Quad II KT88 overheating?
Gino
much hotter on my KT88 amplifier than on my KT66. It's almost too hot
to touch whereas the KT66 I can touch with no problem because it's
merely warm. Is this normal or is it dangerous? I've just picked these
up 2nd hand from someone who's had them lying around for the past 15
years.
What is the difference between these 2 amps?
F. Gagliano, A. Walker
down when using the '66's. They're made for '66's, so using the heavier
duty 88's may well be your problem.
Allen Walker
Mike Coatham
transformer failure is guaranteed - but don't take my word for it - you'll
find out soon enough .
Why would you want to use KT88's in a Quad II anyway??
Mats Wiklander
It's perhaps the re-issue of the Quad II named Quad II-Forty. That one
uses KT88s instead of KT66s. Anyway it was just a thought.
--
Cheers,
Mats Wiklander
Society Of High Tension Audio
velve...@nospam.yahoo.com (remove nospam for replies)
http://www.geocities.com/velvetlogic
Russ Sadd
Gino,
Remove those KT88s from your other Quad II *NOW*! Quad never manufactured a
Quad II with KT88s. The Quad II is meant to take KT66s or 6L6s. The previous
owner has clearly made a terrible mistake and put in the wrong valves!
This would mean that your Quad II was suddenly having to furnish more heater
current and anode current, which is why the transformers are overheating so
noticeably. This is not normal, and yes, this is potentially dangerous. If
you carry on running these like this, you will sooner or later burn out the
transformers.
There is, funnily enough, a "Quad II-40" that came out in 1999 and uses
KT88s, but it is a 40W amplifier and much, much larger and heavier than a
Quad II. And yes, its transformers and power supply are correspondingly
larger.
Best regards,
Russ Sadd
Birmingham, UK
E-mail: gri...@dircon.co.uk
WWW: http://www.griffon.dircon.co.uk
JukinGeo
cases are most likely either the power or output transformers, if they are
getting too hot to touch discontinue the use of the amplifier. Compare it
to the other one you have, if they are identical, then someone put the wrong
output tubes in the amplfier. The KT88 has a much higher loading on the
transformer, and most surely will blow it up if contiued to be used with the
KT88's. If the amps are identical (and only after an internal
inspectioni), Take the KT88's out and take the KT66's from your other amp
and put them in this amp, make sure you bias the amp properly if need be and
run it for a while. If the problem disappears, then you know what you have
to do.
Geo
Gino
for the advice guys. Anybody want to buy or exchange 2 x GEC KT88s, I need 2 x
KT66.
Gino Ricci
gino_...@hotmail.com
Gino
Gino
Wesres
Quad II electolytics are reliable. If both amplifiers exhibit the same
overheating it is unlikely that both amps have the same problem. This also
goes for GZ32 troubles. The most likely trouble is the use of KT88's in place
of KT66's. Filament draw of KT88's tend to be higher than the '66s. Also, the
88s will require a cathode bias resister of a higher value than the 180 ohms
required by the 66s. The point is that the 88s are drawing much more current
than the 66s causing the small case (the filter choke) and the medium sized
case (output transformer) to run much hotter than normal. I strongly recommend
finding KT66s to replace the KT88s in the Quad II.
Best regards,
Terry
Western Reserve Audio, Inc
Cleveland
PS also check that the mains voltage selectors are set properly.
Simo Paakkanen
"Gino" <g...@g.com> wrote in message news:388B74BE...@g.com...
> What does bias the amp mean?
AFAIK, Quad II's don't have any adjustments for bias. At least I can't find
any on mine.. ;-) Anyone know any better?
// Simo Paakkanen
(pr...@saunalahti.NOSPAM.fi)
Mike Coatham
KT66's and leave the amp to do what it does best - reproduce music
accurately.
Vismetro
current of the KT66 the power trans. will overheat and toast. The additional
power of the KT88 can also toast the output trans. CHANGE THE TUBES BACK TO
KT66, 5881 OR 6L6s !
Yves
>
> The 2 metal rectangular cases near the valves on my Quad II is getting
> much hotter on my KT88 amplifier than on my KT66. It's almost too hot
> to touch whereas the KT66 I can touch with no problem because it's
> merely warm. Is this normal or is it dangerous? I've just picked these
> up 2nd hand from someone who's had them lying around for the past 15
> years.
> What is the difference between these 2 amps?
Hi Gino.
Change the KT88 NOW...the Mod II is not designed for them.
Use 6L6 (not metal tubes) or KT66.
To answer your question, YES it is dangerous, you might burn your
supply transformer...and the price is ouch!!!.
Hope this helps
--
Yves
Remove the to reply
Personnel
Quad tube preamp (QCII) mono, and Quad tube tuner (AM) both in working
condition. Reasonably clean looking, ie: minor scratches. No rust.
$150 u.s.d. each unit + shipping.
Sylvain Giguere
page...@quebectel.com
Personnel
good transfos and reasonable price. I live near Quebec, Canada.
Sylvain Giguere
page...@quebectel.com
retr...@bigpond.com
Gino <g...@g.com> wrote:
> I have put in the KT66s from the other amp and it no longer overheats!
Thanks
> for the advice guys. Anybody want to buy or exchange 2 x GEC KT88s, I
need 2 x
> KT66.
>
I can supply New Old Stock GEC KT66 at A$125 each (about US$80). For
details see http://www.users.bigpond.com/retrovox/geckt66.html
--
David Crittle
retr...@bigpond.com
http://www.users.bigpond.com/retrovox
*******************
Sent via Deja.com http://www.deja.com/
Before you buy.