Ii modded my WDKT88 and am very satified

[Equalizer]

Excuse the title error.
I've been after one of these kits since 5th Dec 2009 since before Matthew Snell took over. I was absolutely priviliged with the way I was able to be supplied with the kit and all building advice. He was also a great supporter of the amp so far as fault diagnostics were to be put to right.

First of all, the kit and instructions were a straight forward build. Some of the modifications involved bringing this amp to a specification of forgive me for swearing AudioNote specification and yes I think this amp would achieve a comparison for the KT88 valve version but with a nicer looking chassis.

I used silver hook up wire Teflon sheathed for the XL version. Blackgate std signal valves for the signal board. Clarity caps as standard. CMC silver binding posts and audio note RCAs. 1.5m silver speaker wire for the output transformers to the speaker posts.

Please remember not to use flux on the tag boards. I found voltages arcing between tags because of the acid in the flux. No problem, Matthew kindly gave me spare schottky diodes.

The Amp sounds absolutely shocking with realism from Lowther Fidelio speakers (PM7A). I am running New old stock RCA 5751 in place of the ECC83 and 3-D imaging forward of the speaker is so enjoyable. I have found that kiwame resistors to me sound best on the driver boards and tantalums were they can be found and the same for the rest of the boards. I did try metal film but the bass quality is more defined with the kiwames at such an affordable price.
Previous speaker drivers were Fostex FE206 En and although they did not have a balanced sound, God did they have bass.

I listen to all sorts of music and piano is really hard to get right. Scriabin sounds so well put together that instead of feeling like I should feel a special atmosphere of the piano in front of me I feel as though I would feel if it were there in front of me without a mimic of the what I should prefer it to sound like. This is real.

I heard it not to drive down the ears as push pull valve listeners claims but articulate with detail that I have not heard from previously. The ultra linear is good.

I am using a Mdac burnt in as source from a 8000cd player as transport.

Prodigy sounds like I have never been able to comprehend with detail I only beg to crave to hear more for from this band and this amplifier does it. conjuring up images in front of me that make me feel I needed to hear it this way for the first time.


My HD3S SET has Black gate N types for the heaters and Stds for the Grids and tantalums throughout and it would have to be played very quietly to achieve the sound of the KT88 at any volume level. The KT88 is nicely held in Class A stage amplification.

The supply is a balanced conditioned power supply from Air link transformers and I beg you to make the changes for kiwames and tants and silver and add one of these power supplys' which will give you the midrange you will perceive and get the **** out of the mains. The amp is good but the improvement is not subtle. The amp is still stunning without the power supply.

Svets or NOS GECs - smiling with either tube. Svets are a fifth of the price.

Finally I incorporated a 'top switch' which I fell in love with as pure satisfaction for my baby. It switches on the secondary windings of the supply transformer after warming the output valves and works a treat. The switch cost £2.50 and is mounted about 1/2cm from the edge of the IEC socket carefully wired.

The Svets and GECs should last the next 10yrs and I would not change this amp for the world.

I can replace the cathode resistors for 57 pence for a pack of 5 resistors should a output valve go and the screen grids are four standard 100 ohm metal films as supplied in the kit. Nothing fancy and just there to protect the supply transformer in any event so maintenance is economic . I'm very happy with it.

Thank you Matthew who was able to spot my ultralinear taps on the output transformers.

The amp is the single input version by the way but I have direct source form the dac.
Schottky diodes make sense for zero switching times and similar as I have read form valve rectifier but I would definitely recommend the air link transformers Balanced conditioned power supply for these schottkys.

Im not interested in any other amp now considering what you can simply put under the chassis of one of these WDKT88 amplifiers. Why pay stupid money.

[justin brown]

Just noticed this post - I have been busy of late. Thank you for your detailed synopsis. My WAD 300bpp stereo is still unmodded, so this certainly gives me something to think about. Although I built the phono3sxl at Christmas, I am still a newbie to this interesting hobby and I get quite frustrated at times as I simply don't have the time (at this stage in my life) to learn. Never mind... One day I'll be able to commit...

[Equalizer]

I have never heard but would always like to hear a 300B amplifier.
I have heard they have bass of depth.
The KT88 draw me to this amplifier from a hybrid design by Radford.
By supping the WDKT88 there is a benefit this really gets close to the music with overall transparency.
I would say that modifications such as shottky rectification is close to a valve rectifier but I have not heard.
Carbon composites in the power supply offer enough if what is needed for the PS circuit part. I wouldn't use any other type.
In the signal path descent capacitors will provide a better bass response. Having said the I used decent caps in the heater of the HD3s and bass was night and day. It became effortless.

If I was going to use other caps such as Elma Silmic capacitors in the signal which offer a warm and nearly as deep presentation to blackgate capacitors then I would have to do something like have valve rectification or very fast switching diodes to give a very clearer presentation and provides accurate bass. Also meaty driver valve would also be mandatory over something like a GE type in my view with a transparent signal tube like a Sylvania.

Polypropylene caps with quality carbon comps give a fun factor with music synergy which allows the music to be almost there for not much money. I remember when I put polypropylene suppression capacitors in my HD3S. A heavier presentation for some preferred types of music.

For resistor values that I could not find off the shelf I visited http://www.sengpielaudio.com/calculator-paralresist.htm
and scrolling down to the bottom of the page I found how to make my value.
Working out your resistor values using your desired resistor value can simply be done by offering the resistors to be put in parallel for your resistor upgrade at the resistor lead out connections. In this case run the two resistor in parallel together.

I did this to the anode output of the WDKT88 ecc83 on the signal board which feeds the driver boards and the results are cleaner with two tantalum in parallel.
I also did this to get a 750 ohm value for the grid of the ECL83 of my HD3S.

This might require putting the speakers back closer to the wall if one finds there to be clarity which upsets the balance but this mod really grew on me.

I even removed the Airlink transformer power supply and did the suppression filter modification on both the HD3S and WDKT88 which works fine.

I sold the highly transparent MDac but I had this originally with a kiwame carbon composite for the ecc83 anode output resistor and the result worked. More accurate was this sound.

I might try blending the 500k using kiwame in parallel with 390k tantalum in parallel of the anode resistor off the ecc83 on the signal board and see if it offers the benefits of a bit of warmth to the sound or if I prefer the refinement, and that if I don't feel I prefer this then it would be necessary to keep the original tantalum resistors in place.

I told Matthew Snell I wasn't going to part with my amp and I am not. I told him the that I would sell my Headphone amp and even bought a new facia for the HD3S. I wont. I find myself with the headphone amp now and in the future the amp will come out once again.