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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Also some files are djvu so you need djvu viewer to open them. Looking for alted manual? The basic circuit topology is very similar to a standard Williamson, so as a first draft you could try converting it to straight Williamson.

Yes, my password is: Of course, don’t leave it running like that for too long. I agree with the low signal when feeding the input square waves as I wouldn’t want to fry the trannies or pwr sply. The difference in bias voltage between the 2 schematics remains a mystery.

I have lived and breathed tubes for the past 50 years and still sltec at the amazing things that they can do! Is this a good assumption? By chance, is your ‘scope a dual trace type with which you can superimpose the 5168a You could suffer a fatal electrical shock!

And if the amp continues to sound great, they would never think to bring it in to a service tech I have a friend who has used his Audio Research stuff for 20 years and has never had it looked at- he says it sounds just fine. It would have been helpful if they printed a serial range for each one, and even more helpful if they specified the plate voltages of the el34s.


Register a new account. Posted September 18, 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. Both appear to be unaltered printings on Altec released manuals and other than this one change they appear identical.

Vintage Altec Lansing 1568A Mono Block Tube Amplifier

The chances are, even if it does increase the distortion a bit, you may not even notice a difference when playing music. In any event, you certainly have a good handle on what’s needed here to answer the bias question. You certainly won’t hurt anything by running the tubes at a lower plate current. Tubes are all NOS and barely broken in with maybe 50 hours on them. Fanatic, I do have a scope I could look at the change with.

Also, in case you are not familiar with it, check zltec www. Az erosito reszet elegge macera szetszedni egyszer korabban mar nekiestemugyhogy ezert merult fel a kerdes, hogy a fentiek alapjan erdemes-e vele me’g tokoreszni, vagy kuka.

A guy named Tom Tutay does mods for them.

Altec 1568A Amplifier

These Altec amps were used in the finest movie theatres for multi-channel reproduction of Cinemascope magnetic soundtracks.

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: However, one can make some circuit changes in the interest of better sound. I do have a scope I could look at the change with. Discussion in ‘ Tube Audio ‘ started by ke4mclAug 2, Again, check out the online articles on that- it’s much easier to explain with pix than in words.


PalustrisAug 2, The power supply is good, but could use a choke and good caps.

These amps were designed to be “bullet proof” and idiot proof. There are some nice articles aktec which show how to interpret deviations in the waveform appearance and form some correlation with distortion.

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ALTEC A Service Manual download, schematics, eeprom, repair info for electronics experts

PhototoneAug 2, You can try that for multiple frequencies to get some appreciation of what’s happening across the audio band. The amps I have were set at very close to volts bias and operate fine at this setting and sound absolutely astounding. Just off the shoulder of Orion.

In most amps, the latec will not be symmetrical. Log in or Sign up. As a matter of fact I do have a dual trace rather slow at 15Mhz but not a problem for audio stuff scope, also have two 8 ohm watt Dale power resistors, signal generator for both sine and square, variac, Audio Control SA RTA, various Fluke multi-meters Sign in Already have an account?

Your last name alhec definitely a credit to your interest in the subject!!!

I recently purchased a pair of Altec A EL34 based mono tube amps.