Allen Ensemble on MDS-25

[JonD]

I have a few questions about my Allen Ensemble and MDS-25 (drawer model).

1.) Audio input - the ADC audio mixer only had one channel available for input. While I tried using the Rhythm 1 & 2 in I found out that it was not expressed. Only Channel 4A was available and expressed. Would there be a better way to connect it? Should I get an additional mixer module of some type and rearrange? (Any concerns about the organ having enough power to do this etc.)

2.) Volume - even though the unit is turned up to maximum volume things like the "Flute Celeste" are markedly different in volume than the one from the console. The Ensemble stop is dwarfed by the one from the organ at lowest volume. Is that normal? I saw no other volume adjustment on the Ensemble that was available. Thoughts?

3.) When the Ensemble was installed there was a significant hum on the audio. Attaching a the grounding screw and grounding it to the instrument eliminated it. Any worry with it there?

Thanks for any info/options.

Regards,
j

[myorgan]

JonD,

Welcome to the Forum. I hope you continue to participate here.

While you are waiting for a better answer than I can give (I've never used a drawer model on a MDS-25), you can search the Forum for your answer by clicking on the word Forum above: What's New? | Forum | Gallery | FAQ | Classifieds. Once you have done that, on the right-hand side of the page, you can click in the search blank and type (quotes included): "Allen Ensemble" and it will provide several results for you to read past posts. I seem to remember someone posted a user's guide on the Forum in the past 5 years or so.

Alternately, you can look at the bottom of this thread, and it will have Similar Threads listed.

Again, welcome to the Forum, and I hope you enjoy your time here.

Michael

[jbird604]

The MDS-25 is a "W-4" organ, so ORGAN VOICE expression takes place on the ADC Mixer assembly rather than in the cage, as with later models.

But the Expander does not need to be plugged into an expressed input! It gets an expression signal from the MIDI stream, and the voices will in fact be expressed with whichever manual division they are played from. At least that's the way MIDI is supposed to work on all MDS models. I hope that is the case with your MDS-25. It certainly works that way on my MDS-45.

So you should run the Expander into the unusued "rhythm" inputs J498 and J499. This will send the Expander voices into the organ speakers in stereo mode. And, as I said, they will express with whichever expression pedal controls the division you are coupling a MIDI voice to. Even if you have separate MIDI voices coupled to each manual, each voice will express individually with its own division. Amazing, isn't it!

This should solve your problem as to where to connect the Expander's audio outputs.

It's possible that the control marked R20 will adjust the volume of the rhythm inputs. It is so indicated on one of the pics on the tech site, but it doesn't show up in the schematic, so I can't say for sure.

I can't say why you are getting too low a signal level, as the output of the Expander is standard line level, same as the outputs of the cage boards. Perhaps it will work correctly when connected to the rhythm inputs as it was designed to be.

The hum you heard was indeed a normal artifact when the Expander is not directly grounded to the organ via the ground screw. The shields on the RCA cables float above ground, so they are not sufficient grounding to keep the Expander from humming. No problem as long as it is properly grounded via the screw.

[JonD]

John:

Thanks for your reply. I think when I tried that before I lost reverb with the Rhythm in. Could be wrong....but I may try it again. Will let you know!

Jon D.

- - - Updated - - -

Tried to attach audio diagram. It looks like the Rhythm inputs bypass the ADR......so that wouldn't be good. You see?

[jbird604]

Yes, I see. Running the Expander into the rhythm inputs will get you no reverb on those sounds. So if you use the ADR, that presents a problem.

It doesn't look like Allen really provided a good solution for your conundrum here. One possibility is to get a little $69 Behringer reverb and run the Expander audio into it, then take the output of the Behringer to the rhythm inputs. That would put reverb on the Expander voices, even though it would be a different type from the main voices. But that might be OK, if you adjust the Behringer's parameters to closely match the reverb length of the ADR. I have used this little unit on numerous organs and I think it has a lovely reverb, even though it's very inexpensive.

That's about all I can think of.

[Larrytow]

John,

Could you please provide the Behringer reverb model # for the one you use ? Is it similar to a Nanoverb ? That would be handy for JonD, and I might just get one to play with in the shop. Decent used Nanoverbs are getting harder to find.

[jbird604]

Behringer Minifex FEX800. Sells for $69.99 through various channels, such as:

https://www.adorama.com/befex800.htm...hoC9YAQAvD_BwE

It's a neat little unit, probably similar to the Nanoverb. Like a typical unit of this type, it has stereo inputs and outputs at normal line level. There are 16 preset effects, Cathedral and Concert being the two I find most useful for organ reverb. The setup is very simple. Just connect it inline between the source and the audio inputs of the organ, adjust the input level so that overload won't occur on the loudest sounds you will ever play, and adjust the output level to match the requirements of the mixer input you are using.

There are two ways to adjust the reverb beyond just selecting one of the 16 presets. An "Edit" knob lets you adjust the overall length and density of the reverb, and a wet/dry mix knob lets you control the balance between live sound and reflected.

Using these adjustments, I'd think one could regulate the reverb until it sounds very similar if not identical to the reverb provided by the ADR-4 unit in the Allen organ, so the Expander sounds would blend right in with the reverberated organ stops.

[JonD]

John:

Could I add another Allen mixer in here? I have a (trying to recall) USRM/USEM 3? So run the cage output from, say 1 and 3 into it along with the Expander and then plug its output into the Audio processor? I'm assuming there is enough power in the MDS to drive that, right?

[jbird604]

If you have a spare USEM, hook it up and try it. I assume you have a diagram that shows how the mixing takes place in that unit. It is used in various models to combine channels right out of the cage.

There IS a drawback to what you propose to do though -- If you mix the Expander audio into the cage audio ahead of the ADC mixer board, your Expander audio will get expressed twice. Once by the MIDI circuitry inside the Expander, and then again by the expression circuits of the ADC mixer. There is no getting around that. That's why it's best to put the Expander audio into the rhythm jacks, because you don't want to add an extra layer of expression to the Expander voices. They are automatically expressed by the Expander itself with the division from which you play them, and adding another layer of expression may produce a weird effect, almost like a wah-wah pedal or something.

That's why my recommendation is still to add a simple reverb processor ahead of the ADC mixer board so you can reverberate the Expander voices without subjecting them to unnecessary and possibly deleterious expression.

It won't hurt anything to try what you propose, but keep in mind what the drawbacks are. Post your results for future reference.