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Old 10th November 2005, 11:49 PM   #21
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In this NS10 schematic, there is hidden another elegance, NP's style. Look at the arrangement of Q2, Q3, R8. If you look at it, there's nothing special, just ordinary connection. But it really clever. This arrangement makes the Q2 works towards a CCS with value of 0V6/R8. Q2 doesn't experience current fluctuation, it works in steady current, even the output current is fluctuating with signal (because the load is Resistor, R9).

Look at the attached schematic.

The designer wanted to have steady current for Q53's load. He put Q8, D15, D16, R104, R110, Q42 (that's 6 components) for achieving that effect. NS10 only puts Q2,Q3,R8 (3 components) to have the same effect.
The final load is the same, plain R, R9 for NS10 and R112 for the attachment.

Beautifull, right.......
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Old 11th November 2005, 12:04 AM   #22
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by lumanauw
In this NS10 schematic, there is hidden another elegance, NP's style. Look at the arrangement of Q2, Q3, R8. If you look at it, there's nothing special, just ordinary connection. But it really clever. This arrangement makes the Q2 works towards a CCS with value of 0V6/R8. Q2 doesn't experience current fluctuation, it works in steady current, even the output current is fluctuating with signal (because the load is Resistor, R9).

Look at the attached schematic.

The designer wanted to have steady current for Q53's load. He put Q8, D15, D16, R104, R110, Q42 (that's 6 components) for achieving that effect. NS10 only puts Q2,Q3,R8 (3 components) to have the same effect.
The final load is the same, plain R, R9 for NS10 and R112 for the attachment.

Beautifull, right.......
huh-you confused me for a moment...then I realize that attached shmtc is just for comparison......

couldn't agree more with you about elegancy......

simple things are most hard to make it right........
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Old 11th November 2005, 03:11 AM   #23
tmblack is offline tmblack  United Kingdom
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Have a look at this review:

http://forum.audiogon.com/cgi-bin/fr...4&zzlFerrari&&

Amazingly low distortion and speed for such a simple design but should we expect anything less from NP?

Can you measure the specs of your re-engineered unit to see if they are similar?

Tom

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Old 11th November 2005, 03:43 AM   #24
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That review is from yours truly. Have always thought that this NS 10 from Threshold, was often under appreciated and over looked as a genuine break through in solid state preamps.

By the look of this thread it appears that there is a renewed interest in the NS 10.

With the work that Jon Soderberg has done on the NS 10, it will serve my needs for the foreseeable future. The overall sonic signature of the NS 10 is incredible. And to think that this was NP first preamp is nothing short of a tour de force.

If you can find one of these, the search is worth the effort. In 47 years have had a lot of amps and preamps including other Threshold pre amps. But I gotta tell'ya the NS 10 is something special, although it came out in 1976 or 1977 or so.
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Old 11th November 2005, 12:09 PM   #25
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Hi, Tmblack,

Quote:
Can you measure the specs of your re-engineered unit to see if they are similar?
I don't know how to measure those specs like in the review. Can you show me how to measure those numbers?

From the review, yeoldstereo = ferrari?

This NS10 is special. If you look for a transistor based preamp that sounds like tube, this is the one, because it is a singleton system, not a differential system. That's why the sound is more "complete" like the review said.

If you have heard this preamp, and go back to ANY (yes, I mean ANY) preamp that based on differential system, you will feel that something is "missing" in the differential based system (compared to this singleton based system). But remember, the choice for Q1 is important, it dictates what pattern of the harmonics, by the input/output transfer function of this Q1. I like Jfet better in the place of Q1.

Another important aspect : FAST. It has feedback to emitors, current feedback, it's much faster than feedback to opposite base (inverting input in differential system). This feedback ensures linearity (if you compare it to non-feedback system)

It consist only a single stage, make it faster and have minimal phase shift. No wonder the review said the response is up to Mhz number. If the frequency response is up to Mhz numbers, the phase shift within the first 20khz bandwith should be very small.

