Fin said:
I haven't compared the two DAC's discussed here but I can tell you I'm very happy with the TDA1543 NOS DAC that I just recently purchased from Peter Daniel. If I revisited my CD67 I would definitely consider the TDA1543 MOD.
Regards,
Dan
dantwomey said:
If similar parts were used, BG N for coupling etc., same I/V resistor, it should sound at least as good, by virtue of bypassing the S/PDIF receiver (presumably the ubiquitous CS8412/4).
Re: Re: Re: Paging Ray...
Hi Glenn,
The frequency that Farnell specifies is actually the testfrequency at which the inductance is measured. If you look at the original datasheet you'll discover they just copied something they thought was right. The real resonant freq. should be a few hundred kHz, if not even higher. The fact that they are chokes refers to the higher current capabilities, but that's not an issue here. An advantage though is that the DC resistance is low and the core is made of material that does not saturate easily, so distortion should be pretty low through these chokes, although I haven't actually measured it.
As for the ZAPfilter: too much money for a handful of discrete parts 😀. Of course the outputstage sounds better!
.
Current draw is about 13mA for each channel, excluding the regulators.
Ray.
Glenn2 said:Cheers Ray - the only thing I was worried about was the spec for the Panasonics says 'resonant frequency 10kHz'. The other inductors have this way outside the audio band. The idea of a component in a filter resonating at 10kHz scared me.
There's also the inductor vs choke terminology.
I might plug all the data into switchercad and see if it makes any difference.
Also, do you know what the current draw of your circuit is?
Also, people say great things of the Zapfilter.... it's a shunt-regulated, class A discrete output stage, as is yours. Yours should sound as good if not better as it actually does some proper filtering of those PWM square waves! (I've read that the Zap does not like them much and you have to string RC on its inputs or you get noise)
Hi Glenn,
The frequency that Farnell specifies is actually the testfrequency at which the inductance is measured. If you look at the original datasheet you'll discover they just copied something they thought was right. The real resonant freq. should be a few hundred kHz, if not even higher. The fact that they are chokes refers to the higher current capabilities, but that's not an issue here. An advantage though is that the DC resistance is low and the core is made of material that does not saturate easily, so distortion should be pretty low through these chokes, although I haven't actually measured it.
As for the ZAPfilter: too much money for a handful of discrete parts 😀. Of course the outputstage sounds better!
.Current draw is about 13mA for each channel, excluding the regulators.
Ray.
Cheers Ray.
Why do you think the post-reg caps are necessary?
I always thought the shunt reg should mean they're not if it's close to the device being powered. The whole circuit is class A, no?
I think Guido says they aren't needed... or did you build for 7812/7912 and put the shunts in after?
Sorry for all these questions (apologies if they are stupid ones)....
Why do you think the post-reg caps are necessary?
I always thought the shunt reg should mean they're not if it's close to the device being powered. The whole circuit is class A, no?
I think Guido says they aren't needed... or did you build for 7812/7912 and put the shunts in after?
Sorry for all these questions (apologies if they are stupid ones)....
Glenn2 said:Cheers Ray.
Why do you think the post-reg caps are necessary?
I always thought the shunt reg should mean they're not if it's close to the device being powered. The whole circuit is class A, no?
I think Guido says they aren't needed... or did you build for 7812/7912 and put the shunts in after?
Sorry for all these questions (apologies if they are stupid ones)....
A question is never stupid, unless one knows the answer already
The circuit is indeed class-A, current draw is constant. The PCB is universal, so you can put ordinairy 78/79xx regs on, or something more fancy. I don't know if the shunts work better with or without the output caps, seems to me a few nice BG's won't hurt 😀.
Experimenting is mandatory here
!Ray
I'll definitely be giving it a try.
One more for the road:
Do you think "2SK170" will do or important to get BL for correct Idss? I know Grandata is cheap for postage and instant despatch you see but they don't specifiy the type.
Ok another:
And how many am I likely to need to get reasonable well-matched pairs?
