bowtie427ss
Lunatic Member
Not really a shortage of participants there, it's a rather reserved and exclusive place that keeps secrets well.
Altec Amps.... YUM!!!!!
- Thread starter similost
- Start date
sometimes you just have to tell somebody how much you'd pay for them if they got pulled before the demo and not ask questions when they get delivered. i have no issues with saving things from bulldozers.
those amps are nice. i have a few here waiting for me to recap them.
Mine....
After a closer look at the EL34's, James prolly did get the better of the deal. I've got a mish mosh of tubes here....
The 2 brown base are dual flying saucer getters (Ruski?), and the other 2 are black base dual ring getters
Three of these have copper posts, with single getters that have almost a dual concentric set of rings one inside the other. The last is a single getter with no other remarkable features....
Oh well....
After a closer look at the EL34's, James prolly did get the better of the deal. I've got a mish mosh of tubes here....
The 2 brown base are dual flying saucer getters (Ruski?), and the other 2 are black base dual ring getters
Three of these have copper posts, with single getters that have almost a dual concentric set of rings one inside the other. The last is a single getter with no other remarkable features....
Oh well....
Variac? What's that?...
Nah, I ain't gonna fire 'em up until I do at least a minimum recap....
Nah, I ain't gonna fire 'em up until I do at least a minimum recap....
similost
Rockin and Rollin....
I haven't touched mine since I got them. I've been pretty busy with other stuff. I may go ahead and fire them up on a variac after I get everything moved to the basement though.
You may want to check with Bowtie. He has several sets of these amps, and knows pretty well what they sound like.
You may want to check with Bowtie. He has several sets of these amps, and knows pretty well what they sound like.
Ditto...
mine are still in the que.....:sigh:
bharper, are those mods just a restore or is there more?....
mine are still in the que.....:sigh:
bharper, are those mods just a restore or is there more?....
bowtie427ss
Lunatic Member
Note the "Pentode/Triode" switch. He's gone the whole extra 9 yards with these, and i suspect they're awesome.:yes:
Now, if only we all lived about a thousand miles closer to each other.
I've been havin so much fun with this little SE amp that Bricktop built that i've kinda of forgotten about the altecs for the time being. When the current budget strain eases a bit, i'll get something in motion with the altecs early this fall for some fun listening and posts this winter.
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zenith2134
Lunatic Member
Having been around a few PA rigs myself, I can attest to the long term reliability and overall sweet sound of this type of amp.
In elementary school, (private school, 4 levels, outside thing, lot of wiring) they had a small consolette made of wood in the office with a solid state mono amp and about 4 tube auxiliary amps to each level. At the speaker boxes, there were small controls near the room's light switch for master level and also, microphone back to the consolette though not all rooms worked anymore by '93 or so. It is obvious to me now that they were all tube at one point and the SS power amp came later.
In high school, they used Bogen exclusively. Maybe because they were a Brooklyn company. Tubes, not sure what kind, and lots of them. Those units ran forever it seemed and sounded damn good through all that wire.
In elementary school, (private school, 4 levels, outside thing, lot of wiring) they had a small consolette made of wood in the office with a solid state mono amp and about 4 tube auxiliary amps to each level. At the speaker boxes, there were small controls near the room's light switch for master level and also, microphone back to the consolette though not all rooms worked anymore by '93 or so. It is obvious to me now that they were all tube at one point and the SS power amp came later.
In high school, they used Bogen exclusively. Maybe because they were a Brooklyn company. Tubes, not sure what kind, and lots of them. Those units ran forever it seemed and sounded damn good through all that wire.
similost
Rockin and Rollin....
I've read up on this amp shown before. Maybe I saw them for sale on the bay? I can't remember, but I do remember those little blue buttons were for reading and setting the bias on each individual output tube..
I'll be running my Altecs along side a pair of Bogens, so I'll have kinda the better of the good PA's for my system.
