advertisement


DIY Hicap w Mr Tibbs earthing mod?

Appologies again for double posting

You can get the transformer made to fit whatever space you have got. I seem to understand that Naim kit likes big VA transformers so I asked mine to be as large as could be done at a maximum height of 44mm.

12415319.9d5fe409.1024.jpg


as you can see mines a little wider than the Nap90`s ;)

Justin
 
@juz400

i wrote him 2 times a mail but he do not write back , the trasmformer guy.

how much money did the tm460 a cost?

nice regards jürgen

the mr tipp cap did i must screw in my nait 3 something ?
 
Patience Jürgen,
It is the end of the TAX year in the UK at the moment, All companies are very busy!
Im not looking forward to monday, we stayed behind to get a head start on next week as the new TAX year starts!
 
Cheers, yes I'll need to consider layout and size first as I'm currently using a half width box and don't fancy drilling and laying out another.
 
ok sorry but how much is the transformer?

and do you someody who want buy my ovator s600?

where i can buy like original naim cases?
 
thank you but i think it is really to much money for alu:)
and 30 pound to shipping is also to much.

but where can i found help to diy my own hi cap und an diy nap 250?

nice regards jürgen

i found that juz 400 cap is really nice but he havn´t time to help:)
 
My Prototype is now built and working

12479363.7810e193.1024.jpg




12479367.c924e702.1024.jpg


I dont know if these capacitors are any good for this purpose, I had them lying around from another project. The rectifier diodes are Q-Speeds

I have not tried the Naim side of the psu side yet as the current unloaded voltage is 38.3v
I purchased 2 x TeddyRegs from misterc6 set at 37vin/28vout a while back (Thanks misterc6 :D )
I now have to take the Nac92 into surgery!

The layout i have nicked from Neiljadmans Nait3 fun and games mods
http://www.pinkfishmedia.net/forum/showthread.php?t=76926


12484659.075b940b.1024.jpg


I would like to connect 1A and 1B to one reg and 2A and 2B to the other reg
On the right hand side of the pics, the boxes show a cut link that I belive is for the nait3 and takes the place of the 5 pin plug(black doodad in the din socket)

I have a few Questions..
1) My psu is giving out 38.3v, is that ok for the teddyregs?

2a) Is there anything I need to change if I run at 27v?
2b) I see that the capacitors in the top right pic are 10uf 25v
Can I use the psu from a nap90 to power this area?
I reconnect the link back that was cut out.

3) the 27ohm resistors, do I still need to use them if using the teddyregs?
has NJ got rid of them or just moved them, the pics confuse me a little!

4) Do I need heatsinks?
NJ`s using 4 regs, I guess mine will use a little more power

5) How are you getting on David?
Looking forward to more pics, It will look great in one of those cases!

Any help here will be awesome, Im dying to put it all back together!
Cheers,
Justin
 
@juzz400

hi justin how are you, is your teddy cap ready? did it works good?
how much money you pay for the transformer?

nice regards jürgen

if you have time please write me back
 
I have a few Questions..
1) My psu is giving out 38.3v, is that ok for the teddyregs?

2a) Is there anything I need to change if I run at 27v?
2b) I see that the capacitors in the top right pic are 10uf 25v
Can I use the psu from a nap90 to power this area?
I reconnect the link back that was cut out.

3) the 27ohm resistors, do I still need to use them if using the teddyregs?
has NJ got rid of them or just moved them, the pics confuse me a little!

4) Do I need heatsinks?
NJ`s using 4 regs, I guess mine will use a little more power
OK I will try:
1) Yes
2a) Not sure I understand your question:
If you mean "in the NAC92" the response is "No". There is nothing to change in the NAC92 due to the higher voltage (24V -> 27V).
It is "admitted" (is it ?) that running the NAC with 27V instead of 24V may bring some improvement in sound quality.
You have STRs with a variable resistor so you can have a try.
The first thing IMHO is to try the STRs not connected and to set them to 27V.
then connect them and check if the voltage is still at 27V ... otherwise adjust.
2b) The yellow capacitors are the tants and are the signal coupling capacitors that are set to half of the PSU values i.e. below 20V.
No problem with them.
The blue ones should have higher voltage.
2c) (yes it is another one :p)
The single rail coming from the NAP90 is at 24V to power the NAC. 24V is far below what your STRs need as input to bring 27V ...
One possibility would be to bypass the small regulator of the NAP90 ...
3) If your STRs are local i.e. beside the NAC circuitry, then yes you may remove the 27R resistors but keep the 47uF.
4) I dont think it is really necessary. Check the temp after a while and decide then.

