Double Bass Yamahiko output

[DoubleMIDI]

One last update, I’ve now tried three different capacitor values on patch cords. 3.3nf, 4.7nf, and 2.2nf. I didn’t play any gigs with the 4.7nf cord.

What I like the best is the 2.2nf value. It cuts the least from the output and seems to attenuate the upper mids the least as well. In a room playing by myself or on a nice quiet gig with no drummer, the 3.3nf sounds great, but overall the 2,2nf value is the most useful to me. It still removes the annoying clipping on the low E that I was getting, but it leaves plenty of output for loud gigs. It does tame the upper mids, not quite as much as the higher value capacitors, but on some gigs, i.e big band-with-loud-drummer, you need those upper mids.

My intention is to play a few months of gigs with the 2.2nf in the cord, and if I’m still happy with it, install a cap in the output jack of the yamahiko.

You might also want to try a value in between like 2.7 nF before you install a cap into the jack.

 

[Matt Power]

You might also want to try a value in between like 2.7 nF before you install a cap into the jack.

For those of us who are kinda stoopid, can you possibly show a diagram of how said fancy electric capacitor gets soldered into the circuit? Also, best source for a 2.7 capacitor?

Please don't blame me for missing a chromosome...I am also a percussionist. Ug.

 

[Endlesssolo]

You might also want to try a value in between like 2.7 nF before you install a cap into the jack.

I just used the three options that Yamahiko offers in their custom patch cords, I’m done experimenting. There’s not that much difference between the 2.2 and 3.3 nf in terms of output and sound. I would mostly advise anyone doing this to consider skipping the 4.7 nf unless you really want to pad the output.

 

[fdeck]

For those of us who are kinda stoopid, can you possibly show a diagram of how said fancy electric capacitor gets soldered into the circuit? Also, best source for a 2.7 capacitor?

Please don't blame me for missing a chromosome...I am also a percussionist. Ug.

Yeah, gimme a sec.

 

[fdeck]

Here's a part from my favorite distributor, Mouser Electronics:

Link Removed

Shown in the picture is a cap of the same shape and size, that I use in one of my products. I just laid it in, and didn't solder it, but you can see that each terminal of the cap gets soldered to one terminal of the plug.

Depending on the type of plug, it may require some bending of the wires to get it in so the cap will fit back on.

 

[Maple]

This is great info - thanks! I don't really need to attenuate my Yamahiko pickup with my current rig but this would have been good to know for other setups. I have two sensors on my bass but only use the bass side sensor. It seems to sound better than joining the two with the jumper.
I used to have two sensors blended with the Grace Felix and in an effort to downsize my gear, I have distilled it down to just amp and bass

Here's a technical question - maybe best for @DoubleMIDI or @fdeck -
Suppose someone has a two sensor yamahiko setup.
they install the attenuator capacitor into the jumper cable that goes between the two pickups.

My suspicion is that it will still affect both pickups equally. essentially the piezos and the capacitor act as three capacitors in parallel.
would there be a way to attenuate one pickup but not the other? Like by adding a resistor in line?
I've often wondered if a passive attenuator could make a second element work better.

 

[DoubleMIDI]

This is great info - thanks! I don't really need to attenuate my Yamahiko pickup with my current rig but this would have been good to know for other setups. I have two sensors on my bass but only use the bass side sensor. It seems to sound better than joining the two with the jumper.
I used to have two sensors blended with the Grace Felix and in an effort to downsize my gear, I have distilled it down to just amp and bass

Here's a technical question - maybe best for @DoubleMIDI or @fdeck -
Suppose someone has a two sensor yamahiko setup.
they install the attenuator capacitor into the jumper cable that goes between the two pickups.

My suspicion is that it will still affect both pickups equally. essentially the piezos and the capacitor act as three capacitors in parallel.
would there be a way to attenuate one pickup but not the other? Like by adding a resistor in line?
I've often wondered if a passive attenuator could make a second element work better.

View attachment 7224468

Francis can answer that better than me, but In my experience parallel passive wired piezos loose some of the frequency content to the other piezo as piezos are sensors and actors and get driven by a received voltage.
It is simpler to manufacture and cheaper to just connect piezo sensors with a cable in parallel, so this is the standard, but it does not give you the best results.

