cheers!
oh...now I see the point, just wanted to confirm that these 22uf Jamicon axials (pic of mine before the mods) about which I asked you some time ago (had some doubts as my tester didn't show any voltage on them at all) were replaced with 22uf film caps in your Restek.
so i'll try to get these WIMAs you recommend. Meanwhile, do you really think that 4 of them could somehow improve the overall sound of our amps? Any testing made?
Ian, did you change resistors in the end? I was wondering if replacing them to 5w aluminium could bring any improvement or using metal oxide ones. There was some tip here in this thread regarding metal power resistors, maybe you know some decent brands?
oh...now I see the point, just wanted to confirm that these 22uf Jamicon axials (pic of mine before the mods) about which I asked you some time ago (had some doubts as my tester didn't show any voltage on them at all) were replaced with 22uf film caps in your Restek.
so i'll try to get these WIMAs you recommend. Meanwhile, do you really think that 4 of them could somehow improve the overall sound of our amps? Any testing made?
Ian, did you change resistors in the end? I was wondering if replacing them to 5w aluminium could bring any improvement or using metal oxide ones. There was some tip here in this thread regarding metal power resistors, maybe you know some decent brands?
It widely accepted that elco's in the signal path is a bad thing. They are there to stop DC passing but they do effect audio quality.
People spend a fortune on "audio grade" capacitors for this very reason. The problem with this type of cap is the size. 22uF would normally be very large. It is fairly standard practive for me to replace any caps in the signal path with something better. If i need output caps, I'll use larger Mundorf's or similar, but they are expensive. In this application, the those 22uF are much better then elco's although not as good as something like Mundorf.
I've not swapped any resistors in the amp yet. I may well do now I have the diagram. I'll also look to change any filter caps in the audio path with silvered mica and poss some of the resitors too. I'll keep you posted.
People spend a fortune on "audio grade" capacitors for this very reason. The problem with this type of cap is the size. 22uF would normally be very large. It is fairly standard practive for me to replace any caps in the signal path with something better. If i need output caps, I'll use larger Mundorf's or similar, but they are expensive. In this application, the those 22uF are much better then elco's although not as good as something like Mundorf.
I've not swapped any resistors in the amp yet. I may well do now I have the diagram. I'll also look to change any filter caps in the audio path with silvered mica and poss some of the resitors too. I'll keep you posted.
thanks! now i c the point in these wima capswill swap them too very soon.
Cool! The main feature of these caps is their size for the capacity rating. The original design is better than most in so far as it uses a low value film to bypass the elco. It's still better to remove the elco completely
finally finished amp's upgrade
here is a brief description:
- 4x Elna for Audio 12 000uf in psu
- Panasonic FCs 470 & 220uf in psu
- Nichicon Muse 12x 470uf in output cascade
- opams changed to LME49710HA (thanks Ian, they r great!)
- Elna Tonerex 220uf in power amp section
- Wima MKS 22uf caps between pre and power sections
amp became very brutal and punchy with huge reserve of energy and dynamics, exactly what I wanted for heavy metal music
here is a brief description:
- 4x Elna for Audio 12 000uf in psu
- Panasonic FCs 470 & 220uf in psu
- Nichicon Muse 12x 470uf in output cascade
- opams changed to LME49710HA (thanks Ian, they r great!)
- Elna Tonerex 220uf in power amp section
- Wima MKS 22uf caps between pre and power sections
amp became very brutal and punchy with huge reserve of energy and dynamics, exactly what I wanted for heavy metal music
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Nice pics! Glad its all come together. As you now hear, its massively well worth it!!!
I notice you are still using the BB2604 in the preamp stage across the back. Have you considered using anything else? I originally used 3 LME49720HA's but ended up opting for a pair of Bursons and removed one of the buffer stages. I guess thats one for a rainy day!!!
I notice you are still using the BB2604 in the preamp stage across the back. Have you considered using anything else? I originally used 3 LME49720HA's but ended up opting for a pair of Bursons and removed one of the buffer stages. I guess thats one for a rainy day!!!
Originally I use 3 20HA's on the preamp stage. The preamp stage is very basic. I think most of the £ went on the power amp! I believe you will gain further clarity and definition by replacing the opamps in the pre stage. I didn't make any other changes other than a mix of ZA and BG caps and the opamps to start. It was a while ago but I seem to remember a significant difference to detail and soundstage when I 1st changed the caps and opamps in the pre.
I used Burson in the end on 2 of the 3. I also bypassed the 1st buffer stage. Burson are worth the money IMHO! They have the gains in detail and presentation but then sound smooth and rounded where the opamps can sometimes be a little edgy?? I couldn't get the Bursons to run in the power stage (the amp stayed in protect mode) but the pair in the pre were a revelation!!
