GENERAL DESCRIPTION. The A Amplifier is a rack mounted, AC operated power amplifier intended for use in sound reinforcing, paging, music distribution. Hi there, up for sale is a Vintage Altec A Tube Amplifier. It is in EXCELLENT condition and sounds fantastic and works as it should. This would be perfect. i’ve read mixed reviews on these online. some say they arent all that special and basically PA amps. i saw some stuff that claims they are good.

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As such, they are designed with certain technical features that would make them immune to most of the common mistakes a non technical operator might make such as running them with no load.

Post or PM if I can help any further. Again, check out the online articles on that- it’s much easier to explain with pix than in words. That said, they sound good as they are. I recently purchased a pair of Altec A 11568a based mono tube amps. This file is downloadable free of charge: Considering that tube characteristics can change quite a bit as they age, a 7 volt bias variation could occur with normal use over time.

Your name or email address: Compare that to the appearance of the input signal from your generator. Log in or Sign up. I agree with the low signal when feeding the input square waves as I wouldn’t want to fry the trannies or pwr sply.

You could 15688a a fatal electrical shock! Sign In Sign Up. To sum it up: Most users of tube equipment, unless they’re really into the technical side, never check tube bias anyway.


altec 1568a, hifi or PA amp?

Do you think they later changed the original bias spec of vdc to in an attempt to make the amp more bullet-proof and have longer tube life, or do you think atec first chose volts and then they felt the plate current just needed to be higher for better operation and sound quality so they revised it to volts? Any comments would greatly be appreciated. You would then need to measure the transformer 1568x easy to do with your signal generator to see which provides the closest match.

The basic circuit topology is very similar to a altev Williamson, so as a first draft you could try converting it to straight Williamson. Share This Page Tweet. Yes, my password is: PalustrisAug 2, Please post your results after doing the experimentation. PRMAug 3, It certainly is possible that they decided, at a later date, to run the tubes cooler to increase longevity.

Through Altec Voice of the Theatre speakers, of course.

They were intended for use in churches, bowling alleys, shopping malls, dance halls, high school auditoriums and, naturally, movie theaters. You need to be a member in order to leave a comment. This, of course, will affect the required load impedance somewhat.

My basic knowledge tells me that if the amp performs well, output tubes algec running at too high a plate current and the amp sounds great at the higher vdc bias plate current, go with that. Register a alyec account. PhototoneAug 3, I assume doing this with a dummy load I also have at or near the maximum rated output level of 40 watts at say 1kHz would probably be a good place to start?


Wanted: Peerless power transformer (for Altec A amplifier)

If you have, or can borrow, a copy of the Radiotron Designer’s Handbook it will give you everything you need to graph virtually anything. Create an account or sign in to comment You need to be a member in order to leave a comment Create an account Sign up for a new account in our community.

One thing I have noticed is there are two versions of factory released schematics running around the web that appear to be identical except for one has a volt bias level and the other has a volt bias level.

To open downloaded files you need acrobat reader or similar pdf reader program. Already have an account? Fanatic, I do have a scope I could look at the change with. A guy named Tom Tutay does mods for them.

In most amps, the clipping will not be symmetrical. Please, do not make a copy of the downloaded manual and do not offer to sell it, just use personally to repair defective appliance!

Also, in case you are not familiar with it, check out www. I suspect that you’re not going to see a huge difference. Both appear to be unaltered printings on Altec released manuals and other than this one change 168a appear identical.

I have have many other power amps that one would think would simply blow these out of the water and I really didn’t expect much with these and was pleasantly surprised. Posted September 18, PRMAlhec 2, It might be a fun experiment!