Hi all, I would like to upgrade the Burr brown 2604 op amps in my MHZS CD 66 tube output cd player, anyone got any ideas for a push in upgrade of similar spec, Thanks Brian.
gasman said:
NE5532
Signetics
date codes 8649 to 8702
😛
It came to my attention in that period there was a special production run for Marantz with tightened specs.
Double crowns so to speak.
Bernhard said:
NE5532
Signetics
date codes 8649 to 8702
😛
It came to my attention in that period there was a special production run for Marantz with tightened specs.
Double crowns so to speak.
Thats interesting Berhard, probably a few lids will be coming off to check that one out if they are date stamped, thanks, Brian.
I was kidding. You too ? 🙄
The best answer to the never ending question, "which op amp" is probably "no op amp"...
My future setup will be: DAC - passive I/V - balanced to SE transformer - passive low impedance analog filter.
The best answer to the never ending question, "which op amp" is probably "no op amp"...
My future setup will be: DAC - passive I/V - balanced to SE transformer - passive low impedance analog filter.
Might nip to maplins tomorrow and get acouple of ne 5532,s and a couple of mc1458,s to try tomorrow, cheap enough to play with, Cheers Brian.
Tried the NE5532,s, seems to be slightly more detail but the sound seems to have hardened up a bit, probably need to burn in , Any ideas on how long burn in time anyone, Cheers. Brian.
Seems to me like a perfect description of going from the opa604 to the ne5532. Burn-in won't change that.gasman said:
Bernhard said:
Been down that path Bernhard, big dynamics and drive sacrifice not to mention added noise.
The only way I found to get the rear end singing with a good current output dac chip, is a proper discrete Trans Impedance amp for the I/V stage and a good discrete class A bipolar output amp, with no caps anywhere between the dac chips output and the rca outputs.
If one cannot build it yourself, the an expensive but perfect ready built one is the LC ZAPII, it has the discrete I/V and output, and a shunt regulated supply.
Cheers George
Attachments
Hi George
16 DACs per channel SE (or balanced) with transformer 1(+1):2 gives 1V / 120 ohm incl. matching filter.
I have now 5kohm filter + buffer and I'm very satisfied, just when I leave out the buffer, I get hf roll off...
30000 DACs per channel with 1:15 transformer will deliver 15Vpp into an 8ohm speaker
16 DACs per channel SE (or balanced) with transformer 1(+1):2 gives 1V / 120 ohm incl. matching filter.
I have now 5kohm filter + buffer and I'm very satisfied, just when I leave out the buffer, I get hf roll off...
30000 DACs per channel with 1:15 transformer will deliver 15Vpp into an 8ohm speaker
miligor said:
Ah, Thanks Miligor, nice to know, have you any recommendations as well as the 5532 a,s thanks Brian.
Hi, some people will probably consider this complete sacriledge, but try substituting with the BB OPA2134 if you can get hold of any (it's not gonna be from Maplins though). I have made direct comparision between the 2 and find the later a bit more controlled and velbehaved. I can send U a couple against a symbolic paypal payment, but they are avaliable from RS comp.
Both the above chips are with fet input's, where as the NE5532A/P is purely bipolar. This will have a most profound influence on the surrounding curcuitry in order to optimize performance. It's quite rare you are able to swop between the 2 topologies with good results, according to humble yours hard earned experience.
Kind regards
a1greatdane
Both the above chips are with fet input's, where as the NE5532A/P is purely bipolar. This will have a most profound influence on the surrounding curcuitry in order to optimize performance. It's quite rare you are able to swop between the 2 topologies with good results, according to humble yours hard earned experience.
Kind regards
a1greatdane
Thanks Miligor for your list.
I have reasently had the good fortune to try the AD8599 (possibly AD897 (single) related), which I obtained from the manufacturer in 2pc. samples. Now there's a thing! There is another thread regarding just that item and started by humble yours. BUT it only comes in SOIC, so you would need a 'brown bear' or similar adaptor to get it to fit a standart DIP outline. Again this is a pure bipolar device with relatively low input impedance like 1458, 4558, 4559, LM833N, LM4562, NE5532A/P, NJR2068, NJR2114 etc.
AD827, OPA2134, OPA2604, TL072 are all FET input with very high input impedance, which in turn means their current demand on the previous and FB curcuit is very modest at audio frequencys. HF if another story, since it takes some current to charge a capacitor, but the input capacitor values on these IC are very, very low. The deviced curcuit is interesting, but I'm not sure it would be the anwser in this case. Normally would would have the FETs on the other side of the IC, in order to boost the imput impedance, not as current 'dumpers' on the output, where bipolar transistors is normaly used, due to their far lower internal impedance. Thge distortion distribution for Bipolar vs. FET 'current dumpers' is however very different, so their might be an argument here.
Food for thought I hope
Best regards
a1greatdane
PS: Back 2 the original issue... the AD627 & AD827 comes very highly rated as Audio IC's with FET inputs, but they are very pricy! Think they might be avaliable from Farnell
I have reasently had the good fortune to try the AD8599 (possibly AD897 (single) related), which I obtained from the manufacturer in 2pc. samples. Now there's a thing! There is another thread regarding just that item and started by humble yours. BUT it only comes in SOIC, so you would need a 'brown bear' or similar adaptor to get it to fit a standart DIP outline. Again this is a pure bipolar device with relatively low input impedance like 1458, 4558, 4559, LM833N, LM4562, NE5532A/P, NJR2068, NJR2114 etc.
AD827, OPA2134, OPA2604, TL072 are all FET input with very high input impedance, which in turn means their current demand on the previous and FB curcuit is very modest at audio frequencys. HF if another story, since it takes some current to charge a capacitor, but the input capacitor values on these IC are very, very low. The deviced curcuit is interesting, but I'm not sure it would be the anwser in this case. Normally would would have the FETs on the other side of the IC, in order to boost the imput impedance, not as current 'dumpers' on the output, where bipolar transistors is normaly used, due to their far lower internal impedance. Thge distortion distribution for Bipolar vs. FET 'current dumpers' is however very different, so their might be an argument here.
Food for thought I hope
Best regards
a1greatdane
PS: Back 2 the original issue... the AD627 & AD827 comes very highly rated as Audio IC's with FET inputs, but they are very pricy! Think they might be avaliable from Farnell
OK. Now I'm see that You have great knowledge and expirience. Please, tell me, can I install in my PDS505 FET OP-AMP+ these FETs, or FET OP-AMP only?
Hi Milligor, I have no much idea about which piece of equipment you are referring to - Sorry. But tell us what's already in there and then there's a better chance for finding a suitable replacement. If you want to do an even more in dept investigation, then I would suggest you get hold of a copy of the schematic and have a look and the surrounding impedance values in order to make a more qualified desision. It is then also possible to perhaps change some of the passive components around the active amplifiers towards your desired goal Ie. lower noise, more dynamics etc.
Good luck
a1greatdane🙂
Good luck
a1greatdane🙂
- Status
- Not open for further replies.