hihopes said:
You may be confused about the circuit.
I said the components used, and I made several changes.
I hope there's no confusion about my system, I didn't expect that.
CDP+DAC+Preamp+Power Amp+Speakers.
There are more sources connected (phono, DVD, tape, PC, etc).
I thought it was clear, even for those who didn't know, just by reading my first post on this thread, what was my intention: to test some current-feedback op-amps and, if better, to upgrade my preamp.
Carlos, we talked several times about using an OPA627+BUF634 inside an integrated amp and I told you that it was not needed, the 627 alone was fine.
I presume that you know the schematic of my amp, as you followed my thread.
As in Brazil it's much earlier than here, I think you were still waking up.
There was no confusion in my mind about your system (until all the questions started - then I began to doubt just about everything (l.o.l.)).
What I was confused by was all the tuning you had to do to get the AD to work the way you wanted it to. I would very much like to try it for myself, but the longer I read your commentary on the process, the more difficult it seemed to be to get right, and the more afraid I began to get about damaging my other equipment by doing something wrong in the circuit.
By the way, are you sure that your preference for the AD is not a result of prejudice brought on by an ecstatic experience with the Jeff Rowland?
What I was confused by was all the tuning you had to do to get the AD to work the way you wanted it to. I would very much like to try it for myself, but the longer I read your commentary on the process, the more difficult it seemed to be to get right, and the more afraid I began to get about damaging my other equipment by doing something wrong in the circuit.
By the way, are you sure that your preference for the AD is not a result of prejudice brought on by an ecstatic experience with the Jeff Rowland?
carlosfm said:
It's the AD815.
My pre was OPA627+BUF634 and I changed it for an AD815.
My pre has always had gain.
Read my posts, Carlos.
Who else?
What?
Carlos, wake up.
I have a single OPA627 biased to class-A on each LM3886 PCB, inside the amp.
Forget the buffer, will you?.
The OPA627+BUF634 was my preamp , wich I now changed for AD815.
I removed one board and installed the other one, inside the preamp.
Let's try to keep this interchange at a "conversation level". No need to put smilies everywhere just because it seems amusing. For me it is tiring and distracting. No need for remarks like wake up or read my mails or any other comment. We are all intelligent adults here who still like to have some fun with electronics, so I don't think nobody needs to be treated as a child who is making noise.
Some aspects of your latest mails was confusing. Period. Nothing to make any trouble about, but I needed some explanation.
I read your mails and probably missed the one where you specified that you used single 627 buffers on every IGC besides the one on your preamp. As that was never mentioned on our private mails either, I was surprised to learn about it just now.
Of course I knew about your interest to replace the 627 + 634 combo with the AD815. I had asked for some AD815 almost a year ago and it was in my list to implement it.
So now that our clocks seem to be synchronized again, let me state that I think you could eliminate the buffers by the IGCs and perhaps have some benefits. In fact I don't see the benefit of using it, as the preamp is not being shared and the drive is high enough.
In any case I tend to minimalize stages, so it may just be my point of view talking.
Carlos
carlmart said:
Carlos, you keep puzzling me today.
I have you in high regard.
I didn't talk anything about private mails.
You asked me about the need (or not) to use the OPA627+BUF634 on my preamp thread.
It's public.
Read this page, please, your confusion seams like is only your confusion:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=16928&perpage=10&pagenumber=35
I answered you there's no need.
Today I was desperate in explaining all this for 1000 times, you ask me all that again, sorry for all the "faces".
carlmart said:
I gave the explanations to you.
Let's continue if you have any more doubt.
carlmart said:
I repeat: the inverting power amp also needs an input buffer.
The interferences I was talking about (the mobile phone) was with the unbuffered power amp being driven by my high-current preamp with a 5 meter shielded interconnect.
Again, I don't want a 5 meter feedback loop.
On the unbuffered power amp I had 10k input impedance (I don't like to use high value resistors on the feedback loop).
On the buffered (NI OPA627) inverting power amp I have 100k input impedance.
I can't remember more advantages right now, I just tell you this is technically better and it also sounds better to me.
I think that you followed my regulated PSU thread.
If so, you know my power amp.
If not, let me clarify with my schematic.
Oh, I use the LM3886, not the 3875.
Carlos,
Sorry if I was a bit temperamental. I also have you in high regard, so maybe that's why I reacted as I did.
