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Pedulla MVP-5 Preamp/Pickup Problem

VirtuallyReal

VirtuallyReal

Oct 15, 2009
73
0
West Palm Beach, FL
#1
My MVP-5 is making a weird noise every time i turn the blend pot to the center position or to the bridge Pickup. The only way i can make this noise stop is by turning the blend pot all the way to the neck pickup. The bass is a PJ, 1990 Pedulla MVP-5 with original Barts (Pickups and pre).

The only way i can describe the noise is as if you put a microphone in front of a fan... is a noise extremely similar to the sound resulting from breathing slowly and steadily to an open microphone.

I already replaced the blend pot with an original replacement, bought directly from Pedulla.

Pickup output is business as usual; the sound of the bass is the same great sound i'm used to, only with the added, annoying noise i described.

I'm more of a Bridge pickup kinda guy, so this problem have made one of my preferred instruments barely usable... this is driving me insane. Help!
 
#3
SGD Lutherie said:
I think that's a single coil bridge pickup, so it sounds like you are picking up interference when it's in the circuit.

Does this happen everywhere? I'm wondering if you are in a location with some kind of noise source.
Click to expand...

yes, it only happens with this bass, and Nope... it doesn't sound like the typical hi-pitch noise that interference tend to produce; is more of a low-freq sound... i never heard something like that before.

None of my other basses and guitars have ever made such noise, and all my amps are dead quiet, so i don't think is ground/power source related issue either.
 
#4
This one is a head scratcher for sure!

I wonder if you ran the bridge pickup right to the jack if it would make that noise.

I use a 1/4" jack with some wires and alligator clips for testing pickups.

I can't see how the pickup would be crating that noise itself, so the question is what is generating that noise. It might be from the preamp, and then is being picked up by the pickup.

If you try isolating the pickup to the amp, try it with the pickup powered on and not to see if that's part of the issue.
 
#5
Thanks SGD, i'll try that tomorrow.

In a unrelated topic, now things just got even weirder with this bass: i was planning to replace the original preamp on this bass anyways (Stock Bartolini TB/BT Preamp) with an Aguilar OBP-3 (with Stacked Bass/Treble and Push-Pull Mid Pot) and today i did just that, with the help of my tech guy.

We did everything by the book, but when we plugged the bass it just failed to operate. We kept the original Volume and blend pots in it (Aguilar recommends to use the pots suggested by the Pickup manufacturer, and since everything on my bass was original parts, and both the preamp and pickups are made by Bartollini, we assumed that using this same original pots were the way to go)

We also kept the stereo Jack, and then replaced everything else with the parts included in the Aguilar Kit; we even made a pretty decent (cooper foil tape) shielding cage and installed two 1Meg Resistors in the Mid Pot to avoid the click noise it tends to produce; we did everything just as Aguilar suggests.

I just went from head-scratching to hair-pulling!

I'll post some pics, hoping that maybe one of you guys see something we did wrong, (needless to say, i already double-cheked every single wire looking for a misplaced soldering) because, sincerely, we have no idea of what the heck we are missing.

First the weird noise on the bridge pickup... now this... i guess once i manage to solve this puzzle, i'll keep this bass forever! :)
 
#6
Shielding
 

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#10
Honestly, i don't know if the Pickups are active or passive.

The original preamp on this bass is a Bartolini TBIBT, which i just found out (minutes ago) that is basically an NTBT with buffered blend control. Buffered blend are usually present within active pickups (or so i've heard), but given this new piece of info i just gathered, my first action would be to try with a non-buffered blend pot to see if my bass come back to life.

I understand that the OBP-3 Pre works with both passive and active pickups, but to be honest now i'm a bit confused because i just removed the bridge pickup and all i found in the bottom was a hand made inscription that reads "59V66", and i just couldn't find any info on the Bartolini site regarding such pickup model.

Maybe this pickup+preamp combination needs a different blend pot... maybe the bridge pickup had gone bad (that suggestion of wiring the pickup directly to a jack to rule out that sounds good)... y have a couple of "maybe's" already, so tomorrow we'll see! thanks everyone for your help!
 
