Tube Amps / Music Electronics
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|10/22/1997 6:27 AM|
|Steve K||EF86 rules, EF86 rules!!!|
Ok, sorry for that title, but this
amp is making me feel like a kid in
a candy store. Some of you asked me
to post the results of trying the
EF86 preamp in an AC30. All I can
say is WOW!!!! Totally blown away
how great it sounds. I thought it
would be good but never imagined it
would be THIS good. Dynamic, tight,
responsive, touch sensitive, subtle,
extreme, soft, hard, etc... These
all fit. I'm sure the class A
output has alot to do with the
pure magic this tube can bestow on
a guitar signal but it just is
such a totally pure and responsive
tone, I can't even look at any of
my other amps the same now. If
there are any doubters about the
capability of this pentode tube
driving a guitar signal, you are
in for a surprise by trying it!!
It delivers alot more gain than I
thought also. It is alot louder
than the top boost channel or the
normal channel in my amp. It
totally responds fantastic when
being fed either a strat OR a LP
and either a Tube Screamer or a
Bixonic Expandora OD pedal. The
later one being, as expected, the
better of the two. I was going
to disable the master volume I
installed in this amp untill I
realized it works great with the
EF86 channel. What a GREAT tube.
I hope it can hold up in this amp.
The Svetlana EF86 appears to be
built like a Russian tank also.
The only two speakers I've tried
so far are an EVM 12L 200 watter
which is very clean but delivers
excellent bass responce with this
amp and a Celestion G70 also works
quite well and offers more grit
but is lacking in the bottom.
The brilliance switch is ok but
only works for me with a LP
feeding it. It adds too much
treble to a strat. It seems to me
that the sweet switch offers a
somewhat similar tone to the top
boost channel but not near as
bell like and crisp. I could
lose this switch and not miss it.
If I were to recommend this
project to someone now, I'd
suggest starting with just the
EF86 preamp and building in a
Fender style reverb instead of
the top boost and normal channels.
I found that adding a touch of
classic analog delay to the input
is enough to satisfy my reverb
levels. Though I am not a loud
player anymore, 30 watts seems to
be the minimum power I could live
with for this type of amp. I
have not finished testing all the
levels yet and still get a fair
preamp hum through the normal
and EF86 channels but not the top
boost channel at all. So I need
to trace that down. Probably a
high voltage wire crossing or a
bad ground somewhere. Since the
top boost channel is dead quiet,
I'm optimistic its quickly
curable... I hope...
Sorry for the long post. I
usually try to avoid that but I
thought I knew most all the great
amp tones out there but till I
tried the EF86 AC30, I didn't
know squat!!! It simply must be
heard to be appreciated...
|10/22/1997 8:06 AM|
The main reason amp manufacturers stopped using small signal pentodes was that they can be very microphonic, far more than the typical triode input stages. This creates a problem in combos. Shock mounting is recomended. Also make sure the EF86 internal shield is grounded to reduce hum.
But, I agree they sound great. I have an amp where all the preamp tubes and driver are pentodes (6SJ7).
|Book Of The Day||
The Ultimate Tone, Volume III by Kevin O'Connor
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|10/28/1997 2:27 PM|
Could I use the EF86 in my Vox/Korg AC30 reissue without modification? If so, where would it be placed in the preamp chain?
I'm currently considering some other options for tailoring the sound of my new amp, so if there are useful tips, I would appreciate any advice.
|10/28/1997 2:32 PM|
The amp would need modification. The EF86 is a single pentode. Your preamp tubes are dual triode.
|10/29/1997 5:25 AM|
Hi,, I believe the new AC30 is PC bd.
based so you'd have to jump through
a few hoops to cut into that but if
you have the space for another tube
in my opinion it would be most likely
worth it as this tube sounds great
with this power section!!! Just add
the EF86 circuit (only about 8
components plus tube) and put the
center wiper of the EF86 vol pot to
a 220k res and add that to sum into
the inverter coupling cap with the
other channels 220k res. If you didn't
want to void the warranty, you could
just build this preamp in a small box
but then you'd want to add a line-in
somewhere for it but I'd bet this
circuit as a preamp box would be
|10/29/1997 5:57 AM|
Steve - I'm glad to hear your EF86 project
went well. Based on your enthusiastic review
I may incorporate this tube in my next
project. BTW, several months ago a guy (I
seem to remember he was from Europe) posted
here and was saying he had built an amp he
claimed produced OP tube type distortion in
preamp stages using the EF86. I remember
several people asking him to contact them or
send schematics. Were you one of the folks
asking him for more info, and if so, did you
ever hear from him? Just curious.
|10/29/1997 8:02 AM|
Hi Pat,, I'm not sure but I do remember
getting some good feedback from the
fellow from Holland I think, Yves I
believe was his name. Sorry if I have
that wrong but I can't locate the mail
I saved from him. Sounded like he did
quite abit of experimenting with this
tube and I would love to have some of
the values he came up with. I'll
eventually start tweaking values on
this myself but need to do my homework
first to know and understand exactly
what the hell I'm doing.... Besides,
I'm having too much fun with this amp
now to take it apart again anytime
soon... I simply can't believe I
havn't heard or seen more things done
with this tube in the guitar amp
world. Maybe it won't last. Maybe
other problems will show up later,
but I know I'm now hooked on using
it so I'll do whatever it takes to
keep using it...
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