WD PreII Model attenuator

[maccavelli87]

Hello, I have a WD Pre II Valve Preamplifier.

pic here . . . http://www.flickr.com/photos/96251808@N04/8812189528/

and here . . . http://www.flickr.com/photos/96251808@N04/8801402443/

can someone tell me the stepped attenuator 'pot' that was used.
Is it by Alps or someone similar? It seems to be a 23 step model.
thanks

[pre65]

It was not part of the original kit.

[John Caswell]

Looks like a homebrew to me

John

[Greg.]

It's certainly not Alps or anything connected with that make. The switch looks to me like a cheap option available on eBay from the Far East. The resistors could be by anyone but they may possibly be Phillips as sold by Maplin which although budget, do very well in this particular application. If it works for you in your Pre-amp, I'd stick with it unless you have issues that concern you. Probably it is very good albeit purists will challenge the quality of build and construction. If it works, don't be tempted to 'fix it'.

[bob orbell]

That looks to me to be the passive pre II, the top cover has no ventilation slots, but it came with a Alps pot.

[andrew ivimey]

I saw that on ebay and thought it very over priced. Even the knobs are cheap substitutes. If it works as it should its probably a nice passive attenuator (my passive uses transformers, my pre2 has gain) but imho we almost always can do with some more welly and impedance matching (exception is e.g. the original WAD300BPP), which I look for in a preamp.

This one will have started as an ordinary pre2 and the owner has made it into a passive for reasons of his own.

[maccavelli87]

Originally Posted by andrew ivimey

I saw that on ebay and thought it very over priced. Even the knobs are cheap substitutes. If it works as it should its probably a nice passive attenuator (my passive uses transformers, my pre2 has gain) but imho we almost always can do with some more welly and impedance matching (exception is e.g. the original WAD300BPP), which I look for in a preamp.

This one will have started as an ordinary pre2 and the owner has made it into a passive for reasons of his own.

ok thanks for the advice, so it has been modified then. Ok, so what do you think is it's worth. I paid somewhere in the region of £250 for it about 5 years ago.

[pre65]

It's only worth what an interested party is prepared to pay, but that's not really much help.

[Greg.]

I've looked at this again and think Bob has a valid point with the top cover being unslotted. That would indeed suggest it is an original WAD Pre II passive kit. Andrew is also right. The original heavy chrome plated brass knobs have been replaced with cheaper aluminium types. Also the tape/source switch looks different to what I thought was originally issued with this kit but I might be wrong on this. The 'Shark' signal cable is correct. Can you post a photo to also show the source switch and selector switch from the inside, please? Bob may be right in suggesting the Pre II passive came with an Alps pot, but I know early versions came with a stepped attenuator as you have. I don't recall that particular 23 position switch being included and there does seem to be a mix of resistors from different sources/manufacturer. Maybe. The original builder just purchased the chassis from WAD and fitted his own components of choice. Around the time, Nick Lucas wrote an article on building a stepped attenuator which was published in the Hi-Fi World DIY supplement which I believe was linked to your particular kit. I can forward you a copy if you PM me your email address.

As to what it's worth, that is difficult to assess and probably boils down to whatever the potential buyer is prepared to pay. Because of the number of signal wires going too and from it, it looks like it is the original series resistor attenuator build. Those who know realise better options are the shunt and ladder designs. Potential purchasers may want to buy it for the chassis parts alone, but otherwise, I doubt you will attract bids from knowledgable audiofools.

[davebms]

photos in the august 2001 (page 107) mag show exactly that pre with
that switch

dave