I'll be running my Altecs along side a pair of Bogens, so I'll have kinda the better of the good PA's for my system.
similost
Rockin and Rollin....
I haven't shopped very hard for parts, but I'm figuring less than $200 so long as that doesn't include tubes... I'd bet if you don't buy the cans, but put caps inder the chassis to replace them, maybe a little over $100... I'm not the kind of guy that spends $30 for every cap...
I gave 6 for mine, and that was a pretty decent deal..
I gave 6 for mine, and that was a pretty decent deal..
bowtie427ss
Lunatic Member
I kinda like this route, especially when the original cans are date code correct/matching to that of the amp and other components since i'm going for more of a restoration of the original, rather than heavily modded.
zenith2134
Lunatic Member
Somewhere in between seems to work well for mono and stereo tube units of varying sizes IME. Don't spend 30-40 bucks a cap, but don't get the cheapest you can find either from your supplier(s).
And similost--I totally agree that you are going to have quite a nice system around those. Like you say, the better of the good PA rigs. Add some vinyl and you're set.
And similost--I totally agree that you are going to have quite a nice system around those. Like you say, the better of the good PA rigs. Add some vinyl and you're set.
bharper
tube junkie...
Hey Analog A....
I bought two 1569's about 5 years ago off ebay, neither worked, and the one shown was extremely rough. Tranny's were extremely rusty on this one, the chassis too, and someone had started to mod it that did not have a clue. They had started adding dc filaments to get rid of a ground loop, had already removed the tube rectifiers and sockets, and about half of the wiring was hanging out. I bought the pair for $200, ya don't see that today on ebay.
Pulled the transformers, wire brushed the cores and endbells, painted the endbells with satin black, and sprayed the cores with about three coats of hair spray to seal them (works great).
The two blue electrolytic caps were already there, in series, for the hv. No filtering was there for the two driver tubes, or the output tube screens.
So, I decided to use what was at hand, and see if I could make it better, as well as more versatile at the same time.
I had four angela 47mfd polypropylene caps that I bought cheap off ebay, so used two for the driver filtering, one on the top of the plate resistor of each, then bypassed with a .01 solen too. Used a 22mfd solen for the screen filtering. Went to a solen in the first driver stage.
Next, the thing I did not like about the 1569 was that they have no cathode resistors, only one bias pot, and technically you would need to run matched quads to really get the potential out of these amps sound wise, so you do not unbalance the dc current on the output transformer.
With all the rectifier sockets missing, and that area already hacked some, I decided to go ahead and mill out the rectifier area, make a cover panel, and add four 10k bias pots, and a vintage meter from late 40's early 50's era. And a minature rotary switch to select which tube you are reading. 10 ohm dale resistors were added to each output tube's cathode, and wired to the rotary swith with silver/teflon wiring.
Without the cathode resistors, there is no way to measure bias current on an individual tube on these amps, I guess you just swap tubes if you see red plating.
Went to four solen coupling caps for the output grids so could individually bias them, and added four small electrolytics to bypass the pot's wipers for more stablility.
Then added a toggle switch to either insert a 47 ohm resistor from the plates of the paralled tubes to their paralled screens, or to pick up the filtered screen voltage from the 22mfd solen, which is dropped in voltage from the vcc with a rather large wire wound dale resistor. That gives the triode/pentode mode of operation.
So, just upgraded the coupling caps, filter caps for the drivers and screens, added individual bias setting and reading, triode/pentode mode, solid state rectification, and rebuilt the bias supply. Only additional mod will probably be to move to hexfred rectifiers for the hv and bias.
Now I have a very stable, very fast, open, musical amp. Dead quiet, no hum, little or no hiss. With the bias mods, I can run pretty much any output tubes I want, pairs, quads, matched, not matched, mixed. In the pictures it is running EI kt90's.
To me all these mods made perfect sense (but I am some what nuts...), and the result was this amp acheiving I believe a higher level of performance, and a lot more user convenience on tube selection and biasing. This amp will probably become my main test mule for tube performance, testing and matching duties. Some day will have to get off my azz and modify the second amp I have to match this one, a pair is a lot more useful.
