Question - how to get more reverb on Marshall JTM 30 ?
mini
happy with except for reverb volume.
It's not the reverb duration but the fact that I have the reverb volume
turned all up all the time and at times I would like a little more reverb
juice.
The reverb tank is connected with phono plugs and I'm thinking along the
lines of replacing the reverb unit, rather than mess with the circuitry.
A variety of tanks are available here at catalogue page 59 (sorry can't link
directly) http://www.tubesandmore.com/
Can anyone please suggest what I should be looking for and if possible a UK
supplier would be preferred for custom reasons.
Fender amps normally have nice reverb (to my ears) so I tend to lean towards
a Fender replacement tank.
However I don't know how sensitive tanks are to the circuitry which also
brings me to how many ohms input I should be looking for ?
That is provided replacing the tank will help at all?
Thanks for reading
Mini
Slashed Zero
> happy with except for reverb volume.
I have a JTM60 and for my needs the reverb's mostly around 5 or 6 - maybe
you need some more, but at 10 I find the reverb already over the top. For
extra 'heavenly' cleans, I use my Boss Super Chorus pedal. So maybe there's
simply something wrong with the reverb in yur particular Marshall?...
I must say that I know what you're talking about with the more heavy reverb
on Fenders (which sounds almost chorus-like to me), but I'm not sure whether
that has to do with the reverb tank only. I'd say it has something to do
with the Fender sound being more treble-oriented and the Marshall pumping
more mids - I don't think you're ever going to get the reverbed cleans of
the Fender out of your JTM30.
If you need more reverb, you could try an extra reverb pedal. Boss (and a
lot of other manufacturers) make these. One of the benefits is that you can
get very heavy reverb if you want plus you'll be able to switch reverb off
by hitting the pedal -- the reverb on the Marshall JTMs isn't
foot-switchable.
Chris Berry
"mini" <mini...@removemsn.com> wrote in message
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If you're looking for more reverb, it's just a matter of changing a couple
of resistors in the reverb return line of your reverb circuit for more gain
on the TL071 there.
I've yet to hear a Marshall that had too much reverb though - probably
because I grew out of it early enough.
Changing the tank isn't a recomendable solution though. Expect to pay about
£10 for opening up the amp and having £0.10 worth of parts replaced... Time
costs money..
cb
Stewart Ward
Fender or Marshall will generally have similar reverb trays fitted.
Changing to a Fender tray is not the answer as they are likely to be
generically similar (Accutronics). Some manufacturers use better 'drive'
and 'recovery' circuits than others, so this is what your problem could be.
There is not a simple replacement fix for this problem... it's how it was
designed.
You would be best advised to take it to a good service technician who could
increase the gain of the drive or recovery circuit, whichever is
appropriate, to overcome the lack of reverb signal. If it's valve circuit,
this may not be quite so simple.
This advice is based on experience of a wide range of amplifiers and is not
intended as a dig at any particular manufacturers. I worked with
Accutronics/Morley for twelve years and have all their data to hand.
www.soundenhancements.com for more technical info.
Good luck.
--
Best regards,
Stewart Ward
www.award-session.com
Tel: 01256 477 222 - Int'l: +44 1256 477 222
Speakers, cables, amps & pedals, guitars, servicing.
2004 - 25th Year of Session amplifiers.
"mini" <mini...@removemsn.com> wrote in message
news:c8tf13$123r$1...@news.cybercity.dk...
jim harris
spring tank modeller!
jim
"mini" <mini...@removemsn.com> wrote in message
news:c8tf13$123r$1...@news.cybercity.dk...
mini
> To be honest, reverb tanks are mostly all the same (four basic
> types), so Fender or Marshall will generally have similar reverb
> trays fitted. Changing to a Fender tray is not the answer as they are
> likely to be generically similar (Accutronics). Some manufacturers
> use better 'drive' and 'recovery' circuits than others, so this is
> what your problem could be. There is not a simple replacement fix
> for this problem... it's how it was designed.
>
> You would be best advised to take it to a good service technician who
> could increase the gain of the drive or recovery circuit, whichever is
> appropriate, to overcome the lack of reverb signal. If it's valve
> circuit, this may not be quite so simple.
>
> This advice is based on experience of a wide range of amplifiers and
> is not intended as a dig at any particular manufacturers. I worked
> with Accutronics/Morley for twelve years and have all their data to
> hand. www.soundenhancements.com for more technical info.
>
> Good luck.
Thanks - you are right on the dot and so is Chris - it probably ends with a
mod after all.
