Ropie said:How is this thread useful to anyone hoping to do any DIY?? It needs a damn good edit to get it back into any sort of useful shape (you can edit this post out too while you're at it).
I agree with several posts that point out that much of DIYaudio.com is not really about DIY audio anymore...
I'm beginning to agree with you...
I leave to the moderators the deletion of irrelevant posts here (including mine).
Lots of work, I know.😀
But please, although off-topic, don't delete the posts about my beautiful Epos speakers.
If you have not made a Gainclone before, please build one without the regulators first (use 1000 uF Panasonic FCs on the pins). Get that working properly and then add the regulator circuit. You will only need to remove the 1000 uFs and replace with the 33-100 uFs. 😉 [/B][/QUOTE]
Hi Nuuk
I have done the inverted gain clone.
1000 uf per rail. Using 220k/10k then follow by 250k/10. DC off set something like 77/80 mv per channel. Putting additional 10k at the other input to ground may reduce the DC offset, but make the amp less interesting.
The bass and highs are ok, but mid are thin, not like valve sound.
Then I change the circuit to NI. Wow things much improved! DC off set gone down to 5/6 mv per channel.
Overall sonic improvements are getting better.
Later, I change from Pana FC 1000uF caps to Pana FC 2200uF and at the same time I did my pre (OPA+BUFF) and regulate the pre supply with 7818/7918 and use 200pf caps.
THIS IS REAL GOOD.
The background gets darker, the mid improves lot more. Dynamic becomes wider.
I am busy listening until Carlosfm (thanks) reported that he add regulator for LM 3875.
I am asking why LM 338 and not LM 317/337 since the 3875 use very little current and how to split my x’former from. 18-0-18 to 24-0 0-24 suddenly all the polemic started.
Now, I wish, I would like to increase my x’former voltages?
Best regards,
Hi Nuuk
I have done the inverted gain clone.
1000 uf per rail. Using 220k/10k then follow by 250k/10. DC off set something like 77/80 mv per channel. Putting additional 10k at the other input to ground may reduce the DC offset, but make the amp less interesting.
The bass and highs are ok, but mid are thin, not like valve sound.
Then I change the circuit to NI. Wow things much improved! DC off set gone down to 5/6 mv per channel.
Overall sonic improvements are getting better.
Later, I change from Pana FC 1000uF caps to Pana FC 2200uF and at the same time I did my pre (OPA+BUFF) and regulate the pre supply with 7818/7918 and use 200pf caps.
THIS IS REAL GOOD.
The background gets darker, the mid improves lot more. Dynamic becomes wider.
I am busy listening until Carlosfm (thanks) reported that he add regulator for LM 3875.
I am asking why LM 338 and not LM 317/337 since the 3875 use very little current and how to split my x’former from. 18-0-18 to 24-0 0-24 suddenly all the polemic started.
Now, I wish, I would like to increase my x’former voltages?
Best regards,
carlosfm said:
But please, although off-topic, don't delete the posts about my beautiful Epos speakers.
Posts about our favourite bits of kit that go with our DIY efforts are fine, I'm sure 😉
azamkita said:
Yes, that's what I always said, this thing benefits in using a good pre.
And inverted, with input buffer is the best.
Without it, it's inferior to NI.
With it, it's better.
azamkita said:I am asking why LM 338 and not LM 317/337 since the 3875 use very little current and how to split my x’former from. 18-0-18 to 24-0 0-24 suddenly all the polemic started.
Now, I wish, I would like to increase my x’former voltages?
Best regards,
azamkita, I think I answered to your questions, you had a thread, right?
Forget the 317/337, too weak for this, use the LM338.
To transform a CT trafo to independent secondaries is easy (as I explained), but to get more voltage you had to wind more wire in the secondaries, I wouldn't do that.
Use that trafo, I regulated a 18v toroid last weak and got +/- 20.5v, with some margin (I could get 1 volt more).
