Forum Top Banner Ad

Collapse

Ebay Classic organs

Collapse

Announcement

Collapse
No announcement yet.

Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!

Collapse
This topic is closed.
X
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



    Hello everyone,</p>

    I know the topic of adding a reverb unit to an analog organ has been talked about before on this forum. But, my question involves an issue that I could not find. </p>

    My organ (Rodgers Scarborough 750B) is equiped with a spring reverb unit. So, in order to install the Alesis Microverb, I simply took the RCA reverb input and output that already existed for the spring reverb and hooked them up to the Alesis. My problem is this: the mix is NOT right in terms of swell and great reverb. When I set the reverb correctly for the swell trumpets (which sound AWESOME with the Alesis), the reverb on the great is insanely overdone and distorts quite a bit. So, I then set the reverb lower for the great and I get practically no reverb on my swell trumpets. Does anyone know how I could solve this problem? I don't have a technical manual so I don't know where all of the adjusters are (at least the ones that aren't clearly labeled). I'm not very experienced in fixing organs either, so it might be obvious to some of you and just not to me.
    </p>

    Another option...if I spliced in to the lines between the pre-amp boards (swell and great) and the amp input, would that potentially solve my problem? I did have this issue before I added the Alesis (very little reverb for the swell with the spring reverb) so I'm wondering if the problem is with the reverb wiring or something and not with the actual mix.
    </p>

    Any help or suggestions would be greatly appreciated!!! If you know where I could find a technical manual too, that would be really helpful. </p>

    Thanks!!!</p>

    Mark
    </p>

  • #2
    Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



    <p class="MsoNormal"><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; color: navy; font-family: Arial;">Hi Mark,</span></font></p><p class="MsoNormal"><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; color: navy; font-family: Arial;">I just sold my 740B </span></font><st1:city><st1:place><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; color: navy; font-family: Arial;">Glasgow</span></font></st1:place></st1:city><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; color: navy; font-family: Arial;"> that seemed to have a
    similar connection for the reverb. <span style=""></span>Mine
    did not originally come with the Rodgers spring reverb but I added a <span class="SpellE">Behringer</span> DSP for reverb. <span style=""></span>I’ve got a number of instruments and I’ve used
    both the <span class="SpellE">Behringer</span> DSP and <span class="SpellE">Alesis</span> <span class="SpellE">Nanoverb</span> units on them with
    excellent results once you get the input and output levels
    set.<o:p>
    </o:p></span></font></p>

    <p class="MsoNormal"><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; color: navy; font-family: Arial;">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. <span style=""></span>After adding reverb to this mono mix they just
    feed it back into all the final preamp channels then out to the power amps.
    <span style="">Except for a single console adjustment to change the overall level of reverb that's injected back into the signal everything else associated with the Rodgers reverb circuits appears to be fixed. </span>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.<o:p>
    </o:p></span></font></p>
    <p class="MsoNormal"><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; color: navy; font-family: Arial;">If you’ve got the <span class="SpellE">Alesis</span> set for the same input and output levels as the
    spring unit they should function very similarly. <span style=""></span>The <span class="SpellE">Alesis</span> will
    distort if the input is too high and perhaps clip the output if that’s set too
    high.<o:p></o:p></span></font></p>


    <p class="MsoNormal"><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; color: navy; font-family: Arial;">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.<span style=""> </span>I leave the near speakers dry without reverb
    and put the reverb into a remote speaker(s). <span style=""></span>I’ve got an <span class="SpellE">Alesis</span>
    <span class="SpellE">Nanoverb</span> 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. <span style=""></span>You could take the mono reverb out from the
    750B into a reverb and out to a separate amp and speaker to try
    it.<o:p>
    </o:p></span></font></p>
    <p class="MsoNormal"><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; color: navy; font-family: Arial;">You can order a
    technical manual directly from your Rodgers dealer for these analog organs but
    they’re quite expensive (I was quoted almost $200).<span style=""> </span>I got a copy of
    a preliminary manual off <span class="SpellE">ebay</span> that had 99% of the info
    I needed for $40 or so.<span style=""> </span>It was missing a
    couple of pages that were to be supplied in the final
    version but there was enough information there to work with.<o:p></o:p></span></font></p>

