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Help with Nac72 Regs wiring please

Mynamemynaim said:
PS
For anyone thinking "he's still got that standard volume pot connected"
well yes....but its set to full volume permanently, the RSL cards are set to minimum...and the volume is controlled by the remote control
This in its self makes a nice improvement if you have RSL remote cards!
Click to expand...



Finally got round to removing the volume control (and the balance too)

51530967849_212ab12243_c.jpg
[/url]2021-09-29_08-00-07 by rock solid, on Flickr

51531179100_9de0bbc809_c.jpg
[/url]2021-09-29_08-00-29 by rock solid, on Flickr

I put "pins" into the holes so that I could easily solder resistors to them for volume reduction (remember I have RSL cards for volume control) and any balance needed

The balance is better than with the control in....so I have just bridged the pins ...easy enough
The volume, I wanted to reduce the "overall level" so I've popped a pair of 15K resistors (matched pair) onto the posts...and that has had the desired effect of replacing the missing balance resistance and also reducing the overall volume level so the RSL cards work better

I fully realise all this is 15 years too late for most people...but a modded nac72 is such a nice Preamp ...don't dismiss it if you are on a budget!!

Ps
I'm not going to just leave the holes in the front panel ... I just haven't quite finished machining the alloy holders for the knobs yet...that will sit though the panel and the old knobs push onto them
 
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Superb work glad to hear it has made a significant improvement. Yes I did think the SC was all about bringing more regs into the system and everything I have read says the work best closer to the amp than the power supply.
Not sure I can do that to a 72 tho lol.
Would it work on a 32.5?
Other question is my power supplies are Avondale based as such I think the max is 35v, would this work ie taking the dual 35 v output and running it through further regs to split it out?
 
Yes it would all work just as well with a duel rail 32 as on mine
TBH I've spent thousands on naim gear over the years...so a few hundred on a 72 is not a lot...and it punches well above its weight in this format

Most of the Avondale power supplies can be wound up to a higher voltage (via the trim screw on the blue pot) but I don't know what the maximum is...but if it is 35v ...then with ALWSR's I've found that 4 or 5volts headroom is enough for them to work...so

35volts supply to 30v alwsr to 25v alwsr in the nac32.5

But the Avondale supply is regulated already
So why not just use that straight into the onboard superregs?
 
I like the ide of multiple regs the TPR2 from Les at Avondale any good? I might have enough bits to make a dual supply ie equivalent of 2 hicaps using TPRZ boards if they were cranked up would give 4 off 35v to add 4 further regs, would it be possible to do a less intrusive mod ie a second din socket so like 2 hicaps (power only) and the ability to swap cards as kind of spoiled for choice with 821A and NJ321 and NJ729 on the way. Funds don't allow for RSL remote boards but that where I want to get to eventually.
 
Avondale power supplies are very good...you won't have any issues if you're supplying super regs with them
I did seriously consider what you are suggesting...ie umbilical cords taking the power to the back of the 72 after all , your spoit for choice with unused 5pin dins (assuming you're not got multiple sources...I've just got the P8 and the NDS)

But in the end, I decided to get the regs as close as possible
Naim put everything in a separate box and then send the signal to it and then back again!
and that still sounds Ok :D..so think you will be fine

Don't forget my first (testing?) setup was very unintrusive...being.. hicap clone with ALWSRs supplying the back socket of the 72 , then two more ALWSR inside the 72 wired to the duel rails of the board
This did sound good and I was very pleased with it (thread and pictures somewhere!**)
But I wasn't prepared for the difference doing it "properly" made..
You could always do it in little stages, as I did

** Edit.. think it was here
https://pinkfishmedia.net/forum/threads/alwsr-best-wiring-practice-inside-nac-72.255975/
 
Has anyone use the Avondale TPR2 regs?

I know nothing about them, or how they compare, I have mixture of Avondale power supplies, APX and TPX1.5, so like what they do. The idea as explored in this thread of multiple onboards regs is appealing. As I would be using either Avondale 821A and linking out the 729 OR NJ 321 and NJ729 boards the idea of splitting the supplies with an additional regulator.

I would be approaching it slightly different by using 2 avondale power supplies probably TPR1.5s turned up to about 35v , then being reduced by another set of regs to bring it back down and directly power the boards.

