ThePre

For everyone who has soldering iron burns on the carpet

Moderators: The Krew, The Kurators

User avatar
Mr Onion
Site Moderator
Posts: 8455
Joined: Sun Feb 23, 2014 2:13 pm
Location: Between two Super 20's

ThePre

Post by Mr Onion »

ThePreBlack3.jpg


Whats ThePre I hear you ask. Its my latest project to (hopefully) improve on my existing NACish 72 PreAmp.

The Idea

The NAIM NAC72 (upon which my PreAmp is based) is a fantastic Pre, even by todays standards but has one major failing for those of advancing years. No remote control. There is little free space inside a 72's case so it would need a total rebuild. Yes, I could replace it with a 282, 252 or even a 552 but at an ever increasing cost and all of them have facilities and features I would never use. All I need is 4 or 5 inputs and a volume control.

Research

You can buy 'remote control' modules on Auction Sites, mainly from China. Most say they have an 'Alps Blue' but at the stated cost quality has to be questionable, and even a genuine 'Blue' is not as good as the non remote controllable Noble I already have. Others have 'ladder resistors' but again at what quality. What I want is a quality package that can easily be added to NAC 72 based boards.

TKD make a fantastic sounding remote controllable Potentiometer, and HiFiCollective make a modular Remote control system that works perfectly with the TKD

tkd-motorised-front-new-350.jpg
glasshouse-remote-control-350_0.jpg
glasshouse-selector-parts-made-up-350.jpg

So with that the idea started to become reality.


Why "ThePre"?

Why not? I had the space where the bling badge was removed so I needed something classy looking to fill the space. I am not putting NAIM on the box, cos it ain't NAIM.
You do not have the required permissions to view the files attached to this post.
James


Fluted Afro LP12, Khan, KEEL, Karousel, Urika, Radikal (with Allium Skin Mods), EKOS SE/1, sKale, DVXX-2mkII
NAIM CD 5si with Marigo Lab Aida CD Mat
ThePre, ZAP 250, Kudos Super 20's
User avatar
Mr Onion
Site Moderator
Posts: 8455
Joined: Sun Feb 23, 2014 2:13 pm
Location: Between two Super 20's

Re: ThePre

Post by Mr Onion »

Boards

My NACish 72 uses a custom board designed by Neil James that has space for 4 TeddyRegs and allows you to use either the original NAC 72 321/729 daughter boards or Neils own improved ones. I have tried it with both, but have stuck with Neils as they are just better being based on the same circuit that is in the NAC 52.


motherboard.JPG

boards_front.JPG

boards_back.JPG



Teddy has spend the last 12 years or so working on improving his regulators, going through the SuperTeddyReg and latterly the MiniTeddyReg which is not much larger than a TO220 semiconductor package. Great idea, small and space saving too. Far better and precise regulation than a HiCap, probably more like a NAIM DR module.
mini_teddy_regs.JPG


Put the two together and the result will be better than a NAC 52, maybe better than a NAC 252


The remote control boards use the industry standard RC5 codes, as does my NAIM CD player and there are conflicts which I could not resolve. Luckily the Remote Control Kit designer can re program it to work with an Apple TV remote control which is paired with its receiver to avoid such conflicts. Not a cheap option as such expertise does not come cheap, but it will remove hours of frustration.


Case

Simple requirements, difficult to satisfy. It needs a space enough for all the components, look smart, and have a 'window' to allow the remote control commands to be read then the figure 8 LED to be seen. After checking many many sites I found this.

case-1.jpg

The backplate is available in many versions, but none fitted my needs. The seller was happy to supply a 'blank' for me to drill myself.

Other Components

The TeddyRegs need +30v the Remote module needs ~12v, so a double power supply while seeming excessive was the obvious answer as it keeps the signal and control circuits totally separate. NAIM have also had the same idea. So I ordered a Custom Audio Quality transformer from Canterbury Windings, and a 'normal' transformer and other bits from either CPC, HiFiCollective or my parts box.

The Power Supplies will be assembled in seperate case to keep the noise away from the sensitive bits.

(The remote control boards could be powered from a simple SMTP 'wall wart' but they are so noisy they usually add Mhz crud back into the mains supply. We don't want that hence the OTT linear supply)
You do not have the required permissions to view the files attached to this post.
James


Fluted Afro LP12, Khan, KEEL, Karousel, Urika, Radikal (with Allium Skin Mods), EKOS SE/1, sKale, DVXX-2mkII
NAIM CD 5si with Marigo Lab Aida CD Mat
ThePre, ZAP 250, Kudos Super 20's
User avatar
Mr Onion
Site Moderator
Posts: 8455
Joined: Sun Feb 23, 2014 2:13 pm
Location: Between two Super 20's

Re: ThePre

Post by Mr Onion »

Starting work

The first thing to do after getting the layout right was to drill the holes. 7 DIN sockets, 2 Power sockets and a grounding post on the back. Lots of measuring, measure again, and re measure then a little work with the Bench Drill and I have

back-after.JPG

Neat and tidy, and not at all cramped.

