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Pictures of my very modified NAC102

Teddy, that is really how it goes!

Surprisingly, with certain inductor combination, I realised that TA seems to take more power than the gain stage! Did not measure it ever - just observed how it was taking voltage down by the current thru the inductors.

While gain stage by it's count, reapped more by the dedicated 0V runs than the TA.

Now, I am having each resistor and transistor separated by their own dedicated RC but VBE has been in my mind long time. Nice to see you did it. I have no doubts what so ever for your results.

This is (as Andy once said about the dedicated 0V runs) how the very best preamps are made. At least one way to make it.

Thanks for your effort and splendid photos, Teddy!

Must say I envy your space in 102. I gotta do it in a shoebox 62.

Oz

P.S. You need a lot more 0V runs from your gain stages!
Then you'll know. That is the enlightenment. A Super-NAC has to breathe freely!
One common 0V rail from a stage is like having a hyperventilation going on.. :p
 
Hi Linnik,

>>>Must say I envy your space in 102. I gotta do it in a shoebox 62.

Have you seen this thread:
http://www.pinkfishmedia.net/forum/showthread.php?t=22627

I'm working on a PCB that will:
-fit in a shoe-box case.
-Implement proper star-earthing (or dedicated 0V runs as you call them)
-Have room for any sort of exotic caps you care to use.

As that's all on the PCB, you end up with lots of room in the case to play around with power supply options.

...Oh and it allows simple implementation of the 'split rail' configuration as well...


It's very much still a work in progress right now, please have a look - I'd welcome your feedback.

Jim.
 
That looks a nice effort indeed, Jim!

I had been on the thread but not while your PCB plans were there.

Very tempting, must say!

Oz

-- Father X'mas of the Spaghetti NAC --
 
The post is a bit out of date, I must update it soon.

Once I complete the design, I'm considering offering it as a group buy if there is any interest.

Jim.
 
Linnik said:
You need a lot more 0V runs from your gain stages!
Then you'll know. That is the enlightenment. A Super-NAC has to breathe freely!
One common 0V rail from a stage is like having a hyperventilation going on.. :p
Click to expand...

I think that the 102 PCB is better designed than older models wrt the 0V runs, it already has something close to what you have done, implemented as part of the PCB. Saying that, I still plan to have VBEs for the 0V (or -V runs) runs too, it will be part of a split rail mod that I'm planning. In this case I'll only need one -V run to the VBEs board that supplies all the VBEs.

Teddy
 
Jiiim said:
The post is a bit out of date, I must update it soon.

Once I complete the design, I'm considering offering it as a group buy if there is any interest.

Jim.
Click to expand...

Always interested!

In trials to get my bird's nest, spaghetti, 3-dimensional, NAC for a true flat one.

Oz
 
Hi Teddy, having been through this thread a few times I was interested to know your views on the decoupling caps. It would appear that connecting the vbes leaves the 56mf oscon hanging on to one end of the gain boards. In the case of the TA boards there is a decoupling cap at each end of the board suggesting a problem with potential instability. Does this matter?? Or have you hidden a few extra caps underneath? Cheers Andy.
 
IIRC I'm using some film capacitors under the PCB for decoupling. All coupling capacitors are SMR (again, under the PCB). I recently replaced the feedback from mil spec tantalum to 47uF MMK(thanks Carl), it's a great improvement. The VBE ladders have changed since I took the pictures and they are now all made of film capacitors. No more electrolitics in my 102.

BTW, I'm running it now without superregulators, just VBEs, and it sounds just great.
 
Hi Teddy, I am a little curious about your current setup.

Are you using vbes on all separate powerrail resistors in the gain and buffer section and still powering them with your switch mode psu?

What's the spec on the vbes you are using, what voltage drop do they give, do they have some kind of regulatory function or are they simply very good at filtering HF stuff.

Have you made any adjustments to you grounding paths X'mas style?

A lot of questions from a total beginner, so please forgive any lack of common obvious knowledge.

P.s. Your Minicapnapsc is a work of art and has totally blown the minds of some of my naim friends here in Sweden :) d.s.
 
I think you have to look at minimal return on modified kit. We hope to gain a lot of improvement for a lot less cost than an upgrade and the fun of wielding a soldering iron.
I wouldn't be keen to buy a modified bit of kit without a fair bit of recommendation and guarrantee.
So I have an Avondale cd3 but might not be keen if it hadn't been improved by Les.
Cheers Andy.
 
Agent_Cooper79 said:
Hi Teddy, I am a little curious about your current setup.

Are you using vbes on all separate powerrail resistors in the gain and buffer section and still powering them with your switch mode psu?

What's the spec on the vbes you are using, what voltage drop do they give, do they have some kind of regulatory function or are they simply very good at filtering HF stuff.

Have you made any adjustments to you grounding paths X'mas style?

A lot of questions from a total beginner, so please forgive any lack of common obvious knowledge.

P.s. Your Minicapnapsc is a work of art and has totally blown the minds of some of my naim friends here in Sweden :) d.s.
Click to expand...

Yes, I'm using a VBE for each resistor, as for the PSU, I'm changing all the time, Experimenting.... Currently I ran out of MiniCapSc so I use a HP PSU. The VBE ladder dropout is about 0.7V

These VBEs can be made of 3.3uF MKS, 10K, and bc547. Just use Martin's design from the PinkFlea, but other values can be used too.

No I didn't make changes to the ground path. Well, I did one, The feedback capacitor's ground (47uF MMK) is connected directly to the ground star.

Glad to hear you enjoy the PSU :)
 
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