Michaelson & Austin TVA-1 info

[JDeV]

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



Thank you.

[stoolpigeon]

Hi, are you repairing or making a copy?

sp

[JDeV]

Want to make a copy. (Try to at least)

[stoolpigeon]

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

[KJ2005]

[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

[brianco]

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.

[aardvarkash10]

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.

[KJ2005]

Originally Posted by brianco

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

[KJ2005]

Originally Posted by kimjul2005

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

[stoolpigeon]

Hi Kim,

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

sp