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Old 4th March 2005, 08:57 PM   #11
sickss is offline sickss  United States
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Thanks Reinout...I have already shot an email to heart.

The price you quoted ...is that NLG? the conversion should put it about 225 bucks if my math is right....I received a quote from a local source....about 3 times that amount! I hope they get back to me.

As far as output is concerned. I am currently dissipating 2200 watts into 3 subs, solid state. I could use a little more...and would love to get away from the clipping of the solid state amp.

I have used the 833 in RF....this is a very simple circuit design. I am not very familiar with controlling the output on a audio design. What would be the problems associated with OTL? Is their anyway to model this?


Also, how much lead time does heart normally need? I would like to get going on this ASAP.

I have included a link to the current subs I am using...this may change a great deal until the project is complete...but for now These are the most musical drivers I have found.

www.reaudio.com

((model 15 XXX)

Thanks for all the help!

Dennis
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Old 5th March 2005, 12:06 AM   #12
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Quote:
Originally posted by sickss
The price you quoted ...is that NLG? the conversion should put it about 225 bucks if my math is right....

Wishful thinking - that price was in Euros.
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Old 5th March 2005, 12:20 AM   #13
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Just curious, how loud is the music you are listening to? I have an SE 845 driving 89db speakers with plenty of headroom. What brand of sub needs 2200 watts of driving power? It sounds very inefficient to me.

What does anyone think about running some big triodes in class B for maximum power?
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Old 5th March 2005, 06:02 AM   #14
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Default tranny reply

Sorry Sickss,

just as Jeff Mai noted....it is in euro's. 369 is (exchange rate 1.3 - ish) around $ 480 US. Certainly not cheap.....but i do hope you never thought that a 833-based amp was going to be cheap in the first place.

I can stand for the quality. To be honest i delivered special kapton-foil to the company to be used in this design. Normally the isolate primaries/secondaries with the good/classical Kraft paper. with their vacuum impregnation and 12 hours hardening (!) in an oven you get a real solid transformer. But the Kraft-paper is only good for 1 kV. In order to go to higher voltages.....they standard multiply the paper to come to the required isolation class. But that will take up much winding room....so less space for copper winding....so thinner wire (ratio's will be fixed)....so resistance.....AAAARRRRGGHHHH.
I bought a roll of Kapton-foil. Extremely thin....but good for 7.5 kV ! And ordered my transformers with a mixed combination of Kraft-paper + Kapton-foil. The foil for the isolation; the paper for soaking up the laquer which after the over treatment will be as hard as a rock.
When you want those trannies.....i'll "donate" the Kapton-foil for this project. It is bloody expensive but i like to see more 833-amps around.

Th picture shows the EI96-size interstage (interstage 300B to 833A) and the EI126 output transformer.
"Your" EI180 is twice the size......please do count in postage.....
Simple question from my side: i believe a EI150 will do nicely. large enough diameter copper; no DC (PP-design)......

Leadtime can be fast enough.....the company is not really promoting these products (there is much more money to be earned as importers/distributors of audio-gear) so if you want to proceed......i offer to be your middle-man. It works always better if there is some "pressure". No money involved !!!!!
If you want i'll find out the difference for my pricing (will be 369 without VAT) and your USA-pricing (can be without VAT ????).

Reinout
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Old 5th March 2005, 09:18 PM   #15
sickss is offline sickss  United States
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reinout,
That pricing is still very acceptable. I am hoping to keep a budget of 5-7K usd. If not...oh well, I believe it can be done for less than half...but I wany a nice looking piece also.


I will spend some more time this weekend modeling the output stage...Hopefully I can get moving on this next week. I will let you know. And I certainly appreciate your offer.

astouffer...very loud. and I am dissipating that power across 3 subs, not 1.

Still no response on a OTL design?

Thanks
Dennis
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Old 5th March 2005, 11:15 PM   #16
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OTL = Output Transformer Less

In other words there is nothing between the tube(s) and the load. If the load is 8 ohms, the output impedance needs to be 8 ohms or lower, or else the power transferred drops. The greater the mismatch the less power transferred.

An 833 is a very high plate Z tube, as apparently you already know.

The only possibility is to couple using the cathode, which then makes it unity gain, meaning you need to swing the grid a huge amount of volts - a design problem for sure.

And then the cathode probably won't be anywhere near as low a Z as you need...

The typical OTL is a "totem pole" arrangement using multiple tubes to acheive close to the requisite output impedance - and using feedback. Typically used are tubes like the 6336 and the Russian 6C33C.

But to get hundreds of watts, or even a hundred watts in OTL you need quite a large bank of tubes...

There are some variations in design that are worth considering if you are going to build an OTL, but I'd probably not opt for an OTL as a sub amp...

A suggestion for yuks - try putting a very large 1 or 2 ohm resistor in series with your subs and see if that makes them sound anything like they did with the tube amps that you liked with them? That will reduce the damping factor down to close to what a "normal" feedback type tube amp would have (on the order of <10) as opposed to the DF likely with your high power solid state amps which is >100 and maybe into the thousands...

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Old 5th March 2005, 11:18 PM   #17
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Default Re: finished amp

Quote:
Originally posted by ReinoutdV
Hi Sickss,

As promised a picture of my 833 amp. Not for only bass-output.

Your design: PP 833......what is the speaker you're going to drive. Or are you planning to power up a stadium ?!

Picture only one channel: upper part audioamp. Lower part the external power supply.

Reinout

Reinout,

Spectacular looking piece of DIY gear!!

What is your chassis?
How did you get the glass done that holds the 833?
What did you use for the 833 socket??
What is the top finish on the chassis?

Congratulations! Fine work!



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Old 6th March 2005, 12:33 AM   #18
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Default Re: Re: finished amp

Quote:
Originally posted by bear
Spectacular looking piece of DIY gear!!

What is your chassis?
How did you get the glass done that holds the 833?
What did you use for the 833 socket??
What is the top finish on the chassis?
There's a lot of info about this amp in another thread starting with this post:

http://www.diyaudio.com/forums/showt...753#post328753

It's a fantastic effort!
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Old 6th March 2005, 02:29 AM   #19
sickss is offline sickss  United States
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bear,
I am aware of these issues with the OTL design... I was more looking for a solution?

Thanks
Dennis
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Old 7th March 2005, 03:25 PM   #20
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The solution is not an 833...

The solution is likely a 6336 or 6C33C, and a pile of them...

for an OTL...

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