Threshold NS10 Lineamp PCB

[AndrewT]

Is this oscillation on every board or only under certain conditions?

it was in the version sent to Janneman for pre-production testing.

 

[CeeVee]

Is this oscillation on every board or only under certain conditions?

In my case i had a bit of a rat's nest so i cannot rule out the wiring.

 

[luvdunhill]

I'm still in the process of testing my version, but haven't seen any oscillation with very light loads. If anyone else would be willing to help, I think I have a few more board sets.

 

[PTSOUNDLAB]

Hello friends

I build an NS10 with apassgear schematic http://www.ptsoundlab.com/temp/ns10/ligne.jpg (thanks to him !!!) and with my PSU http://www.ptsoundlab.com/temp/ns10/alim.jpg

The sound is marvelous ! Very good details and dynamic, beautiful basses. A very pleasant preamplifier.

I tried to add to it a RIAA stage, I included original components in apassgear schematic (see in black) http://www.ptsoundlab.com/temp/ns10/riaa.jpg

At the same time, I added the head amp for MC http://www.ptsoundlab.com/temp/ns10/prepre.jpg

The result is very very good, no audible noise and a very good integrated preamplifier.

BUT, I have an issue. The line stage give a lot of basses and is perfect, but the RIAA stage don't give realy enough basses. It seems that the RIAA curve is respected but with basses behind.
Treble seems ok but the lack of basses give me the feeling that they are a little high.

Could someone have an idea of why ? what is the error in my schematic ? or how can I improve basses ?

Thanks a lot in advance if you can help me.

Cordially

Pascal

 

[arensattic]

Dear Pascal,

This reply refers to you noticeing a lack of bass in the sound produced by the NS10 RIAA stage. When I examined the schematic posted at your website (PT Soundlab), I noticed that your schematic has two series-connected 301k resistors shunting the RIAA network. This shunt results in a rather severe reduction of bass, as compared to the original RIAA curve. Removing the shunt may give you the bass which you are missing....

May be the shunt is a modification of the original NS10 circuit, in order to attenuate subsonic garbage from warped records. But I guess the action of the shunt is rather too severe. Perhaps the father (auctor intellectualis) of the NS10 circuit, Nelson Pass, may comment?

These are my five cents from The Netherlands (I have run some PSpice simulations which indicate that the statements I made above are correct).

Best regards,

Aren van Waarde (aka Arens Attic)

 

[PTSOUNDLAB]

Thank you very much Aren
I will try tomorrow and let you know the result.

Otherwise, without this issue with RIAA, this preamp is a killer, very nice sound with F5 amplifier.
I'm a fanatic of valve amplifiers and preamplifiers, and I don't love a lot solid state,... except Nelson jobs, I love all Nelson amplifiers and preamplifiers.

Cordially

Pascal

 

[PTSOUNDLAB]

Hello Aren

the issue is the same with or without 301K resistors, lack of bass

So now i see two possibilities

- false RIAA network

- bad capacitors in RIAA network

I will order new capacitors to verify. For the RIAA network, it is the one I saw in all schematics.....

http://www.ptsoundlab.com/temp/ns10/sl10-riaa.gif

http://www.ptsoundlab.com/temp/ns10/RK%20Ronningstad's%20version%20of%20the%20NS10.pdf
I tried with 18,2K like RK or 16,5K like original and it's the same

http://www.ptsoundlab.com/temp/ns10/sl10-sch.gif

...., so I think it is good ?

If I don't make mistake, RIAA Network is made by 16K5//4,7nF 301K//15nF

Thank you for your help

Cordially

Pascal

 

[Robert the cat]

NS-10 Preamp service manual / original schematics

Does anyone have a copy of the original NS-10 service manual, or at least the original schematic? Urgent! .... DIY AUDIO Member: "Robert the cat"

 

[Zen Mod]

buried in Pass forum

you'll find everything

 

[VintageAmp]

Need help with missing chip

No Service manual ever existed that I know of.
If any one with an NS 10 could look under the hood for me I would be grateful.
I need to know about a 14 pin DIP near the right front of main board. This early unit has a one piece gain circuit PCB. The 14 pin socket is next to a FT 317 w/ heat sink. What is the chip and the orientation? Any help mucho appreciated.

 

[Zen Mod]

.

 

[Nelson Pass]

Sorry that I don't have the info.

It may be that the 14 pin dip is a quad op amp used for the offset. You
can find that out by examining the connections of the pins or by seeing
whether the op amp is present on the individual gain modules.

 

[Zen Mod]

Treshold Treasure ?? while Papa was there : NS10 Preamplifier | Zen Mod Blog

 

[Malotron]

There is so much gold on the boards...like opening Marsellus Wallace's briefcase

Aloha
-Mal

 

[R-K Rønningstad]

LM723 is a voltage regulator.
http://www.ti.com/lit/ds/symlink/lm723.pdf
Regds

 

[R-K Rønningstad]

NS10 inside

This is inside my NS10. LM307 near the right gain control, close to the PCB edge.
Capacitors are replaced. Seems also the mono/stereo switch has been bypassed. Also new RCA sockets at the rear panel.

 

[R-K Rønningstad]

NS10 and his brother

Here is the NS10 with the 400A. (iPhone camera...)

 

[Zen Mod]

Fugly!

 

[R-K Rønningstad]

Even more so inside the 400A. I am sitting here looking into it like some doctor of medicine wondering shall I just close it again? Well, I am going to close it. But I will do some surgery on it, maybe replace some vital parts. I'll find a 400A thread and post the pictures maybe.

 

[R-K Rønningstad]

So the picture of the damaged inside is here: http://www.diyaudio.com/forums/pass-labs/95067-repair-question-re-threshold-400a-47.html#post4034628