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Double Bass DI box with piezo pickup?

Gruff

Gruff

May 19, 2021
338
730
Wales, UK
#1
I have a double bass fitted with a Realist Life Line pickup, and another about to be fitted with Realist Copperhead pickup. In rehearsals I either connect the pickup either directly to a Markbass "Little Marcus 250" with the gain turned up a bit, or via a Boss GEB-7 preamp/EQ pedal.

We have a gig in a couple of weeks with a PA, so I'm wondering whether just to stick with the GEB-7 and expect the sound guy can work with a jack lead. Or whether to get a DI box, and if I go that route whether to have an active DI straight from the pickup, or whether the GEB-7 with a passive DI box would work.
 
#2
If you want to use a DI directly following the passive piezo pickup, you need an active one with an input impedance of several MegOhms which are often hard to find. Typically the Countryman are cited to work well.
Keep in mind that with (almost?) any DI the input impedance of the DI and the amp are connected in parallel and lowers the total resulting impedance, in worst case the half if both are the same, otherwise just a bit more than half of the lower one.
So it does influence the sound at least a bit doing it that way.

If you connect an active or passive DI after a preamp, the preamp typically ha no problem driving amp and DI together, so this is a better solution if you use a preamp.
If you use a passive DI, get a good one. It‘s the quality of the transformer that can degrade the sound.

There might be a DI out in your amp that you can use. Most Markbass amps have an input impedance of about 500 KOhms, so you better use a buffer or preamp in front of it.

BTW, any active effect unit drives a passive DI well. Just make sure that the input impedance is at least 1 MegOhms.

Keep in mind that any change of your GEB-7 settings goes to the board as well if you put the DI behind it. That might be way you want, but don’t change the settings after the sound check unless you have a dumb board operator. Use the amp controls then to change your stage sound.
 
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#3
I never recommended sending the piezo signal unprocessed to the board, even with a quality buffer/DI. That leaves you at mercy of the EQ capabilities of the sound person, and that's a crap shoot unless you're playing some highly professional stages.

I learned this lesson the hard way thinking it would simplify my setup. It did do that, but boy did it complicate the gig. At least use your EQ pedal first, or even better a dedicated pre. Maybe that Markbass would even work well.

My signal chain that goes to my amp is identical to what I DI to FOH.
 
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#4
Radial makes two piezo-specific DIs. They are active, though, and requireds phantom power...no battery option. Both have high pass filters onboard. They are more expensive than a lot of passive DIs.

PZ-DI $260

pzdi-thumb-768x770.png

StageBug SB-4 $95

sb-4-34-thumb.jpg
 
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#5
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#6
Gruff said:
I have a double bass fitted with a Realist Life Line pickup, and another about to be fitted with Realist Copperhead pickup. In rehearsals I either connect the pickup either directly to a Markbass "Little Marcus 250" with the gain turned up a bit, or via a Boss GEB-7 preamp/EQ pedal.

We have a gig in a couple of weeks with a PA, so I'm wondering whether just to stick with the GEB-7 and expect the sound guy can work with a jack lead. Or whether to get a DI box, and if I go that route whether to have an active DI straight from the pickup, or whether the GEB-7 with a passive DI box would work.
Click to expand...

The Realist pickups are designed to just be plugged into any amplifier with a 1 Meg Ohm load. Unfortunately, nearly all of the Markbass Amps, including your Little Marcus 250 are set at 500 K Ohms. The best of the affordable DI’s is the Counrtyman 75, but before you purchase a DI, check with the sound person at the venue to see if they have a DI that will work with a Piezo pickup. Many of them will, but do your homework and check out the PDF’s on their DI’s Just my take. You could also definitely use the GEB-7 as your buffer preamp into the Markbass and use the DI on the Little Marcus 250 out to the P.A. :)

P.S. The input impedance of the Boss GEB 7 is 1 Meg Ohm, so that will work as a buffer preamp, but it’s just not a DI with a balanced output.:)
 
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#7
I highly recommend adding a high pass filter in your signal chain. A piezo will have the bwow sound to it in certain rooms and the hpf will tame that sound. I have a Broughton messenger which does both, a Broughton “always on” hpf which works as will as an FDeck hpf. All helpful. I sometimes use these with my orchid mute/DI (yes, I have too much gear) which also has a 10 Mohm input.