#12
also i found this info on the preamp; it says it is a PASSIVE preamp so now im really confused!

please check out this link:

Invalid Link Removed

Does that means this bass has Active pickup and a Passive preamp? this preamp does uses a 9 volt battery, but since this info says that the tone control is passive (preamp), does it means that the battery is for the pickup?

Maybe is a dumb question; sorry, i'm no expert in electronics, but if someone could clarify this to me it would help a lot.
 
#13
If the pickups are active, would i still be able to test them by wiring them directly to a jack?
If not, what is the correct way to wire an active pickup using the Aguilar OBP-3 preamp?
The instructions on the OBP-3 have no specific info on how to wire active pickups, or even where to wire the pickup ground.
 
#14
VirtuallyReal said:
Buffered blend are usually present within active pickups (or so i've heard)
Click to expand...

Not true. Active pickups are already buffered, so they don't need further buffering.

Invalid Link Removed

Those Barts are passive. You wold have a red power wire coming from them if they were active. Bartolini only made a couple of active pickups over the years; 8TC Active P-Bass, 9E Active Jazz, 9E Jazz with NTMB.

I have a customer with an 80s MVP-5 and it has passive pickups. His has an NTBT preamp.

Buffers for passive pickups prevents them from interacting, which is why most blend controls don't work well. As you start to mix the pickups they load each other down. Pickup loading (along with phase induced comb filtering) is also what partly contributes to that notched midrange tone when both pickups are on.
 
#15
Thanks; i wasn't sure of that, hence the "so i've heard".

So... what should i do? should i use a different blend pot? or should this "buffered" one will work fine with the OBP-3? i ask you this because last night i found out that the Bartolini TBIBT preamp (the one originally installed on my bass) is actually a passive preamp with 2 magnetic buffered inputs plus 2 band (Bass and Treble) tone control.

My tech guy is on its way, so we'll try all of your suggestions to see what comes out; BTW, you've been very helpful, thanks!
 
#16
VirtuallyReal said:
also i found this info on the preamp; it says it is a PASSIVE preamp so now im really confused!

Does that means this bass has Active pickup and a Passive preamp? this preamp does uses a 9 volt battery, but since this info says that the tone control is passive (preamp), does it means that the battery is for the pickup?
Click to expand...
I think it means it's for passive pickups, active ones should use different pots.
 
#17
When I joined your thread I decided to get my ThunderBass out for play after a year and found it had a different sound as always which I also post my thread here too.
Mine is with active soap bar pickups with buffer and 3 separate tone circuit. I always love the sound from this bass but not sure waht happen to it.
 
#18
Problem solved. Changed the Blend pot and everything worked just fine; apparently that old blend pot only worked with the previous preamp on the bass (the Bartolini TBIBT).

In the meantime, i simply "borrowed" the blend pot from another of my basses that also has an Aguilar OBP-3 in it, and everything worked just fine.

Thanks to everyone for the tips, specially SGD Lutherie for all the follow up; your tips were spot-on!

First thing we did was to test the pickup soldered directly to the volume pot, and it worked fine; then we bypassed the blend pot, connecting only the bridge pickup directly to the volume pot, and also worked fine.

So, there you go, that "buffered" blend pot was the cause of all my troubles.
Needless to say, now my MVP-5 sound killer with the added features of the OBP-3!

Again, thanks to all!
 
#19
Did the Bart preamp make a noise like this:

Invalid Link Removed

by any chance (a couple of strums with it on bridge pickup, then blend moved to neck pickup and another couple of strums to give an idea of the noisiness)? I've just bought a Sei with the TBIBT preamp in it and it seems to have the same problem. I suspect an issue with the buffer for the neck pickup - bass hadn't been used for years so perhaps something, maybe an electrolytic capacitor, has popped when powering it up again.

Is the TBIBT encapsulated? Mine's a bit tucked away so I haven't extracted it to have a good look yet.
 
#20
Sorry it took me so long to reply; that's EXACTLY the same noise my preamp was making. If you come up with a solution (other than disposing it) please let me know!

I already replaced this preamp with an Aguilar OBP-3 and my Pedulla MVP-5 is now a completely different beast! before the upgrade it was pretty awesome, now it went way-beyond-the-awesome-barrier.

if you fail to solve this issue with the bart pre, i highly recommend the Aguilar upgrade.
 

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