Bartolini HR 5.4AP/918 Harness 3 position toggle?

Hello everybody, new user here. Anybody have this pre-amp? Or know it? I can’t find much info besides technical specs, and I just don’t know what it does… I think its supposed to be cutoff or boost switch and I don’t know how it works, can’t figure it out, and I’m not sure if it’s even wired right.

I have a Peavey TL-5 Bass that had some issues a few years back with the electronics. I had the guts replaced with the Bartolini above. The Peavey pickups are the same. I didn’t do the job, and I never got to speak with the Technician that did it. Paid the bill and walked out of the shop.

Knobs-- Vol, Blend, HI, Mid, Lo are all good, and overall I like my tone and adjustments. It was definitely an upgrade.

BUT, I have a toggle switch that I don’t know what it does in each position? I have flattened my amp EQ and tried several times to play and see what I can figure out, but I’ve had no success.

Any help is appreciated. It drives me crazy to have a switch that I don’t know what it does or controls… it’s right at my fingertips. Thanks.

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It’s apparently a 3-position toggle for the frequency of the midrange knob. Nice feature, allows you to scoop or boost in different places.

Also, your volume should be a push/pull that bypasses the preamp (i.e. an active/passive switch). Another nice feature. Looks like a nice preamp to me.


Thank you, thank you, Howard. It does sound nice. One day coming out of the case/storage it just started crackling a lot with some garbled rumbling—kinda like a combination of dirty pots and a dead battery too. .

I knew about the volume knob. It pulls out easily… on/off.

I really appreciate the beta on the toggle. The original build had a 2 position toggle here that changed/active to passive. That was an easy switch to figure out.

This one has been more challenging.

So late last night, I did stumble into some of the functionality of the toggle— before your response. … it’s been driving me crazy. While playing thru headphones and ringing out some bigger whole notes I can hear the switch change settings when you flip thru toggle positions. I can hear some difference now via headphones…but honestly at low practice amp volumes it has evaded me…

The headphones made a huge difference. Now, I am wondering if I see the difference via a software program… I don’t own any studio software, but maybe Garage band has some kind of eq to check out? I do have an interface already for my Mac, so it’s easy for me to plug in.

Any thoughts on that?

Now I’m off… searchin for the sound…

Thanks again.

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Dunno about GarageBand, but Reaper has a plugin called ReaFIR that does a fourier-transformed display of the signal.

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