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Aguilar obp 3 volume push/pull

kuuuks

kuuuks

Supporting Member
Jul 22, 2010
600
388
#1
installing ob3 with push pull passive active. ....I'm using bourns 500k pot, I called bestbassgear.com to find see if I needed a resistor on the volume just like a mid push/pull and the guy said no also added that ALPHA is the only volume pot for push/pull that works well with aguilars...anyone used bourn or any other 500k for aguilar that's not alpha?
 
#2
Huh, they have really known their stuff every time I've dealt with them, but that does sound odd - I would have asked for a more detailed explanation. Working on a couple of OPB-3 setups myself, redoing the one in my Kania for sweepable mids, caps just arrived today.
 
#3
bholder said:
Huh, they have really known their stuff every time I've dealt with them, but that does sound odd - I would have asked for a more detailed explanation. Working on a couple of OPB-3 setups myself, redoing the one in my Kania for sweepable mids, caps just arrived today.
Click to expand...
He said the volume push/pull doesn't require any resistors and without the right pot there's a possibility of a pop sound when you engage it but with the Alpha pots he's used so many of them for push/pull active passive without getting any pops.....I'm just going to use the Bourns if it pops I will buy the ALPHA and swap it out....
 
#4
My OBP-3 wiring has a push/pull active/passive on the tone pot. I didn't use a resistor, and didn't worry about what brand pot I used. It doesn't pop. I'm going to be cracking it open in just a minute, anyway. If I can tell what brand the pot is, I'll post it here.
 
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#7
My Kania is wired with a simple sdpdt for active / passive, no resistor, no popping. What's so different about the pot switch that it should have the problem? (Hard to say without knowing exactly what causes the popping issue.)
 
#9
CrashClint said:
I had the Alpha pot on mine and it didn't pop. I think if I were to install another OBP3 I would go for a higher value pot on the tone controls as a little tweak makes a big change, I rather have more subtle change.
Click to expand...

What would you consider as a higher pot can you share some examples of higher pots please
 
#14
When an active-passive switch pops, technically the problem is with the preamp design, not the switch. The pop is usually an input or output coupling cap that doesn't have an earth reference. IOW, when the output or input is disconnected, it's floating, usually at 4.5V. Then when you connect a pickup or an output jack or whatever, it snaps to zero volts (earth) and creates the pop sound. The resistor that could bleed this voltage and keep that side of the cap at earth may have been overlooked in the design stage, because the preamp was never intended to be wired in a certain configuration. (I'm speaking in general here, and not specifically about aguilar products. I haven't installed one for a few years, so can't speak for the OP's particular pre.)

I can only imagine that the reason one push-pull pops and the other doesn't for a preamp with a floating coupling cap, is that one switch is make-before-break and the other isn't. Or the guy has old stock of one brand and the switch contacts needed cleaning. (Dirty contacts can also cause switch noise.)

As for using other value pots for an active preamp. I wouldn't recommend it, although you can't really hurt anything by trying I guess. If the obp3 is like most 3-band preamps with a 3-way baxandall wrapped around an opamp, then as long as the pots are linear and the same value, anything from 20K to 100k should work, although I'd think the centre frequencies might shift slightly, and the cut/boost range would also be effected. Again, just speaking generally here. An educated guess. Oh, and if you have a stacked treble and bass control, then you might have trouble finding a pot other than 50K that's linear anyway.
 
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#15
Good educated guess, it did slightly alter the center frequencies and it had a little effect on the cut/boost range, nothing horrible but I did notice it. You can get the 1ook pot here [Invalid or Expired Link Removed]


RobbieK said:
I'd think the centre frequencies might shift slightly, and the cut/boost range would also be effected. Again, just speaking generally here. An educated guess.
Click to expand...
 
#17
kuuuks said:
installing ob3 with push pull passive active. ....I'm using bourns 500k pot, I called bestbassgear.com to find see if I needed a resistor on the volume just like a mid push/pull and the guy said no also added that ALPHA is the only volume pot for push/pull that works well with aguilars...anyone used bourn or any other 500k for aguilar that's not alpha?
Click to expand...
the problem used to be the push/pull on old pot that the contacts were make-before-break. We used to modify them.
Now most of the p/p you buy from music supplier are break-before-make

at least this was the problem we encountered back then
 
#20
Hi! Rather than create a new topic I decided to reply here and resurrect and old thread. I am going to have a obp 3 installed in my bass. I have all the pots except the volume push pull (for passive active). The technician that is going to install the obp told me that there's no difference between DPDT pots or not and that both will work.
Is this correct because i read different things around the web.

Any help will be most welcome.
 

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