I think I would want to keep the main board powered an keep the naim logo etc or that more hassle than it worth? or better yet use the old 32.5,less to worry about.

so question here is what regs would be best to use to further regulate an avondale power supply? I know nothing about ALWSR or where to get them etc, looking back on old threads some say it was superior to teddyregs but have superteddy regs improved on this? Then to further complicate it looking on Avondale website Les now has TPR2 where do they factor in?

All advice welcomed this not my area of expertise but keen to get as much out the shoe box amps as possible, worst case \i have the 102 to fall back onto!
 
Would love to be able to talk knowledgeably and further on this subject...
But sadly I've reached the end of the help I can offer:( (a man's go to know his limitations...Clint Eastwood?)
Hope someone comes along to help and good luck...it's well worth the effort to do this
 
I had 2x tpr2 in a 72 years ago, swapped out for an msx and ended up with 4 str in the 72 chassis, split across phono and gain boards, no time aligned boards fitted. All versions sounded great, very little diffetence between them, just a slight shift in emphasis and smoothness from one area to another.
 
So the TPR2 is worth a try then or the STR better? I generally have found Les stuff to be very good. Starting from a TPX the supply is well regulated to begin with.
Am questioning if a second power supply is only to provide more regulation. If a single TPX or similar can comfortably run a 72 then may only need the one but split into 4 regs my only concern is the voltage drop, as want to keep the 25v at least
 
Once you have the circuits locally regulated I think it's small differences, not better or worse, just a little bit different. It'll come down to personal preference.
 
Mynamemynaim said:
Finally got round to removing the volume control (and the balance too)

51530967849_212ab12243_c.jpg
[/url]2021-09-29_08-00-07 by rock solid, on Flickr

51531179100_9de0bbc809_c.jpg
[/url]2021-09-29_08-00-29 by rock solid, on Flickr

I put "pins" into the holes so that I could easily solder resistors to them for volume reduction (remember I have RSL cards for volume control) and any balance needed

The balance is better than with the control in....so I have just bridged the pins ...easy enough
The volume, I wanted to reduce the "overall level" so I've popped a pair of 15K resistors (matched pair) onto the posts...and that has had the desired effect of replacing the missing balance resistance and also reducing the overall volume level so the RSL cards work better

I fully realise all this is 15 years too late for most people...but a modded nac72 is such a nice Preamp ...don't dismiss it if you are on a budget!!

Ps
I'm not going to just leave the holes in the front panel ... I just haven't quite finished machining the alloy holders for the knobs yet...that will sit though the panel and the old knobs push onto them
Click to expand...


Very neat. Great work.
 
I do have a complete set of late edition boards all unused at this time ...including MM and MC cards

And realistically...I'm not going back to naim boards.
However, I've made the mistake of selling off stuff and then regretting it in the past...so they can stay in the cupboard a bit longer.... sorry
 
Final instalment of this mini project?
Fire up the lathe and make a couple of mounts for the balance and volume knobs to get the outside looking standard again

but first...Kit Ryan (RSL) advised that his sound cards should be set to their highest output setting for best sound...and I was slightly concerned that my "sound stage" just didn't seem quite right on the left hand side, since my volume removal exercise
So...I put another set of resistors in (to complete the voltage divider circuit) by measuring the original volume pot at approximately the position I thought I might need
This worked out to being 1K ohm and 18K ohm for both channels (again matched resistors)

This has resulted in a greatly improved sound stage (why???) and I'm totally happy with everything now:)
Also the overall volume at any (remote controlled) volume position is lower...making the volume even more usable that before (keeping Mrs MnMn happy)

Couple of pictures to finish what is hopefully the end of this tweak now


51587685851_e867d47083_c.jpg
[/url]2021-10-14_12-22-13 by rock solid, on Flickr

New resistor layout and also showing back of alloy mounts

51587690541_ed807ef3f5_c.jpg
[/url]2021-10-14_03-55-00 by rock solid, on Flickr

51586848217_52d0a476d5_c.jpg
[/url]2021-10-14_12-23-13 by rock solid, on Flickr

New mounts held in by tight fit!


51587684081_2edffbe992_c.jpg
[/url]2021-10-14_12-21-33 by rock solid, on Flickr

Finished result ....with OCD matching knob positions :rolleyes:
 
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