Most of us sometimes need some more patience on getting some point taken, and apparently this was my turn.
In my head your IGC had no individual buffers, so that was the reason of my confusion.
May be the need to use those buffers or not is one point we disagree on, though I share most of your applications policies, as you may have seen from my comments on the Forum. E.g.: using 3886 instead of 3875, using regulators, using a solid-state buffer/preamp to isolate the IGC from the pot, etc.
There are areas I would like to go further (and probably will on my setups) like using more sophisticated regulators (based on Jung's design) and making bi-amp designs, with the buffers actually equalizing.
So let's go sharing on our test experiences.
Carlos
Sorry if I was a bit temperamental. I also have you in high regard, so maybe that's why I reacted as I did.
Most of us sometimes need some more patience on getting some point taken, and apparently this was my turn.
In my head your IGC had no individual buffers, so that was the reason of my confusion.
May be the need to use those buffers or not is one point we disagree on, though I share most of your applications policies, as you may have seen from my comments on the Forum. E.g.: using 3886 instead of 3875, using regulators, using a solid-state buffer/preamp to isolate the IGC from the pot, etc.
There are areas I would like to go further (and probably will on my setups) like using more sophisticated regulators (based on Jung's design) and making bi-amp designs, with the buffers actually equalizing.
So let's go sharing on our test experiences.
Carlos
hihopes said:
Not at all, it was based on my listening tests with my pre, the TPA6120 and the AD815.
I don't say that my implementation of the AD815 sounds better or at the same level as the Jeff Rowland.
It would be nice to try, though.
Those who know me can recognize how I love the OPA627+BUF634.
I still do.
The AD815 was a challenge for me at all levels, I was not so convinced it was superior.
carlmart said:
I tested bi-amping with this power amp for the bass and a regulated LM1875 power amp for the tweeters.
Results were very good, and what's more, I don't know if I would gain much with active crossovers as my speakers (Epos 11) have direct bass (no crossover) and only a cap on the tweeter.
I don't have this bi-amping setup right now because of lack of space.
The deam video should already be history by now.
carlmart said:
Of course, let's do it.
About long interconnects and speaker cables...
I have a similar situation to yours, Carlos. My living room is 20'x16' (6m x ~5m) with the speakers along the 20' wall and the audio system/TV between them.
I would like to move the audio rack to the sidewall and get it out of direct view, but that would require my speaker cables to go from 8' (2.5m) to 20'+. I'm not too comfortable with this idea.
On the other hand, I could place the NI LM3875's between the speakers on the floors and keep the current 8' cables and just make 8' IC's using your buffered approach.
What do you think?
I live in suburb next to the ocean with open fields all around, so I think that RFI problems would be minimal. In fact, there is almost no way to pick radio channels here without cable TV service (allowing that there is much more than AM/FM swirling out there).
I have a similar situation to yours, Carlos. My living room is 20'x16' (6m x ~5m) with the speakers along the 20' wall and the audio system/TV between them.
I would like to move the audio rack to the sidewall and get it out of direct view, but that would require my speaker cables to go from 8' (2.5m) to 20'+. I'm not too comfortable with this idea.
On the other hand, I could place the NI LM3875's between the speakers on the floors and keep the current 8' cables and just make 8' IC's using your buffered approach.
What do you think?
I live in suburb next to the ocean with open fields all around, so I think that RFI problems would be minimal. In fact, there is almost no way to pick radio channels here without cable TV service (allowing that there is much more than AM/FM swirling out there).
carlosfm said:
Is my conclusion of the AD815 being the better of these a valid one or do you guys need to see a schematic?
Take it easy, I'll finish the schematic as soon as possible.
I'm sorry, but I've been busy with other things lately and I only have two hands.
1. Your conclusion is valid. I'm sure some may disagree, but that's no biggie. You prefer it, and that's all that is needed.
2. Schematic - some of us don't have the knowledge or skill to really put together a package like this. You do. If you are willing to share your knowledge and the results, those of us that can merely buy parts and assemble are likely to be eternally grateful. It allows US to try it for ourselves and see which we prefer. Maybe our implementation isn't perfect. And that's OK too, assuming we're happy with the results. Maybe we don't come to the same conclusion as you. That too is OK, because sometimes it's a total system synergy deal. Speakers, cables, source, many variables. So, if you help others reach audio nirvana (or get closer) that's a good thing, right?
