Lee.
Superb. Well I'll be trying 2 x 68uF on my 7220 soon. ESR will only just be lower than one 35V/220uF ZA though...
I don't know what that one's doing. It's not PP but polyester, 1uF. It replaced a 1.5uF bipolar Nichicon MUSE...
The bigger caps are ZLH 330/35 and the smaller one is 100/16 ZA.
Simon
The bigger caps are ZLH 330/35 and the smaller one is 100/16 ZA.
Simon
philpoole said:
Hi Phil,
(Sorry for the OT Simon...)
My well trained 9yo son just picked up a CD624 today from a verge rubbish collection and took it home. It seems to work fine, tracking OK and not skipping.
Anyway, did you mod your 624? I was just wondering about its potential here, given its excellent....err...'price'. 😉 I know it's a bitstream model and doesn't have the 1541, so doesn't belong here, but a quick answer/opinion would be appreciated.
Stu