WD/WAD HD83 Mk2

[Pingushome]

Hi ,
So after the kind help from snowman al and Bob, thanks to you both, the Maplin mains filter being built and I’ve now got the bug again!
I was thinking my hd83 could do with a brush up. There’s a very small in balance between channels and a slight russell when music is very quiet. Neither is enough to need a checkout really but I inherited it form a friend and it’s getting a bit long in the tooth now I think.
So I was thinking new caps/better, bigger psu caps, different diodes, and some Mills resistors for the bigger ones, check replace other resistors. Probably a pair of new valves too.
Or should I just go for the XL upgrade from Matthew?
Alternately I could go for the 3S pcb and upgrade it to a 3S. That was on the cards a while ago but then didn’t think, and still don’t think, I’d need the impedance matching anyway.
I’d be interested to know what others have done to their amps and the results. Any suggestions or thoughts on parts, makes, values would be gratefully received
Thanks
Martin

[BOONDI]

Itchy fingers.....

A good upgrade to psu caps is to simply replace with higher voltage lower esr. I used 450v rubicons. Also coupling caps replaced with high quality polypropylene types of same value. As for resistors, you could try foils in the signal paths. As for valves, Watford valves have stumbled onto a limited stock of Amprex Ecl83's but they cost a bit more than the mullard types. For the diodes, some on here will no doubt have recommendations for their own particular silent ultra fast super dooper favourites.....

[bob orbell]

Agree with Boondi on the power supply, Nichicon do some very good, very low ESR capacitors with which you can hear the change, they also do some very high price ones, Nick Lucas has then at Hi-Fi Collective, make sure you are sitting down though when you look at the price. Wima MKP10 coupling capacitors are also very good. Bob

[Pingushome]

Thank you both for your advice I’ve had the amp apart and after a critical look and remembering g what a pain it was soldering all those pin connections I’ve decided that discretion is the better part……..until the hum gets worse.
So it’s a change of valves for now, having just broken one.

I’ll try those Amprex, Boondi as you say only a couple of quid extra

Bob, yes always amusing looking at Hifi collective, deep pockets a must.

Thanks again for the advice I think a “conservative” upgrade when it becomes unavoidable

Martin

[A.N. Beal]

Dear Martin,
I can suggest two methods for hunting dry joints in case these are contributing to your 'rustling' and hum noises.
1. With the amplifier on and connected to loudspeakers, poke connections with a plastic chopstick and if any make crackling noises resolder them.
2. Examine connections with a bright torch and magnifying glass and resolder any which look less than perfect.
Regards,
Alasdair

[BOONDI]

I bought some of the amprex. Only a few hours listening with my cheaper sony phones, but sound as good as the mullards already. My reference denon phones are still in the boxes from my house move about 8 yrs ago.

As per Bob's suggestion, the mkp wima 10 caps are a good cheap option. I used them extensively in my homebuilt phono and in my Heathkit monoblock rebuild. Am considering using them again when i rebuild some of the other junk I have lying in boxes....

The ones on the WD site the sax are also a good cap. I tried some ruskie pio as couplers, they sound lovely and warm and with excellent clarity but I suspect that like all pio they will eventually turn leaky electrically. I will eventually put mkp back in so as to avoid red anodes of death.

Take your time, get the circuit and stare it down, make a list of things to replace and when you are ready, get the iron on....