Altec Amps.... YUM!!!!!
- Thread starter similost
- Start date
similost
Rockin and Rollin....
Oh no.. I very much enjoyed checking out your amps and hearing what you've done to them. It also made me consider some of the things you've done.. but then if I were to do some of that, then I wonder about the value should I ever (I doubt it though) decide to sell them.
I really like your idea of setting the bias for each tube, especially because of how hard it is trying to keep a spare set of matched quads around. I'd like to be able to just replace one tube at a time if one goes bad.. not a whole set..
Do you by chance have a schematic of all the changes noted on it? I'd really like to compare that to an original schematic and decide if some of these changes might be something to consider instead of actual value..
I really like your idea of setting the bias for each tube, especially because of how hard it is trying to keep a spare set of matched quads around. I'd like to be able to just replace one tube at a time if one goes bad.. not a whole set..
Do you by chance have a schematic of all the changes noted on it? I'd really like to compare that to an original schematic and decide if some of these changes might be something to consider instead of actual value..
Ditto. Around here there is no such thing as TMI, unless it is something about personal hygiene habits or something....:yuck:
bharper
tube junkie...
Hey Similost,
Per say I do not have a schematic, as a matter a fact I did not even have the original when the mods were done. The bias circuit is fairly simple, and the triode mod, and you could perform these until they could be removed. Such as mount the meter, switch, and bias pots on a plate at 90 degrees to the top of the amp, so you could remove later. Even put the triode mod switch on that plate too (just don't touch the back of the switch, or christmas tree time, and you are the tree). I used this amp to match kt90's last night, getting ready to launch the new to me antique sound labs monoblocks that arrived yesterday.
I will in the next few days try to put something together for you.
Another crazy idea is I could just ship this amp without tubes up to bowtie for a month or so for him to test against his altecs, and really find out how effective the mods are. By not having rectifier tubes, that filament current is saved, and allows the power transformer to easly work with bigger output tubes, and you do have a little more plate voltage for those too. I have never tested them, but I expect this amp would be unbelievable with the reissue genelex kt88's.
Even though many of these amps did end up in pa service, they were not really pa amps. If you check the factory spec's, I'm pretty sure with the great iron in these that the factory spec was out to 20khz, and that my friend is not a pa amp.
Brian
Per say I do not have a schematic, as a matter a fact I did not even have the original when the mods were done. The bias circuit is fairly simple, and the triode mod, and you could perform these until they could be removed. Such as mount the meter, switch, and bias pots on a plate at 90 degrees to the top of the amp, so you could remove later. Even put the triode mod switch on that plate too (just don't touch the back of the switch, or christmas tree time, and you are the tree). I used this amp to match kt90's last night, getting ready to launch the new to me antique sound labs monoblocks that arrived yesterday.
I will in the next few days try to put something together for you.
Another crazy idea is I could just ship this amp without tubes up to bowtie for a month or so for him to test against his altecs, and really find out how effective the mods are. By not having rectifier tubes, that filament current is saved, and allows the power transformer to easly work with bigger output tubes, and you do have a little more plate voltage for those too. I have never tested them, but I expect this amp would be unbelievable with the reissue genelex kt88's.
Even though many of these amps did end up in pa service, they were not really pa amps. If you check the factory spec's, I'm pretty sure with the great iron in these that the factory spec was out to 20khz, and that my friend is not a pa amp.
Brian
bowtie427ss
Lunatic Member
Please don't tell the naysayers, per the factory sheet rated freq resp is 5hz to 30,000hz +/- 1db for both the 1568 and 1569.
At full rated power the 1568 claims 40watts @2%thd 40-20,000hz, and the 1569 claims 80watts @5%thd 40-20,000hz.
@2%thd 60-20,000hz
Both amps also give a secondary freq response rating of 1hz to 100,000hz (+/- 4db 1568, +/- 5db 1569)
But, in all honesty i'm not holding onto a lot of hope for the integrity of that waveform at 1hz.
I desperately need a new signal generator, when that happens i intend to see for myself what these trannys look like near the extremes of their "claimed" BW.
At full rated power the 1568 claims 40watts @2%thd 40-20,000hz, and the 1569 claims 80watts @5%thd 40-20,000hz.
@2%thd 60-20,000hz
Both amps also give a secondary freq response rating of 1hz to 100,000hz (+/- 4db 1568, +/- 5db 1569)
But, in all honesty i'm not holding onto a lot of hope for the integrity of that waveform at 1hz.
I desperately need a new signal generator, when that happens i intend to see for myself what these trannys look like near the extremes of their "claimed" BW.
