Double Bass Steve Rodby on amplification

[Greg Clinkingbeard]

Right! I NEVER even bring a pick up to a studio. If you even have it in the bag engineers will fight you for it!
Speaking of that heyday, Fred Hopkins always sounds great even though you can hear he has the grossest amp/pick up setup!

I spent three days in the studio in June cutting a jazz CD. Before going in, I got my bass sounding as good as possible. Quiver off, all buzzes fixed, endpin stuck firmly in the floor and the bass was really singing. The leader, playing piano grabbed the best mics for himself and the best one left for me was an AKG 414 so that's what I got. Not a bad mic at all but in the end it was moot. The engineer took a pickup feed (just as insurance ), but ended up mixing it in maybe 20%. The playback in the studio was beautiful so I didn't argue.

After the date, he and the guy writing checks got into an argument so the guy writing checks moved all the files to another studio which didn't use Pro Tools. In the process, the mic track (among others) didn't transfer so I was stuck with just pickup.
He then mixed it going for a 'Ron Carter' sound 'cause he 'wanted to hear the bass'.?.?.?

Long and short? IF I ever have to go direct, it will be signed in blood that nobody mixes it but me. The mic was beautiful so ***?

 

[Greg Clinkingbeard]

With regard to phase, he speaks as if the speaker output is either in phase or out of phase with the acoustic output of the bass. Nothing could be further from the truth. Amplifiers, tone controls, and speaker cabs produce phase shifts that can range from 0 through 360 degrees. The output of the speaker at a specific frequency might be 90 degrees out of phase with the output of the bass. In such a case, inverting phase will get you nowhere, as that will cause the phase shift of 270 degrees (basically back to 90 degrees). This is the reason that sometimes phase inversion does not substantially affect feedback at all.

I agree with you, but most preamps with phase correction only provide phase inversion. The Doubler is the only one I know of that is variable. Even then, I suspect that it would only be helpful for problem frequencies because, as you say, other frequencies may be reversed.

I've never found the phase inversion to be very helpful myself.

 

[Thunderthumbs73]

Wonderful. Listening now. So nice to see Steve's name pop up again. Thank you for sharing.

 

[drurb]

I agree with you, but most preamps with phase correction only provide phase inversion. The Doubler is the only one I know of that is variable. Even then, I suspect that it would only be helpful for problem frequencies because, as you say, other frequencies may be reversed.

I've never found the phase inversion to be very helpful myself.

So, what's the "but?" It seems you agree with the whole of what I said. Phase inversion aiding feedback is a crapshoot; sometimes it really helps and sometimes not. Both phase inversion and variable phase shift can solve a problem at one frequency and create a problem at another! It's really a somewhat complicated affair.

Geekazoid warning:
Moving your speaker different distances from the bass produces what's called a linear phase-shift (the phase-shift is proportional to frequency). This is the case of a pure time delay-- all frequencies are delayed by a constant time. Various tone controls and filters can impose further linear and non-linear phase-shifts on top of that yielding various "group delays."
End geekazoid warning

The bottom line is that neither phase inversion or variable phase over a broad band of frequencies would be expected to reliably fight feedback. What would likely work well would be phase-inversion and pure-time delay (best implemented via a digital delay-line). I don't think we'll be seeing anyone offering that combination on a bass amp very soon!

I think all such tweaking really yields diminishing returns. There are tried and true effective ways to fight feedback. UncleToad provided a fine list in another thread.

 

[PB+J]

I would agree--I've sometimes had the phase switch on the schertler work wonders and sometimes had it do nothing or create a different setof problems

 

[Greg Clinkingbeard]

The point I meant to make in spite of my poor communication skills tonight is that isn't flipping a switch on an Fdeck HPF, Fishman or any other phase inversion switch the same as inverting the phase at the speaker? I realize that I ended up not typing what I intended to.
You seemed to take issue with Steve's method and I want to point out that, unless I misunderstand how switches work, it has the same effect as flipping a switch on a preamp.

 

[drurb]

The point I meant to make in spite of my poor communication skills tonight is that isn't flipping a switch on an Fdeck HPF, Fishman or any other phase inversion switch the same as inverting the phase at the speaker? I realize that I ended up not typing what I intended to.
You seemed to take issue with Steve's method and I want to point out that, unless I misunderstand how switches work, it has the same effect as flipping a switch on a preamp.

Ah, I see. You are absolutely right. A phase-inversion switch has the same effect as flipping the connections at the speaker. I didn't mean to take issue with Steve's method. I just was pointing out that he was speaking as if the output from the speaker is either in or out of phase with the acoustic output of the bass when, in reality, it's much more complex. That complexity makes phase inversion (accomplished electronically or by flipping speaker leads) far less than the panacea he implies in terms of taming feedback. As we seem to agree here, it often doesn't help at all and there's good reasons for that, considering the physics. So, as I see it, you and I are in complete agreement about all of this.

