Difference Between 6550 & KT 88
Mr. Anderson
Can anyone tell me what the difference is between the 6550 & KT 88 tubes.
I understand that the KT88 is more powerful. Does either tube sound better?
My amps came with the 6550 type tubes and I am looking to re-tube them.
They are SFI mono blocks and take 16 tubes, so its a little costly. I also,
heard the the Tube Art from China is very good and sounds like the old
Genelex tubes. Any recommendations would be great.
Thanks in advance
M
Patrick Turner
"Mr. Anderson" wrote:
The original KT88 and 6550 had differances, and the data which exists
tells you what these are, but many old amps can use either, without
rebiasing or changeing the loads of B+.
But today, the differences are blurred.
I recently tested samples of Sovtek KT88, and EH6550,
and the electronic character was identical.
The Sovtek KT88 probably isn't as visually impressive as the original
GEC type, but it does the job.
Meanwhile, the EH brand of 6550 tries to make the glass and lettering
look as spectacular as the original version, and the name Electro Harmonix
probably appeals to buyers more than "Sovtek", which has the identity
which sounds more lowly.
Meanwhile the guts of either tube is identical, and the price is similar.
ARC use the EH6550.
I re-biased one recently.
New Sensor Corp offer a reasonable price and if you buy 50 pcs,
the price is very nice, and maybe you can sell
the balance on to others.
The sound difference between output tubes is hard to pin down,
and varies from user to user.
I think the tube loading, amount of NFB, and the total
circuit design including the driver stage is just as important as the brand
of the output tubes. It would have to be, surely?
Then the preamp also affects the sound.
Patrick Turner.
Ken Gilbert
> Can anyone tell me what the difference is between the 6550 & KT 88 tubes.
> I understand that the KT88 is more powerful. Does either tube sound better?
hey m.
no tube is more or less powerful than another. what's different is
the power dissipation each is capable of. let's use a nice handy
water analogy.
ok. the power supply is akin to the pipes that supply some ammount of
water (ie the current) at some degree of pressure (voltage) to your
house. the tube is like the faucet, or valve, as those smarmy brits
like to call 'em. :) so anyway, if you've got say a fire hydrant in
your house, you need a big ass valve to control that high pressure,
and to open up wide enough to allow a sufficient amount of water
through. on the other hand, if you've just got a little plant mister,
you neither need nor want high volume high pressure water coming out..
so you use small diameter tubing which feeds into a little valve.
now, you can't expect to have a 1/4 inch diameter copper tube, running
into a fire hydrant, supply all the flow and pressure you need. nor
would you expect a small valve to contend with the high pressures of a
fire hydrant output. so you size the valve to the demands of the
water circuit.
it's the same way with tubes. you can put a big ass valve where a
small one used to be, but you probably will NOT make more power out of
your amp. why? well, the power supply has been designed to make just
enough current and voltage to get the job done. more than that would
have made the amp more costly than it needed to be, and the bean
counters don't like that. so it's just sufficient.
having said all that, YES, in an amp designed to MAKE more power
output from a kt88 vs a 6550 you WILL get more power output. the
capability is there in terms of the valve handling more power, but it
doesn't necessarily mean that the power supply (the water works
leading up to your faucet) will be able to supply it.
plus, in our analogy we also have to contend with the output
transformer, which is designed to take just a certain amount of power,
and no more (at least with fidelity). you can think of this as the
hose connected downstream of your valve/faucet. you can't get 1000
gallons per minute out of a garden hose, no matter how hard you try.
in the same way the output tranny will limit your max power for a
given amount of distortion.
now as far as sound quality, i can't really comment. just know that
there are very very few "bad tubes" that cannot be made to sound
good.. if the circuit is there to exploit their strengths and cater to
their weaknesses. your best bet is to listen to someone else who has
direct experience with an amp just like yours.
hth
ken gilbert
Rod Keys
working and sounds okay don't go to the expense of new tubes. Spending the $$$
elsewhere, like speaker upgrades or something which will make a much more
noticeable difference in sound.
The differences between 6550's and KT-88's are small and I think you're right,
the KT-88 has a slightly higher power dissipation rating. That said, putting
KT-88's in an amp designed for 6550's will not increase the amp's power. It's
not like replacing a 75 watt light bulb with a 100. It's the other way around.
