[analogorgans] Re: Rodgers 750B Reverb Schematic Problem...Please help
- From: "Gary Cervenka" <cervenka@xxxxxxxxxxxxx>
- To: <analogorgans@xxxxxxxxxxxxx>
- Date: Wed, 9 Sep 2009 10:28:16 -0700
Hi Mark,
I just sold my 740B Glasgow that seemed to have a similar connection for
the reverb. Mine did not originally come with the Rodgers spring reverb
but I added a Behringer DSP for reverb. I've got a number of
instruments and I've used both the Behringer DSP and Alesis Nanoverb
units on them with excellent results once you get the input and output
levels set.
I don't have a schematic for the 750B but on the 740B and other Rodgers
designs they're simply taking a fixed resistive mix of the various
channels (3 on the 740B) just before the final preamp stage as a mono
signal. After adding reverb to this mono mix they just feed it back
into all the final preamp channels then out to the power amps. I could
imagine that Rodgers might have changed the reverb mix going back into
the pedal channel but I would think they would treat all manual voices
the same.
If you've got the Alesis set for the same input and output levels as the
spring unit they should function very similarly. The Alesis will
distort if the input is too high and perhaps clip the output if that's
set too high.
I personally like to use a separate amp and speaker for the reverb, it
seems more realistic to me to have the reverb sound remote from the main
speakers. I leave the near speakers dry without reverb and put the
reverb into a remote speaker(s). I've got an Alesis Nanoverb taking the
two channels from a 321B and feeding them off to separate Rodgers S-100
amps with Allen HC-12 speakers at the other end of the room and it
sounds great. You could take the mono reverb out from the 750B into a
reverb and out to a separate amp and speaker to try it.
You can order a technical manual directly from your Rodgers dealer for
these analog organs but they're quite expensive. I got a copy of a
preliminary manual off ebay that had 99% of the info I needed for $40 or
so. It was missing a couple of pages that were to be supplied in the
final version.
I just picked up another Alesis Nanoverb that I'm going to be installing
on the 740B so I'll let you know if I run into any issues.
Gary
-----Original Message-----
From: analogorgans-bounce@xxxxxxxxxxxxx
[mailto:analogorgans-bounce@xxxxxxxxxxxxx] On Behalf Of Sommerfeld, Mark
Sent: Wednesday, September 09, 2009 7:52 AM
To: analogorgans@xxxxxxxxxxxxx
Subject: [analogorgans] Rodgers 750B Reverb Schematic Problem...Please
help
Hi everyone,
I am trying to connect an Alesis Reverb unit to my Rodgers 750B Analog
Organ. It was originally equipped with a spring-type reverb and I tried
connecting the Alesis directly to the existing RCA input and output of
the reverb on the organ and it didn't really work. Here's my problem.
When I set the reverb to the level I want for the Swell (specifically
the swell trumpets, which sound awesome with the reverb!), it results in
a huge amount of distortion and excessive reverb on the Great.
Conversely, if I set the reverb unit to work with the Great, I end up
with little, if any, reverb on the Swell. The mix is off! I did have
this problem before I switched over from the spring reverb too.
So, I have a couple of questions. First, does anyone have the technical
manual for the Rodgers 750B Scarborough with the schematics or know
where I can find one? That would be of great help to me! Second, is it
possible that my problem is with the existing reverb, which means that I
should just bypass it and connect the Alesis between the preamp and the
amp input? If I do that, would it make sense to add potentiometers to
each line (main, swell, great, etc) so that I can control the input into
the Alesis? If so, what size should I get, etc? Also, I am also not
sure of exactly where to connect the reverb output. Do I connect that
to the amp input and does it really matter which input I use on the amp,
so long as I get a main channel? My organ has external speakers in my
living room and it has 3 or 4 channels.
So, I have a lot of questions :). I am not very experienced with organ
repair and would greatly appreciate any help from you all!
Thanks in advance,
Mark
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