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Old 27th May 2008, 10:17 AM   #1
JDeV is offline JDeV  South Africa
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Default Michaelson & Austin TVA-1 info

Can anybody help me with resistor wattage ratings, capacitor voltage ratings and bias setting values for this amp. please?

Click the image to open in full size.

Thank you.
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Old 27th May 2008, 12:14 PM   #2
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Hi, are you repairing or making a copy?

sp
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Old 27th May 2008, 12:18 PM   #3
JDeV is offline JDeV  South Africa
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Want to make a copy. (Try to at least)
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Old 27th May 2008, 12:46 PM   #4
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Nice photos here:

http://www.jogis-roehrenbude.de/Roeh...VA-1/TVA-1.htm

My friend has one like this. I was going to copy it for a mono sub amp but when I pulled off the bottom cover there were a few differences between the actual component values and the schematic values.

I gave up but would still be keen to make a copy because it is a great sounding amp.

If someone knows about this circuit or can check values I might be able to borrow my friends again.

sp
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Old 19th November 2009, 05:36 PM   #5
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[QUOTE=stoolpigeon;


I gave up but would still be keen to make a copy because it is a great sounding amp.

If someone knows about this circuit or can check values I might be able to borrow my friends again.

sp[/QUOTE]

Hi

I am about to make a TVA-1 "clone" . Please take a look at: leakstereo20

The intension is to make an upgrade version of the famous amplifier, with regulated fet-psu for the drivertubes. The drivers may be changed along with the messurement of the output power. I need the approx. 60-70 watt power for my AR3a speakers. For the time being the tubepreamp to drive the TVA-1 copy takes all the time available. The first attempt to make the TVA-1 was made 14 years ago. Look at: AR3a

It would be a great help if you could borrow your friends TVA-1 and check out the component values - whether the component values is similar to the original circuit.

One detail: the 330K resistor in the negative bias circuit may have to be changed to 100K ( maybe also the 0,47uF to 1,5uF) because old KT88 draws a higher amount of mA as when the internal resistance changes with age of the outputtubes.

Some nice pictures from a japanese hi-fi freak:


Michaelson Austin TVA-1

Michaelson Austin TVA-1

Michaelson Austin TVA-1

Michaelson Austin TVA-1

Michaelson Austin TVA-1

regards

Kim
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Old 19th November 2009, 06:09 PM   #6
brianco is offline brianco  Ireland
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Some early models were known to go on fire....I know of several instances. This may well explain the difference in component values mentioned above.
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Old 19th November 2009, 06:54 PM   #7
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hiya jdev - without wanting to be tooooo critical, if you are unable to deduce those three things from the schematic and a bit of background understanding, you may be well advised to try something a little easier.
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Old 20th November 2009, 11:38 AM   #8
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Quote:
Originally Posted by brianco View Post
Some early models were known to go on fire....I know of several instances. This may well explain the difference in component values mentioned above.
Yes - I talked to a German Hi-fi entusiast, who checked out a very erly TVA-1 to be exactly identical to the shown circuit. Find the amplifier here: Restauration TVA 1 .
Mr. Knipschild did not have any experience with his TVA-1 and burning components or tubes. On the other hand some hi-fi people had called for help with heat and fire from TVA-1 amplifiers.

Another guy in Belgium stated that some strange unexplained changes has been made to later versiones of the TVA-1.

I have heard the original without checking the values of the components. I am very sorry I did'nt. This amplifier sounded as one of the best I have ever listen to when talking about push-pull with power beyond 30 watt.

If anyone has the answer whether the stated circuit can be verified as identical to the real TVA-1 amplifier, I would like to know?

regards
Kim
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Old 20th November 2009, 08:09 PM   #9
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Quote:
Originally Posted by kimjul2005 View Post

If anyone has the answer whether the stated circuit can be verified as identical to the real TVA-1 amplifier, I would like to know?

regards
Kim
After I have checked out several japanese renoval TVA-1 amplifiers from the close-up pictures taken ( as mentioned above erlier) , the following circuit comes up:

If one looks close to the mentioned pictures, some older versions uses 47R as cathode resistor for the KT88, while later amplifiers has 33R hooked up to GND. In the feed-back circuit the original circuit says 3K9 parallel with 470P - where as the seen print on the pictures shows 3K3 /330P. Otherwise the rest of the attached circuit should be identical with the real TVA-1 amplifier from Michaelson & Austin.

As for the feed-back resistor - and capsize it all depends on the chosen OP's if one don't have the original types in stock.

For JDev:

Look at the pictures and you will get an idea of the resistor wattage if you unable to calculate the optimal size.

Regards
Kim
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File Type: gif michaelsonandaustintva1 Japan.GIF (35.0 KB, 808 views)
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Old 25th November 2009, 12:11 PM   #10
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Hi Kim,

Coincidentally, I am collecting a box of transformers from him this weekend. I will check if he still has it.

sp
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