Threshold NS-10 and M1 info. wanted

[Deoreo]

Hello,
I just picked up these two items, but cannot find
much information about them. Ideally, I would like
some basic operating instructions, and original
specifications. A couple particular questions -
there are two main outputs,is one pair inverting?
In order for me to get the preamp to work with a
stereo amp I must use the right output from one
set, and the left output from the OTHER set, why?
There are two phono inputs - do they both offer the
same amount of gain, or is one dedicated to MC use
with the M1 unit? The quality of components, and
construction appear to be of very high quality. Are
there any details on the design topology, and components
avaliable? Would this be a good preamp to check over,
and replace any out of spec. items, or should I spend
money on a more current design (coda maybe)?
Finally, this preamp dates from 1977, how long was it
in production, and were very many of them produced?
Lots of questions, I know, but I believe this is a
Nelson Pass designed product, so I hope I came to the
right place!! Any help would be great,
Steve

[roddyama]

Hi Steve,

I thought you'd have a better chance at an answer here in the Pass Labs forum since Mr Pass did own Threshold at that time.

[Nelson Pass]

Actually, it sounds like it has been modified or is broken.

For help and information, I recommend Jon Soderbeg

vintageamp@earthlink.net

[roddyama]

Nelson,

They're like having kids, even though they have long since left the nest, they will always be your kids.

[Deoreo]

Thanks for the information, I was unsure
if Jon did work on preamps, so I started here.
The pre. works and sounds good, so I bet since
the outputs are not correct this is probably from
a past service - the filter caps in the power supply
were replaced - I'll bet the output jacks were
removed from the chassis and replaced incorrectly.
Thanks again for the info.

Steve

[yeoldestereo]

Just had Jon Soderberg of Vintage Amp go through the NS 10 I have.

Jon advised this was a prototype NS 10, not the standard production NS 10.

Was fully operational when I received it, but being some 28 years in service, decided to send to Jon for a check out and any needed service. Replaced all non film caps and additional work done of the modules. Sounds fabulous, great build quality, as we have come to expect.

Connected to a Threshold 400A power amp. Amazing to me that after 47 years in this hobby, I keep going back to the early Threshold gear. For me there is just something special about this gear, and now when I can afford most high end gear, its become back to the future - Kinda weird in some respects.

Anyway I highly recommend Jon for any and all service work on Threshold products. Great work,price is right, and knows what he is doing. Hard to find today.

[Nelson Pass]

I'm very pleased to hear that the NS10 is still working out for
you. The M1 remains a unique circuit that no one seems to
have copied, much like the I/V converter of the D1.

Also, I'm pleased to hear good things about Jon, as we continue
to recommend him for Threshold service issues.

[yeoldestereo]

Nelson, hard to believe that someone hasn't ripped off this design, as your designs have been ripped of more times than I can remember in the past 30 years or so.

Jon has worked on several Threshold items for me and have always been most impressed with his work. I recommend him very highly and have sent him many clients.

Forgot to tell Jon to replace the Volume pot. But I can handle that chore. Any ideas on which one to use? I have a Noble 50K around here somewhere, use that or something else?

For me the NS 10 is just magical. Perhaps not everyones cup of tea, but for me and quite a few others it remains after all these years a bench mark pre amp. As the 400A power amp remains a bench mark power amplifier.

[lumanauw]

For me the NS 10 is just magical.

NS 10 is known as the first Threshold preamplifier. I don't know much about Threshold history (but I can ask Jacco )

From several Threshold preamp schematic floating around here, like NS10, Fet10, SL10, I REALLY suspect that NS10 is the best sounding one (even it is the first released).

I make a "back-engineered" NS10 preamp using the schematic provided by NP (no values), and use the first transistor with Jfet (K30), the sound is MMMAAARRRVVVEEELLLOOOUUUSSS.

I think about it for several weeks. Why? It is a single transistor system (not differential), and the more you look at the schematic, you will realize that it is essentially a CFP with gain (like JLH). CFP is considered 1 stage, right? So, it is 1 stage, with good linearity (there is feedback, current feedback-to emitors, very fast), no harmonic canceling. It's hard to have high order harmonics with this approach, but you can get super detailing and very fast response. What else do you want?

[Zen Mod]

Originally posted by lumanauw


NS 10 is known as the first Threshold preamplifier. I don't know much about Threshold history (but I can ask Jacco )

From several Threshold preamp schematic floating around here, like NS10, Fet10, SL10, I REALLY suspect that NS10 is the best sounding one (even it is the first released).

I make a "back-engineered" NS10 preamp using the schematic provided by NP (no values), and use the first transistor with Jfet (K30), the sound is MMMAAARRRVVVEEELLLOOOUUUSSS.

I think about it for several weeks. Why? It is a single transistor system (not differential), and the more you look at the schematic, you will realize that it is essentially a CFP with gain (like JLH). CFP is considered 1 stage, right? So, it is 1 stage, with good linearity (there is feedback, current feedback-to emitors, very fast), no harmonic canceling. It's hard to have high order harmonics with this approach, but you can get super detailing and very fast response. What else do you want?

hm-I know my sh#t with tubes,just because I put more than just few years in passion for various tube stages and topologies .....but I have not equal knowledge (ie - feel ) with transistors or I just have not enough time to use same approach (reading,lookin' thinkin' , buildin' and tweakin.... ) .........
can you share that "back-engineered " schmtic with us (me) ?

dumb Choky