Author Topic: Elf experiment (Read 189 times)

David Houck · « **on:** April 30, 2006, 12:00:46 PM »

Those of you who have Elf systems might find this interesting.

In my rig, both my reverb unit and my Elf have, and only have, cannon (mic cable) inputs and outputs. For a while I was using 1/4 to cannon adapters to get in and out of the reverb unit and to get in to the Elf (the power amp has cannon connectors, so short mic cables connect the Elf to the amp). The impedence mismatch on the front end of the reverb was a problem and I had to carefully place it in the signal chain and carefully set all the gain controls to get it to play nice.

Then a few months ago I put a passive direct box in front of the reverb and that made a big difference. The system was a lot easier to work with and I had more flexibility in adjusting the various gain controls.

Today I tried two things. First I moved the reverb unit with its front end direct box down the path to where it was in front of the Elf; thus the output of the reverb and the input of the Elf were both cannon connectors and I could connect them with a mic cable.

That failed miserably. No matter what adjustments I made to the Elf, the input and output controls of the reverb, or the signal going to the reverb, I could not get a clean tone from the speakers.

Next I took the reverb out of the path and placed the direct box in front of the Elf. This failed as well. Again, I could not get a clean tone from the speakers.

So I put everything back the way it was and I now know not to put a direct box in front of the Elf!

2400wattman · « **Reply #1 on:** April 30, 2006, 09:20:14 PM »

I wish I had that kind of time to experiment w/ my gear!

jlpicard · « **Reply #2 on:** April 30, 2006, 09:52:49 PM »

Dave, I am bit confused. Why are you sending reverb to the ELF at all? Isn't the ELF system strickly for extending low frequency of a cab especially designed as a compact sub? I'm only slightly familiar with the operation of an ELF system but if my assumtion of the operation of an ELF is correct, I would crossover the reverb so as not to introduce to much low frequency to the signal. That would clean it up much like the way a xover is used to clean up a chorus unit designed for bass.

bob · « **Reply #3 on:** April 30, 2006, 10:42:42 PM »

Dave will have to fill in the details, but perhaps I can give him a head start.

The ELF unit is itself a crossover. You can run a full range signal into it, then split the output to an ELF sub and a standard cab. Now, the crossover point and overlap are only adjustable by internal jumpers, and it's hard to find the documentation on that (I would love to have a copy, for the low end model, if anyone can oblige).

So one approach is to run a full signal into the ELF unit, then take the split outputs into two different amps (or channels), and out to the speakers. You have an option here, as to whether the input is mono or stereo, though the ELF sub output is summed-mono (the upper range output can be mono or stereo).

An alternative, which I happen to use, is to split before the ELF. I run the output from one channel of my SF-2 into the ELF but only use the sub-out (into one amp channel), and the other SF-2 output goes straight into the other amp channel, which drives my non-ELF cabinet full range.

So much for background, I haven't a clue what this means for reverb or other effects. I keep thinking I would like to use just a tiny smidgen of reverb (non-digital...), and if I ever get around to it, I would want it on the lows even more than the highs.

So I'm curious to hear more about the configuration here, and what it means to not get a clean tone.

keith_h · « **Reply #4 on:** May 01, 2006, 07:34:04 AM »

Bob pretty much covered it all. There is one other thing that the integrator does and that is compensate for the different time delays between the low, mid and high frequencies. I run mine with the ELF handling both the lows and the highs (stereo mode on the ELF unit).

Keith

David Houck · « **Reply #5 on:** May 01, 2006, 05:03:24 PM »

Adam; Hah! It probably says something about the state of my social calendar.

Michael; as Bob and Keith have responded, the Elf is essentially a crossover. I have a mono signal going in, with the sub out and a mono high out.

Bob; re not get a clean tone. It's very distorted even at low volumes. And it's not warm and fuzzy distortion, but jagged. Not the kind of thing you want your speakers to reproduce.

Bob; what was it you wanted to know about the configuration? Are you asking about the entire signal path?

bob · « **Reply #6 on:** May 01, 2006, 07:04:24 PM »

I guess I'm not sure what I'm asking about... so you should probably just skip it.

Even if you described the entire signal path, I wouldn't understand enough to know why you were getting the kind of distortion you describe. You seem to be suggesting that it has to do with the ELF integrator somehow, but we don't really know why or how.

David Houck · « **Reply #7 on:** May 02, 2006, 06:22:42 AM »

Bob; my guess is that by putting the direct box in front of the Elf I was creating an impedence mismatch. I am in an area here in which I have no knowledge or skills.

Normally, in a bass or guitar rig, everything is connected together with 1/4 jacks. And generally, I've come to associate 1/4 jacks with high impedence and to associate cannon jacks (mic cables) with low impedence.

When I purchased my reverb unit (T.C. Electronic M*One XL), I had not focused on the fact that all of the connections were cannon connections. This unit was probably designed for studio use rather than for a bass rig. I had some 1/4 to cannon adaptors around the house and used those to connect the reverb unit to everything else. I had a lot of problems with noise which I attibuted to an impedence mismatch, but by reducing the amount of signal going in to the reverb unit I was able to get it to work.

I subsequently received suggestions from a couple people to put a direct box in front of the reverb unit. That worked very well. The reverb unit is much happier.

When I got the Elf, it too only had cannon connectors and I used the adaptors once again to connect to the rig. (The power amp has cannon inputs in addition to 1/4 inputs, so mic cables connect the Elf to the power amp.) If the Elf gets too much low end signal, it will distort. I have noticed that I can attentuate that with the compressor/limiter; and for the most part it's not a problem. But it did get me to thinking that perhaps there is an impedence mismatch here like there was with the reverb unit and that by putting a direct box in front of the Elf it too would have a happier existence. But rather than solving an impedence problem I think I was actually creating an impedence problem by putting the direct box in front of the Elf. The Elf just did not like having that direct box connected to it.

bassman10096 · « **Reply #8 on:** May 02, 2006, 09:11:30 AM »

Dave: The distortion is definitely not right. I don't have anything like it with my (mono sub only) ELF configuration, but have not seen that when I've used the integrator in stereo as you have. My plugs are the same as you describe.

Have you talked to BagEnd? It's going back a year and a half or two, but Dan Saraceno, a BagEnd tech geek spent a ton of time with me working through a problem most manufacturers would have let me suffer with. His contact info was:
Dan Saraceno
Technical Support
Bag End Loudspeakers
(847)382-4550
ds@bagend.com

Seems worth a try at least.
Bill

David Houck · « **Reply #9 on:** May 02, 2006, 06:40:54 PM »

Thanks Bill; I'll give it some thought. I would want to have my ducks in a row first. My rig is setup around my Maple bass, and with that bass I'm not having a problem. But when I which to the '77, that bass just has a lot more low end. The problem may more accurately described (or not) as a square wave; kind of a low frequency slap. You're probably right; this might be something that the techs at Bag End may have run across before.