Altec 1570B help

knie0012

Good day,

I'm looking at a pair of 1570Bs, and was told they are both working and operating as expected. The photos below are of the amps; it appears they have been "updated" with new caps and unknown what else without comparing them first hand to a schematic.

I've attempted to find what the best way to test these is and haven't found a great answer.

My plan would be to purchase and do a complete restore on them (eventually), but would still like to set them up and use them until I have time to start.

Does anybody have any experience or first hand knowledge with these?

pitdogg2

I don't but I know Doc would get all sweaty in spots 😜 @mhardy6647.
They look pretty sweet!
If you need a place to store them I'm more than willing to help with that
😬

SeleniumFalcon

I have a bit of experience with them. Be careful there are some lethal voltages under the hood, 935v on the output tubes.

knie0012

For sure, and always a good reminder!!

Based on that photo, I believe I was reading an old post of yours (?) where you restored two of them? Powder coated the chassis and did a complete point to point rewire?

If so, possible to pick your brain off line in regards to materials (parts and components) and testing procedures you went through?

SeleniumFalcon

Sure, off line or via this thread is fine. This is where I would begin learning about the amp. There's a modification described by Tom Tutay:

https://www.worldradiohistory.com/Archive-All-Audio/Archive-Vacuum-Tube-Valley/Vacuum-Tube-Valley-Issue-07.pdf

SCompRacer

Nice amps! The tech got artsy with some of the leads.

935v wowsa. I was setting bias under a tube amp and my pinky strayed to 450vdc once. Just once....

What are the specs on that chassis mount load resistor Ken?

SeleniumFalcon

Any artsy wiring you can blame on me, I did the construction. I can be extremely "Germanic" at times. The power resistor is 8 ohms at 250 watts, I think.
The 1570B amp checked out at 163 watts if I remember correctly, using directly heated triodes in a push pull mode. They were used everywhere, bus stations, sports stadiums, movie theaters and big churches, sometimes 24/7.
"Passengers now departing Baltimore and headed to Philadelphia and all points north please board bus number 17".

knie0012

I've been doing a fair amount of research on a full restore on these. I really enjoy the challenge and the process but I am questioning if these would be worth the time and money.

@SeleniumFalcon did you end up incorporating all of the Tom Tutay mods? I'm really intrigued by the slow start relay and the separate power transformer, as it relates to choking the input power supply
for the input and drive stage tubes.

Also, looking at your past posts regarding your rebuild, and even your photo here, what wire did you end up using? Was it the same wire for all aspects/components? And excuse my ignorance, what are the "posts" or "manifolds" that the wires are terminating into? I can't seem to locate part numbers or even style of hardware that is. Long shot, do you or did you ever compile a list of what parts/pieces/components you used on your restore?

Thanks in advance for any information and patience!!

SeleniumFalcon

I've owned quite a few amplifiers of the years: Dynaco, Harmon-Kardon (vacuum tube and transistor), Marantz, Audio Research, Sony, conrad-johnson, Quad and enjoyed them all. The Altec's are my favorites. I learned a lot building them and enjoyed working with Tom, he was always extremely patient and very generous. I'm sure you would have enjoyed working with him as well.
To the best of my knowledge I believe I included everything he designed. I used Wonder Wire which is a silver content solid wire that was originally used as the leads of Wonder Caps (probably the first designer cap in audio). I found a Teflon sleeve that goes over the wire as an insulator. It is possible Michael Percy might have some left. The connection posts are terminal blocks, also made from Teflon with gold plated turrets installed. I think I got those on eBay. I don't believe I ever compiled a parts list, many of the parts I bought from Tom: filter caps, transformers, coils and some resistors. I used V-Caps for critical signal path areas and bought things like fuse holders myself. I tarted up some things like the AC transformers I had the bell housings powder coated candy apple red for example and the Altec green enclosures became black and silver.
Good luck on your project.

knie0012

Good info, sir!

Do you have an opinion - did you go with heavier gauge wire on any of the legs besides the 19ga wonder wire?

Also, if you had to guess, what would be a safe number of feet it took to complete both amps?

As always, thank you for your thoughts and patience!
Jason

SeleniumFalcon

Hi Jason,
I think I used a fairly heavy gauge solid copper wire as the grounding path. McMaster-Carr sells very pure copper rods in different lengths.
I'm afraid I'd just be guessing on the length of wire needed, I think I bought the Wonder Wire in 50' roll and I bought a second roll and have some of it left.