KEL84 Monoblock

[Paul Welsby]

If this is a really stupid idea then please just say "paul your an idiot" and i will shut up.

But i was thinking of trying to utilise my KEL84 in some way and make a pair of monoblock amps.

Now would it be feasable to have the power supply in one box and the two seperate channels in the two blocks? Fed power by an umbilical.

I would then not have to buy any new iron work.


OR is it possible to buy another KEL84 (now that thats almost possible) and alter the layout to make it a monoblock per "amp". (i hope that makes sense)

Thanks for any info

Paul

[NealG]

What secondary taps does the '84 have?

If suitable buy another and bridge the channels on both to monoblock (I do this with my 300B's). You'll need to adjust feedback components though.

Or just buy another and bi-wire to your 'speakers, IE you then have a mono amp per driver. You can experiment with one amp driving Bass / Mid, the other treble or one amp chassis / 'speaker.

[Paul Welsby]

Im just about to go with a single driver full range design.....

[Mike G]

Hi Paul,

I'm sure Neville Roberts wrote an article about KEL84 amps some while ago, I can't remember if it was to use two as mono blocks, or whether he Bi-amped them. I'm sure whatever he did, the results were pleasing.

Since building my Pre11 / KAT6550, my Kel84 has gathered dust. I'm now thinking of purchasing a second one and Bi-amping. I'll follow this thread with interest. Let us know how you get on.

I'll try and find the article and report back!

Mike.

[Mike G]

Hi,

Have only managed to find a small article about converting a KEL84 into a power amp. The writer (Neville??) manage to obtain two KEL84 kits with blank front plates from WAD. The article also states R2/R3 was changed from 1m to 100k.

I've also seen on the old WAD BB, the FAQ about Bi-amping with amps of different sensitivity and gain. With my KEL84 gathering dust, since my KAT6550 was completed about two years ago, it's kind of got me thinking!!!

Anyone here Bi- amped with a KAT6550 and KEL84?? - Or is it really not worth it?

Mike.

[Paul Welsby]

Would i be right in thinking that one of ECF80's wouldnt be needed as you would only be splitting one channel?

Paul

[andrew ivimey]

Paul, sorry to put my damper in things but ...

KEL84 is difficult to do much messing about with because of the PCB.

Using two and bi-amping is about the best solution but on the other hand if you are going single driver speakers you don't need loads of power (unless ... what kind of single drivers do you have in mind?!) and anyway then you don't need to bi-amp.

If you built a huge and beefy pSU in one box and split the power rails in a
KEL84, I wonder, you may get improved sound but I doubt it would be worth the effort.

....................

Ditch push pull and go single ended. That is a worthwhile upgrade.

[Paul Welsby]

To be honest i didnt think this was going to be a runner. I was waiting for the "not worth the effect" post.

Think i will go back to my idea of starting to build Triode Dicks Little Ceaser this summer.


Paul

[Gerry]

Interesting.
On Sunday at the Phono shoot-out we plugged in Adrian's KEL84 to the Maggies....most of the amps struggled (300, 845) a bit, but Adrian's did a great job. I was amazed...so was Nick G and others.
It had a lovely sound...amazing considering the output and it was on an 8 ohmm tap.
The questioning of mono-blocking/bridging came up. It is something I would like to investigate. Nick felt the feedback might be a problem...but...maybe possible.
I'm afriad I'm too much of a novice for the calcuations etc. But would love to try!
Needless to say Nicks 211 was sounding damm good by the end of the day driving the Maggies....lots of playing around....but worth it! (Moving the TT had a dramatic effect!)
Regards

[Paul Welsby]

Originally Posted by Gerry

Interesting.
On Sunday at the Phono shoot-out we plugged in Adrian's KEL84 to the Maggies....most of the amps struggled (300, 845) a bit, but Adrian's did a great job. I was amazed...so was Nick G and others.
It had a lovely sound...amazing considering the output and it was on an 8 ohmm tap.
The questioning of mono-blocking/bridging came up. It is something I would like to investigate. Nick felt the feedback might be a problem...but...maybe possible.
I'm afriad I'm too much of a novice for the calcuations etc. But would love to try!
Needless to say Nicks 211 was sounding damm good by the end of the day driving the Maggies....lots of playing around....but worth it! (Moving the TT had a dramatic effect!)
Regards

As i have stated before i havent heard any other valve amps apart from my modded KEL84. But it does astound me that whenever all these amps are grouped together there always seems to be very nice words, and astonishment for how good the little EL84 sounds.

This was one of the reasons i thought about trying to extract every last inch of detail out of mine (by going all guns and mono blocking with expensive output transformers etc etc). i like the idea of turning up to meets (somethng i do plan to do but work makes it hard) with a percieved turnip and proving its a real jewel.

"The EL84 knocked the sox off the 300B's" is a line im looking forward to being wrote in the near future....

Paul

(however i decided this was probably above my level of ability so im saving up for the new WD 300B(£105 in the pot so far!))