No need to blush, R-K. A lot of us have been looking for the actual schematic of the NS10 preamp. Its very nice to actually have it posted here at last😉
Steen😎
Steen,
To me it looks like the 2 schematics(RIAA stage and Preamp Stage) are quite similar, and in fact could utilize the same PCB for either which is sort of what I was trying to say earlier. If you bypass the RIAA filter stuff and use slightly different values you get the line stage.
This would make for a very flexible PCB.
What do you think?
To me it looks like the 2 schematics(RIAA stage and Preamp Stage) are quite similar, and in fact could utilize the same PCB for either which is sort of what I was trying to say earlier. If you bypass the RIAA filter stuff and use slightly different values you get the line stage.
This would make for a very flexible PCB.
What do you think?
I dont think you can do that. The RIAA circuit amplifies the signal from the grammo to linelevel only, and you need the normal linestage following it to amplifiy the signal further to get a normal poweramp signal level.
Steen🙂
BTW I think I have an original NS10 comming my way, including the elusive box😎
steenoe said:
Steen, I am not saying you just one PCB for both. I am saying you could use the same PCB design for two functions. So you would use the PCB twice, so two PCBs. 🙂
Oh, ofcourse. I see that now. Sorry, I was just too fast again😉
As I said in the previous post, there is a good chance that I will get my hands on a Threshold NS10 including the Moving coil box.
That would be really nice🙂 All I need is a Threshold A400 or A4000 then😀 I would love to restore such a pair to prestine condition🙂
Steen😎
Sure. It is standing on top of my desk here at work. The power switch has to be replaced. I going to bring the camera and some nice pictures will be taken and posted somewhere. BTW it is the early version, non-cascoded input.
RK
RK
All of this going on since I turn my back to the forum for a couple of hours. My God...
Steen, that would be 😎 if you get yourself a set of original NS10 + the 400a
Thanks again R-K for sharing with us 😎
Steen, that would be 😎 if you get yourself a set of original NS10 + the 400a
Thanks again R-K for sharing with us 😎
Yeah, I decided that it was time to get those amps that started the whole "Pass-mania"😀 I think the preamp is gonna work out, the guy just needed a few days to think about it. But overall the deal seems to go😎 My intention is to restore it to at least as good as new. Or better than new, if thats possible🙂 I allready have some Rifa axial electrolytics in mind😉
Steen😎
steenoe said:
please-gimme day or two for nice and easy and killer single supply proposall....
my preciouss have 2. birthday tomorrow,and I'm preparing one little party for closest familly in saturday.........barbicue etc
😀
russ-can you wait few days with pcbs?
or just with final version?
I'll like to include finnal PSU elements on each stage ,at least shunt reg ,if not even CCS and shunt reg.....
or just with final version?
I'll like to include finnal PSU elements on each stage ,at least shunt reg ,if not even CCS and shunt reg.....
Seems that Steen still wants to build and “up to date version” of this classic NS10 preamp and since the nearest “original” topology we have is what R-K posted --as a RIAA pre-- we need to do some clean up and decide some component values.
For this I took R-K’s posted schematic and redraw it as a Line pre but we need to go over it to check values and topology, set FB values for needed gain plus decide on some enhancements to the circuit for an upgraded version.
There are some things that are easy to upgrade such as
- C1, replace with a 1u film cap
- C8, replace with a 10u film cap
- C5 & C6, replace it with a 100u plus a film bypass
- C9 + C10, bigger rail decoupling – included already
- D1 & D2 (MSD7000) replace with a couple of diodes (1N914?)
- Bypass D1/D2 as suggested on R-K’s Schem plus R15 resistor (John Curl suggestion to reduce noise)
- Active devices, to previous suggestions
- Other suggestions?
Now, which Opamp to use?
I know that Russ may be working on a nice PCB so this will help to set components and values for his work.
For this I took R-K’s posted schematic and redraw it as a Line pre but we need to go over it to check values and topology, set FB values for needed gain plus decide on some enhancements to the circuit for an upgraded version.
There are some things that are easy to upgrade such as
- C1, replace with a 1u film cap
- C8, replace with a 10u film cap
- C5 & C6, replace it with a 100u plus a film bypass
- C9 + C10, bigger rail decoupling – included already
- D1 & D2 (MSD7000) replace with a couple of diodes (1N914?)
- Bypass D1/D2 as suggested on R-K’s Schem plus R15 resistor (John Curl suggestion to reduce noise)
- Active devices, to previous suggestions
- Other suggestions?
Now, which Opamp to use?
I know that Russ may be working on a nice PCB so this will help to set components and values for his work.
Attachments
NS10 DC servo opamp
I see the LM307 is obsolete, but there should not be any very special requirements to the NS10 DC servo opamp. Why not copy what e.g. Erno Borbely uses?
RK
I see the LM307 is obsolete, but there should not be any very special requirements to the NS10 DC servo opamp. Why not copy what e.g. Erno Borbely uses?
RK
Mr Pass stated he used the crummiest opamp he could find in his toolbox.
He wasn't kidding, the LM307 is as bad as it gets, even an ancient 741 is better.
He wasn't kidding, the LM307 is as bad as it gets, even an ancient 741 is better.
apassgear said:
I think that's wort to try without local rail decoupling;
dedicated shunt stage will do that
in any case-it's convenient to make place for ,say,100UF cap and try without it
opamp
like NP sez somewhere-crummiest you find;
just look at RC constant on output of OP......
- Status
- Not open for further replies.