Aguilar OBP3 mid frequency

[JHBassist]

I know this may sound like a dumb question but I just got the OBP-3 with the push pull mid control in my Spector and I'm wondering which is which? Like which position is 400 and which is 800 I'm not very knowledgeable about frequencies and what not since this is the first preamp I've had with frequency control. Sorry if that's an incredibly dumb question but I can't figure out which frequency is the pushed in position and which is the pulled position.

 

[FunkMetalBass]

You could look at the wiring, but the easiest way to tell is just to boost the mids all the way, cut the treble and bass, and just listen to each setting. The 800 Hz mode will be more clanky and nasaly. 400 Hz mode will sound thick and almost boomy.

I think the schematic shows 800 in the down position, 400 in the up, but I wouldn't assume that yours is wired exactly as the schematic shows.

 

[JHBassist]

Thanks for the info I appreciate it. I'm new to this preamp so I haven't figured it out completely yet.

 

[5StringPocket]

I have a Roscoe SKB3005 with Bart pickups and an Aggie OBP-3 with volume, balance, stacked bass/treble, and 400/800 switchable mids on a push/pull pot. 800 is a useful frequency for me but 400, not so much. Cutting took too much meat out and adding sounded kind of boxy. I heard 550 Hz was prominent in that singing fretless mwah sound and it also is where my Streamliner 900 amp has a pronounced dip so I wanted to check this out. I changed the low mid frequency on my OBP-3 preamp from 400 to 550 Hz with mid voicing Option #6 on page 5 of Aguilar's OBP-3 wiring diagram.
[Invalid or Expired Link Removed]
550 Hz seems to have a more musical sounding cut/boost than 400. Boosting this frequency also restores the normal Streamliner dip in that region, leaving me free to use the mid at 2500 Hz which sounds better with most of my cabs. Flattening out the mids this way (along with the Jan NOS 5751 in V1 position) really makes the STM900/Roscoe pairing sweet. I found this was a worthwhile improvement to the mid-voicing.

 

[Fingerz]

I've taken ownership of a bass with the ABP-3, and has a push pull mid frequency select/adjust pot.

When you are in one mode (frequency) or the other, does the pre remain set where you last left the other frequency? Or does that just become flat whilst you are in the other setting?

i.e: If I cut the 800, does that remain cut when I go into the 400 frequency and adjust that? Or would 800 revert to a default 'flat' position when it's not selected?

I would hear this in a band setting but it's really hard to tell at home on ears.


Thanks!

 

[5StringPocket]

I believe the mid cut/boost position stays the same when you shift frequencies. The cut/boost is a pot while the frequency select is an independent switch.

 

[Fingerz]

Thanks. I answered my own question when I plugged the bass into my hifi (don't have my amp set up at home often). As i suspected, it's a 'one or the other' situation, whichever frequency you're not using reverts to flat. Mine is an 18V, way too powerful but I think that headroom really helps keeps things sweet, just have to make tiny adjustments.
I thought I'd post my findings here FWIW

 

[chinjazz]

I have a Roscoe SKB3005 with Bart pickups and an Aggie OBP-3 with volume, balance, stacked bass/treble, and 400/800 switchable mids on a push/pull pot. 800 is a useful frequency for me but 400, not so much. Cutting took too much meat out and adding sounded kind of boxy. I heard 550 Hz was prominent in that singing fretless mwah sound and it also is where my Streamliner 900 amp has a pronounced dip so I wanted to check this out. I changed the low mid frequency on my OBP-3 preamp from 400 to 550 Hz with mid voicing Option #6 on page 5 of Aguilar's OBP-3 wiring diagram.
[Invalid or Expired Link Removed]
550 Hz seems to have a more musical sounding cut/boost than 400. Boosting this frequency also restores the normal Streamliner dip in that region, leaving me free to use the mid at 2500 Hz which sounds better with most of my cabs. Flattening out the mids this way (along with the Jan NOS 5751 in V1 position) really makes the STM900/Roscoe pairing sweet. I found this was a worthwhile improvement to the mid-voicing.

Hi @5StringPocket,

This is a very old post, but thought I'd ask a question if you recall any details from 9 years ago
Do you remember where you got the two caps for the Mid switch to get the 550 Hz?

I'm looking to try the same configuration #6 on the wiring digram.

C1 - 0.0016uF - I found this one: [Invalid or Expired Link Removed]

C2 - 0.072uF (Hard to locate, or identify one on the web).

I'm new to identifying, and experimenting with these sorts of caps on this finer detail level.

Also would like to know (for anyone else reading this thread) if for instruments, does it make any difference on type of caps to use? Outside of making sure they're rated for the desired voltage...

Thanks
Adam

 

[iplay5strings]

As KJung said, there's so much more to it than that. Marcus plays a bass with a 2 band preamp and has no problems getting a good slap sound

That's because he has hot wound jazz pickups running through a boost only Treble/Bass (originally TCT, now Sadowsky) circuit, which naturally creates a perceived mid dip from the treble and bass being boosted. So he's actually not cutting any mids (at least not from his bass preamp), they just aren't being emphasized like the treble and bass are.

 

[5StringPocket]

Hi @5StringPocket,

This is a very old post, but thought I'd ask a question if you recall any details from 9 years ago
Do you remember where you got the two caps for the Mid switch to get the 550 Hz?

I'm looking to try the same configuration #6 on the wiring digram.

View attachment 4736397

C1 - 0.0016uF - I found this one: [Invalid or Expired Link Removed]

C2 - 0.072uF (Hard to locate, or identify one on the web).

I'm new to identifying, and experimenting with these sorts of caps on this finer detail level.

Also would like to know (for anyone else reading this thread) if for instruments, does it make any difference on type of caps to use? Outside of making sure they're rated for the desired voltage...

Thanks
Adam

StewMac is a good place to start. I’d stick with small ceramic caps for bass preamps. Call them if you have questions.
Search - StewMac

 

[Modulus 96]

Hello there, just acquired a bass with obp3 pre with the push/pull mid pot, the instrument is a Modulus Funk Unlimited MM+J 5. The mid knob doesn't make much of a difference in tone when adjusted. In the "down" (push/pull) position, which I guess would be 400hz, there is no change in tone when rolled up or down. In the up/pull position (800 possibly?) there's an unexpected slight boost when I roll the knob down, but nothing to the other side.

Thoughts on the above? My first inclination is that the pot is wired up wrong, but I really don't know...