cap break-in
Yes it will break in the caps. There is a significant amount of hf current flowing all the time. It would be quicker with an audio signal added though.
Roger
matjans said:
Yes it will break in the caps. There is a significant amount of hf current flowing all the time. It would be quicker with an audio signal added though.
Roger
Back to the 627's
I would highly recommend an eBay search for OPA627[au]'s. They are a popular surplus item, it appears.
A quick search revealed 10 for $34.99 inc shipping worldwide...
I would highly recommend an eBay search for OPA627[au]'s. They are a popular surplus item, it appears.
A quick search revealed 10 for $34.99 inc shipping worldwide...
Sample abuse
I agree with your sentiment but due to the volume of product available I doubt they were samples. The scary thing is they might be rejects!😱
Roger
tobias_svensk said:
I agree with your sentiment but due to the volume of product available I doubt they were samples. The scary thing is they might be rejects!😱
Roger
Roger,
1. Any news on the new .68uf 63v Auricaps
2. Any problems with your UCD's running with the bigger 450v Auricap.
Thanks
1. Any news on the new .68uf 63v Auricaps
2. Any problems with your UCD's running with the bigger 450v Auricap.
Thanks
Cap question
No word yet but it shouldn't be too much longer till I get the engineering samples.
I haven’t noticed any problem with having longer leads on the 450v caps but I am sure that there is a lot more EMI being generated. As these modules are completely enclosed this is a non issue for this application. I am not sure of what I am giving up sonically with the added inductance but there sure doesn’t seem to be much of a penalty, this amp is true reference quality!
Roger
No word yet but it shouldn't be too much longer till I get the engineering samples.
I haven’t noticed any problem with having longer leads on the 450v caps but I am sure that there is a lot more EMI being generated. As these modules are completely enclosed this is a non issue for this application. I am not sure of what I am giving up sonically with the added inductance but there sure doesn’t seem to be much of a penalty, this amp is true reference quality!
Roger
OPA627 replacement
Just curious how you replaced the previous chip with the OPA627. am thinking of trying AD797. Don't know if this would be a drop in replacement.
Ray
Just curious how you replaced the previous chip with the OPA627. am thinking of trying AD797. Don't know if this would be a drop in replacement.
Ray
Question:
Ucd 400AD
Is the surface mount OPA 627 a drop in replacement for the AD8620?
If not what is the exact adapter that is required?
Thanks,
Don
Ucd 400AD
Is the surface mount OPA 627 a drop in replacement for the AD8620?
If not what is the exact adapter that is required?
Thanks,
Don
Stevenacnj said:
The 627 only have one channel (mono amp-op). The AD8620 is a dual channel.
You should use 2 of them on a small CMS adaptor + maybe more caps around.
The OPA627 is prefered for I/V conversion output circuit. If you like BB sound, try OPA2134. A sincerely good op-amp.
Personal emails
To all,
I receive direct questions in emails from the forum from time to time and feel the need to make a statement. I will be glad to help out with a specific problem if I can. If I can’t I will tell you so. I will not do a redesign of a piece of equipment to correct a problem or make improvements with out getting paid, I just can’t afford to take the time! Most of the questions sent to me would be of interest to others and should be posted. Save the email for off topic stuff.
All this said there is one other thing that needs to be addressed. If you want a personal email answered you will have to include who you are in it. This means your name and your posting handle. I will not answer anonymous emails. If you are not a poster and need a question answered, please jump in and ask! Everyone began somewhere and there are no dumb questions, just some that don’t make any sense. We all realize there is a language problem here and take that into account. Please try to use a spell checker if you can. It does help if the spelling is correct even if the word is wrong.
Moderator, Any chance of some of this being put in the general guide lines?
Roger
To all,
I receive direct questions in emails from the forum from time to time and feel the need to make a statement. I will be glad to help out with a specific problem if I can. If I can’t I will tell you so. I will not do a redesign of a piece of equipment to correct a problem or make improvements with out getting paid, I just can’t afford to take the time! Most of the questions sent to me would be of interest to others and should be posted. Save the email for off topic stuff.
All this said there is one other thing that needs to be addressed. If you want a personal email answered you will have to include who you are in it. This means your name and your posting handle. I will not answer anonymous emails. If you are not a poster and need a question answered, please jump in and ask! Everyone began somewhere and there are no dumb questions, just some that don’t make any sense. We all realize there is a language problem here and take that into account. Please try to use a spell checker if you can. It does help if the spelling is correct even if the word is wrong.
Moderator, Any chance of some of this being put in the general guide lines?
Roger
The Hypex HG has an independent PS circuit for pre-amp use. These could be used to power the UcD180's and 400's input stage.
Has anyone tried this? Powering the opamps (is there more than just the opamps?) from a different power supply?
