threshold PCR1

[bagigios]

Anyone knows something about it?

Schematics, specifications, etc...

thanks

 

[Nelson Pass]

PCR1: repeating an earlier email response:

Yes, that's what it looks like. There were a few built
and floated around, and the circuits used massively parallel
stages to do the job, but the parts consumption was enormous
and we didn't consider it practical enough to commit to market.

 

[Magura]

Any chance to see a "back o' napkin" of the schematic or just the basic topology?

Magura

 

[Nelson Pass]

Something like 25 parallel gain stages, each using a diff pair
driving a voltage gain device.

 

[Magura]

What was the benefit of that? I can only come up with drawbacks like monster capacitance issues???

Magura

 

[Zen Mod]

What was the benefit of that? I can only come up with drawbacks like monster capacitance issues???

Magura

noise
transconductance
driving capability

anyway-what I know

 

[RobertS61]

Beautiful combination with a pair Threshold Stasis 1's.
Didn't Krell built these kind of pre-amps with their KRS series?

 

[RobertS61]

Another hidden prototype this 810A Class A amplifier?
How many prototypes we don't know of did make it one way or the other to the market?

 

[Nelson Pass]

I recall that was referred to as the locomotive, and taken to CES in the
late 70's. 400 watts or so. I think two pair were made.

Shortest description would be a bridged 400A

 

[RobertS61]

I recall that was referred to as the locomotive, and taken to CES in the
late 70's. 400 watts or so. I think two pair were made.

Shortest description would be a bridged 400A

Great name the locomotive. Do you ever miss that time in Sacramento, first years of Threshold, only competition from Mark Levinson?

 

[Nelson Pass]

No, and ML amplifiers showed up a couple years later.

But I like competitors, understanding that they are good
for business and help keep you sharp.

 

[RobertS61]

The first ML-2 Class A (power) amplifier with the 'E-Core' transformer was introduced in 1976 their first pre-amp the LNP-2 (only 5 LNP-1's were made) was introduced in 1973.
MLAS Ltd. (Mark Levinson Audio Systems) was grounded in 1972 by the person Mark Levinson.
Don't think Threshold corp. was much earlier with their pre- and poweramps.
Thought your first product was introduced in 1975 the 800A

 

[Nelson Pass]

I recall 1977, and it is confirmed here:

Mark Levinson Vintage Audio Gear: ML-2 | Monophonic Class A Power Amplifier | 25 W | 1977 - 1986

 

[RobertS61]

There's a guy on DIYaudio that bought a pair of ML-2's in 1976. But it's a moot point because the first Threshold amplifiers were from 1975 and moreover in 1977 I never heard of Threshold or Mark Levinson amplifiers for that matter, I thought the quadro B&O rig of my grandpa was the best money could buy ;-). So I wasn't even "there" and you were...

 

[Nelson Pass]

I was barely there either....

 

[RobertS61]

Haha, too much grass or just a the carefree unconsciousness of the adolescent?

 

[nickgreek]

I'm looking for a service manual for Threshold PCR1 preamplifier Could anyone help me? Thanks and regards
Nick

 

[RobertS61]

I'm looking for a service manual for Threshold PCR1 preamplifier Could anyone help me? Thanks and regards
Nick

Did you buy the one from CJM Audio?

There's no servicemanual of it there were only two or three made.

 

[nickgreek]

RobertS 61 thank you so much!!!!!!!!!!!!!

 

[Nelson Pass]

However, the PCR is not a difficult circuit to figure out - it's just a lot of them
in parallel. and fortunately they are on socketed boards.