Double Bass Schertler Dyn B with Parametric EQ

[Monte]

For those who were interested by my experiments earlier, I had a friend who
is a great sound man help me find some good setting for making the Dyn B
sound better.

He listened both through studio monitors and headphones. As a reference, the
bass was also mic'd with an AKG 414. I told him that my goal was to make the
sound as close as possible to a good mic.

I used a Behringer Ultra Q PEQ 2200 5 band parametric equalizer on the
Schertler Dyn B, going through an Allen & Heath board.

Here are some of the settings that really improved the sound. Keep in mind
that these would obviously not be exact depending on instrument, placement
of the Dyn B, room, etc. However, they would be good places to start
fiddling.

First thing was the pass filters. We set the input level at zero, the low
pass to roll off below 40 hz. Left the high pass all the way up.

The most obnoxious frequency was found at about 150 hz. This is the one the
Schertler specs tell you about. We applied a bandwidth cut of about 0.8 with
the level at -5.

The second frequency we cut was at 350 hz. The bandwidth was set at 1.5, and
the level at about -3.

Last was a boost at about 1.8 k. The bandwidth was about 1.5, and the level
at about +4.

When all was said and done, the difference between the AKG 414 and the
Schertler was pretty negligible. The biggest difference was the cut at 150.
The other two settings helped but were not as drastic.

Monte

 

[Vunz]

Thanx for the review of the test. It was really informative. One question, though: did you also experiment with the placement of the transducer, or was it at a fixed spot? I noticed that, by changing the position of the pickup, the resonance frequency was changed, too. This way, I can use the resonance filter on my Schertler preamp far more effectively.

Vincent

 

[Monte]

Thanx for the review of the test. It was really informative. One question, though: did you also experiment with the placement of the transducer, or was it at a fixed spot? I noticed that, by changing the position of the pickup, the resonance frequency was changed, too. This way, I can use the resonance filter on my Schertler preamp far more effectively.

Vincent

It has been my experience on two basses that I can generally find a spot that sounds clearest, so I leave it there and eq for the rest. I know pretty close where that spot is, so I don't really move it around.

I've never experienced the resonance frequency changing by moving it. On both basses I've used it on, Bb on the G string was really "honky" sounding, no matter where I put it.

I believe the resonance filter on the Schertler Pre-amp is set for the resonance around 150.

Monte

 

[Bob Branstetter]

If I'm correctly understanding what you guys are talking about, I believe you are actually talking about filtering out the 1st harmonic of the true resonance frequency of the body (A0). The true resonance frequency of the body for most of the instruments I've tested falls in the 70 to 80Hz range.

 

[Vunz]

I've never experienced the resonance frequency changing by moving it. On both basses I've used it on, Bb on the G string was really "honky" sounding, no matter where I put it.

I believe the resonance filter on the Schertler Pre-amp is set for the resonance around 150.

Monte

interesting... When I changed the position of the pickup from appr. the middle of the top to a position above the soundpost, I was able to filter out the exaggeration of the lower mids far more easily. Where have you positioned the Dyn-B, and between which positions did you change?

BTW, the frequency of teh Schertler preamp is set at 180 Hz.

Vincent

 

[Monte]

interesting... When I changed the position of the pickup from appr. the middle of the top to a position above the soundpost, I was able to filter out the exaggeration of the lower mids far more easily. Where have you positioned the Dyn-B, and between which positions did you change?

BTW, the frequency of teh Schertler preamp is set at 180 Hz.

Vincent

I moved it several places below, under, and above the bridge. It now sits below the bridge a couple of inches, and slightly to the G side of the bridge from the center.

I knew that about the Schertler Pre amp. I have also seen that they have said before the frequency is 150 and others where they say 180 (like in the Pre A II manual). I know that where mine was positioned, the clarity was better at 150 than at 180, which explains why the Pre AII made things clearer than no preamp, but it wasn't perfect. Maybe your positioning does change the resonance to closer to 180 than 150.

The thing I like about not using the Pre AII is that a parametric doesn't add any gain to the signal. When going directly into a PA, you aren't preamping the signal twice, which seems to keep the signal cleaner and distortion free at a higher volume. I often found that when using the Pre AII, I would have the gain on the Pre AII set as low as possible, which meant I really had to jack up the volume at the board to get any volume.

Of course the Pre AII is the right solution when playing into the Pub speakers and not using the house PA.

Monte

 

[Vunz]

The thing I like about not using the Pre AII is that a parametric doesn't add any gain to the signal. When going directly into a PA, you aren't preamping the signal twice, which seems to keep the signal cleaner and distortion free at a higher volume. I often found that when using the Pre AII, I would have the gain on the Pre AII set as low as possible, which meant I really had to jack up the volume at the board to get any volume.

In my experience, when using the dry out output on my PreA II the gain poses no problem. It acts just as a regular DI out. Only the "wet" output has a significant increase in gain. Do you give the Dry out or the wet output to the board when using the PreA II?

Vincent

 

[Monte]

In my experience, when using the dry out output on my PreA II the gain poses no problem. It acts just as a regular DI out. Only the "wet" output has a significant increase in gain. Do you give the Dry out or the wet output to the board when using the PreA II?

Vincent

I use the dry out. The problem is that you have both the gain on the preamp and the gain on the board. Both have to be up for it to work, but you lose clarity. I really wish there was a way to bypass the gain and use just the resonance filter.

The wet works fine into the Pub speaker by keeping the gain below 50% and using the volume knob to increase the volume.

Monte

 

[Happy Steve]

I have been gigging with the Dyn B lately. Monte's settings worked pretty well in an Impulse response I generated. They work even better on my Presonus Eureka, as I have the option of 80Hz hpf.

Trawling through the Dyn B stuff on TB, I found this in an old classified ( SOLD - Schertler Acoustic Preamp for Dyn-B Bass Transducer )
Hopefully this picture can settle this long-standing dispute re 150Hz vs 180Hz ...

I have one of these old preamps, and I pulled the 'filter' out, and mine had '150' underneath.

Steve

 

[Co.]

The placement of the Schertler Dyn is very important, since it is going to influence your choice of filtering a lot.
While I stick to Schertler's recommendations for playing live, for recording, the best place I found, was on the bass bar, a few cm obve the foot of the bridge. Not much brightness there, but the most natural dynamics, without nasty resonances.

 

[Happy Steve]

Thanks for this tip @Co. I had not tried that location before I saw your post, and it works well on my bass. It is now my 'go to' location for the Dyn B, and very repeatable.


I find I am still using the preamp 'Resonance' control anywhere between the 'Stage' and 'Studio' positions depending on how close I am to the speaker, plus volume level. I increase it until I can't hear any more 'echo' within the body of the bass. I have been using a little Roland AC60 amp, and it required a bit of extra bass, but no more fiddling with mids to get rid of those nasty tones.
I had two gigs this weekend through supplied Ampeg SVT backline amps with 4 x 10" speakers on small stages. I ran the Schertler pre ( the old version 1) XLR out (no EQ) to a Shure transformer into the SVT effects return (so no EQ on the amp either) and everyone was happy with the sound. No feedback except for transmission up through a bouncy spot on the stage on one sound check - that was quickly solved with a bit of carpet and a twist of the polarity setting on the Dyn B XLR.

(Happy ) Steve