Tube with Power IC Output Stage - JLTi

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#421
nowater said:


Thanks for your tips. Why won't it take a balanced input directly? Is it because the balanced input must first be averaged to ground to prevent amplified DC on the opamp's output?
Grant
Click to expand...

It is such a large topic. May I suggest to click on this link, it should download a 160 page "Op Amps For Everyone" book by Ron Mancini. It covers non-inverting, inverting and 'differential' - this is the one you're querying.

http://homepage.mac.com/tbitson/weather/TI_OpAmp_Tutorial.pdf

The best part of it: It's free!

Joe R.
 
#422
Thanks Joe for the hybrid idea. I am just wondering -- maybe Joe or others with more experiences can help -- if the hybrid gainclone can be operated using +/- 24V rails. I think the op-amp can do it, how about the 6922 tube? Will there be any modification to the circuits?
 
#423

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#426
Nielsio said:
Joe,

Have you sold many amps yet? And to Europe maybe? How long would an order take?

Regards,
Niels
Click to expand...

Most of them have been sold in Australia and New Zealand. None in the U.S. as they have 115V AC (late this year or early next year some will be made). There are two in Europe at the moment with a third on the way.

We are arranging for an on-line review out of Europe soon. When it eventuates, will make an annoucement on this forum.

If you are interested in one, I have current stock and can send one immediately. For EUR 1100.00 which includes Economy Air Freight (it's quick this time of year). It's sent in a plain box with private names only. On the other occasions there have been no additional charges from customs. So the price I quoted should be all that is needed to pay.

I will be at the European Triode Festival in the south of Germany, near Lake Constance (Bodensee), the first weekend of December. I believe the place is called Langenargen.

Yes, I will have a JLTi amp there, ready to be compared with the best?

There is going to be some interesting stuff there. I hope they will make Saturday Dec 6th will be 'open day' where non-paying participaters will be able to attend. We, Allen Wright and myself, will be there from Thursday to Sunday.

Joe R.



Joe R.
 
#427
agent.5 said:
Thanks Joe for the hybrid idea. I am just wondering -- maybe Joe or others with more experiences can help -- if the hybrid gainclone can be operated using +/- 24V rails. I think the op-amp can do it, how about the 6922 tube? Will there be any modification to the circuits?
Click to expand...

Yes, the circuit will work without changes. I may be inclined to reduce the 10K value to negaive 24V to 7K5 or 8K2. This will keep the current up and it drops with lower voltages.

Some 6922 may not be as happy with +/-24V as others. So try more than one might be a good idea. I have never run them that low so I don't speak from experience, only what others have said.

Go ahead and construct it, I am confident you will like it.

Joe R.
 
#431
Most of them have been sold in Australia and New Zealand. None in the U.S. as they have 115V AC (late this year or early next year some will be made). There are two in Europe at the moment with a third on the way.

We are arranging for an on-line review out of Europe soon. When it eventuates, will make an annoucement on this forum.

If you are interested in one, I have current stock and can send one immediately. For EUR 1100.00 which includes Economy Air Freight (it's quick this time of year). It's sent in a plain box with private names only. On the other occasions there have been no additional charges from customs. So the price I quoted should be all that is needed to pay.
Click to expand...

Ok. Thanks very much for the information. I was asking this because I might be interested in buying one at a later stadium.

I will be at the European Triode Festival in the south of Germany, near Lake Constance (Bodensee), the first weekend of December. I believe the place is called Langenargen.

Yes, I will have a JLTi amp there, ready to be compared with the best?

There is going to be some interesting stuff there. I hope they will make Saturday Dec 6th will be 'open day' where non-paying participaters will be able to attend. We, Allen Wright and myself, will be there from Thursday to Sunday.
Click to expand...

Good to hear! Let's hope I can make it.
 
#432
Hi Joe & others,
Firstly, I've built two Gainclones. Neither are inverted and I don't own either of them! One belongs to my Sister and the other is my Brother's. Ever since I heard the first one, I fell in love with them. They may not be the best amp I've ever heard / built - but certainly have the highest QPP rating (Quality Per Pound 😉 ). I'm hoping that your superb work will change that and make them the best I've heard... :yes:

Here are my questions...I like to play my music loud (when my fiance goes out of course! :cop: ) I don't feel that the gainclones go loud enough for my liking. I was thinking about bridging two LM3875TF s. I have 10 of them and would like to use them rather than buying 3886s. I see that in the schematic you have one tube shared between both channels. I am wanting to build monoblocks. Can I just use half the tube successfully or is there a way to use both sides? Maybe use the buffer after the invertor and then I can use both sides of the tube for each chip.

Please bear with these seemingly stupid questions - but I've never had anything to do with tubes or bridged amps.

Thanks!!!
Gaz
 
#433
Hey Rarkov:
I was thinking along similar lines, and am even more ignorant than you. 😉 I also want monoblocks and I'm pretty sure you can just use half the tube. BUT, why not use both sides to make a balanced amp or parallel or something. I'm getting the idea around here that using two chips in a balanced config doesn't automatically get you more power, BUT I think it would probably dispurse the heat better and allow higher voltage? Parallel is that different? I think so and prob does put out more power.
Boy , now they're clutching their head in amazement at my pathetic puddle of knowlege!!!

My main point is that you meant to say use one side of the tube for each chip(2 total) in the monoblock I think.
 
#436
Hi Dave,
I had to read that a few times for it to sink in! I thought you were making some kind of joke at first! :scratch: Just me being stupid!

I didn't know if it was possible to use just half of the tube. It would save on money I suppose to wire it as you suggested. Another stupid question - I have never seen let alone heard tubes before...Does using half of a tube as opposed to both halves effect the aesthetics?

Cheers,
Gaz
 
#437
Hi,

I have never seen let alone heard tubes before...Does using half of a tube as opposed to both halves effect the aesthetics?
Click to expand...

Nah...

What you can do too with a CF as this is wire both halves in parallel for even better current drive and lower Zo.
This requires well match triode halves as current hogging will occur otherwise but that's another chapter.

Personally I'd stick to Dave's idea though, it's elegant enough and easy to swap around the tubes every year or so.

Pinout of the 6DJ8 and kin:

Cheers,

😉
 

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