    <p class="MsoNormal"><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; color: navy; font-family: Arial;">I just picked up
    another <span class="SpellE">Alesis</span> <span class="SpellE">Nanoverb</span> that
    I’m going to be installing on the 740B so I’ll let you know if I run into any
    issues.</span></font></p><p class="MsoNormal"></p>

    Gary

    Current: Rodgers 340 "Special", Gulbransen Rialto K (Both Versions), Allen Theatre Deluxe, Rodgers Olympic 333, Roland Atelier AT70 (I hope)
    History: Rodgers 321B, Rodgers 740B, Gulbransen Theatrum, Hammond H-133, Thomas Malibu, Heathkit/Thomas Paramount

    Comment


    • #3
      Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



      Mark,</P>


      I have the service manual for the 750B at home and will look it up. USUALLY, Rodgers of this vintage had a mixing board, with pots to control how much signal was mixed into the reverb driver. I'll check it out &amp; advise tomorrow. Send me a PM if you want copies of the appropriate drawings, but if you want a complete manual, contact Rodgers. They'll probably sell it to you. If not, then your local Rodgers dealer will likely order it for you and sell it to you. </P>


      Toodles.</P>

      Comment


      • #4
        Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



        Thanks Gary! </p>

        So, if the signal injected into the reverb is fixed, as you say (and as it appears to be to me), then could I connect the Alesis by taking a mono mix of everything just before the amp input (ignoring the existing reverb) and put pots to control the input of the different channels (sw, gt main, gt flutes, and pedal)? I would then presumably wire the reverb output back in to the amp input or possibly make my own channel, right? The second alternative would then give me a "remote sound" as you say if I positioned the speakers correctly.</p>

        This might be a dumb question, but can I combine channels to free up one for the reverb if I wanted too? I have four channels and it's just in my living room. I'm thinking I could combine something and then free up a channel and speaker for my reverb. </p>

        Thanks so much! Your help is great!</p>

        Mark
        </p>


        </p>

        Comment


        • #5
          Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



          Toodles, </p>

          Yes, please let me know what you find. I found the swell mix volume and that did nothing to the reverb so I fear that it's fixed as Gary said. </p>

          What do you think about my option in my post above?</p>

          Thanks so much!!</p>

          Mark
          </p>

          Comment


          • #6
            Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



            My manual shows that there are separate level controls at the preamps and at the power amps on the 750. The summing to the reverb driver is AFTER the preamp level controls and these same level controls also feed the amplifier drivers. The preamp levels are on the output (preamp) board, and the amplifiers and their level controls are on the power supply.</P>


            This might be the issue:</P>
            <BLOCKQUOTE>


            If the swell is set high at the preamp and low at the amp; AND</P>


            the great is set low at the preamp and high at the amp; THEN</P>


            both will sound OK thru the speakers, but the swell would distort if the reverb is set to be OK on the Great, or the Great wouldn't have much reverb if the swell were set to be OK.</P>


            Cure: set the preamp levelsso they are equal, and adjust the speaker levels as needed at the amps.</P></BLOCKQUOTE>


            One reason this might occur is if there are big differences in speaker efficiency and it was compensated for at the preamp instead of at the amp. </P>


            I do NOT recommend using one channel for organ and one for reverb--analog organs really sound a lot better if the channels are separated. Also, there is no reason why you should not be able to get the reverb drive signal to behave properly. </P>


            Here's a way to check the preamp levels: </P>
            <BLOCKQUOTE>


            1. Mute the speakers. I think the organ has a headphone jack, and just plugging in a set of headphones ought to mute the speakers; also the "Main Speakers Off" might do the same.</P>


            2. Take the input into the reverb spring and plug it into a separate stereo amplifier &amp; speakers (or headphone); have the organ off when you make these connections, and make sure the swell shoes are closed, and the amp volume is turned down. Note that only one channel on the stereo will be working, since you're only connecting one channel. (I have a small Radio Shack stereo amp for just this type of test purposes--it's very handy, but any stereo will work with a line-level input).</P>


            3. Turn on the organ, and slowly bring up the volume on the amp &amp; swell shoes: listen for a balance between all divisions, stops, etc; if it's out of balance, then the preamp level are not set correctly. If this is the case, adjust those levels for balance by ear. Mid-position is probably best.</P>


            4. With power off, disconnect the stereo amp. Reconnect the reverb (spring or digital). Test the balance through the organ speakers (disconnect headphones from organ/turn on the Main Speakers). You'll certainly have to readjust the level at the amplifiers if you made any significant changes to the preamp levels.</P></BLOCKQUOTE>