the funny thing is, my Acoustic Image amp can do it all without the gear I previously mentioned.

there are many ways to get you what you want. Sounds like you’ve got time to figure things out. Try what the guys above mentioned and think about an hpf. Good luck
 
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#10
To be able to win the battle against dumb board operators you need two preamps (or two in one with separate outputs). One for your amp and one for the board, that should have EQ, a HPF and a DI out. Both should be fed by a buffered piezo signal, so a simple piezo buffer can do that. (If you connect both to the passive piezo you have parallel impedances again which might be acceptable with 10 MegOhms input impedance for both.)
You don’t want to kill your carefully dialed in stage sound by dropping the bass EQ only because the board operator means bass needs (more) bass.

But there is a cheap solution for bad board operators. Pull the DI cable out and dial your stage volume a bit higher. Not the best solution, but probably better than what you had before.
 
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#14
Some great replies here, thanks everyone! Especially the recommendations for decent DI boxes. Lots to think over. Better I think to wait a while and work towards something decent, rather than something cheap now. Particularly as...

Ric Vice said:
use the DI on the Little Marcus 250 out to the P.A. :)
Click to expand...

is a great solution for this gig! OK, so I'll be the only one on stage with an amp, but I can live with that. :)
 

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#16
The Countryman is indeed 10Meg on the input. But the Thru is just a parallel link. So, if you run the Thru to your amp, the pickup sees the input impedance of the amp.

The Radial PZDI has a switch so the Thru can be configure as a parallel link or buffered. Set the switch to buffered and the pickup will only see the input impedance of the PZDI. The input impedance can be set to 220K, 1Meg, and 10Meg.
upload_2022-5-30_15-21-0.png



Per the Radial SB-4 bock diagram, the Thru is buffered on this pedal all the time.
upload_2022-5-30_15-18-44.png


The PZDI has a much richer feature set, but the SB-4 has a 5Meg input impedance, which may be closer to ideal (depends on the pickup).
 
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#17
Wasnex said:
The Radial PZDI has a switch so the Thru can be configure as a parallel link or buffered. Set the switch to buffered and the pickup will only see the input impedance of the PZDI. The input impedance can be set to 220K, 1Meg, and 10Meg.
View attachment 4706037
Click to expand...

Useful information, thanks! Yesterday a DI was just an abstract concept to me, today I start to understand a bit more about them!
 
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#18
Sounds like you have a solution for the short term, which is great! Long term I promise you it will be worth your money to get some kind of preamp/impedance buffer. There are a few lower cost, but still high quality options (not necessarily ascending cost order):

Platinum Stage Pro
Tonebone AC Driver
Headway EDM-1 HE
LR Baggs Align EQ

The last one doesn't have a DI, but is still a nice little box.

(Edited for spelling mistake)
 
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#19
Gruff said:
It's a mixture of bluegrass and folk-rock. The other guys are all using microphones or pickups of some kind (guitars, mandolin, banjos).
Click to expand...

If the band is amp-free, also consider the L.R. Baggs Para DI. I keep one in my gig bag for amp-less gigs because it has EQ controls and runs off a 9V battery when the board cannot supply phantom power. I first saw one in use by name bluegrassers like Sam Bush back in the 90s, good enough for Sam, good enough for me ;)

para-di-acoustic-guitar-preamp-di-2.jpg
 
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#20
I think the OP has figured out what to do for the short term and not have to invest in a proprietary DI. I always had this issue when I was using
my Walter Woods amps (I still have a Electroacoustic Ultra). For the most part the FOH sound companies in my area had Countryman DI's so it
wasn't much of an issue. Occasionally, I'd hit a smaller venue that used cheaper DI's but not that often. At this point almost every amp has
a DI built in, even that tiny BAM 200 has one. Sure they aren't the best, but they get the job done. His Markbass Marcus 250 has it's own DI
and the Boss EQ takes care of the input impedance moving it to 1 Meg Ohm which is perfectly fine for the Realist pickups IME. Just my take
of course.
 

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