Here's another shot, this time closer view of
board construction.
This was made about 1972. It delivered 60 watts per
channel and constituted a first effort at keeping a
follower stage always forward biased (a predecessor
to dynamic bias)
Tomorrow I'll see about a schematic.
board construction.
This was made about 1972. It delivered 60 watts per
channel and constituted a first effort at keeping a
follower stage always forward biased (a predecessor
to dynamic bias)
Tomorrow I'll see about a schematic.
Attachments
Nelson Pass said:
I was still in high school... looks like the top would be kinda tricky to put on.
Thanx for the pics.
dave
I remember when I finally got up the courage to simply throw away all my 10 and 20% carbon composition resistors and commit to (<i>gasp!</i>) 5% from then on. Now I've gotten so used to 2% that I can't bring myself to throw them away, even though the 1% Dales cost me less to buy. Somewhere along the way I lost my affinity for the 10% parts and confess to flinching when I see a silver tolerance band. I'm not sure when I became such a snob...looks as though I'll have to sit myself down and give myself a good talking to for the simple reason that a lot of fine amps were built using pretty vague values.
I managed to work this same sort of creeping snobbery into a scene in one of my stories once upon a time. It's subtle; you never notice it creeping up on you, but the realization is sudden.
What's the pot for? Input level, bias, or feedback?
For what it's worth, I think my first circuit was a crossover, the guts of which I happened to come across in the bottom of a box the other day.
Grey
I managed to work this same sort of creeping snobbery into a scene in one of my stories once upon a time. It's subtle; you never notice it creeping up on you, but the realization is sudden.
What's the pot for? Input level, bias, or feedback?
For what it's worth, I think my first circuit was a crossover, the guts of which I happened to come across in the bottom of a box the other day.
Grey
Originally posted by Nelson Pass
cheers, mark 🙂
PS: If you ever need help cleaning it out .... I'm sure we could find you a couple of helpers !!!
Nelson ..... does this mean you really do have the holy grail ?
cheers, mark 🙂
PS: If you ever need help cleaning it out .... I'm sure we could find you a couple of helpers !!!
Yes, I like this idea of the Passcam.
The board looks a lot like that of a set of Ark amps I own of that period, pre Jurasic if I recall (aka Phase Linear 700B and 400.)
It looks quite industrial and very American in construction compared to the Japanese (plastic ) amps of the day
Those spring loaded heatsinks were quite popular then as per the carbon power resistors.
regards
macka
The board looks a lot like that of a set of Ark amps I own of that period, pre Jurasic if I recall (aka Phase Linear 700B and 400.)
It looks quite industrial and very American in construction compared to the Japanese (plastic ) amps of the day
Those spring loaded heatsinks were quite popular then as per the carbon power resistors.
regards
macka
That's ok, I wasn't even born yet! Shoot, my parents weren't even out of high school!
Nelson,
Thanks for showing us your human side once in a while... even still, it looks a lot more ambitious than the power supply I build in the pan of an old spring reverb, haha. And, it is a whole lot nicer than the mic preamp I tried to build out of a couple transistors and an op-amp (man, did that ever suck!)
In 1972 I was dancing to disco on my sister's JC Penney AM/FM recevier with built in 8 track. And I could not imagine a better system ( back then).
😎
😎
Damn, your first was prettier than my first... For a first project, the construction dones't look bad at all. My first amp got dismantled shortly after it was built (it looked pretty bad).
classic post
I think we need a new forum category to archive classic posts. If this isn't one then I don't know what is...
-willryu
I think we need a new forum category to archive classic posts. If this isn't one then I don't know what is...
-willryu
fbj
Do you have a habit of doing things 4 years before they happened? The hustle was released in October 1976 and fly robin fly didn't come out until the following year.
Well I don't know what you where doing, nania but I know what I was doing then. I was 16 years old back then. And coming from a very large African American family with roots ( more than a 100 years) in the Southern USA and West Coast (California), I can tell you that disco was around. So do more reseach before you speak up, cause there is a whole other world out there.
FBJ
Well, I don't dispute that you were dancing back then but it wasn't to disco. I think if you check the facts you'll see that the disco phenom originated in NYC around 1977. Nice try though😉
Well, I don't dispute that you were dancing back then but it wasn't to disco. I think if you check the facts you'll see that the disco phenom originated in NYC around 1977. Nice try though😉
Here is the simplified schematic, which I drew this morning.