3. Take your time! If folks are rushing you, they could be putting together their own design! Otherwise, I say that good things come to those that have patience.
I will soon be putting together some new amps, buffers, etc. Much of what I will be trying is knowledge I gleaned and gained reading your posts. And without your schematics, some of it very possibly would not be happening (mostly, the amp buffer and pre-amp. and now I have two pre's to try! but your regulated p/s schematic with specific bypass info was most helpful in understanding clearly your posts)
People like you enable some of us with other areas of expertise but a thorough enjoyment of DIY audio to actually TRY things, do things, that we otherwise wouldn't.
You're not the only one this post really should be read by.
Many people are enabling this. But you seem to get frustrated by those of us that have a hard time connecting the dots. So, you get the novel written just for you. enjoy.
and happy listening.
C
carlosfm,
May be I am not a guy who not qualified to speak too much here. But I agree with those who try to explain their feeling to you. I might be one of them. I build GC with basic schematic with my friend before I met you in this DIYForum.com. My results are suck and I have spend thousands of My country money in this junk (not working GC). I have no choice searching for real GC. And I found you and a group of GC DIYer. But the more you explain, the more I got confuse because I can't imagine the changes and the effect you got.
That is why I am hoping you to provide detail info for us. Thanks for your schematics.
May be I am not a guy who not qualified to speak too much here. But I agree with those who try to explain their feeling to you. I might be one of them. I build GC with basic schematic with my friend before I met you in this DIYForum.com. My results are suck and I have spend thousands of My country money in this junk (not working GC). I have no choice searching for real GC. And I found you and a group of GC DIYer. But the more you explain, the more I got confuse because I can't imagine the changes and the effect you got.
That is why I am hoping you to provide detail info for us. Thanks for your schematics.
To me, it seems that the last few posts illustrate a classical dilema. Carlos can either keep experimenting and developing the GC OR he can slow down and use the time to make circuit diagrams and perhaps a website BUT he can't do both!
So we have people desperate to see what Carlos will do next, and another group who are equally desperate to realise what he just done!
My policy is to try something and then write it up (clearly I hope) on Decibel Dungeon, but unlike me, poor old Carlos has to go out to work and does not have the time to do the same.
I can't help thinking though, that a circuit diagram at the beginning of a thread like this, with components clearly numbered would prevent some of the misunderstandings that arise later when the various modifications are announced or discussed.
These are just my thoughts on the situation, and no criticism of anybody.
So we have people desperate to see what Carlos will do next, and another group who are equally desperate to realise what he just done!
My policy is to try something and then write it up (clearly I hope) on Decibel Dungeon, but unlike me, poor old Carlos has to go out to work and does not have the time to do the same.
I can't help thinking though, that a circuit diagram at the beginning of a thread like this, with components clearly numbered would prevent some of the misunderstandings that arise later when the various modifications are announced or discussed.
These are just my thoughts on the situation, and no criticism of anybody.
Nuuk, on spot.
Cjd too.
Guys, when I opened this thread I was (re)searching.
So, if I posted an initial schematic it would be of no use.
After too many changes, when I finished the board, I started making the schematic. It was very late that night.
It's halfway done, but some other things got in the way.
And as I said, I have been very busy.
The kitchen now has a new floor, new furniture, almost everything is new.
Also, I had to organize my bench, I couldn't move with all those parts and circuits all around.
I was loosing too much time with this chaos, to search for a part was a mess.
Give me some days, the schematic will be posted.
Cjd too.
Guys, when I opened this thread I was (re)searching.
So, if I posted an initial schematic it would be of no use.
After too many changes, when I finished the board, I started making the schematic. It was very late that night.
It's halfway done, but some other things got in the way.
And as I said, I have been very busy.
The kitchen now has a new floor, new furniture, almost everything is new.
Also, I had to organize my bench, I couldn't move with all those parts and circuits all around.
I was loosing too much time with this chaos, to search for a part was a mess.
Give me some days, the schematic will be posted.
May be I understand how carlosfm feel... I am from Software solution field. Sometimes I expect everyone know what I am doing and I will assume you guys know what I have explain which myself understand what I am trying say. Actually I make people more confuse.
I don't blame carlosfm for that. Let's close this issue conversation and continue what we suppose to discuss? Every body happy, right?
I don't blame carlosfm for that. Let's close this issue conversation and continue what we suppose to discuss? Every body happy, right?
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