My first amp

Nelson Pass · 23rd July 2002, 11:10 PM

By way of encouraging you lurking DIYers, I present
a photo of the very first amplifier I built from scratch
by myself.

It was gathering dust in my storage racks (think of the
warehouse at the end of Raiders of the Lost Ark), and
I've been meaning to rehabilitate it.

Nelson Pass · 23rd July 2002, 11:14 PM

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.

planet10 · 24th July 2002, 12:15 AM

Quote:

Originally posted by Nelson Pass
This was made about 1972

I was still in high school... looks like the top would be kinda tricky to put on.

Thanx for the pics.

dave

GRollins · 24th July 2002, 02:30 AM

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

mefinnis · 24th July 2002, 01:07 PM

Originally posted by Nelson Pass

Quote:

It was gathering dust in my storage racks (think of the warehouse at the end of Raiders of the Lost Ark) ....

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 !!!

macka · 24th July 2002, 01:22 PM

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

SteveG · 24th July 2002, 02:09 PM

Quote:

I was still in high school...

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!)

Gabevee · 24th July 2002, 06:45 PM

My lord! It has been a loooooooong time since I have seen 10% resistors!

Gabe

FBJ · 24th July 2002, 07:18 PM

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).

JoeBob · 24th July 2002, 07:21 PM

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).

24th July 2002, 06:45 PM	#8
Gabevee diyAudio Member Join Date: Feb 2002 Location: Richmond, VA.	My lord! It has been a loooooooong time since I have seen 10% resistors! Gabe __________________ Gabe CGV Electronics Home of the CGV-300B amplifier on a budget

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24th July 2002, 02:30 AM	#4
GRollins diyAudio Member Join Date: Feb 2001 Location: Columbia, SC	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

24th July 2002, 01:22 PM	#6
macka diyAudio Member Join Date: Dec 2001 Location: Australia	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

24th July 2002, 07:18 PM	#9
FBJ diyAudio Member Join Date: Mar 2002 Location: USA	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).

24th July 2002, 07:21 PM	#10
JoeBob diyAudio Member Join Date: Nov 2001 Location: Montreal, Canada	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).