            As for separate reverb speakers, I wholeheartedly endorse this approach. One for each corner of the room, high on the wall (6ft or so with 8ft ceilings). The source of reverb echoes is NEVER the same location as the instrument, it is always the room reflections. These speakers do NOT need to be full range (there is very little reverb over 6K Hz and for some reason the bass doesn't seem to be important, at least to my ears). I've found that standard, bookshelf stereo speakers with 6-1/2 inch woofers work very nicely (I prefer JBl home speakers, but that's my ears. NotethatJBL tends to make fairly efficient speakers so you don't need lots of watts from your amp.</P>


            But you still should have pretty good reverb if you put the reverb signal back into the main organ speakers, and that's a very good place to start. </P>


            FYI, Rodgers used to charge $25 to $40 for a technical manual, but maybe they've raised their prices. Look for them on e-bay, too.</P>


            Toodles.</P>
            <P mce_keep="true"></P>

            Comment


            • #7
              Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



              Hi All,

              Looks like the 750 audio is a bit different than the 740B. The channel preamps are adjustable but they feed a fixed resistive mix to the mono reverb jack, there aren't any level adjustments on the power amp. I was assuming that all was well with the spring reverb connected but if that wasn't the case then Toodles outlined a good way to get everything back on track and balanced out. A misadjustment of the preamp and power amp stages sounds like it could be the issue.
              </p>

              I too would not generally recommend modifying the organ to re-purpose one of the existing channels for the reverb. I think you'll find it much easier and more satisfying to do it the "right way". A suitable amp and speaker for reverb is easy to find and more channels, amps, speakers is always better ;^) The big issue with most of these modifications is that most folks never take the time to document the changes they make. Not only does that drive the next owner crazy you would be surprised how much you can forget about your modification the next time you have to work on it.
              </p>

              On the 740B Rodgers was kind enough to put a stripe of silver paint across each of the 100's of pots to mark the factory settings. I've returned to those as a starting point from time to time. Not sure if they did that on other models or if it was a standard Rodgers factory practice. </p>

              I paid about $35 for my 321B tech manual so I was surprise when Rodgers wanted a fortune for the 740B manual. Perhaps they misquoted. I picked up a copy off ebay for $40 from that fellow that's always selling the Rodgers manuals. It was an excellent copy with all the large fold out diagrams, nicely bound, etc. The only downside was that it was preliminary and missing a few sheets that were being finalized. Unless you dug into the manual it wasn't apparant that it was preliminary so I didn't pursue the issue with the seller but I would certianly confirm that it is a complete manual before I bought another on ebay. It gave me enough to work with the instrument but now I may have an issue with the instrument now that I've got it over at the new owners. Looks like I might have a problem with the Antiphonal output and my manual has detailed block diagrams of the output board but not a detailed schematic that was being prepared for the final manual version :^)</p>

              I've posted around for it but so far no luck. Toodles you wouldn't happen to have a schematic for the 5008-308 output preamp for the 740B would you?</p>

              Keep us posted on what you find out with those adjustments.</p>

              </p>
              Gary

              Current: Rodgers 340 "Special", Gulbransen Rialto K (Both Versions), Allen Theatre Deluxe, Rodgers Olympic 333, Roland Atelier AT70 (I hope)
              History: Rodgers 321B, Rodgers 740B, Gulbransen Theatrum, Hammond H-133, Thomas Malibu, Heathkit/Thomas Paramount

              Comment


              • #8
                Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!

                <meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="ProgId" content="Word.Document"><meta name="Generator" content="Microsoft Word 12"><meta name="Originator" content="Microsoft Word 12"><link href="file:///C:%5CDOCUME%7E1%5CMark%5CLOCALS%7E1%5CTemp%5Cmsoht mlclip1%5C01%5Cclip_filelist.xml" rel="File-List"><link href="file:///C:%5CDOCUME%7E1%5CMark%5CLOCALS%7E1%5CTemp%5Cmsoht mlclip1%5C01%5Cclip_themedata.thmx" rel="themeData"><link href="file:///C:%5CDOCUME%7E1%5CMark%5CLOCALS%7E1%5CTemp%5Cmsoht mlclip1%5C01%5Cclip_colorschememapping.xml" rel="colorSchemeMapping"><!--[if gte mso 9]><xml>