The tank is precisely an Accutronics 3 springs - the print says 8DB2C1D
which would make it a model 8 right?
I can change a resistor myself if I can get to it so my concern is more the
mechanics of the amp which is very compact and needs to be taken apart.
It's basically a tube amp but Marshall used op amps here and there which
surprise me some but I must confess it sounds very good for my liking.
Tone controls seem very effective.
I have put up a pic + the schematics on my webby if you care to have a look.
http://home.worldonline.dk/brinck/
I think if R32 is reduced in size volume may increase but the ohms could be
off then.
Another angle could possibly be to change the R17 to higher value to
increase amplification. Changing 1k to 2k2 should give about 6db which
should be plenty.
Please let me know what you think - maybe I have overlooked a better
solution.
I only play at home for fun and it such a nice little amp that fits nicely
between keyboard and piano and still makes it possible to imitate good old
mainly clean strat sounds with plenty twang (a Telecaster is on the wish
list).
I have a Boss RV3 (in the loop) wich has some OK digital reverb, but when
set to give echo at the same time it sounds crappy.
Mini
mini
> a look.
>
> http://home.worldonline.dk/brinck/
>
>
>
> I think if R32 is reduced in size volume may increase but the ohms
> could be off then.
>
> Another angle could possibly be to change the R17 to higher value to
> increase amplification. Changing 1k to 2k2 should give about 6db which
> should be plenty.
>
> Please let me know what you think - maybe I have overlooked a better
> solution.
I looked up the date on the reverb unit:
It's an Accutronics type 8
input res. = 310 ohm
output res = 2575 ohm
Decay = medium
Connectors = input insulated - output grounded
no locking device
Vertical mounting
Recommnedation for which resistor to change to what please :))
Mini
Chris Berry
I could tell you but it's probably a good deal better if you took it and the
schematic to an electronics repair guy and explain what you want done.
Better still would be an amp tech but those have a pretty bad rep as far as
I can remember.... So a Reputable one would be good (Don't forget the
capital R)
cb
icarusi
news:tnnurseNOUCE99-ACB...@singer.cent.gla.ac.uk...
> In article <c8v79d$m3t$1...@news7.svr.pol.co.uk>,
> "Stewart Ward" <stewar...@award-session.fsbusiness.co.uk> wrote:
>
> > www.soundenhancements.com
>
> Interesting little piece on the history of the spring reverb unit.
IIRC according to that data there's always the possibility the reverb tank
hasn't been mounted in the position it was initally designed for, in which
case it may work, up to a point, but not as well as when it's mounted in the
position it was designed to operate.
Icarusi
--
remove the 00 to reply
Stewart Ward
> Tone controls seem very effective.
Very unusual in my experience of these models - JTM60. Bass control has
hardly any range.
> I have put up a pic + the schematics on my webby if you care to have a
look.
>
> http://home.worldonline.dk/brinck/
>
> I think if R32 is reduced in size volume may increase but the ohms could
be
> off then.
I could not open the jtm30_pre.pdf file. Would you email it to me... and
the PA too just for my records. I don't usually need circuits, but I need
to see which resistor needs changing and what to.
Stewart Ward
x> I looked up the date on the reverb unit:
> It's an Accutronics type 8
> input res. = 310 ohm
> output res = 2575 ohm
> Decay = medium
> Connectors = input insulated - output grounded
> no locking device
> Vertical mounting
>
> Recommnedation for which resistor to change to what please :))
>
> Mini
Not that simple, Mini. First you have to decide if the spring is getting
enough drive. If not, increasing the gain of the recovery could cause the
spring to induce acoustic feedback between itself and the speaker(s) when
you turn up the reverb volume control.
If you give the spring excessive drive, the poor old (inadequate) op-amp
Marshall often use to drive their reverbs will get hot and/or burn out the
driver tranducer. Whichever, it will be a very distorted drive signal. You
must be prepared for the fact that this circuit is a bare bones design and
may not be that improvable, sorry to say. However, send me the PDF anyway.
mini
> tank hasn't been mounted in the position it was initally designed
> for, in which case it may work, up to a point, but not as well as
> when it's mounted in the position it was designed to operate.
>
> Icarusi
In my case the reverb tank is mounted vertical just as intended according to
the id number 8DB2C1D which correspond to this:
Accutronics type 8
input res. = 310 ohm
output res = 2575 ohm
Decay = medium
Connectors = input insulated - output grounded
no locking device
Vertical mounting
Mini