For the resistor you need to look at the whole thing in front of the first amp stage that is at least the input impedance resistor in the (pre-)amp.
These two resistors act in series and depending on the impedance defining resistor reduce the volume of the first piezo at a different amount (and depending on the value has hardly an audible influence).
So one more thing that is dependent on the (pre-)amp connected.

I strongly recommend individual impedance buffers for both sensors, with a phase flip for one or both of them. Then connect the outputs (after a 10kOhms resistor on both outputs to avoid a short circuit). Anything else can be handled by the amp connected.
It would also not be very complicated to add a second buffer (3-4 resistors, a JFET and maybe a small capacitor and a jumper) in a HPFpre, but that would need a new PCB, so I doubt that will happen (at least soon). A TRS cable could be used to transport both signals individually from sensor jack to preamp and that wouldn’t need a change in the HPFpre case at all. But the room might be too limited in the case for a larger PCB. Would work with mono TS cables too as the plug will shorten the second (ring) buffer, so no noise from an open input. Just don’t use a TRS cable for a mono (TS) jack on the transducer side as that will give you an open input on he ring.

Here is the story how I found out that buffering individually is better for the sound:

Before I made a new pickup system for my keyhole Clevinger EUB that I bought used, I had a piezo disk below the bass bridge foot and a piezo sensor in a bridge slot between the upper two strings, wired in parallel.

When I disconnected the bridge slot piezo, the sound was much better, but the highest string weak in the amp signal. There was also a simple passive EBG tone and volume control which degraded the sound further.
My (non-ideal) amplification solution was to make a double impedance buffer, have a phase flip for one sensor (which I later hard wired to inversion), a mix pot behind and a (non-ideal) last stage to strengthen the signal for the passive EBG tone and volume control (with some slight modifications).

The sound is very good, but the output voltage is low because I used piezo disks (below the bridge feet) which are mostly bending sensitive for pressure, the JFETs I used were non-optimal (attenuating) and there was no voltage amplification happening (not enough room in the compartment for battery and a larger PCB). For more volume (amp gain already fully open) I use a small external amplifier to get more output, but also get a noticeable hiss that reminds me to change something in the future.

But I got compliments for the sound from members of my big band when I took it there once as they were used to hear the ply DB with an Underwood that resides in the rehearsal space.

 

[Endlesssolo]

I’m now looking for another 1/4” 20 Yamahiko element and the little jumper cable to try the dual element sound. On most gigs I’m very happy with the single element sound, but there are some scenarios where I simply need more edge. What I’m envisioning is the ability to just remove the jumper cable between the two elements on my quieter gigs but use both when things get loud and muddy.

So if anyone has one they would like to sell or rent, I would be very grateful.

 

[JBarz]

I switched to dual element in both my basses. It’s a double edge sword in that it evens out the timbre significantly through the whole range of the instruments, but there’s definitely a degree of phase-induced castration on the low end of the mid range. Sometimes I really miss those balls! Ultimately, evenness of timbre wins for me for what I’m going for these days.

 

[DoubleMIDI]

You might want to find a better soundpost position to have all strings equally well represented with one pickup element only.

 

[Endlesssolo]

You might want to find a better soundpost position to have all strings equally well represented with one pickup element only.

Can you elaborate on that? It sounds interesting.

 

[DoubleMIDI]

Can you elaborate on that? It sounds interesting.

I initially had the soundpost too close to the bridge foot (and maybe also too much inward) and needed a two element bridge wing pickup to get the high strings equally well represented. Didn’t work with E-side only, the high strings (specially my high C) was too quiet and weak in the pickup signal.
After my luthier put the soundpost more south (and probably outward, I think he said he shortened it a bit, maybe too much pressure too) single side pickups (bridge wing/foot E-side only, Full Circle, etc.) worked for all strings equally well.

 

[DoubleMIDI]

I had a bad experience overdriving an amp input of an amp that I have used with my bass a while ago with the single element Yamahiko on the bass side bridge leg.
Never had that problem with my own DB amp (GB Shuttle 3.0).

Anyway, I thought I should install a capacitor to lower the output for the next concert there.
I looked through my collection of electronic parts but only found a 1500 pF (=1.5 nF) and a 3900 pF (=3.9 nF) styroflex capacitor but no value in between. Thought I should try both and used a Carlsbro BG amp that was ready to be used.
The 3900 pF dropped the volume (only tried the higher strings) so much that I hardly heard anything out of the amp. The 1500 pF was better but below the manufacturers recommendation of 2200 pF.