                Normal
                0




                false
                false
                false

                EN-US
                X-NONE
                X-NONE













                MicrosoftInternetExplorer4













                </xml><![endif]--><!--[if gte mso 9]><xml>











































































































































                </xml><![endif]--><style>

                </style><!--[if gte mso 10]>
                <style>
                /* Style Definitions */
                table.MsoNormalTable
                {mso-style-name:"Table Normal";
                mso-tstyle-rowband-size:0;
                mso-tstyle-colband-size:0;
                mso-style-noshow:yes;
                mso-style-priority:99;
                mso-style-qformat:yes;
                mso-style-parent:"";
                mso-padding-alt:0in 5.4pt 0in 5.4pt;
                mso-para-margin:0in;
                mso-para-margin-bottom:.0001pt;
                text-indent:.5in;
                mso-pagination:widow-orphan;
                font-size:11.0pt;
                font-family:"Calibri","sans-serif";
                mso-ascii-font-family:Calibri;
                mso-ascii-theme-font:minor-latin;
                mso-fareast-font-family:"Times New Roman";
                mso-fareast-theme-font:minor-fareast;
                mso-hansi-font-family:Calibri;
                mso-hansi-theme-font:minor-latin;}
                </style>
                <![endif]-->



                Wow! You guys are awesome!!! Thanks for your
                input and suggestions.</p>



                Toodles - While I haven't tried it yet, I am nearly 100%
                sure that you found my problem! That makes sense with all of the issues that
                I've been having and I will definitely try adjusting the preamp and amp
                levels. Unfortunately, I had to close my organ up this morning and won't
                get to it until next week, but I'll let you know what I find (I "stole" the
                reverb unit from my Church organ and had to bring it back for Sunday.
                I'll "get it back" next week :). </p>



                Toodles and Tinker - I am really new to all this, so
                please forgive my endless questions, but what exactly do you mean by a
                "suitable" amp and speaker for separate reverb? I think I want to do that
                but I don't really know where to start. Would something like a stereo
                amplifier work or do I need something diff? How many watts do I
                need? As for speakers, am I looking for something with a woofer and
                tweeter, two-way, three-way, size, etc? Maybe, could you guys just tell
                me the specs on what you have or any specifics that I should look for? I
                would love to do this myself and I think I could easily do it, but I don't know
                what to buy. Again, both of your help is greatly appreciated! I
                honestly didn't expect such pertinent and detailed responses. You guys
                are great!</p>



                Thanks again,</p>



                Mark </p>



                Comment


                • #9
                  Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



                  Mark:</P>


                  Suitable means somethingwith a reasonable frequency range and power: figure 64 Hz thru 6 kHzrange for the speakers(high end is NOT critical here) and 35-60 watts of power for the amps. Reverb power level is LOTS lower than the main power level (remember, this is reflected sound that has already started to lose its amplitude).</P>


                  I've used JBL 2-way systems with a 6-1/2 inch woofer very nicely, along with home stereo amps. If you use 8-ohm speakers, you can usually parallel 2 speakers on each channel, to have 4 speakers (one per corner) so one stereo amp would do. I had a Yamaha DSP-1 with 4 separate outputs (one per corner) and ran 2 pairs of stereo amps. Nothing particularly fancy is required here, just don't buy "junk". Moderate quality is fine.</P>


                  See these: http://cgi.--------/Pair-of-JBL-2600...d=p3286.c0.m14They'd probably work just fine.</P>


                  My fondness for JBL is because I like their tonal signature and efficiency. Others may not care for them.</P>


                  If you want to spend some time looking at neat stuff, see: www.partsexpress.com</P>


                  Toodles.</P>

                  Comment


                  • #10
                    Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



                    Tinker,</P>


                    I've got the 770 schematics &amp; the 830. I'll see if either of these is the 5008-308 or close. Rodgers manuals took a nosedive in quality (my opinion) with the 650-705-740-770-780 series, and I think they only published preliminary versions. You have to have multiple manuals to get it all, I think, and even then somethings seem missing.</P>


                    The 770 preamp is based on the 840, but not so fully stuffed. It's about 10 pages, if I recall correctly! It would probably get you what you needed, even if its a different board, but I'll check &amp; advise.</P>


                    Toodles.</P>
                    <P mce_keep="true"></P>

                    Comment


                    • #11
                      Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