Hope it helps :)
Cheers,
Olivier
 
Hi Olivier,
many thanks for taking the time to answer my questions!
I should have said the blue electrolytics in the top right of the pic, they are 10uf 25v but as this part of the Nac92 is powered by one of the naps they are safe!
It must be said that you MUST check inside your `92 if you intend to run it at anything above 24v. In the early models they use axial mounted caps with
25v rating and theres 10 of them to go POP! :p
Yup, the yellow tants are new kemets, fitted during this build. I have finished fitting the teddyregs, They are running fine at roughly 28v and are cool to the touch

I had fun on the initial powerup!
No green naim logo! WTF?? I triple checked everything!
powered down, checked the connections, powered up, checked the power,
teddy1 check, teddy2 check, nap check. whats wrong???

I then twigged!
When I left the AUDIO connectors disconected from the minidsp`s to check for any dodgy voltages coming out the nac, There was NO ground to the Nap90 psu! D`oh!!:D
I am considering changing this, running a powerlead from the nap90 psu and cutting the pcb ground from the psu to connector, Im not sure on this as Im sure all the grounds are connected at the psu side of the nap.

I have tried mr Tibbs idea from the `pre-amp Nirvana` thread: http://www.pinkfishmedia.net/forum/showthread.php?t=16840&page=17
I guess I need some more teddyregs!

12494265.9dff6643.1024.jpg


Impressions over the last few days..

More and tighter bass, a bigger sound, seems to have left the speakers altogether. Before on some notes and sounds you pinpointed the speaker, not any more!
More low level detail is there and overall it really boogies now!
I guess I need to sort out the 47uF 35V electrolytics now..

David,
I think you have something to look forward to here, have you ordered a toroid yet? Im looking forward to seeing more pictures of your build!

Cheers
Justin
 
Hi all!

Sorry for recent radio silence - work has been taking its toll. That, and I realised I had the wrong toroidal from Farnell, so I've gone ahead and ordered a nice one from Canterbury. So no building to do until that arrives... :(

In the meantime, however, I've refreshed by NAPSC clone. I'd bought a cheap little 24V DC power supply (wal-wart) and put a current-limiting regulator on it, but when I plugged it in I found the little blighter made a horrible high pitched whine (the power supply, not the hifi!!) Eventually I discovered that this was due to the transformer being of the "switch mode" variety. So I've swapped it for a standard non-switch mode one, and all's wonderfully silent now!! :cool:

As soon as the new toroidal arrives I'll continue with the Hicap build. I have to admit that I'm a bit sheepish about showing pictures of the case - I made a right balls-up of drilling the holes for the DIN sockets... :eek:

I also need to think about making the cables for the hicap. I'm going to attempt Mr Tibb's earthing mod via the cables so that I keep the NAC unmodded.

I'll let you know how I get on!

David

PS - Justin, what are the blue circuit boards in your prototype? In fact, what is your prototype in the first place? I had thought you were just building a power supply, but those look like DACs or something!!
 
Hi David!

The `prototype` is just an old plywood pallet I cut up at work roughly the same size as HiFi kit, fitted a rear panel and painted it black:cool: I also found four pleasant looking feet from a crappy old dvd player and bunged them on too. Its just something knocked up so I could get cracking and build something! I intend to squeeze all this into a empty nap90/flatcap case when I see one in time! :(

The blue pcb`s are two MiniDSP`s
They are digital active crossovers, the preamp out audio is digitized, fed into a DSP, processed however you want then fed to a 2/3/4 way DAC system which then connects to your poweramps.
There is a USB connector to connect to your PC or Mac and software to set your crossover points(up to 48db), parametric equalization, delays, phase reversals and all sorts of other fun stuff!

You can do this in REAL time! I have the MiniDSP software running with HOLMImpulse in the background, an ECM8000 mic and stand set up to measure the frequency response after I change settings on the MiniDSP.

I have never played with a Snaxo type active crossover but I can imagine with the MiniDSP set up like a Snaxo it would lose simply because of the amount of electronics in the audio signal path.
For speaker development, I dont think there is anything better than the Mini

The 2 input 4 output version I have is VERY good value for money, I cannot recomend them enough if you want to play around with active speakers!! :)
Thier customer service is excellent, I think you can get screw terminals fitted instead of phono sockets, just let them know when ordered!

http://www.minidsp.com/
http://www.holmacoustics.com/holmimpulse.php

I wouldnt worry too much about mistakes on the rear panel, once its in place and being enjoyed, the front will be the part you smile at!

