Altec 1570 amplifiers

[airboss]

Is anyone using 1570, push pull 811A triode, amps in a home system??

Is the base tight and well articulated? I would imagine that the mids-highs are very nice indeed.

Any thoughts?

[jmarkwart]

I've had, and heard, several 1570's in home systems over the years. The biggest problem I remember was getting them quiet enough, both mechanically and output-hum wise. The mechanical is mostly from buzzing metal panels and can be damped out, or the offending panel removed. The output hum is usually a result of noisy voaltage amp tubes and/or mis-matched 811 pairs. Plan to swap a few tubes for lowest hum if you're driving Altecs! On the bench the bass output fell off pretty quickly below about 50Hz if I recall(it's been a few years). The filaments on those 811s will brightly light up, and also heat up, your room! Fun amps to mess with but they are heavy and hot. They sounded surprisingly good and had plenty of headroom though.
Hope that helps,
Jeff

[airboss]

Thanks Fellers:
I've used 811A's and 572B's in linear amplifiers before. I've spent lots of time under the hood with high power triods so to speak. I suspect they would be a handfull in a home system. Something about being the only one on the block I guess. A pair of 833A's (think Colman lantern here) in push pull would be nice if you could find the transformers......hehehehehehehe. Just kidding. I'll check out the sources DG but I suspect I'll lean towards something a bit more conventional when all the dust settles. My system now is far from high end and when I get the 8K's in line, I'll know more about the direction I want to go. Remote control for sure. MX-130 pre and DIY 811A's SET......yea maybe that-a-way.

[JON W]

GLAD YOU ASKED!
YES, THE 1570's HAVE ALL THE PROBLEMS MENTIONED ABOVE.
NOW LISTEN TO THE DETAIL IN THE HIGH FREQUENCY "GREAT IMAGEING". AS FAR AS LOW RESPONSE GOES, I USE THEM FOR MUSIC. THEY ARE TIGHT DOWN TO 50 Hz. NON OF MY RECORDINGS HAVE EARTHQUAKES ON THEM SO THE HOUSE IS STILL SAFE. THEY HAVE SO MUCH HEADROOM.
NO NEED FOR A FIREPLACE. MY WIFE AND I JUST WARM OUR FEET AND WATCH THE GLOW OF THOSE 811's.
IMPROVING THE POWER SUPPLY WILL DEFINATELY HELP,
ESPECIALLY THE LOW FREQUENCY. JON

[dennis gilliam]

Try

Tom Tutay
Transition Audio Design
24 Elm Avenue SE
Fort Walton Beach, Florida 32548-5622
Phone-850-244-3041

Tutay does Altec 1570 Modifications. He repairs, custom designs and builds tube preamplifiers and power amplifiers. A nice feature a few issues ago in Vacuum Tube Valley magazine, about just your question.

DG

[RClark]

holy cow guys------the 1570 might use 811 tubes but tubes do not completely define an amp--------the 1570 has a wimpy output transformer with a core that is smaller than that used in even the 1568 or 1569-------the 1570 is at best a voice quality paging amp and cannot produce low distortion bass at any reasonable level------and i have seen a few of the so called "hopped up" units------they even used the original output transformers-------it reminds me of PT Barnums famous statement.............RC

[rolandr]

Have three of them been waiting to get my hands on SOUND PRACTICES #16 for the peerless mod info ... whatever that was. If anybody has SP#16 would appreciate a copy of the article(pay whatever). Basically agree with Richard...limited LF because of undersize OPT...Originally used mostly as PA, still used in outdoor movie theaters
like drive ins. Well built chasis!!!