Next drill the base for the PCB's mounting pillars. As before measure and re measure. The 'problem' was that as soon as I had decided on the layout and drilled the holes I had a rethink and moved things around. Hence the unused and blocked off holes in the base. The front panel hole needed slightly enlarging for the TKD pot and a blind hole for the anti rotation 'pips' on the Pot and Input selector and the drilling is all done.

inside-drilled.JPG
You do not have the required permissions to view the files attached to this post.
James


Fluted Afro LP12, Khan, KEEL, Karousel, Urika, Radikal (with Allium Skin Mods), EKOS SE/1, sKale, DVXX-2mkII
NAIM CD 5si with Marigo Lab Aida CD Mat
ThePre, ZAP 250, Kudos Super 20's
User avatar
Mr Onion
Site Moderator
Posts: 8455
Joined: Sun Feb 23, 2014 2:13 pm
Location: Between two Super 20's

Re: ThePre

Post by Mr Onion »

Mounting the boards


First the Remote Control boards. The IR Receiver needed removing from the board and putting close to the front window. Also the 5 core lead from the Control board to the Input board needed lengthening. All fairly simple to do. the bigger problem was the Fig 8 display, which is supplied as red. Looks OK in its own right but awful in the context of the rest of my system.

Good News:- NAIM Green Fig 8 displays are readily available

Bad News:- They are a different pinout. Lots of time with the multimeter and datasheets allowed me to figure out how to wire it to rest of the boards. Again, check, check and check again.

... and it didn't work. Checked again, corrected 3 connections. Still no joy. Checked again and one segment on the chip was fried :oops: New chip ordered and all was well.

All mounted in the case and we have



Remote Connections.jpg

Next the backplate needs wiring up and connecting to the Input and Remote control boards. The reason for the output going through the remote control board is that 1) they come supplied with a switch on delay negating several extra components on the main PCB and 2) the reprogrammed remote now has a mute facility using that switch on delay relay.


Backplate connections are fairly easy, if a little crowded. All fairly self explanatory except for the bundle of signal ground wired which will terminate at the motherboard to keep the star earthing intact.

backplate_complete.JPG

Connecting the signal wires to the input and output relay boards completed this stage.

case_no_MB.jpg
You do not have the required permissions to view the files attached to this post.
James


Fluted Afro LP12, Khan, KEEL, Karousel, Urika, Radikal (with Allium Skin Mods), EKOS SE/1, sKale, DVXX-2mkII
NAIM CD 5si with Marigo Lab Aida CD Mat
ThePre, ZAP 250, Kudos Super 20's
User avatar
Mr Onion
Site Moderator
Posts: 8455
Joined: Sun Feb 23, 2014 2:13 pm
Location: Between two Super 20's

Re: ThePre

Post by Mr Onion »

Populating the Motherboard

The Motherboard has space for Four TeddyRegs which is easily adapted for the new MiniTeddyRegs by adding one powersupply bypass capacitor and 2 links per regulator. The space for a Balance control is bypassed with Z Foil Resistors and I am adding attenuation of ~16db, again with a Z Foil resistor by using otherwise unused pads on the board. Yes I could have made do without this board, and constructed something on some Veroboard but this has two advantages.

1) It has all of the hole spacing correct where the 321 and 729 boards 'plug in'
2) The Star Earthing has been taken care of.
(well, three advantages)
3) Its far neater


motherboard_populated.JPG


All of the existing TeddyReg components bypassed and sockets added for the MiniTeddyregs.
You do not have the required permissions to view the files attached to this post.
James


Fluted Afro LP12, Khan, KEEL, Karousel, Urika, Radikal (with Allium Skin Mods), EKOS SE/1, sKale, DVXX-2mkII
NAIM CD 5si with Marigo Lab Aida CD Mat
ThePre, ZAP 250, Kudos Super 20's
User avatar
Mr Onion
Site Moderator
Posts: 8455
Joined: Sun Feb 23, 2014 2:13 pm
Location: Between two Super 20's

Re: ThePre

Post by Mr Onion »

Connecting it all together

All thats needed now is connecting the three boards and volume control together. Lots of point to point wiring needing patience and lots of checking (as usual)

I added a 3.5mm jack to the front panel for convenience when playing from the LapTop. I connected this to the 2 'out' pins of input 5 and then made a 5 PIN DIN plug with pins 1 and 3 bridged and 4 and 5 bridged. Thus plugging that in has the effect of connect the jack to input 5. Perhaps not the ideal solution but gives me the option of 5 DIN inputs should the need arise.

complete _inside.JPG

Then its out with the multimeter again to check that everything that should be connected is connected, and everything that should be isolated is isolated.
You do not have the required permissions to view the files attached to this post.
James


Fluted Afro LP12, Khan, KEEL, Karousel, Urika, Radikal (with Allium Skin Mods), EKOS SE/1, sKale, DVXX-2mkII
NAIM CD 5si with Marigo Lab Aida CD Mat
ThePre, ZAP 250, Kudos Super 20's
User avatar
Mr Onion
Site Moderator
Posts: 8455
Joined: Sun Feb 23, 2014 2:13 pm
Location: Between two Super 20's

Re: ThePre

Post by Mr Onion »

Power Supply


I started with one of these, which is the same size and construction as the one for the Pre Amp but obviously without any cutouts on the front.