Try this test. Play this preamp to the fastest musical programme you have. Maybe a heavy classical full orchestra, maybe a heavy jazz with that big bass guitar with the fastest finger playing it, maybe the fastest piano+cymbal combo you have, or anything you can find. This preamp will pass all that musical test with excellent grade. You can hear each musical instrument clearly without mud, no matter how fast the whole music is.
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Old 11th November 2005, 04:17 PM   #26
tmblack is offline tmblack  United Kingdom
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Quote:
I don't know how to measure those specs like in the review. Can you show me how to measure those numbers?
You need a radio frequency generator and at least 50Mhz oscilloscope
I would think to measure propagation delay and freq. response of real unit but my simulation says it only goes to a Mhz or 2.

But I can't buy the 2SK30. How about 2N5458 or 2N3819?

I can't get the output transformer for Choky's preamp, so maybe an actual tube like 6922 would make a real sweet replacement for Q1?

Regards,

Tom

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Old 11th November 2005, 05:03 PM   #27
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To truly appreciate the NS 10 listen to the early Telarc digital to LP recordings, although most of these are in CD format now, the LPs were truly over the edge recordings. Most of these were done in late 70s and at that time provided a glimpse into the then coming digital medium.

Theshold supplied many preamps and power amps to Telarc for these recordings, as they were the only products at that time that were capable to handle these extreme recordings.

The Telarc LPs were cut at 1/2 speed in pure digital and transferred to analog LP. Absolutely no compression,limiting or editing was used in this process. The muscians had to be right on from the start and play without fault. Several of the early Telarc LPs won grammys for their technical achievement. I was with CBS at the time and this type of recording caught us of guard and soon after we started developing the digital to LP process.

When the early Threshold gear made its debut, many of the High End salons of the time used these Telarc recordings to demo the Threshold product.

One such was the Frederick Fennel Telarc 5038. This is a glorious piece of work not only to listen to, but as an use to evaluate a system. It is difficult to play properly and will tax all components to their maximum response. Picture of this LP appears with this post. This album has powerful low and high frequency transients and I urge due caution in playing this for the first time. Over the years I have seen this album destroy a lot of gear due to lack of caution. If you find this LP, be most careful and use very moderate volume settings, till you are comfortable that your gear is capable of the demands placed upon it by this recording. At times this recording is frightening, the hair will stand up on your neck and you will swear the anvil strikes and snare drum passages are about to literally come through the speakers!

However a properly operating Threshold NS 10 will handle this piece like a knife through hot butter, with that being said this recording has a way of exposing other weakness's in the audio system.

Yep yeoldestereo is Ferrari on Audiogon. Been in this hobby since 1957 when it was kits,tubes and mono. I haven't done any building or modding for quite some time. In fact last kit I did was a Hafler DH200 for a friend of mine and that was 1984 I think.

Without question the membership here is far more gifted than I when it comes to actual execution of these designs. With that being said my hat is off to the respondents of this thread. In a short time now I have learned a lot on the technical side.

My best to all of you.
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Old 11th November 2005, 05:18 PM   #28
mlloyd1 is offline mlloyd1  United States
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this Leach design preamp from many years ago had a non-differential line stage:
http://users.ece.gatech.edu/~mleach/...b77article.pdf

i wonder how it sounds in comparison; i used a duplicate differential stage as my line dirver when i built this years ago.

mlloyd1


Quote:
Originally posted by lumanauw
Hi, Tmblack,

...This NS10 is special. If you look for a transistor based preamp that sounds like tube, this is the one, because it is a singleton system, not a differential system. That's why the sound is more "complete" like the review said.

...
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Old 11th November 2005, 06:44 PM   #29
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Quote:
Originally posted by yeoldestereo
That review is from yours truly. Have always thought that this NS 10 from Threshold, was often under appreciated and over looked as a genuine break through in solid state preamps.
By the photo I see that it was indeed one of the originals, as the
later units had blue anodizing on the circuit shields and did not
also have a mu-metal case on the transformer.

The published specs:
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Old 11th November 2005, 10:09 PM   #30
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Quote:
But I can't buy the 2SK30. How about 2N5458 or 2N3819?
I've also tried K117 Jfet for Q1. I still like K30 better in place of Q1.
You can try various devices for Q1, they will sound different. Most Jfet or bipolar will fit, because the voltage is only +/-25V, Q1 willl only experience half of that or 25V.
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