I agree that these mods to many collectors may have decreased the value of an appreciating altec market out there, but to a true audiophile who wants performance, I would expect that considerable value has been added. With the rough condition it was in, and the low investment in the initial purchase, I was less interested in collecting than getting the performance of this amp up to another level, a level I could not afford to buy outright, but could invest some time and a few parts in and end up with heck of an amp.
Sure works a lot better and looks a lot better than what I started with. Took a mess and made something out of it.
Brian
I bought two 1569's about 5 years ago off ebay, neither worked, and the one shown was extremely rough. Tranny's were extremely rusty on this one, the chassis too, and someone had started to mod it that did not have a clue. They had started adding dc filaments to get rid of a ground loop, had already removed the tube rectifiers and sockets, and about half of the wiring was hanging out. I bought the pair for $200, ya don't see that today on ebay.
Pulled the transformers, wire brushed the cores and endbells, painted the endbells with satin black, and sprayed the cores with about three coats of hair spray to seal them (works great).
The two blue electrolytic caps were already there, in series, for the hv. No filtering was there for the two driver tubes, or the output tube screens.
So, I decided to use what was at hand, and see if I could make it better, as well as more versatile at the same time.
I had four angela 47mfd polypropylene caps that I bought cheap off ebay, so used two for the driver filtering, one on the top of the plate resistor of each, then bypassed with a .01 solen too. Used a 22mfd solen for the screen filtering. Went to a solen in the first driver stage.
Next, the thing I did not like about the 1569 was that they have no cathode resistors, only one bias pot, and technically you would need to run matched quads to really get the potential out of these amps sound wise, so you do not unbalance the dc current on the output transformer.
With all the rectifier sockets missing, and that area already hacked some, I decided to go ahead and mill out the rectifier area, make a cover panel, and add four 10k bias pots, and a vintage meter from late 40's early 50's era. And a minature rotary switch to select which tube you are reading. 10 ohm dale resistors were added to each output tube's cathode, and wired to the rotary swith with silver/teflon wiring.
Without the cathode resistors, there is no way to measure bias current on an individual tube on these amps, I guess you just swap tubes if you see red plating.
Went to four solen coupling caps for the output grids so could individually bias them, and added four small electrolytics to bypass the pot's wipers for more stablility.
Then added a toggle switch to either insert a 47 ohm resistor from the plates of the paralled tubes to their paralled screens, or to pick up the filtered screen voltage from the 22mfd solen, which is dropped in voltage from the vcc with a rather large wire wound dale resistor. That gives the triode/pentode mode of operation.
So, just upgraded the coupling caps, filter caps for the drivers and screens, added individual bias setting and reading, triode/pentode mode, solid state rectification, and rebuilt the bias supply. Only additional mod will probably be to move to hexfred rectifiers for the hv and bias.
Now I have a very stable, very fast, open, musical amp. Dead quiet, no hum, little or no hiss. With the bias mods, I can run pretty much any output tubes I want, pairs, quads, matched, not matched, mixed. In the pictures it is running EI kt90's.
To me all these mods made perfect sense (but I am some what nuts...), and the result was this amp acheiving I believe a higher level of performance, and a lot more user convenience on tube selection and biasing. This amp will probably become my main test mule for tube performance, testing and matching duties. Some day will have to get off my azz and modify the second amp I have to match this one, a pair is a lot more useful.
I agree that these mods to many collectors may have decreased the value of an appreciating altec market out there, but to a true audiophile who wants performance, I would expect that considerable value has been added. With the rough condition it was in, and the low investment in the initial purchase, I was less interested in collecting than getting the performance of this amp up to another level, a level I could not afford to buy outright, but could invest some time and a few parts in and end up with heck of an amp.
Sure works a lot better and looks a lot better than what I started with. Took a mess and made something out of it.
Brian
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