Vacuum Tube OTL power amp!!

[Alastair E]

Hmmm....

Not sure a small 2A diode will put up with the 'inrush current' if used in the two O/P stage rail supplies....

May need bigger diodes, or guess you could paralell em up....

 

[M Gregg]

The Alpairs are getting another bashing, 3hrs so far again

Poco Legend...

You got to think current with this.....cables, fuses, diodes,
sun tan...LOL

Snow machine for cooling...oven gloves for the volume control....LOL

Its working great......

Regards
M. Gregg

 

[flatheadmurre]

The toroids has arrived.

The smallest one in the picture is supposed to be a 500VA 2x115.

BUT it´s now a 50VA 2x15

Talked to airlink they apologized and makes me a new one in a week !!!!!

This is now officially the Murphys law OTL amp.

 

[flatheadmurre]

You´re probably right about the diodes.

Have some from a UPS they will be more up to the job.

Still angry about the transformers.

 

[M Gregg]

The toroids has arrived.

The smallest one in the picture is supposed to be a 500VA 2x115.

An externally hosted image should be here but it was not working when we last tested it.

BUT it´s now a 50VA 2x15

Talked to airlink they apologized and makes me a new one in a week !!!!!

This is now officially the Murphys law OTL amp.

50VA 2x15?

Thats a shame....What Transformer specs are you using?
Do you know the physical size of the 500VA 2x115.
Can you build arround it. (leave a space).
Are all the others OK?


Regards
M. Gregg

 

[flatheadmurre]

I got the measurements for the toroid but there´s a little lack of trust right now.

It´s very crowded inside so i´ll finish the small signal HT and then it´s back to waiting.

 

[M Gregg]

I got the measurements for the toroid but there´s a little lack of trust right now.

It´s very crowded inside so i´ll finish the small signal HT and then it´s back to waiting.

I used

TT0913.<<Airlink.

I had no problems with them. YMMV.

Do you not trust them?

Regards
M. Gregg

 

[M Gregg]

Post 66# and 67#and 68# this thread.

Depends on your input mains voltage!

I thought you were using a local company?



Regards
M. Gregg

 

[flatheadmurre]

I used

TT0913.<<Airlink.

I had no problems with them. YMMV.

Do you not trust them?

Regards
M. Gregg

Thats a nice one with shield, didn´t spot it.

Change of order coming up.

No problem with trusting Airlink.

Just a little anger management fighting windmills and i´ll be my nice self again LOL

 

[M Gregg]

What mains supply voltage do you have?
Post 66# and 67#and 68# this thread.

Depends on your input mains voltage!

Sure you will get there, I found this a strange build it can be tight for room. Also I had to retrain myself to think current first then voltage. Because normal valve is voltage first then current is normaly low.



Regards
M. Gregg

 

[flatheadmurre]

I got some from noratel the 24v heater toroid i´m going to use but the stepdown was on the low side with about 110 unloaded.

Another triout came from the swedish hammond reseller and it was running hotter then ..... at 1A /winding so a nogo even when specs said 400VA

 

[M Gregg]

Also post 43# and 44#.

Good information!

Have to sign out .....catch you laters!


Regards
M. Gregg

 

[flatheadmurre]

Solution to overpopulated inside.

Start stacking things outside !!!

From the beginning the space was intended for chokes but smallsignal HT fits fine.

Time for some regulators.

 

[M Gregg]

Just a quick comment while I remember,

http://www.diyaudio.com/forums/tubes-valves/183896-high-end-preamplifier-ecc82-21.html

This links to the neon protection Grid-cathode.
More information!

Regards
M. Gregg

 

[Alastair E]

This is now officially the Murphys law OTL amp.

Well,--You can guarantee if I'm in the slightest bit involved in a project, It will definately turn into some kind of Audiophile Faulty-Towers.....

Murphy's Law OTL....

Hmm-- I quite like it!

 

[flatheadmurre]

And Flatheadmurres law says Murphy was an optimist

 

[M Gregg]

And Flatheadmurres law says Murphy was an optimist

...LOL

 

[Alastair E]

Well-- I'm gonna bring this OTL into the '21st century'.....

Just bought one of these from fleagay--

eBay - The UK's Online Marketplace

I'm fed up of having to get up and turn volume down when SHMBO complains its too loud....!

 

[M Gregg]

Well-- I'm gonna bring this OTL into the '21st century'.....

Just bought one of these from fleagay--

eBay - The UK's Online Marketplace

I'm fed up of having to get up and turn volume down when SHMBO complains its too loud....!

That looks interesting!
Your going to build a mark 2 aint ya?
With lots of pictures.

Yep loads of volume with just one heater running....

LOL.....

Regards
M. Gregg

 

[Alastair E]

Yup--Need to make something that at least Looks half tidy.

Currently (And this is why there's no pics) the current version looks nothing much more than a breadboard-in-a-box.--ie, a Pile 'o scrap...
--Sounds nice though!

Ive been messing round since I first built it, so many variations and alterations, a 'nice' build wouldn't have got modded much, so would have limited 'research'....

Only one thing more I would like to try, and thats to MOSFET load the second gain stage,--See if its worth the effort...

--I tried MOSFET followers driving the 6C33C, but no huge leap forward in sound for the extra parts etc, so has returned to the scheme as you have it....