Thanks Pete,
I suspected the same, but I'm not getting any spinning at all if I just turn it on normally and that's what I'd expect if the clock signal was bad.
I only get a quickly spinning anticlockwise disc in service mode P01 and P02
Hi Pete,
The DOS won't work with the TDA1541. The TDA has a single current output and the DOS is designed to worh with a DAC that has two voltage outputs.
Google hint: you need a discrete I/V converter for the 1541 😉
Thanks to Ray and Ben I have hooked up my DOS-CFP board on my CD63, but I am disappointed with the sound: it sounds tinny and non-musical. I just hooked up the left side and left the old analogue on the right side for comparison. The output measured on my scope is about .8V peak to peak (the old output section is about 2V). I took the DOS power from C803/804 (fed by 30VA, 2 X 15V torroid). The voltage measured as it enters the board is -24V/+24V and is 24V between the + and - rails. There is about 4.3V across R5 giving 1.8mA for T3/4. I don't know how to measure the current for T6.
1) Should the output be so low?
2) I have only done the clock and transformers so far - does it just need more modding to bring out the benefits of the DOS CFP?
3) Is there a way to feed a sine wave into the analogue sections for direct comparison of the outputs (record a CD with different tones)?
Henry
1) Should the output be so low?
2) I have only done the clock and transformers so far - does it just need more modding to bring out the benefits of the DOS CFP?
3) Is there a way to feed a sine wave into the analogue sections for direct comparison of the outputs (record a CD with different tones)?
Henry
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Theye are small Russian PIO caps:
Paper IN OIL PIO Capacitors 3300pF 630V K40Y 9 LOT OF 10 NEW | eBay
I have some MKP film caps I could substitute.
Also: I altered the transistors from the ones on Ray's original schematic (see post 20553).
Henry
Try shorting them out (as long as your pre-amp has DC blocking on its input, otherwise replace.) You need a value 600+ times larger to avoid low frequency roll-off.
2.2uF is probably the minimum, better still 3.3uF
2.2uF is probably the minimum, better still 3.3uF
Oh. I might have some big Jantzen silver Caps from an old crossover project I could try, I will have to dig around in the morning.
1 Pair 2pcs OF Jantzen Silver Z CAP MKP Capacitors 2 800 1200V ALL Values | eBay
I thought that small caps were good for small signals?
1 Pair 2pcs OF Jantzen Silver Z CAP MKP Capacitors 2 800 1200V ALL Values | eBay
I thought that small caps were good for small signals?
Ouch - now I see what you mean by small!! I was thinking they were 3.3uF - but they are 3.3nf instead. I wonder how I have managed so far...
I agree. The input impedance is 25Kohms - so 3.3uF would be good. There is no DC blocking on the amp.
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Yes, it's a factor 1000 too small 😱 No wonder it sounds a bit thin 😉
Well you have done alright so far, the board is working and should be fine if you change the caps.
Regards,
Ray
Thanks Ray, I put in 100uF similics and the DOS-CFP is now working nicely. I am thinking of replacing them with Mcap EVO Aluminium Oil Capacitors 3.3uf. I haven't have time to compare to the old analogue but will this afternoon.
Next I will be upgrading the caps in the PSU. I also want to put regs in but there is a confusing array of options. I also don't want to spend a fortune. I have seen these on ebay:
TI TPS7A4700 15V 1A 4.17uVrms Ultra Low Noise LDO Voltage Regulator | eBay
Do you have a suggestion of how to do a minimal regs upgrade that would help realise the potential of my torroid/clock/DOS upgrades?
Next I will be upgrading the caps in the PSU. I also want to put regs in but there is a confusing array of options. I also don't want to spend a fortune. I have seen these on ebay:
TI TPS7A4700 15V 1A 4.17uVrms Ultra Low Noise LDO Voltage Regulator | eBay
Do you have a suggestion of how to do a minimal regs upgrade that would help realise the potential of my torroid/clock/DOS upgrades?
Those eBay regs aren't even that cheap considering they're an unknown quantity. If you want low cost 3-pin replacements then I think Paul Hynes series regs are well worth considering.
I'm very happy with my Jung/Didden super regs, which are DIY and cost-effective, but they take up a lot more space than the 3-pin jobbies.
Fidelity Audio S-Powers and Tentlabs Shunts are more expensive, but they are tried and tested on the DOS by people on here. There may be others.
I'm very happy with my Jung/Didden super regs, which are DIY and cost-effective, but they take up a lot more space than the 3-pin jobbies.
Fidelity Audio S-Powers and Tentlabs Shunts are more expensive, but they are tried and tested on the DOS by people on here. There may be others.
Choice of coupling caps and regs will make or break the sound of your DOS. It's worth taking your time to research the options, and you can always just stick with what you have a bit longer if it means you can justify getting parts you feel good about.
Talking about minimal reg upgrades, have you regulated your servo ICs yet? Don't forget to do that! One of the best bangs for your buck that you can get.
Great that it's working now. I have the EVO caps in my SA8400 SACD player and I like them very much. There are better sounding caps, but they cost a lot more. I think they are a very good value! If your budget permits, get the Silver/Gold-Oil! They are more expensive, but they'll last a lifetime and you'll enjoy listening to them every day. I mostly order them at Partsconnexion when they have a discount going, this can save you up to 25%.
Hi Ben, the ebay guy only sells these regs and has already sold >3000 with 100% approval (if you believe the stats). So I am thinking of giving them a try at £16 each. There are other diy audio threads looking at TPS7A4700: http://www.diyaudio.com/forums/powe...oise-symmetrical-psu-tps7a4701-tps7a3301.html
Also: http://www.diyaudio.com/forums/vend...jects-available-here-bal-bal-se-se-lpuhp.html
The ADM7151 actually looks good but I can't find a PCB for it. Unfortunately I haven't been able to find a comparison of either chip to an established super reg in audio circuits😕.
Henry
I have been scrolling through past posts to try and get a good idea of which regs are best (thanks for the servo recommendation). If you were to rank which would most benefit the SQ of these what would it be?
Servo (2) (+5v) (R122 & R123)
DAC (3) (+5V) (UD200, RD01 & RD04)
Decoder (2) (+5V) (R508 & R510)
DOS-CFP (2) (+12V/-12V) (Replace LM78/9 on board)
Are there any chips that would benefit from non super regs (eg using Ray’s LM317)?
Servo (2) (+5v) (R122 & R123)
DAC (3) (+5V) (UD200, RD01 & RD04)
Decoder (2) (+5V) (R508 & R510)
DOS-CFP (2) (+12V/-12V) (Replace LM78/9 on board)
Are there any chips that would benefit from non super regs (eg using Ray’s LM317)?
What I’ve already done to my CD63:
Clock (Flea) is already on its own torroid as recommended on Ray’s site.
The rest of the power is fed by 30VA 2X15V, 50VA 2X12V and 7VA 2X12 as recommended by Higlander.
It is easy enough to do Ray’s PSU regs (Q801/2 -> LM317/337 and Q811 -> MC805ACT) so I will do those soon.
Henry
Clock (Flea) is already on its own torroid as recommended on Ray’s site.
The rest of the power is fed by 30VA 2X15V, 50VA 2X12V and 7VA 2X12 as recommended by Higlander.
It is easy enough to do Ray’s PSU regs (Q801/2 -> LM317/337 and Q811 -> MC805ACT) so I will do those soon.
Henry