bridging option for WD88

[mikew27]

How practical would it be to offer an option for WD88 single input design outputs to be bridged to increase output power & current & tolerance to low impedance speakers?

I have read that McIntosh's classic MC275 can be bridged from stereo to mono reducing minimum load capability to 2 Ohms mono from 4 Ohms stereo. (BTW is this because 2 output transformers are used to drive one load?)

Would this be of interest to any one else?
This might be an interim stopgap for monoblocks in the absence of a new WD design to replace the WAD300PP design.

[john & Jake the dog]

Hi I asked the following related question with no takers,


can valve amps be bridged in general, the kel84 in particular?
If so is there more than one method with valves?

any takers?

[mikew27]

Hello John & Jake the dog.

I just though this might be an easier way for WD to increase their appeal.

From your posts you have a lot more practical experience (ie >0) than I.
Hopefully if we post the question enough times maybe someone will get tired of seeing it & submit an answer

[david counter]

in theory anything is possible but how you would implement it I don't know, perhaps Dr.John will be along to answer it,

I don't know if people have noticed but some of our more vocal experts have left the forum, this I feel is in part due to people ignoring their advice and still asking the same questions,

it's a very sad day for our forum

[john & Jake the dog]

hi David,
I ask as I am trying to find cost effective ways of upgrading my system.
Bridging an 84 would mean buying another 84 for the other channel.
Then I could possibly power my isobariks.
Nothing lost if I bridge one and connect one up.
If it doesn't work then it would be WD25t's after I have sold the isobariks.

Don't quite know what you mean regarding people leaving because of previously answered questions, but new people to the hobby tend to ask the same questions this is where a decent forum search and Newbie Faq section comes in.

[david counter]

sorry John if it didn't make sense,
there was a time not so long ago when questions like this would have been answered very quickly, most of the experts seem to have left causing a bit of a vacuum,
I was just putting forward a thought as to why they had left the forum

[john & Jake the dog]

Hi David,
Being fairly new here I hadn't noticed the lack of answers really, just thought that my question must have been a stoopid one , I do that sometimes

[Mike G]

Hi All,

I too have noticed some members being quieter of late, who have previously been long standing supporters of WAD and WD, but would sugest that they are just hovering in the background (not lurking as has previously been mentioned), maybe reading but not replying. I'm almost certain they have not left the site, and if you were interested you can easily check when members last visited. No one is obliged to post so prehaps there are just no threads of interest to them at present.

With a little imagination It doesn't take much to track down alternative forums, and I for one know where some members are active, i'd join them myself, but the talk is mainly of scratch built projects at a level that is currently above my undersatnding! I currently log into at least three other BB's depending on the type of help or advice I'm looking for.

As a long standing member, but infrequent poster, the tone of some threads have certainly changed over the last few months. At one point it seemed it was "have a go at WD and their products" month, and maybe some of the advice was going unheeded!


I think this was just a misunderstanding by some members, maybe new to kit building and with rather different expectations.

I'm still not sure a Newbies room is required, we have never needed one before, and this creates yet another area to be searched out for threads. My personal feeling is that newbies questions are more likely to go unoticed, if placed there. Put them in the main forum, and they will certainly be more visable.

The FAQ section has existed for a very long time, and is often added to, so maybe checking it once in a while for updates maybe worthwhile.

I feel Peter has answered all threads sufficiently. We are now approaching peak holiday time - it maybe some people are actually having a break from their PC's!

Anyway - just my opinion - we are all entitled to them!

Mike.

[Phil Y]

Hello Mike & John,
I will just start by saying i stand to be corrected on any of what follows. My understanding of bridging is that you phase invert one channel and then hang the speaker between the 2 positive speaker outputs so you get a kind of push pull effect so increased power. I had the thought of doing this years ago with my pair of Stereo 20s but when i sat and had a think about it i decided it is not easily possible. This is because if you invert one signal at the input all you have done is connect one input to ground because of the way the amps are built(ie non balanced) and the same is true at the output because again you have +ve and ground not +ve and -ve outputs. I think you would need an amp with balanced in and out to avoid this. It might be possible to do something around the phase splitter but with the KEL84 being built on a pcb this would be a lot of hassle. John, i know you want to use your your Linn's but speakers really have come a long way in the last 20 years. Have you given any good largish modern speakers a listen with the '84. If you have, i apologise but if not i would give it a go. You won't find anything that sounds exactly like the Linn's, but if you give your ears a chance to adjust you might be pleasantly suprised. Again if you have been through that process and have come back to the Linn's i apologise.

I hope the technical bit helps, all the best, Phil.

[Shian7]

Hi Phil,

John has heard my speakers briefly which are quite substantial chunks of wood with differentially tuned twin quarter wave pipes but only half the complement of drivers compared to the Isobarik's, I think he quite liked them though.

John, you are more than welcome to an extended listening!

He also borrowed my '88' for a few days to try with his briks and was pleased with the results, I think (see WD88 and Isobarik thread). Although I've known several people who've owned Isobariks I've never actually had a listen myself so can't comment on the comparison.
From what I understand they are quite 'current hungry' buggers what with having six drivers each, two of which are Kef B139's!!!

Cheers,
Mike.