KEL84 V Stereo 20

[Richard]

Originally Posted by Phil Y

Has any one out there had a chance to compare a Leak stereo 20 to the KEL84?
If so how do they compare regards sound quality? I have been using a stereo 20 for years but i am starting to fancy somthing a bit better and also tidying up my lounge a bit. My pre amp is not very pretty and is just sockets, switches and a couple of cathode followers so i would not miss it. Any opinions welcome.

Hi Phil

I owned an ST20 for a couple of years and rebuilt it with good commercial components inc plastic film caps. It had very good sound and surprised everyone who heard it. However I did end up selling it as mine is a very "full range" system using CD and big speakers. This meant the ST20's lack of low bass in partic was noticeable and the treble a bit fizzy. This gave it a fast but mid-rangy quality - immediately easy and engaging, but ultimately lacking.

I've also had a completely standard KEL84 here for a while. I'd fixed it for someone and it checked through on the bench perfectly to spec (as did that ST20). The sound was quite different to the Leak. Less immediate but better balanced. Personally I found it a little bland but given a choice would have kept it compared with the Leak. Certainly a great amp for the money. Whether it's good enough for you will depend on your tastes and speakers/room etc. I'd get a listen to as many amps as possible.

Rich

[JerryT]

Originally Posted by petercom

At present the transformer is screwed directly to the steel chassis which locks the vibration into the complete amplifier. If the amplifier is placed on a resonant shelf, furniture or cupboard this vibration can resound and be objectionable.

We are looking at the best way of mounting the KEL84 transformer to reduce these, and other, effects and will come back with a mounting recommendation soon.

I've had good results with 1 inch high pressure tap washers for both mains (above the chassis) and chokes (necessarily below the chassis) - much more consistent than cork and the resulting air gap between the transformer and the chassis improves heat loss by convection into the bargain! Low pressure tap washers are too soft IMHO but I'm sure Paul B. will have an expert opinion.

Jerry

[Martin213]

Originally Posted by JerryT

I've had good results with 1 inch high pressure tap washers for both mains (above the chassis) and chokes (necessarily below the chassis) - much more consistent than cork and the resulting air gap between the transformer and the chassis improves heat loss by convection into the bargain! Low pressure tap washers are too soft IMHO but I'm sure Paul B. will have an expert opinion.

Jerry

They also make excellent decouplers between (some) 'speakers and stands
Paul,you'd better stock up mate

(was it hard or soft we used Paul?)

I used 2mm gasket paper (automotive use) under my mains TX and it made no difference at all.
Ill try some other materials and double check everything.
My hum seems to be coming from inside the transformer, not because its reverberating the chassis.
It also gets louder when the TX has warmed up.

[Martin213]

Originally Posted by graeme

I used 2mm gasket paper (automotive use) under my mains TX and it made no difference at all.
Ill try some other materials and double check everything.
My hum seems to be coming from inside the transformer, not because its reverberating the chassis.
It also gets louder when the TX has warmed up.

Graeme,
If you are having problems,please refer it back to Peter.Both you and he are innocent victims in this,i assure you he will remedy this promptly

Kindest Regards

Martin

[Greg.]

Originally Posted by petercom

At present the transformer is screwed directly to the steel chassis which locks the vibration into the complete amplifier. If the amplifier is placed on a resonant shelf, furniture or cupboard this vibration can resound and be objectionable.

This is an interesting point but I'd like a bit of clarification here. Please can we differentiate between electrical hum that is heard through the speakers and that which is heard at the amp itself owing to electrically induced mechanical vibration (buzz).

My interest is that in building my WAD 300B clone, I followed the original instructions for mains Tx mounting which was a direct metal mechanical fixing of the Tx to the chassis although fixing nuts are introduced at the base of the Tx and between the chassis top surface. This allows for ventalation gap to aid cooling.

When I first built my amp, I mounted it on a standard plastic covered chipboard equipment shelf which is the standard shelf of my Target equipment stand. This amp is heavy and it quickly started to bow out of shape, so I replaced it with a more rigid honey comb construction shelf similar to Russ Abbots 'Tortlyte' supplied by http://www.nightingaleaudio.co.uk/index.htm This certainly provided the support needed, but I noticed a significant increase in buzz from the mains Tx. I tightened up all my mounting bolts and there was certainly some clearance to be taken in, but it didn't eradicate the buzz and I continue to live with this now without worry because it doesn't spoil my listening.

In contrast, James who completed his clone amp recently and also recently posted a nice photo in the gallery, mounted his mains Tx on a purposely shaped and cut hard rubber gasket and he has no buzz problems with the amp mounted on a MDF shelf. He doesn't have any heat problems either, but that's probably down to the over specification of the Tx which was a quality feature of WAD kits in their best and early days of production.

What do you think?

Best wishes,

Greg

Originally Posted by Martin213

Graeme,
If you are having problems,please refer it back to Peter.Both you and he are innocent victims in this,i assure you he will remedy this promptly

Kindest Regards

Martin

I will take this up with peter, but only when im sure i cant sort it myself.
I will check all my earthings, just in case, and also try a few different mounting/clamping ideas.
If they all fail i will consult peter.
I will report about everything i try, on one thread or another, so others have the benefit of my experience.

[david counter]

to be fair to you Graeme, apart from checking the earths you have done more than can reasonably be expected to cure the hum,

please talk to Peter and allow him the oppertunity to comment and perhaps change the transformer,

Ok, ill e.mail him tomorrow.

[Phil Y]

Hello Rich, thanks for the comments about the sound of the two amps. This ties up with my thoughts on the stereo 20 although it is the treble end that bothers me more as my speakers are not huge (40 Litre bass reflex). I have come close to replacing my treble units(Scanspeek D2008) several times over the years in the hope of improvement. It sounds like i would have been barking up the wrong tree. The one thing that will cloud the issue a little when i try comparing the two amps is that i am building the KEL84 with the components supplied as i don't have the funds to do otherwise at the moment, but my Stereo 20 is fully decked out with high quality passive components. A mix of Holco H4 and tantalum film resistors, and a mix of paper in oil and polypropylene caps(Kimbercaps)
I suppose this does mean that if i like the KEL84, i will have even more to look forward to down the line.

Cheers, Phil.