PS_case.jpg
... but this case has been delayed in transit so I assembled the Power Supply in two cases. I will update this once I have assembled everything in the new case.

As mentioned before there are two supplies for ThePre. A 12v for the Remote Control and a 30v for the Active boards. A 'normal' Toroidal Transformer for the Remote Boards, and the Audiophile one for the active boards. They produce raw rails for the circuits in the pre to regulate as necessary.
You do not have the required permissions to view the files attached to this post.
James


Fluted Afro LP12, Khan, KEEL, Karousel, Urika, Radikal (with Allium Skin Mods), EKOS SE/1, sKale, DVXX-2mkII
NAIM CD 5si with Marigo Lab Aida CD Mat
ThePre, ZAP 250, Kudos Super 20's
User avatar
Mr Onion
Site Moderator
Posts: 8455
Joined: Sun Feb 23, 2014 2:13 pm
Location: Between two Super 20's

Re: ThePre

Post by Mr Onion »

First Powerup


Before connecting anything I went through all of the soldering again, again and again. Then checked the connections, and checked it again. Once I was happy that nothing was cross connected, no dry solder joints etc I checked the Power Supply outputs.

Everything as expected, so plug the power supply to the pre, hold my breath and turn on.





... and it works. xss02 All voltages correct, nothing exploded or burning. So I guess I had better test it, but I am not risking my Kudos Super 20's, so I plugged it into the Computer Amp and Speaker, switched on, added a signal, and we have music xss03 xss05

PHEW!

So its time to be even braver and plug it into the HiFi :shock: .


... and its still working. Just a couple of little glitches:-
1) Constant low level hum. Cured by adding a ground drain to the 0v on the Remote Control Power Supply.
2) Very slight hum during switch on and mute. Not a big deal but I'm thinking about a fix for it.


completed_front.JPG

completed_back.JPG

"How does it sound?" I hear you ask. Its the same as it was before, but better. Clearer, deeper clearer bass. Very defined vocals, without being clinical. No harshness. AND its remote controllable :smt023 Exactly as you would expect a better PreAmp to sound.

No down sides at all, and the sound will improve over the next few weeks, but to be honest if it doesn't I will still be happy.

Its been a long project, maybe 5 months from idea to completion, and probably about 2 weeks works spread over the months. Worth the time and expense? You bet.
You do not have the required permissions to view the files attached to this post.
James


Fluted Afro LP12, Khan, KEEL, Karousel, Urika, Radikal (with Allium Skin Mods), EKOS SE/1, sKale, DVXX-2mkII
NAIM CD 5si with Marigo Lab Aida CD Mat
ThePre, ZAP 250, Kudos Super 20's
User avatar
Mr Onion
Site Moderator
Posts: 8455
Joined: Sun Feb 23, 2014 2:13 pm
Location: Between two Super 20's

Re: ThePre

Post by Mr Onion »

What did it Cost?


ThePre Case			£  190
Power Supply Case		£   90
Remote Control boards etc 	£  400
Transformer			£   90
Teddy Regs			£  130
Audio Quality cable etc		£  140
Plugs sockets and sunderies 	£  130

Total				£1,170

Add in what I already had

321/729 boards			£  300

Grand Total 			£1,470

Plus about 80 hours including Planning, Drilling, Construction and Bug Fixing


Suppliers

AliExpress Case
Neil James Improved NAIM 321 and 729 boards, plus the motherboard.
Teddy Pardo MiniTeddyRegs
HiFi Collective Remote Control, Z-Foils, other Audiophile Components
Canterbury Windings Bespoke Audiophile Transformers
CPC-Farnell Standard Transformer, DIN sockets and other components
Russ Andrews Audio Cable and Oak Cone Feet

Everything else from my 'odds and sods' box
James


Fluted Afro LP12, Khan, KEEL, Karousel, Urika, Radikal (with Allium Skin Mods), EKOS SE/1, sKale, DVXX-2mkII
NAIM CD 5si with Marigo Lab Aida CD Mat
ThePre, ZAP 250, Kudos Super 20's
User avatar
Coyote Jim
Site Moderator
Posts: 10786
Joined: Sun Feb 23, 2014 6:18 pm
Location: "In The Groove"

Re: ThePre

Post by Coyote Jim »

Image
Here's one for you James.
Very well done and I doff my cap.
This should be read a few times to fully appreciate.
Thank you for sharing we just need your address for a visit and audition now. :shock: 8) :smt023
Turntable - Linn LP12, Karousel, Keel, Ekos SE/1, Kandid, K-Radikal, Urika.
Amplifier - Naim Supernait 3
CD Player - Naim CD5si
Speakers - Kudos X3.
Cables - Linn Silvers & K200 Black.
Support - Target TT4.
HiFi Kabin : Disclaimer