The rest of the amp supplies and puts limits the available power. In most
cases, if the mismatch between tube and the design of the amp is great, the
power output will actually go down (because of issues like transformer
saturation and power supply overload etc.) Putting an extra large shirt on will
not make your chest bigger and if it's way to big it gets in the way of
everything
Sound differences between tubes is splitting hairs. By the time you set the amp
up for the new tubes (by adjusting bias etc.) you'll probably make more
differences in the amp's sound than you could ever hear from the tubes proper.
When you hear people say they like the sound of this tube over it usually means
their amp is set up better for one than the other.
I say skip the project unless the tubes are bad, then replace with as close to
original as you can find.
Rod
B Stewart
KT-88's (from Kevin Deal), and it made all the difference in the world. i
find the 6550 tends to be, perhaps, just a little grainy. the KT-88's are
smooth, powerful, and far more liquid. they actually sound like tubes! ;-)
"Mr. Anderson" <vandalayi...@hotmail.com> wrote in message
news:arsl4v$4vu$1...@slb3.atl.mindspring.net...
>
>
Jim McShane
> i replaced the 6550's in my Sonic Frontiers Power 2 amp
> with Svetlana KT-88's (from Kevin Deal), and it made all
> the difference in the world. i find the 6550 tends to be,
> perhaps, just a little grainy. the KT-88's are smooth,
> powerful, and far more liquid. they actually sound like
> tubes! ;-)
Compared to Svetlana KT-88s almost anything will sound a
bit hotter (harsher). The KT-88 Svets are VERY tubey, the
rolled off top end gives them a "warm" sound, and the soft
tubby bass is also present. This is (unfortunately IMHO)
what people think tubes are supposed to sound like. YMMV,
as each system differs in character. In Mr. Stewart's system
they may be just what he's looking for!
I actually find in MOST applications the Svet 6550C is
a better tube. And I believe the ultimate 6550/KT-88 type
is (of course) the Ei KT-90. But it sure doesn't sound
ANYTHING like a Svetlana KT-88.
BTW, I have 3 Svetlanas on my site for $22.00 ea. Brand new,
genuine, original boxes, the whole schmear.
Jim McShane
Need Tubes? Got a H-K Citation (Pre) Amp?
Check http://pages.prodigy.net/jimmcshane
Repro knobs for Citation gear in stock!
Mark Pearson
Hey!!!!!! Your picking on a tube that I happen to like. Didn't McIntosh
pick the Svetlana KT-88 to install in their reissue amps? Didn't I read
somewhere that Mcintosh said the Svetlana KT-88 measured better than any
output tube they had seen in over 20 years? I really don't find the Svet
KT-88s to be tubby in the bass or soft in the highs in the two amps that I
have used them in (my home brew Dyna MK III type amps and my ARC D70 MKII).
I have a quad of used type III KT-90s I bought from Kevin Deal and I will
gladly trade them to you for a used quad of 6550 tubes that you think sound
better than Svetlana KT-88s. I will even throw in some NOS 12BY7 tubes for
your Citations.
Mark
"Jim McShane" <jimmc...@prodigy.net> wrote in message
news:qQ4F9.745$3n.52...@newssvr15.news.prodigy.com...
Jim McShane
> Your picking on a tube that I happen to like. Didn't McIntosh
> pick the Svetlana KT-88 to install in their reissue amps?
I don't know..
> Didn't I read somewhere that Mcintosh said the Svetlana KT-88
> measured better than any output tube they had seen in over 20 years?
It may have been, since the only other KT-88 in production at
the time was Chinese!
> I really don't find the Svet KT-88s to be tubby in the bass or soft in
> the highs in the two amps that I have used them in (my home brew
> Dyna MK III type amps and my ARC D70 MKII).
Mark, as I mentioned below, you may find your system sounds
different.
> I have a quad of used type III KT-90s I bought from Kevin Deal
> and I will gladly trade them to you for a used quad of 6550 tubes
> that you think sound better than Svetlana KT-88s. I will even throw
> in some NOS 12BY7 tubes for your Citations.
I much prefer the GE & Svetlana 6550C and the KT-90s, but I don't
have any to trade, sorry.
To each their own, we'll have to agree to disagree. But it's really not
a disagreement, since your system and mine are quite different. I will
say though that what I wrote was the feedback I got most often from
customers when I did carry the KT-88s. It was not my opinion alone.
Happy Thanksgiving to you and yours Mark!