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Old 12th July 2004, 10:54 PM   #11
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Hi,

Quote:
I found the Lilliput amp... and it looks really nice... but I was wondering if there were any similar to it, but maybe a tad better. It uses solid state rectification... and from what I understand 6AS7's like slow turn on supplies. Would this hurt the tube?
The Lilliput amp is a very good sounding little amp. In fact, I think I must have mentioned this before, I heard it perform on horn loaded Sowthers a few times and was impressed.

Frankly, I couldn't care less if it used a diode bridge or anything else....The results were there and it obviously worked.
Short of trying every single PS topology out on it it's hard to predict how it's going to sound with this little gem.
Actually it sounded very similar to the AN Baransu 300B amp another friend uses on his Sowthers which is very high praise in anyone's book, I reckon.

If it's any help, I have the complete schematics and text (in Italian) for the Lilliput amp.

Quote:
So, I am leaving now, and shall NOT return to the tube forums again. I will seek help elsewhere...
Common, the tube forum is about as friendly as it gets.
Hang in there, ask whatever questions you like to ask....We're ALL learning here...

Cheers,
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Old 12th July 2004, 11:05 PM   #12
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Hi,

Quote:
I have studies both from the US and Europe from "the good olde days" which bear out the increase in lifespan. Note thatexcessive underheating can shorten life, overheating will DEFINITLY shorten life.
Note also that this information has been put on the forum by yours truly before.

Yours truly also appreciates it when such critical information is given correctly and completely.
A little explanation or some references as to WHY underheating is a good thing would help to show the people new to valves where the pratical limits are....

Oh, the 6AS7, as so many other triodes is related to the 2A3 historically. Whether the DHT gods like it or not.

Cheers,
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Old 13th July 2004, 12:21 AM   #13
alk is offline alk  Europe
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Needtubes hope you read this, frankly, i see no unfriendly attitude from noone. Some ppl are just not interested, that''s all. There are a lot of simple designs out there and simple isn't synonymous of bad. I also like the Lilliput and, if i were you ,would follow Frank's advice. It is simple and cheap - just what you asked for.

But if you get annoyed easily maybe you shouldn't try...what would happen if it doesn't work?
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Old 13th July 2004, 12:38 AM   #14
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Ok... I apologize for that... heh I have been somewhat lacking sleep lately, that could have onset the slight irritation at comments which may not have been meant rudely... So, forget that, if possible. It is too hard to leave this place anyway....

Anyway... Thanks fdegrove for the post about the Lilliput... I had seen the schematic, but was wondering if there was somethign better out there. The one I saw was a little unclear, but I think I got all of the parts values off of it.

I have also seen the Svetlana circuit... but it uses a little too high of voltage for my taste. I would be a lot more comfortable with a lot less voltage... Anyway, I will look again at the Lilliput when I return from dinner... compare some prices... and approximate how much that thing would set me back. The problem is not necessarily having the money.... it is parting with it. I just wanted my first project to be cheap... so in case I do fry something, the parts wouldn't break me. Thanks all

edit- alk-- I can be annoyed easily sometimes... but I am really calm for the most part.

EDIT again: Couldn't wait until after dinner to check a few things... Is it possible to substitute a different tube in the driver section of the Lilliput? If so, what would be some suitable ones?
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Old 13th July 2004, 01:02 AM   #15
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Hi,

Glad you changed your mind...

Quote:
I had seen the schematic, but was wondering if there was somethign better out there. The one I saw was a little unclear, but I think I got all of the parts values off of it.
I suppose there's always going to be something "better" out there but if you're looking for a small power amp then the Lilliput is hard to beat and comes with excellent specs to boot.

The scans on the Audiokit site (there are several ones*) aren't doing the kit much justice but the sound really makes up for it.

Regarding your concern about the use of silicon diodes in the PS, most of the noise will be snubbed by the choke and if you really want to you can use Schottky diodes or put snubbers across the 1N4007s.

I heard the kit in its standard form and was already blown away by the sound. It doesn't sound like an overly romantic tubeamp at all but rather crystal clear and precise.
This is how I like an amp to be regardless of topology or genetic persuasion but it may not be to everyone's liking.

All this doesn't really matter to me as with careful choice of passive components it can be made to sound to fit anyone's taste/system, I'm sure. Me, I stick with the neutral/accurate presentation.

Either way, if you need help with the project, I'm sure there's plenty of people around here to lend a hand. Myself included.

* When you're going to the site and are looking at http://www.audiokit.it/ITAENG/KitEle...t/Lillman4.gif
replace Lillman4.gif by Lillman3, *2 etc, to see the rest of the scans.

Cheers and chin up,
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Old 13th July 2004, 01:09 AM   #16
jlsem is offline jlsem  United States
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There was a nice little amp posted elsewhere in this forum which uses half a 12AT7 to drive half a 5998 for a two tube stereo amp. The 5998 is a cousin of the 6AS7G but with higher mu. If you want to use the 6AS7G/6080, I don't see why you couldn't adapt that circuit to use one half of the 6AS7G to drive the other half via a 1:2 interstage transformer with a 1K - 1.5K OPT. Don't let the forum Nazis get you down.

John
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Old 13th July 2004, 01:24 AM   #17
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Default 5998

Hi,

This the one you had in mind, John?

5998 power amp question

It's from the same hand as the Lilliput, BTW.

Cheers,
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Old 13th July 2004, 02:56 AM   #18
jlsem is offline jlsem  United States
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Yes, that's it. Mine is in the works, but I am substituting 7236 for 5998 (it's what I had on hand) and 6BY5GA for expensive 5AR4.

John
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Old 13th July 2004, 03:25 AM   #19
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Default Glad you decided to stay!

You might be able to save on the output transformer by using a MOSFET current source to load your output stage and then using a capacitor to couple to your smaller) output transformer which will no longer have to handle the DC bias current. Of course you will need to have access to a transformer with adequate high voltage windings.

Check out Steve Bench's description of output circuits here. He also has an amplifier that uses power toriods as output transformers. That amp has no power transformer either so it has to be carefully constructed but it might be worth looking at. Steve's Cheap Output Tranformer Amp
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Old 13th July 2004, 04:05 AM   #20
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Default Re: Glad you decided to stay!

Quote:
Originally posted by mashaffer
[B]You might be able to save on the output transformer by using a MOSFET current source to load your output stage and then using a capacitor to couple to your smaller) output transformer which will no longer have to handle the DC bias current. Of course you will need to have access to a transformer with adequate high voltage windings.
commonly called parafeed... a choke is often used instead of a current source.

Quote:
That amp has no power transformer
I cannot emphasize enuff how dangerous this is... and if your insurance company ever finds out after your house burns down, you are likely out of luck.

dave
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