 

[Gary Lynch]

I don't much about any on all this tech jive, but I do know one thing for sure. Buying an EA Doubler made my life a heck of a lot easier. Chanel #2 with the notch and phase controls and whatever else may be built into that amp was like a gift from the supreme powers of creation.

 

[drurb]

I don't much about any on all this tech jive, but I do know one thing for sure. Buying an EA Doubler made my life a heck of a lot easier. Chanel #2 with the notch and phase controls and whatever else may be built into that amp was like a gift from the supreme powers of creation.

Hey, if it works for you, then there's no arguing about it. I suspect the notch filter is especially useful for cutting feedback-- a technique that's been used for decades. It's interesting to go back and read this thread on the Doubler and seek out the highlighted term "phase."

 

[Ric Vice]

...... Not a bad mic at all but in the end it was moot. The engineer took a pickup feed (just as insurance ), but ended up mixing it in maybe 20%. The playback in the studio was beautiful so I didn't argue............

I had a very similar situation last October where I did a recording and I purposely warrned the engineer agianst using a signal from the Realist with the signal from the DPA 4099.
When I left the studion that day I liked the sound from the mic.

............ In the process, the mic track (among others) didn't transfer so I was stuck with just pickup. He then mixed it going for a 'Ron Carter' sound 'cause he 'wanted to hear the bass'.?.?.?

Unfortunately, when I got the mp3 to listen to the Realist was the only thing I could hear on the track and it sounded, well like a Realist. Ron Carter was using that sound at one time, but if you listen to the very early recordings he did with Bobby Timmons, he has a beautiful acoustic sound.

Long and short? IF I ever have to go direct, it will be signed in blood that nobody mixes it but me. The mic was beautiful so ***?

Clink I agree with you, so from now on my Realist is "broken"

Ric

 

[Gary Lynch]

Hey, if it works for you, then there's no arguing about it. I suspect the notch filter is especially useful for cutting feedback-- a technique that's been used for decades. It's interesting to go back and read this thread on the Doubler and seek out the highlighted term "phase."

Read it. You are right on. And compared to other DI's I've used with a notch, the EA Doubler notch and even the amp/ & cabinet with notch turned off has a lot less feedback for me. The phase shifting is something I do not have to use very often and is not as dramatic as the notch (for me anyway). I'm easy to please. I play all my inturments thru the Doubler and EA NL-210. I even use it for my Godin archtop which has one P-90.

 

[PB+J]

The notch is a good tool, I use it all the time. But Rodby's argument about impedance is interesting. I just remember what I thought when I plugged a full circle into an Avalon U5: I could still hear all the piezo-ish characteristics, but they were no longer harsh and grating. I'm assuming that was an artifact of a good impedance match, but maybe not.

 

[drurb]

The notch is a good tool, I use it all the time. But Rodby's argument about impedance is interesting. I just remember what I thought when I plugged a full circle into an Avalon U5: I could still hear all the piezo-ish characteristics, but they were no longer harsh and grating. I'm assuming that was an artifact of a good impedance match, but maybe not.

Well, as I've said, once that input impedance is high enough, you're good to go. That's why fdeck's pre/HPF is such a gem to have.

 

[PB+J]

You might indeed be absolutely right. But I'd kind of like to try it, to see if there's a difference. I can solder, and read a schematic. If it's a cheap thing to make I'd like to see if I hear a difference. I sometimes double on guitar, and I wonder if using a variable impedance would let me use one amp for both more easily.

 

[Vic Koler]

I spent three days in the studio in June cutting a jazz CD. Before going in, I got my bass sounding as good as possible. Quiver off, all buzzes fixed, endpin stuck firmly in the floor and the bass was really singing. The leader, playing piano grabbed the best mics for himself and the best one left for me was an AKG 414 so that's what I got. Not a bad mic at all but in the end it was moot. The engineer took a pickup feed (just as insurance ), but ended up mixing it in maybe 20%. The playback in the studio was beautiful so I didn't argue.

After the date, he and the guy writing checks got into an argument so the guy writing checks moved all the files to another studio which didn't use Pro Tools. In the process, the mic track (among others) didn't transfer so I was stuck with just pickup.
He then mixed it going for a 'Ron Carter' sound 'cause he 'wanted to hear the bass'.?.?.?

Long and short? IF I ever have to go direct, it will be signed in blood that nobody mixes it but me. The mic was beautiful so ***?

And this is why I never allow the engineer to take the pick-up unless it is someone I know well and trust.