So I thought I should check the capacitance of the Yamahiko. I have a cheap Chinese multifunction meter that can check a lot of things displaying the result on a graphic display. It‘s cheap but works well and the capacitance of the piezo was displayed as 1200 pF (=1.2 nF). The value of the other capacitor was also displayed correctly compared what was stamped onto them.

Since the bridged dual element Yamahiko has no problems with an output volume overdriving an amp input and this means two capacitances of 1200 pF each in parallel, 1200 pF should be the safe lowest capacitance to be installed in parallel (means hot to ground) to lower the output volume to a safe level. So my 1500 pF capacitor should be safe.

But when I tried the lower strings with the capacitor installed, they were extremely boomy, even still when the bass eq was turned down completely.
Maybe the higher frequencies were a lot more attenuated than the lower ones which would result not such a body sound.
This was not my experience with my GB Shuttle 3.0 and no installed capacitor where I thought the bass is even a bit weak, compared to a lot of other bridge mounted pickups.

I have no idea what the input impedance of the Carlsbro is, but probably a bit low. Putting an Ehrlund preamp in between (4.7 MegOhms) made it much better, need to check a 10 MegOhms preamp tomorrow.

I didn’t expect that, so I need to check without the capacitor again tomorrow. And maybe the GB amp too.

In two days I have a big band concert with that amp that didn’t work with the Y last time. Since the bass I usually play there was not available in two of the last rehearsals I decided better to bring my own. More or less last second.
If I don’t find a good solution for the Yamahiko and that amp I may need to use the Shadow NFX (bridge foot pickup, but a bit soft sounding) or the Shadow SH-950 (bridge wing pickup) or bring my DB amp too.

Basically I just wanted to tell you the capacitance of a Yamahiko piezo element and that the range of experimenting might make sense to extend down to 1200 pF (1.2 nF).

I keep you up what I find out the next days.

 

[JBarz]

That’s interesting, but if I may - you might have different, more desierable results with some non-polarized little green film caps …. I don’t really know what I’m talking about, but I do wonder if different styles/types of capacitors may respond differently for this application

 

[DoubleMIDI]

Styroflex capacitors are non-polarized axial synthetic film capacitors.
I don‘t think anything else (except glass capacitors) are better.
But I continue my testing in a few minutes.

 

[JBarz]

Neat! Like I say, pardon my ignorance. Excited to see what you come up with!

 

[DoubleMIDI]

Well, testing done, gig done (but with my GB).
I think I read (probably from @agedhorse) that the GB Shuttle 3.0 has a built-in highpass filter.
That’s the reason why I was so astonished that with the Carlsbro amp I got so much bass.

A slight resonance changed (or got introduced after installing the 1.5 nF capacitor, but that might also depend on the input impedance of the amp.
So best to use an high impedance buffer/preamp when using different amps.

BTW, I used the GB Shuttle 3,0-10T together with GB Focus 112 for the BigBand gig. Enough power even when it got louder. The -10T alone might have got to it’s limits but the Focus 112 sounds nicer and the -10T gives some punch to the band.

So, the capacitor stays in the Y-jack.

 

[agedhorse]

Well, testing done, gig done (but with my GB).
I think I read (probably from @agedhorse) that the GB Shuttle 3.0 has a built-in highpass filter.
That’s the reason why I was so astonished that with the Carlsbro amp I got so much bass.

A slight resonance changed (or got introduced after installing the 1.5 nF capacitor, but that might also depend on the input impedance of the amp.
So best to use an high impedance buffer/preamp when using different amps.

BTW, I used the GB Shuttle 3,0-10T together with GB Focus 112 for the BigBand gig. Enough power even when it got louder. The -10T alone might have got to it’s limits but the Focus 112 sounds nicer and the -10T gives some punch to the band.

So, the capacitor stays in the Y-jack.

There are a couple of things going on aside from the HPF on the amp. The input impedance is 1M which helps reduce the resonant peak(s) from the piezo pickups. This under-damped resonance is one of the major disadvantages of a 10M input impedance. The other is the greatly increased tribo-electric noise from the cable combined with the increased noise floor from the preamp itself.