PSU3 and Phono3 build

[FreddieT]

I have now completed the build of the Phono3 and a PSU and thought there may be some interest in my experiences. Matthew told me that I was the guinea pig for the newly revised and printed instructions to add to the fun. The finished units don't look homebuilt (unlike my passive pre!) and I haven't had adverse comments about appearance.

As I have a sensitive power amp (K5881 MkII) I asked John prior to purchase about compatibility with the Phono3. As a result, the unit shipped with 5751s in place of the ECC83s giving a 2dB gain reduction.

PSU

This was very straightforward with no issues in the build. The only minor niggle is the necessity to scrape the paint off the lid & chassis to earth the lid. The area around the binding post on the chassis has been masked prior to painting and you get a nice metal surface with no scraping. It took me a little over 3 hours including checking & testing to build; which demonstrates the instructions are easy to follow.

Phono3

A little less straightforward. The major gripe is the pitch of the holes on the PCB for the carbon film resistors is too small, leading to lots of careful wire bending under the body of the resistor. The holes for the cartride load resistors need to be a little larger to accomodate pins if you are going to change the loading (as I did). The pitch was too large for one of the capacitors as well. The chassis lid interface paint was again an issue. That said, this is a great kit and there are no major problems and the instructions are clear and easy to follow.

Testing

It worked on switch on and sounded OK cold. Always a good start!
Most of the voltages were low on test when compared with the -15% figure of the nominal figures expected. I spoke with John and we concluded that this was due to the 5751. I confirmed this by swapping the input valves for ECC83s (left over from another project) and they then came in spot on. The increased gain isn't as much of an issue - the Troika (remember those?) is very low output so the extra gain doesn't cramp up the volume control in my passive pre. John also pointed me at details for an inverse RIAA network (Google 'reverse riaa network Hagerman') which allowed me to tweak the trimmers to get the best square wave.

Listening

With the 5751s and 47k cartridge load (100 ohms seen by the cartridge) the Phono3 sounds detailed & lively with an excellent stereo image - something I wasn't used to having had Naim kit! I have heard things in the mix that I never knew was on the record, after 30 years it was a shock. With some LPs it was a little hard at the top end, but on some sounded great. Well chuffed even before running in. To tame things I have changed the cartridge load to give 400 ohms seen by the cartridge; close to the Linn recommended load. This has tamed things a tad; and is more listenable on bright discs. However, it may have robbed some detail I feel. I might go somewhere in between. I have also swapped the valves for ECC83s (leaving a single 5751 as the cathode follower) as mentioned previously; but I may go back to all 5751s when I have settled the load issue. Depends what sounds right.

Summary

Great kits, great value. They are easier to construct than the K5881 was in the 1990s and I look forward to a forthcoming 300B power amp just because the valve looks proper! Serously, WD deserves to do well with these kits. Thanks for keeping the company going.

[bob orbell]

Glad to here your phono3 is working good, yes I know what you mean about the pitch for the resistors but it dose keep them away from the PCB. I have tried many diffrent valves in my phono after reading the imfo. in the FAQ, tweek's and found the same as you 5751's too bright, so I now use 7025 Philips in the gain stage and sovtek 5751 in the output, very nice by way I use a cathode follower in a Pre 3 case because I too need no gain, I find this way better than a passive, mind you, it's horses for corses. BOB

[FreddieT]

Bob,

Thanks for the reply. Are you using a shunt volume control with your cathode follower pre to help with the (too much) gain issue in your set up? I'm using a conventional potentiometer set up which is OK with the Phono3. However, the DAC (I'm using a Naim NV-I [don't ask but it is temporary] at present whilst contemplating a Rega DAC) is consigned to only the first 45 degrees of travel on the pot.

I was wondering how a shunt arrangement would sound especially if buffered. Is your cathode follower similar to the old WAD pre amp design?

F

[bob orbell]

Hello FreddieT, I run my CF pre with a WD WA88 and a WAD KAT 6550 , the former drives the bass/mid and the latter drives the tweeter's. No I do not use the shunt pot mod as this would not give enough gain, a CF gives about .97% gain, so at full volume from CD I have about 2volts at the power amps. Normal listing is with the volume control at half way. I used a pre2 PCB to mount all the components on and added a remote volume all in a pre3 case, I will try and post some pictures, if I can fathem out how to do it. BOB

[FreddieT]

Bob,

Understood - I'd be interested in the pictures if you can figure out how to post them! I'm planning including remote control to my passive (motor driven Alps) and also input select & mute. I shall be sure to leave enough room for a CF for later experiments.

I don't suppose Matthew has any stock of the Pre2 PCBs; it does seem to be a neat solution?

F

[Matthew Snell]

Nope. Can't help you on that. Soz,

Matthew

[bob orbell]

001.jpg Here is my pre with CF and remote volume.BOB

[Greg.]

Hi Bob,

Wow, that's a very interesting application of CF on (I think) the Pre II PCB. Am I right on that?

As you know, not needing gain but certainly needing sparkle in the music, like you I use Pre II converted to CF to feed my Original C1995 WAD 300B PP clone. Initially I did the conversion using the Pre II PCB as recorded here in the FAQ section. Being totally satisfied with the result, I converted to a hardwire version with boutique components and some other alterations to the controls.

Personally I'm not interested in the remote volume control, but I admire the way you've fitted it all into the chassis in a professional and tidy manner. It looks great!

This is mine.




Regards,

Greg

[bob orbell]

Hi Greg, kind words indeed, yes it is a pre2 board with all componets on the board and copper wire links on the under side, originally it was a pre2, but it always sounded thin and lacking bass and far too much gain, so I converted to CF as in the FAQ, latter on I acquired a pre3 case and two more pre2 boards added the remote and the rest is history. It gives a very nice sound with bag's of bass too, better I think than the pre3 which is a tad to bright for me. Look's like your's is in a 2 case and have you hard wired the signal leads direct?. BOB

[Greg.]

Hi Bob,

yep, all interconnects are hardwired in with a couple of auxillary phono inputs as standard for versatility. I use IPL Acoustic IC2 interconnect which I've been happy with for years. Other hook up between switches is IPL Acoustic IC1. The tape toggle switch has been replaced with a two position rotary to facilitate the switches set at the rear of the chassis. The selector switch is Elma. The Alps blue has been shunted with Riken resistors. The capacitors are TNT DynamiCap and resistors Kiwame apart from the signal resistor which is Vishay bulk foil. It sounds far better than the original Pre II and performs better than Pre III IMHO. Others have converted after listening as a result

Regards,

Greg