Get the bits and bobs you need to make the cables and we will help you roll them! :D

Justin
 
Right, so emailed Canterbury, and should have the transformer in the next day or two.

So I need to think about the cable I'm making!

I'm going to have one end from the P/S carrying 2x 24V and 2x 0V, and have two connectors at the other end: one with 2x 2V and 1x 0v which will connect to the 'usual' Hicap socket, and the other carrying only 1x 0V which will connect to one of the unused line in/out sockets.

So my questions are:

1) what kind of cable should I use? For audio signals I've got homebrew PTFE coated silverplated OFC copper, and I'm using pure silver connections from pre to power. But I'm guessing that the requirements for optimum power carriage are different to signal transport. Is it just a case of as much metal as possible?

2) Which line in/out socket should I use on the preamp? I'm currently only using the RCA CD line in, and the Tape in/out. So I've plenty to choose from. Does it make any difference which I go for?

3) I'm aware that I'll need to desolder the +ve connection on my cable that currently runs from pre to power, since I'll still need to run the audio signal direct (rather than via the P/S), but will no longer need the +24V from the power. But which socket do I plug my P/S into on the NAC202? Is it still the "upgrade 2" socket?

Thanks for helping out!

Best
David
 
Hi David,

Appologies for no replys for ages!
The 650watt psu blew up in my computer a couple weeks ago and Ive just fitted a new 750. Luck would have it thats all that got fried! I was dreading having to fork out £300 or so for a new Graphics card! :eek:
You have probably built and are enjoying the fruits of your labours by now but here goes

For power requirements, I read on acoustica.org that 1mm core is the most you can fit 4 of into the din plugs. Im using a speakon 4pole connector for my psu connection, you can get some really fat cable into those!

Any spare input socket you have I would think is fine for the other 0v connection.

Your PSU will go into the same socket that a Hicap would normaly go.

Hope you are getting on well!
Justin
 
Hey all,

I finally finished the DIY Hicap and wanted to report back on the end of the project.

As many of you already know, those caps are bloody dangerous when fully charged - I did the textbook noob mistake of shorting the terminals with a multimeter probe - a big flash and bang, and nicely melted probe tip ensued, but luckily nothing and noone else was damaged. So, I duly did what I should have done earlier and made myself a Capacitor Discharge Tool (otherwise know as a lightbulb!) ;) :

7188255200_9ac694d2e5.jpg


The transformer I got from Canterbury is a beast - looks lovely and weights a ton!
7188257462_abb44f2239.jpg


And here's a close-up of one of the two Sjostrom regulators awaiting fitting in the shoebox case:
7188259364_e9834ae3cd.jpg


So from there I went on to make the split-earth cable - you can see that one plug has 2x24V positive wires, and one 0V earth wire, and then there's a separate 0V earth connection as the only connection on a 5 pin DIN plug which I've plugged in to a free socket (Aux 2) on the Nac202. Thanks to Justin and Mr Tibbs himself for pointers on how this was supposed to work!

7188261818_5f8c486d6c.jpg


Lastly, once I was certain that everything should work I started the final assembly in the case:

7188263644_4d34ef8285.jpg


I had read that the closer you can get the rectifiers to the caps the better, so I managed to arrange things so that the +ve leg on the rectifier screwed directly into the cap terminal by soldering a washer directly to it. So in the photo of the final assembly below it's quite hard to pick out the rectifiers.

I put a bit of heat transfer compound between the IC heat spreaders and the case sled so that the whole case is acting as a heatsink. I also attempted to keep the +ve and 0V connections to the power supply output as far as possible from each other and from the cable trunk running from transformer to caps, etc.

So, at long last, here's a picture of the final product:

7188265582_e7bc3bd4b5.jpg


And here it is in my hifi rack, on the right of the middle shelf - no LEDs on the front (just one indicating power running through the rectifiers on the back so you can tell when it's physically switched on), so it's very discreet.

7188267390_345d4d167a.jpg


And, wow, does it sound good! I don't need to describe the benefits - I'm sure you all know what they're like. But all the cliches about 'inky black background', 'tighter bass' and 'more space between instruments' is definitely true!

And of course, and most importantly, there's the pride every time I lose myself in a music listening session of looking at my hifi, and specifically the power supply, and thinking "I made that"!!!

Priceless! :D

So, once again, a huge thanks to Mr Tibbs, and Justin, and everyone else who's given me extremely helpful pointers along the way - I'd never have avoided the plague of the dreaded blue smoke without you!!!

Best
David
 
Superb work David! It's a great feeling, hearing something so good that you've made yourself. You'll get addicted to it...
 


advertisement


Back
Top