                      Thanks Toodles,
                      </p>

                      Any info would be appreciated. I don't mind poking around, tracing etch, drawing my own diagrams, etc. when I can take my time at home but I'd like to be as prepared as possible when I look into this antiphonal problem over at the new owners house. I'm trying to encourage the new organist so I decided to toss in an antiphonal amp and speakers as an "after the sale" extra. Of course it worked when I tested it before moving the organ over to their place and of course that's the only thing that I had trouble with during the installation ;^) I also stuck my neck out and bought her an Alesis Nanoverb that I'm going to install. I had one on it at home so that "should" go smooth. Then I get a call about the combinations not holding when the organ is powered down so I'm sure that's the battery gone bad. I do enjoy working on these things and the daughter and her parents are most appreciative so what the heck. </p>

                      I managed to get them all fired up about theatre organs while they were over at my place checking out the 740B so I introduced them to Miditzer. If I have the nerve and can risk uncovering another issue I'll reconnect the MIDI output and let them have some real fun.</p>

                      Thanks for offering to check.</p>

                      Gary
                      </p>
                      Gary

                      Current: Rodgers 340 "Special", Gulbransen Rialto K (Both Versions), Allen Theatre Deluxe, Rodgers Olympic 333, Roland Atelier AT70 (I hope)
                      History: Rodgers 321B, Rodgers 740B, Gulbransen Theatrum, Hammond H-133, Thomas Malibu, Heathkit/Thomas Paramount

                      Comment


                      • #12
                        Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



                        The 770 &amp; 740 definitely use different circuit boards--parts are not even close to the same locations (juding by the voicing guide). I think the 770 preamp is a reduced stuffing of the 840 board. The 770 is sold as a 4-channel main organ, and the 740 was 3 (if I remember right). Sorry I couldn't help.</P>


                        It is worth calling Rodgers &amp; asking for just this schematic. I did that on a manual that had an illegible copy of one keyer schematic, and they sent me a more legible copy without charge.</P>
                        <P mce_keep="true"></P>


                        The other thing, join the Rodgers Organ group at frog music--someone there might be able to get you the schematic drawing.</P>


                        Toodles.</P>

                        Comment


                        • #13
                          Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



                          Thanks for the tip on calling Rodgers. I'd got some information freebees from them before and just didn't think of that. I had the same request up on the Rodgers group for a while but no responses.</p>

                          And yes, the 740B is a three channel + antiphonal.</p>

                          </p>
                          Gary

                          Current: Rodgers 340 "Special", Gulbransen Rialto K (Both Versions), Allen Theatre Deluxe, Rodgers Olympic 333, Roland Atelier AT70 (I hope)
                          History: Rodgers 321B, Rodgers 740B, Gulbransen Theatrum, Hammond H-133, Thomas Malibu, Heathkit/Thomas Paramount

                          Comment


                          • #14
                            Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!

                            can take a 740 headphone jack as an output to my pa system to amp the sound new kid on the block !!!!!!!!!

                            Comment


                            • #15
                              Re: Rodgers 750 Reverb...wierd mix with crossover to Alesis...Help!



                              Hi William,</p>

                              Are you connecting to a PA to fill a large space or ?? The headphone jack signal level might be a little high but if your amp has some kind of input level control you probably could compensate for that. My 740B had internal amps (3 channels) and it worked fine with external speakers. The antiphonal was a line level output and needed an amp and speaker.</p>

                              I've got a 340 (five channels if you count the Leslie output) that didn't have a headphone jack but I wanted to do some testing and playing around with headphones. Turned out to be the best thing for me since I then decided to make up the patch cords necessary to feed the signals into a little Behringer mixer. The mixer has the headphone jack, outputs, effects loops for reverb, three band equalizers on each channel and the ability to pan the individual signals left/right. All kinds of features that allowed me to get the headphone (or stereo mix) just the way I wanted it. No substitute for lots separate amps and speakers but for headphones or direct recording I think it's the greatest!</p>


                              </p>
                              Gary

                              Current: Rodgers 340 "Special", Gulbransen Rialto K (Both Versions), Allen Theatre Deluxe, Rodgers Olympic 333, Roland Atelier AT70 (I hope)
                              History: Rodgers 321B, Rodgers 740B, Gulbransen Theatrum, Hammond H-133, Thomas Malibu, Heathkit/Thomas Paramount

                              Comment

                              Working...
                              X