That little amp has a LM4780, and with this voltage I get around 20w RMS at 8 ohms, 35w at 4 ohms, fine for me, it's not on my main system, it's driving some "easy" speakers.🙂
instead of "just" using one pair of the lt1083 to feed one mono block lm3886.........how about double regulation - 2 pairs of the lt1083 for one mono block........😉 ........"i'll say no more"........
tbla said:instead of "just" using one pair of the lt1083 to feed one mono block lm3886.........how about double regulation - 2 pairs of the lt1083 for one mono block........😉 ........"i'll say no more"........
Bridge-parallel regulated monoblock?
What about bridge-parallel monoblock with a pair of regs per chip?😱
does anyone know where to get these lm338's / lt1083's in the netherlands ?
RS only has the to-3 package, farnell is mighty expensive...
edit: whoa i was looking at the steel package at farnell. seems they are EUR 2,95 at farnell. Not too bad.
RS only has the to-3 package, farnell is mighty expensive...
edit: whoa i was looking at the steel package at farnell. seems they are EUR 2,95 at farnell. Not too bad.
i hereby claim to be the first to suggest this technic - to be used with power chips.........
😀
and even better.......use a big high quality choke before the regulators.
a first again........
😀
a first again........
😀
matjans said:
Hi Matjans
Zoek op Marktplaats, bij "elektra, TV´s, witgoed" en dan "elektronische onderdelen" naar linear. Iemand bied 10 stuks aan, en hoewel zonder prijs, zou het wel goedkoper zijn dan RS of Farnell. Is zou er ook best twee willen hebben.
Hi all.
Just explaining to Matjans where he can get some LT1083 at a second hand dutch website (kind of e-bay).
What about building a regulator like this one from www.headwize.com using high amperage power opamps (the same that will be used in the amp)?
Erik
No,no,no! I was first to think of that! 😡
An externally hosted image should be here but it was not working when we last tested it.
tbla said:instead of "just" using one pair of the lt1083 to feed one mono block lm3886.........how about double regulation - 2 pairs of the lt1083 for one mono block........😉 ........"i'll say no more"........
I also have thought of this, I am thinking about doing parallel 3x3886, at that time, 1 pair of LT1083 may not be enough to provide the current for both channels.
Since I have a 500VA PS, I can just use 2xLT1083 per channel to provide enough current for my parallel GC. I choosed LT1083 because it seems to have a better load transient response.
My unregulated GC used a dual mono configuration, but the regulated version blows it away with 1 transformer and half the diodes.
BTW, can anyone tell me what the input buffer can do to the sound?
Thanks!
Alex
alexw88 said:
It will "open" it like there's no tomorrow.😀
Suddenly, you have a live performance in your room!😎
Hey, I'm talking seriously, no joking!
tbla was talking "double regulation". (c) 2004 tbla😀
This means regulate, and then regulate again.
For normal use this may have no real advantage.
The advantage I see here is if you have a trafo with too much voltage.
If you regulate in too steps down (smaller voltage difference between in-out), your regs will output more current.
This means regulate, and then regulate again.
For normal use this may have no real advantage.
The advantage I see here is if you have a trafo with too much voltage.
If you regulate in too steps down (smaller voltage difference between in-out), your regs will output more current.
carlos, i remember reading somewhere that you were using a slightly different schematic than the one on pedja's site. what did you change and why?
hehehe...............i like it.....😀
double regulation is better - some even use triple regulation.!!!!!!!!!!!!!!!!!!hey one more - and i haven't even had my first beaujolais yet.......😀
matjans said:
It's posted on this thread.
No idea in what page.
Well, if you have the time, read the thread where I started building this.
There's a link on the first post of this thread.
What I managed was to optimize the sound quality of this regulated PSU (with LM338), with some hints of Nuuk and Pedja, who told me that the output cap could be removed (it was sounding very bad to me with 100uf).
I finally did not remove it, but put a much smaller one, and on the LM3886 chip too.
The LM338 likes to be bypassed (who doesn't?😀 ) very near the input and output pins, and that is in my schematic.
Enjoy the music.😎
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