It's pretty conventional except for the diodes and resistors on
the output stage which keep the output devices in forward
conduction over the operating cycle so they don't turn off.
Of course the diodes turn on and off, but they are very much
faster than the outputs, so it gives better performance in
this regard.
I abandoned this idea for the circuits that went into the
800A (see patent # 3,995,228) but I saw it subsequently in
a Technics amp. Why they were using this instead of the
Hirota circuit is a mystery, except that this circuit didn't
cost anything to build.
Later, SAE released a line of amplifiers using a similar concept
by Barry Thornton, except that the diodes were after the outputs
instead of before. Of course the diodes still switched, but not
the output transistors.
It's pretty conventional except for the diodes and resistors on
the output stage which keep the output devices in forward
conduction over the operating cycle so they don't turn off.
Of course the diodes turn on and off, but they are very much
faster than the outputs, so it gives better performance in
this regard.
I abandoned this idea for the circuits that went into the
800A (see patent # 3,995,228) but I saw it subsequently in
a Technics amp. Why they were using this instead of the
Hirota circuit is a mystery, except that this circuit didn't
cost anything to build.
Later, SAE released a line of amplifiers using a similar concept
by Barry Thornton, except that the diodes were after the outputs
instead of before. Of course the diodes still switched, but not
the output transistors.
Attachments
FBJ,
Maybe you were dancing to "ABC" by the Jackson Five or "Papa was a Rolling Stone" by the Temptations, but "Disco" didn't start till 75/76. The Bee Gees were hated for their #1 song "Jive Talkin", IF you recall. Yes, there was dance music, but not quite like Disco.
And such stuff was routinely sensored and banned in the south in the 70's and even to this day. That is why we don't have Howard Stern in Richmond, VA, but can gladly listen to red neck racist Robert D. Raiford on the John Boy and Billy Big Show.
Be nice. Nania is right. Nania, you should be nice, too.
OK, me too. Now this thread is degenerating. Sorry folks.
Gabe - of multiple DNA contributers. Also of NYC origin, born and lived in for 29 years.
Maybe you were dancing to "ABC" by the Jackson Five or "Papa was a Rolling Stone" by the Temptations, but "Disco" didn't start till 75/76. The Bee Gees were hated for their #1 song "Jive Talkin", IF you recall. Yes, there was dance music, but not quite like Disco.
And such stuff was routinely sensored and banned in the south in the 70's and even to this day. That is why we don't have Howard Stern in Richmond, VA, but can gladly listen to red neck racist Robert D. Raiford on the John Boy and Billy Big Show.
Be nice. Nania is right. Nania, you should be nice, too.
OK, me too. Now this thread is degenerating. Sorry folks.
Gabe - of multiple DNA contributers. Also of NYC origin, born and lived in for 29 years.
In 1972 I decided to dismantle my growing collection of diy PPP tube amps (you know, EL34, 807 etc) and to switch to solid state. Not sure whether that was a good career move....
Cheers, Jan Didden
Cheers, Jan Didden
Nelson,
If I may digress, are you familiar with the Sandman "class S" circuit? He used two diodes to switch the drive current from the drivers to either of the 2 output halves. Both halves were always on, but the drive current was diverted to one or the other. The result was an almost seamless (or at least much more seamless than the normal class AB) match of the two signal halves into the output terminal. Performance was very very high, all but free from xover distortion, no thermal drift, but for some reason it never caught on.
Jan Didden
If I may digress, are you familiar with the Sandman "class S" circuit? He used two diodes to switch the drive current from the drivers to either of the 2 output halves. Both halves were always on, but the drive current was diverted to one or the other. The result was an almost seamless (or at least much more seamless than the normal class AB) match of the two signal halves into the output terminal. Performance was very very high, all but free from xover distortion, no thermal drift, but for some reason it never caught on.
Jan Didden
Very cool first amp.
I wish I still had mine. It was so long ago. In 1972 I was only 1...
My first amp was in 1990 I think, it was a second sememster project and I remember it was a 3 stage amp with Darlingtons in the output.
I also hated and hate Disco. Bliach !!!!
I wish I still had mine. It was so long ago. In 1972 I was only 1...
My first amp was in 1990 I think, it was a second sememster project and I remember it was a 3 stage amp with Darlingtons in the output.
I also hated and hate Disco. Bliach !!!!
- Status
- Not open for further replies.