Using an AO-35 with other input sources and providing a line-level output
ValveTone
Just installed an M3 in my studio. It has the hammond add-on AO-35
reverb unit, which outputs it's signal to a small, seperate speaker
cabinet.
The reverb sounds just great, in fact, so great that I would like to
be able to use it with other sources during mixdown.
So, does anyone have any tips for doing this?
I know it gets it's power, etc. from the M3, so the organ would have
to be on (fine).
It looks like it gets a line-level input from the output of the
internal tube amp of the M3.
It provides (I assume) an 8 ohm speaker level output.
So, I assume I could easily build a switch (or just wire up a 1/4" TS
female plug to the same terminals and leave it there) to allow me to
flip between the M3 input and another line level source (aux from the
SSL console), and also tap off of the output, with proper padding, as
long as the speaker was still hooked up?
Any flaws in my mad plan?
Thanks,
Damon
Randy Hunt
awak...@hotmail.com says...
deal with an extra source of sound in the studio.
ValveTone
> >
> Why a speaker? provide a switchable load resistor and you won't have to
> deal with an extra source of sound in the studio.
From what another tech told me, unless the amp sees a resistance load
that varies with output (like a real speaker) then it will eventually
get overtaxed. Is that what you mean by a "switchable load" resistor?
Also, what about the input? Is it truly just line level?
Thanks for all your help Randy!
Damon
Randy Hunt
awak...@hotmail.com says...
load is a pure resistance. Unfortunately there is no such thing as a
perfect load. Everything has inductance and capacitance. The resistor
is the best way to load the amp. This will not create any problems as
you will probably not drive the amp to full output as a steady state.
Just make sure that the wattage rating of the resistor is equal to or
greater than the output of the amp. You can measure the input signal
level and figure out if the input is line level or not. If you have
access to the service manual look at the voltage levels indicated. The
only thing here is some Hammond sound channels were balanced and some
unbalanced. Again the service manual can tell you what you have. If the
input connector is a standard RCA type audio jack then you have a high
impedance unbalanced input. this will be the easiest for you to use. I
would have to do some digging to be more specific. if you need any more
help, let me know.
Randy
ValveTone
> >
> Well, as a load goes the speaker is not a theoretical load. the perfect
> load is a pure resistance. Unfortunately there is no such thing as a
> perfect load. Everything has inductance and capacitance. The resistor
> is the best way to load the amp. This will not create any problems as
> you will probably not drive the amp to full output as a steady state.
> Just make sure that the wattage rating of the resistor is equal to or
> greater than the output of the amp. You can measure the input signal
> level and figure out if the input is line level or not. If you have
> access to the service manual look at the voltage levels indicated. The
> only thing here is some Hammond sound channels were balanced and some
> unbalanced. Again the service manual can tell you what you have. If the
> input connector is a standard RCA type audio jack then you have a high
> impedance unbalanced input. this will be the easiest for you to use. I
> would have to do some digging to be more specific. if you need any more
> help, let me know.
>
> Randy
Randy,
Thanks for the info! My understanding is that it is a 12W amp driving
an 8 ohm, 8" speaker.
It's the AO-28 hammond preamp (15W) in the M3 and the AO-35 (12W)
reverb amp, if that helps at all. I have schematics for both, but no
service manul. I believe all connections (it's not in front of me) are
barrier terminals.
One more point, the external reverb speaker enclosure (which is just a
small, nicely appointed wooden cabinet with an 8" speaker), has a
small brass dial on the back for adjusting the reverb amount; so, I
assume I could just leave the speaker connected and spin the dial down
to "0".
D
Doug S
>
>Thanks for the info! My understanding is that it is a 12W amp driving
>an 8 ohm, 8" speaker.
>
>It's the AO-28 hammond preamp (15W) in the M3 and the AO-35 (12W)
>reverb amp, if that helps at all. I have schematics for both, but no
>service manul. I believe all connections (it's not in front of me) are
>barrier terminals.
>
>One more point, the external reverb speaker enclosure (which is just a
>small, nicely appointed wooden cabinet with an 8" speaker), has a
>small brass dial on the back for adjusting the reverb amount; so, I
>assume I could just leave the speaker connected and spin the dial down
>to "0".
The M-3 reverb kit is pretty-much the same as was used in earlier A-100
and M-100 series (I have a 1962 A-105 and my church has a 1959 A-100,
both with the AO-35. A friend has 1962 M-103 with an AO-35). The knob
you speak of is probably a 10W 100 ohm wire-wound resistor in series
with the speaker on the output of the AO-35, since that's what an A-100
uses. When the pot is turned all the way down, the reverb is
effectively off. On the M-100 series, they use a few fixed resistors
instead of a pot.
It's pretty-much a rule that you don't run a tube amp without a load.
I have a box to hook a Motion Sound rig to the output of my A-100's AO-28,
and a switch attached to the under-edge of the manuals toggles between
the internal (main) speakers and an 8 ohm 20-or-so watt non-inductive
load resistor. I continue the input to that switch to the reverb, so
the reverb works even if the main speakers are dummied out.
The tank reverbs sound pretty nice. IMHO the necklace reverb is
fragile, but I've never heard one - on the A-100 at my church I
replaced a broken one with a tank.
Doug
--
Doug S. (do...@cc.ysu.edu) (http://cc.ysu.edu/~doug/)
The shadow of a dog never bit anyone -- Kenneth Copeland
The Three R's of Microsoft: Reboot, Reinstall, fixed in next Release -- me
Stamp out html e-mails: http://wearcam.org/nomime.htm