I would also consider the audiogd OPA discrete opamps (I think the sun is supposed to be very similar to Burson!)
Anyway, I PM'd you with some useful info
I used Burson in the end on 2 of the 3. I also bypassed the 1st buffer stage. Burson are worth the money IMHO! They have the gains in detail and presentation but then sound smooth and rounded where the opamps can sometimes be a little edgy?? I couldn't get the Bursons to run in the power stage (the amp stayed in protect mode) but the pair in the pre were a revelation!!
I would also consider the audiogd OPA discrete opamps (I think the sun is supposed to be very similar to Burson!)
Anyway, I PM'd you with some useful info
just have received 3 LME49720HA, haven't tried them in the amp's pre stage yet, but did some tests with my heavily moded Philips Cd350 by replacing LM4562NA with metal 20HAs (signal goes directly to RCA via Mundorf 4.7yf mkp cap). Opams have dedicated power supply using LM317 and 337 and toroidal transformer.
the difference was so huge that I didn't believe that I'm listening to 25 year old CD player, in a few words - great dynamics and stage resolution. Then placed back LM4562NA and it was a bit even boring to listen.
the only drawback of 20HAs is that I can easily hear some kind of noise/ hum from the tweeter when player is on and volume on my Restek is about 9 o'clock (quite loud but I got used to listen music at this volume). If you touch the metal can of opamp noise become more silent. So my question is could I use dual 20HAs opams in the CD player's output stage at all? Could this be a direct replacement or do I need to install some other parts?
As far as I know LME49710HA is a single opamp, does it mean that using two of them will give the same effect as from one 20HA? If yes, I simply should solder them pin to pin?
Ian,
thanks for your mail (PM) Did you get my reply?
Btw, when making some tests with 20HAs, did you leave the amp all resistors attached to the old opams?
the difference was so huge that I didn't believe that I'm listening to 25 year old CD player, in a few words - great dynamics and stage resolution. Then placed back LM4562NA and it was a bit even boring to listen.
the only drawback of 20HAs is that I can easily hear some kind of noise/ hum from the tweeter when player is on and volume on my Restek is about 9 o'clock (quite loud but I got used to listen music at this volume). If you touch the metal can of opamp noise become more silent. So my question is could I use dual 20HAs opams in the CD player's output stage at all? Could this be a direct replacement or do I need to install some other parts?
As far as I know LME49710HA is a single opamp, does it mean that using two of them will give the same effect as from one 20HA? If yes, I simply should solder them pin to pin?
Ian,
thanks for your mail (PM)
Did you get my reply?Btw, when making some tests with 20HAs, did you leave the amp all resistors attached to the old opams?
Hi, got the email, very poor! I should have replied by now!!!
I will respond to the email, but for now, go for it! 10HA for singles and 20HA for duals. I have used them in CD player output stages, amps in fact everywhere I can! My only preference above these is for fully discrete Burson or similar.
If you are picking up noise on the HA's, you could check the can for volts and try connecting it to gnd?? The screening may become more effective???
I didn't remove any resistors in the pre amp stage of the Restek. I only bypassed the 1st opamp. Its possible that the resistors you have above the opamp are underneath the board in mine. I dont remember moving them, but I would have done so when replacing the opamps for sockets.
I will respond to the email, but for now, go for it! 10HA for singles and 20HA for duals. I have used them in CD player output stages, amps in fact everywhere I can! My only preference above these is for fully discrete Burson or similar.
If you are picking up noise on the HA's, you could check the can for volts and try connecting it to gnd?? The screening may become more effective???
I didn't remove any resistors in the pre amp stage of the Restek. I only bypassed the 1st opamp. Its possible that the resistors you have above the opamp are underneath the board in mine. I dont remember moving them, but I would have done so when replacing the opamps for sockets.
checked the opams for volts, both have decent + and - 12v, so should be fine. Tried also connecting the can to gnd, in the end got some huge overheating and it doesn't work any more, so put it into the rubbish bin.
anyway, these were the tests with CD player, not the amp.
Regarding 2x 10HA as a dual 20HA, read that it's even better to use (less bias and distortion, though could be wrong), so maybe using 6x 10HA in the preamp section would be give even better performance? If yes, as I've understood connection should be according to the 20HA's scheme?!
anyway, these were the tests with CD player, not the amp.
Regarding 2x 10HA as a dual 20HA, read that it's even better to use (less bias and distortion, though could be wrong), so maybe using 6x 10HA in the preamp section would be give even better performance? If yes, as I've understood connection should be according to the 20HA's scheme?!
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