833A (GU-48) Amp

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Alex Kitic
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#1096

Post by Alex Kitic »

nickds1 wrote: A pair was on eBay recently for GBP 27K. Didn't sell. Supposedly they retail at USD 250K - the auction stated "HAPPY TO SWAP FOR A CAR OR HOUSE IN FRANCE"
I guess the seller would be happy to get anything near enough to what he has paid it... which must be an interesting story...

That's why I asked whether he has spent the evening at Baron Munchausen's palace. OMG.

At least it inspires people...
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rowuk
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#1097 Trafomatic in Serbia

Post by rowuk »

Here is a Trafomatic in Serbia:
http://www.trafomaticaudio.com/contact.php

They specialize in valve stuff.
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IslandPink
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#1098

Post by IslandPink »

As Alex suggests, I'm very sceptical about those interstage specifications - even with bifilar winding ; not that anyone really needs 2mHz anyway !
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Itchy & Scratchy
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#1099

Post by Itchy & Scratchy »

pre65 wrote:I heard a pair of these tonight. :)

Image

interstage-transformer 833-based 140kg Reference monos outputting 150 watts in class A single-ended triode mode with a 6C45 driving a 300B driving the 833
Trafomatic builds amps of any persuasion particularly since they specialize in custom commissions of late. TruLife does single-ended no-feedback direct-heated triode amps exclusively. What's more, the Greeks categorically reject signal-path capacitors to favor ultra-wide bandwidth interstage transformers of the 2MHz 0.1dB sort.
Circuit topology: Class A, Zero Feedback
Output Power: 150W
Input sensitivity: 1,2V
Dimensions: 55cm(W)x35cm(H)x75cm(D)
Weight: 120kg
AC Power Consumption: 850W
Tubes complement: 1x833A, 1x300B, 1x6C45, 1x5U4G
Inputs: One single ended RCA
Input Impedance: 100kOhm
Transformers (per channel): Two Power Transformers
Two Interstage Transformers
One Output Transformer
Six Chokes

Rather nice. :wink:
Hi Philip,

A few of the Specs are incorrect:

The Dimensions- The Amplifiers are somewhat larger than the dimensions quoted.

Inputs- Both RCA and XLR


Here are some pictures:

https://www.dropbox.com/s/n6rpwusewb8bq ... 2.jpg?dl=0

https://www.dropbox.com/s/bmbk2cxlcq57i ... 0.jpg?dl=0

https://www.dropbox.com/s/c2n26k2so180j ... 4.jpg?dl=0

https://www.dropbox.com/s/196artj7arho6 ... 8.jpg?dl=0

https://www.dropbox.com/s/r9zlrzlzu3h50 ... 1.jpg?dl=0
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jack
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#1100

Post by jack »

You know, for USD 250K I'd have expected rather neater wiring...

Very interesting & informative pictures - thanks for those...

EDIT: Amplifier with about the same amount of "bling" factor http://www.jogis-roehrenbude.de/Leserbr ... -6C33C.htm - but MUCH neater wiring :)
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pre65
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#1101

Post by pre65 »

I need 8 40mm nylon capacitor clamps, 4 per amp.

I found some on e-bay @ £1.76 per 5, so £3.52 per 10 inc post.

Cheap, or what. :wink:

They came today and are just perfect. :D
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rowuk
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#1102 a neat amp is a sign of a sick mind.....

Post by rowuk »

fuzzy placement reduces capacitance and inductance as well as offering an opportunity for discussion...
nickds1 wrote:You know, for USD 250K I'd have expected rather neater wiring...

Very interesting & informative pictures - thanks for those...

EDIT: Amplifier with about the same amount of "bling" factor http://www.jogis-roehrenbude.de/Leserbr ... -6C33C.htm - but MUCH neater wiring :)
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Dave the bass
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#1103 Re: a neat amp is a sign of a sick mind.....

Post by Dave the bass »

rowuk wrote:fuzzy placement reduces capacitance and inductance as well as offering an opportunity for discussion...
Done it! -> http://www.audio-talk.co.uk/phpBB2/view ... postorder=
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shane
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#1104

Post by shane »

One of the things I look forward to as the nights draw in is the return of threads like that one. This time round, I actually understood the tea-cup/doughnut/top-hat relationship. Briefly.
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
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rowuk
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#1105 Re: a neat amp is a sign of a sick mind.....

Post by rowuk »

Actually, I meant "fuzzy" as a higher order organisation. When our "goals" are defined, the product takes a specific shape. We can wire aestetically for the mathematician, electrician, Quality Control Engineer, support team. We can also wire for random interaction, in the hopes of minimal known side effects caused by capacitance, resistance, impedance, induction. Many times the argumentation, regardless of the intention is pure BS because we do not have enough understanding of all of the parameters that really count.

Most important: we get an acceptable result. That means in the beginning, doing it someone elses way and then with time and experience, adding our own stamp on eternity!

That was a great link Dave. Thank you!
Dave the bass wrote:
rowuk wrote:fuzzy placement reduces capacitance and inductance as well as offering an opportunity for discussion...
Done it! -> http://www.audio-talk.co.uk/phpBB2/view ... postorder=
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pre65
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#1106

Post by pre65 »

Thoughts are turning to the 833a rebuild.

Quite a few components were "nicked" to make the GK-71 dual mono power supply, but that was planned ages ago and upgraded transformers and chokes have been purchased with help from Phil Ramsey at Bluebell Audio.I would like to try the Rod Coleman filament modules (two 5A in parallel) but that will be phase 2 I think.

I can't start today, as I'm off to West Yorkshire tonight for a family visit.

So I thought I'd have a quick inspection of the KT66 amp that I use to drive the 833a. I thought a Mundorf coupling cap might pay dividends, but of course it can't because the two sections of 6DN7 are direct coupled. DOH. :wink:
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pre65
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#1107

Post by pre65 »

One trolley is on the bench right now.

I've drilled the mounting holes for the new mains transformer and choke and am now sussing out where to mount the 4 smoothing capacitors.

The caps are 1000uf @ 450v so will end up as 250uf @ 1800v.
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
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pre65
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#1108 Re: 833A (GU-48) Amp

Post by pre65 »

It's a long time since I did anything to these amps, and thoughts are now returning to the bwain regarding progress.

I mentioned capacitors for the power supply in another thread, but here is one I found earlier on Ebay, pity they are in Sweden.

http://www.ebay.co.uk/itm/162022029473? ... EBIDX%3AIT

These are only 2.9 Kg each. :lol:
The only thing necessary for the triumph of evil is for good men to do nothing.

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G-Popz THE easy listening connoisseur. (Philip)
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Greg
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#1109 Re: 833A (GU-48) Amp

Post by Greg »

In the past I have found postal services from Sweden very good.
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pre65
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#1110 Re: 833A (GU-48) Amp

Post by pre65 »

Greg wrote:In the past I have found postal services from Sweden very good.
I agree Greg, but because of the weight it's not cheap. :(
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
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