2KVA audio amplifier

[Opcom]

On a recent road trip, some stuff got traded and I ended up with the skeleton of this audio amplifier. Included are the audio transformer, pair of 4-10000's, and the chassis.

I wrote Undoltz-Dickie for the manual and was told it is a Philips amplifier. They sent me a few pages, what they had on file for this old 1961 model. Here is the document in pdf. It's not too clear what the tubes are but I was told 4-1000's had been subbed for the original Euro types.

outputs: QB5/1750
cathode follower drivers EL34
voltage amplifiers EL34
input voltage amplifiers EL84?

Not familiar with the QB5/1750 but it looks easy to drive.

It might be fun to study the schematic because these things didn't always get to work into a perfect load and the drivers are DC coupled to the output grids.

[W7TFO]

Included are the audio transformer, pair of 4-10000's, and the chassis.

I've never seen a 4-10000.  Must be a rare beast...

73DG

[Opcom]

Must have been sleepy when I was typing 4-1000. The thought of a 4-10000 is interesting though.

I still need to find two air system sockets for the 4-1000A.

People don't like those sockets claiming that they restrict airflow but in this case I'd like to deliver air by hose from a blower a couple feet away to reduce noise. Hope to find a pair inexpensively.

If all works out this will be a subwoofer amp. It ought to have enough headroom. It's not yet clear what the B+ are in this but a guess might be 600 for the low side and 3500-4000 for the high side (that according to the datasheet for the finals).

The oil was drained from the OPT and needs to be replaced.

What is the best non-flammable dielectric oil to use when refilling a high voltage transformer?

[pa0ast]

Oil used in the philips EL6472 Amp is Diala-B from Shell-oil. The Amp has 2 QB5/1750 tubes in the final. Not so shure that 4/1000 tubes will work properly with the same result. There are plenty of QB5/1750 tubes available here  by the way. More info at http://www.radiomuseum.org/r/philips_grossverstaerker_el647200.html    The 1 kW version is the EL6471 with 2 QB3,5/750 tubes.  Amps are used for stadions , airfields , clean mains generator etc. They are build in Eindhoven holland in building SBP philips strijp complex. Some of the guys who build them still live. I can give You an adres of one of them. Anton pa0ast

[flintstone mop]

Is it this beast Patrick???

http://www.youtube.com/watch?v=G7qMVYf85sM


POWER!! It's a hellluva sound

[flintstone mop]

The audio folks from Europe were hard to out-do in the late 50's thru early 70's. Then the Japanese were knocking out Sansui and Kenwood Solid state. Noise so bad that it could be heard even with the volume control turned all the way down.
Then the speakers guys in New England and Seattle came out with some nice book shelf speakers that were hard to beat.

[Opcom]

Oil used in the philips EL6472 Amp is Diala-B from Shell-oil. The Amp has 2 QB5/1750 tubes in the final. Not so shure that 4/1000 tubes will work properly with the same result. There are plenty of QB5/1750 tubes available here  by the way. More info at http://www.radiomuseum.org/r/philips_grossverstaerker_el647200.html    The 1 kW version is the EL6471 with 2 QB3,5/750 tubes.  Amps are used for stadions , airfields , clean mains generator etc. They are build in Eindhoven holland in building SBP philips strijp complex. Some of the guys who build them still live. I can give You an adres of one of them. Anton pa0ast

Now that I have gone through the pictures and put the project start on the web page, I would like to have the contact info for the guy that worked on the design. That would be really super!

Thank you!

http://www.bunkerofdoom.com/philips/el6472/index.html

Noticed the output transformer in mine is a little different from the one in the manual, having more secondary taps.  So I would be grateful to get the address of the guy.

Patrick J

[pa0ast]

Ok if You send me a mail to pa0ast at amsat.org.  then i give you the adres and phone nr. and i will  ask him for his email adress.
Anton

[flintstone mop]

I'm the guilty one to bring this back to the top.
Patrick
The pictures show that you just have the chassis and some transformers? The electronic circuitry and tubes are missing? The youtube link video looks like there were several iterations of this design. I hope, if you are restoring this beast, that you put the glowing rectifier tubes in there and not SS replacements. There were some other purplish tubes in the Youtube that might have been VR's.
And the driver tubes seemed like a pair of 6CA7's. The outputs always show a lot of color even at low volume. They get almost white as you approach MAX munkey. It should be an interesting project to follow.
Good luck
Fred

[pa0ast]

I still have a jerrycan with 20 litres of trafo oil diala B. By the way my diesel runs perfect on it, no problems for years. some years ago we had to throw away some 8000 litres. We did that,  but slowly, the whole workshop drove there diesels on it for a year..  In the factory where they were made , the test load for the amps where hozes with running tap water and lots of 0.1 ohm resistors in it hanging on the ceiling. The amplifier range was from 250 watts with 4 x PE1/100 tubes  till 150 kW amps with watercooled tubes. Most common was the EL6471 1 kW amp with 2x QB3.5-750 tubes and the EL6472 2kW amp with the QB5-1750 tubes.