Re: good by opamp
Hi Aquar,
I'm glad you like the output-stage. The orientation for the BC517 and the 2SK170 is the same; drain-gate-source equals collector-base-emitter, so it is a drop-in replacement 😀.
Regards,
Ray
aquar said:
Hi Aquar,
I'm glad you like the output-stage. The orientation for the BC517 and the 2SK170 is the same; drain-gate-source equals collector-base-emitter, so it is a drop-in replacement 😀.
Regards,
Ray
poynton said:
This is what I originally thought but I see it recommended in many places, including Martin's site (on his Naim CD mods where he uses Os-con). Otherwise I have a very low ESR cap (BG NX 220uF/6.3V) hanging off the o/p of the LM317 you see. Combined with its output inductance creates a resonance that the resistor damps.
The other way to use small reistors if you are worried about the line impedance, is in series with the decoupling cap at the output of the reg. That is, between Vout and ground you connect (R+C).
Thisis effectively a snubber, but requires a small extra cap at the load to deal with HF properly. A very effective combination, actually...
I've only used a little series R where it doesn't matter much - for example, the -15v supply pin of a TDA1541.
Thisis effectively a snubber, but requires a small extra cap at the load to deal with HF properly. A very effective combination, actually...
I've only used a little series R where it doesn't matter much - for example, the -15v supply pin of a TDA1541.
martin clark said:
Well what I've got is 100uF Muse KZ at the LM317 output, then series 0.5R, then BG NX 220uF across the load.
So I suppose I should bin the BG then and use something else?
I can't see how I can easily connect an R in series with the cap but not the load... it's too cramped down there.
Re: Re: good by opamp
Tks Ray, could you explain what is different (sound) if I replace BC517 with 2sk170 ?
Regards
aquar
6h5c said:
Tks Ray, could you explain what is different (sound) if I replace BC517 with 2sk170 ?
Regards
aquar
Aquar, I just wouldn't worry about it; your arrangement obviously works just fine, and a CRC filter can be a very good thing.
If you really want to get nerdy - the added RC combination you have will actually damp the reg/first cap pair (look at it - it' s still a snubber connected to ground. You can drive yourself mad wondering about this stuff...when teh differences in the real world are very, very small)
If you really want to get nerdy - the added RC combination you have will actually damp the reg/first cap pair (look at it - it' s still a snubber connected to ground. You can drive yourself mad wondering about this stuff...when teh differences in the real world are very, very small)
martin clark said:
Aint that the truth!
Out with the R though and not worry about the ESR of the BG? Last time I'll ask - promise!😀
Re: good by opamp
Fantastic news aquar! It inspires me to hurry up and do mine...
Simon
aquar said:
Fantastic news aquar! It inspires me to hurry up and do mine...
Simon
Re: Re: good by opamp
I suppose I cheated by using an LC Audio ZapFilter2, but it is night and day. A clear immediate and obvious improvement with every CD I've tried.
Also, I don't know if any of you remember me getting a duff VAM1202 laser from Grandata, and commenting that it didn't claim to be Philips anywhere on it?
I told them, and they claimed that all their current stock have Philips on the label, and they would replace it.
They did - new one has Philips on the label as promised. It only plays about 50% of the discs I put in, often stops when moving from track to track, and sounds like an electric shaver when moving the sled across the disc. If you play the last track on a disc then press stop, it sounds like a bumblebee is trapped under it.
I'm getting bored changing these damn lasers!
I have to keep putting back the original CDM12.1 each time. (This works fine mostly but occasionally gives up when switching tracks on CDRs.) Grrrr!
SimontY said:
I suppose I cheated by using an LC Audio ZapFilter2, but it is night and day. A clear immediate and obvious improvement with every CD I've tried.
Also, I don't know if any of you remember me getting a duff VAM1202 laser from Grandata, and commenting that it didn't claim to be Philips anywhere on it?
I told them, and they claimed that all their current stock have Philips on the label, and they would replace it.
They did - new one has Philips on the label as promised. It only plays about 50% of the discs I put in, often stops when moving from track to track, and sounds like an electric shaver when moving the sled across the disc. If you play the last track on a disc then press stop, it sounds like a bumblebee is trapped under it.
I'm getting bored changing these damn lasers!
I have to keep putting back the original CDM12.1 each time. (This works fine mostly but occasionally gives up when switching tracks on CDRs.) Grrrr!
SimontY said:
Major PITA.
I think the QC has gone down the pan wherever they make these. The non-Philips one was clearly made in the same factory - it's identical to every minute detail (apart from the label of course) so I think they make them for Philips and sell them separately or just label them as Philips on the sly!
I have a good, perfectly working VAM1202 in my spare player (the 63 that I listen to when my 67 is in pieces - i.e, 90% of the time!) so I think I'll just use that in the 67 and put the old CDM12.1 in the 63 and give up. I bought that VAM1202 a few years ago as a spare but only recently put it in the 63 (which was a dead one I got for virtually nothing).
rowemeister said:
Cheers Brent. I will next time. I may as well get Grandata to replace it again and keep it as a spare - and just hope I never need to use it!
P.S., didn't you have a fix for the problem I have with the original CDM12.1? Namely the radial error when moving from one track to another? Something about a grub screw but I couldn't fathom where this was....
Turn laser over - you will see two torque screws. It's usually the one at the rear of the laser.
Turn it 1/4 turn and test. If its worse put it back to where it was then turn 1/4 turn the other way. If there is an improvement you know you are close and try another 1/4 turn. If there is no difference the laser is crap.
Little adjustment is needed - use your ears and listen to the laser to hear if it sounds crisp and healthy when scanning.
Brent
Turn it 1/4 turn and test. If its worse put it back to where it was then turn 1/4 turn the other way. If there is an improvement you know you are close and try another 1/4 turn. If there is no difference the laser is crap.
Little adjustment is needed - use your ears and listen to the laser to hear if it sounds crisp and healthy when scanning.
Brent
Martin - in your Naim mods you say:
Isn't that what I did with my BG Nx?
Not trying to catch you out here, just a bit confused!
Isn't that what I did with my BG Nx?
Not trying to catch you out here, just a bit confused!