One more for the road:
Do you think "2SK170" will do or important to get BL for correct Idss? I know Grandata is cheap for postage and instant despatch you see but they don't specifiy the type.
Ok another:
And how many am I likely to need to get reasonable well-matched pairs?
I found the BG caps after nice regs improved the sound no end on my discrete pcb.
2SK170 fets. I think I used the GR ,BL or something (they were dearer but also matched).
Brent
2SK170 fets. I think I used the GR ,BL or something (they were dearer but also matched).
Brent
Ray what caps do you have before the descrete pcb (before regs).
I am experimenting and after lots of research and talking to people I have settled on the BG 35V 2200uF VK (supposed to be the best) , they are on back order though🙁
Brent
I am experimenting and after lots of research and talking to people I have settled on the BG 35V 2200uF VK (supposed to be the best) , they are on back order though🙁
Brent
Ah.... they appear to have these boys too.
Saves matching... even if it still doesn't specify group.
Saves matching... even if it still doesn't specify group.
Can I break in here and ask two questions? One: in anyone's experience, how long do the LM4562's take to run in? (I am past the 100hr mark and I think they are still changing) Two: maybe Brent has the answer. I want to by-pass the ops with some caps on the board (under) Malefedo sent me some Wima's (1uF 63etc.) but the leads were too short. The only supplier I found was Farnell, and I don't think they will sell just 2!) Is there a good alternative? where?
Thanks Glenn! The picture is confusing though. It shows u33, which the discription is for 1uf. I guess this is newbie ignorance!?
Better than the Wima? Soldering on the chip legs is scary...no danger of over-heating? Regarding the opamps. Are you the one who found them mechanical as apposed to musical sounding? If so, you were right...but this changes slowly over time. I would like to think they are still burning in😉 I don't know what the caps are supposed to do. I just follow blindly were you guys lead! So far so good! Give me ten more years and I'll be one of the "old masters" initiating the new comers to the longest thread in history (fat chance!) ps I can't see where the other leg goes. Is this the same as using plot 2 and 8 underneath?
Better than the Wima? Soldering on the chip legs is scary...no danger of over-heating? Regarding the opamps. Are you the one who found them mechanical as apposed to musical sounding? If so, you were right...but this changes slowly over time. I would like to think they are still burning in😉 I don't know what the caps are supposed to do. I just follow blindly were you guys lead! So far so good! Give me ten more years and I'll be one of the "old masters" initiating the new comers to the longest thread in history (fat chance!) ps I can't see where the other leg goes. Is this the same as using plot 2 and 8 underneath?
Glenn2 said:
The current through each FET will be 1mA, because the current sink is 2mA, regardless of the group type that's used. The only thing that will change a bit is Ugs. I you want to make two matched pairs I'd say get at least ten pcs. That worked for me last time.
rowemeister said:
BEFORE the regs.... that would be BG standard, at the +/- 16V output of the analog supply that's on-board the player's PCB.
Don't you mean FK? VK's are the powertanks, they don't come in 2200/35 AFAIK.
Regards,
Ray
shepperd said:
They use the same picture for the whole range, that's all.
I wouldn't say these are better as I haven't tried Wimas in this position.
These caps are great at keeping fast op-amps stable, although the LM4562 should be OK without, and maybe these are overkill.
Makes a big difference on LM6172, AD826, AD8065/6 and LT1364 which are all faster chips.
The LM4562 also has spectacular PSRR (power supply rejection ratio) so maybe no cap is best. The only way to know is to try but with this chip I'm not sure you'll hear much of an effect. Others here can comment better because they use this chip.
What the cap does is provide a path around the op-amp for high-frequency noise. You may leak noise from one rail to the other but if the noise is on both rails in equal measure it won't go through the op-amp anyway.
Oh, pins 4 and 8 on a dual op-amp.
I did find them unmusical (and I wasn't the only one) but I'm notoriously impatient. I gave them a few days and yanked them out. What was missing became obvious when it came back (when I put in an AD825 module, though these can sound coarse).