Has anyone tried this? Powering the opamps (is there more than just the opamps?) from a different power supply?
Yves Smolders said:
Still have to do this, ordered some DC-DC convertors.
range 36-75V to + and- 12V
Bgt said:
What converters did you order? A link if you have one would be appreciated. I have been looking for something suitable and have had no luck. Are you planning to power them from the rails?
Roger
quality of UCD input circuit
Hi,
I'm planning to build a high quality passive shunt attenuator for the input to the UCD400. I'm assuming that the general UCD quality is good enough to bother with complex topologies for the preamp like relays for the shunt resistor and high quality resistors 😱
I dont have a schematic of the UCD to tell if there is value in replacing any of the input resistors or other components in the input path? There has been lots of discussion about the coupling capacitor (which can be bypassed) but what about the resistors? I'm assuming that the "audiophile" resistors like vishay, dale etc. do make a difference but I have not tried anything else but the garden variety resistors in my audio circuits.
Also, there should be value in providing a higher quality power supply for the input components of the UCD, and there has been some talk of a more modular UCD700 that will allow inserting a different power supply but no dates have been given. Is it possible to modify the UCD400 circuit to insert a better power supply or is this just too difficult or of marginal value?
Regards,
Dean
Hi,
I'm planning to build a high quality passive shunt attenuator for the input to the UCD400. I'm assuming that the general UCD quality is good enough to bother with complex topologies for the preamp like relays for the shunt resistor and high quality resistors 😱
I dont have a schematic of the UCD to tell if there is value in replacing any of the input resistors or other components in the input path? There has been lots of discussion about the coupling capacitor (which can be bypassed) but what about the resistors? I'm assuming that the "audiophile" resistors like vishay, dale etc. do make a difference but I have not tried anything else but the garden variety resistors in my audio circuits.
Also, there should be value in providing a higher quality power supply for the input components of the UCD, and there has been some talk of a more modular UCD700 that will allow inserting a different power supply but no dates have been given. Is it possible to modify the UCD400 circuit to insert a better power supply or is this just too difficult or of marginal value?
Regards,
Dean
Power supply and stuff.
Hi Dean,
I personally have not noted much difference in sound quality among the various surface mount rectangular shaped MF resistors. Of course I haven’t spent much time doing an actual investigation. They all are non magnetic, have a minimum of parasitics and dissimilar metal connections. In other words as long as they are not run hot they will work fine and should be one of the last things you need to look into. Anyone who has had other experiences please feel free to jump in!
I believe it was Bruno who stated the easiest way to implement the off board power was to remove the 2 regulator transistors and use their emitter pads as the power input connection points. You would have to find a nearby ground connection. He also stated this would probably be worth doing from a sonic stand point.
I am looking into a buck converter replacement for my amps regulators. It would be nice to find a single unit, on board solution. The idea would be to gain in all the important parameters like output impedance, isolation, regulation, efficiency, reliability and audible noise while keeping it fully on the board and powered from the rails. Unfortunately the converter will probably cost as much as the amp from what I have seen so far.
Roger
Hi Dean,
I personally have not noted much difference in sound quality among the various surface mount rectangular shaped MF resistors. Of course I haven’t spent much time doing an actual investigation. They all are non magnetic, have a minimum of parasitics and dissimilar metal connections. In other words as long as they are not run hot they will work fine and should be one of the last things you need to look into. Anyone who has had other experiences please feel free to jump in!
I believe it was Bruno who stated the easiest way to implement the off board power was to remove the 2 regulator transistors and use their emitter pads as the power input connection points. You would have to find a nearby ground connection. He also stated this would probably be worth doing from a sonic stand point.
I am looking into a buck converter replacement for my amps regulators. It would be nice to find a single unit, on board solution. The idea would be to gain in all the important parameters like output impedance, isolation, regulation, efficiency, reliability and audible noise while keeping it fully on the board and powered from the rails. Unfortunately the converter will probably cost as much as the amp from what I have seen so far.
Roger
Thanks for the reply Roger,
I have heard SMD components can sound good. Regarding the power supply, I have a number of high quality jung regulators that are looking for a home, modding the UCD module with them should help. Has anyone actually tried using a better power supply?
Regards,
Dean
I have heard SMD components can sound good. Regarding the power supply, I have a number of high quality jung regulators that are looking for a home, modding the UCD module with them should help. Has anyone actually tried using a better power supply?
Regards,
Dean
Hi,
It goes without saying it will help, a great deal in fact I'd imagine.
If I had three mods only to pick from it would be dc coupling, aux. supplies for the input stage, and the third still undecided.
Regards,
Chris
It goes without saying it will help, a great deal in fact I'd imagine.
If I had three mods only to pick from it would be dc coupling, aux. supplies for the input stage, and the third still undecided.
Regards,
Chris
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