Review: Underhill Dual Filter Onboard Preamp

[bowthing]

Great review. I am currently testing out the ACG and Lusithand preamps. There are things I like very much about both.

OP, can I ask, what specifically did the Underhill add, the Wal-like the richness you speak of, that the other two lacked?

You might talk to Octave basses. He builds Wal-like instruments, and recently built one with an Underhill preamp. He could comment on the sound differences.

 

[SuperFunkyPete]

You might talk to Octave basses. He builds Wal-like instruments, and recently built one with an Underhill preamp. He could comment on the sound differences.

As a matter of fact, I just asked that question on his FB page, awaiting an answer I hope!

 

[slowburnaz]

Well now... this preamp intrigues me. I must get my hands on one.

 

[deepestend]

I'm intrigued by this as well. Has anyone tried one on a jazz type bass?

 

[mrperkolator]

I'm intrigued by this as well. Has anyone tried one on a jazz type bass?

@LowEndLobster put a Lusithand NFP on a Sire Jazz, and a Sire Fretless Jazz. Not exactly the same, but probably same ballpark.

 

[mrperkolator]

 

[bowthing]

The ACG HPF becomes necessary (IMO) because both of the LPFs in the ACG EQ-01 only go up to 3K or so (IIRC)- though without it boosted you essentially have it shut off. I believe the Wal and definitely the Alembic filters (as well as the Lusithand) all go up higher on the LPFs and so that extra control to add highs isn’t really needed in a 2-pickup + 2 filter arrangement (set one pickup with a higher LPF frequency for highs and the other with a lower LPF frequency for punch + character).
I await the newer version of the Underhill that is shown as coming soon that will have adjustable boost at the cutoff

I now have a variable boost filter (0 - 10dB), and a switchable filter 6dB/11dB. All the pieces have been made smaller/cheaper as well. Should fit in just about any bass!

 

[mrperkolator]

I now have a variable boost filter (0 - 10dB), and a switchable filter 6dB/11dB. All the pieces have been made smaller/cheaper as well. Should fit in just about any bass!

Do you have any videos of it in use? Have you considered letting a bass YouTuber demo it? There are several now, not just Lowendlobster. It would make for good content for your website too. I'm rather comfortable with techie stuff, but my brother (better musician) has no clue about tech, but can play better. He would get confused and just ask how it sounds. He cant be the only musician like that. Just a thought. I do enjoy reading the technical details on your site, and here

 

[WG Plum]

Oh my... if those Octave basses really sound like Wals I could be in trouble.

 

[bowthing]

Do you have any videos of it in use? Have you considered letting a bass YouTuber demo it? There are several now, not just Lowendlobster. It would make for good content for your website too. I'm rather comfortable with techie stuff, but my brother (better musician) has no clue about tech, but can play better. He would get confused and just ask how it sounds. He cant be the only musician like that. Just a thought. I do enjoy reading the technical details on your site, and here

That's a great idea. I've been avoiding getting into video, but could really use some.

 

[sunbeast]

Oh my... if those Octave basses really sound like Wals I could be in trouble.

They do look great, and are definitely cheaper than a Wal (though still a major investment!)

 

[sunbeast]

I now have a variable boost filter (0 - 10dB), and a switchable filter 6dB/11dB. All the pieces have been made smaller/cheaper as well. Should fit in just about any bass!

I love all the options you have now. May have to sell something and try one out!

 

[deepestend]

That's a great idea. I've been avoiding getting into video, but could really use some.

yes. I’d love to really hear it. The lobster video is fine but frankly shows off a lot of novel tones that wouldn’t sound good in a mix. I really want to know what this will do for a bass in a mix and how well the buffered mix works.

 

[WG Plum]

They do look great, and are definitely cheaper than a Wal (though still a major investment!)

Reached out to Octave, and they're not making a Mk 1 style bass at this point. Oh well. I'm not interested in a Mk II or III body shape. I'm on the Wal list for when they open up orders again, so back to happily waiting for the real thing.

 

[deepestend]

@bowthing I can see that you now have a jazz bass type preamp on your site... it has three knobs. I have four holes in my jazz plate (side jack). What would be a good way to fill that fourth hole? A filter module? Wait for your bass/treble module?

 

[bowthing]

@bowthing I can see that you now have a jazz bass type preamp on your site... it has three knobs. I have four holes in my jazz plate (side jack). What would be a good way to fill that fourth hole? A filter module? Wait for your bass/treble module?

Try a filter on each pickup. A lot more sounds. The Jazz setup with single filter is pretty similar to a normal tone control. Another option would be a single variable filter. One knob for frequency and one for resonance (plus volume and blend). A broader tone control.

 

[mrperkolator]

That's a great idea. I've been avoiding getting into video, but could really use some.

I just suggested this because the youtube guys already know how to do all the little stuff behind making a decent video. Most of them are content hungry, so as long as nothing derails they seem happy to make videos. It's the big companies trying to force them to be essentially a commercial they dont like.

I'm not in their shoes, but I'd probably be cool with you asking "can you include this test in your video."

and the plus side is... you dont have to get into video!

 

[deepestend]

Try a filter on each pickup. A lot more sounds. The Jazz setup with single filter is pretty similar to a normal tone control. Another option would be a single variable filter. One knob for frequency and one for resonance (plus volume and blend). A broader tone control.

I'm intrigued. I wish I knew more about what I want. I have an EQ pedal that can take care of most of my EQ needs (tech 21 Q/strip), but would love to be able to make my pickups sound a little bit bigger/fuller and tune them to the mix (figure out where that sound fits in). In terms of this preamp, what filter am I looking for? This is for a J style with Nordstrand Big Splits.

Also, does a filter preamp make sense with regular pickups? I know that part of the alembic secret sauce is that their pickups are so low impedance.

 

[NKBassman]

Try a filter on each pickup. A lot more sounds. The Jazz setup with single filter is pretty similar to a normal tone control. Another option would be a single variable filter. One knob for frequency and one for resonance (plus volume and blend). A broader tone control.

After reading through this thread yesterday I perused your website and I'm intrigued... I wish I had a bass I could put one in! I really like the modular setup.

I was wondering if there's any way to get the variable filter Frequency and Boost controls on a single stacked pot?

 

[sunbeast]

I'm intrigued. I wish I knew more about what I want. I have an EQ pedal that can take care of most of my EQ needs (tech 21 Q/strip), but would love to be able to make my pickups sound a little bit bigger/fuller and tune them to the mix (figure out where that sound fits in). In terms of this preamp, what filter am I looking for? This is for a J style with Nordstrand Big Splits.

Also, does a filter preamp make sense with regular pickups? I know that part of the alembic secret sauce is that their pickups are so low impedance.

I’ve used filters with normal pickups and they work just fine in most use cases- what the low impedance pickups offer is a much wider and less peaky natural response. The resonant peak of the Alembic pickups happens above the highest cutoff point of their low-pass filters so there is no ugly point on the sweep with a huge resonance and the filters see a relatively flat frequency response to play with. Typical passive pickups will have a much lower resonant peak so somewhere in the top of the sweep of the filter you may not here much effect and at some point you may get a giant (possibly even slightly clipped depending on the headroom of the preamp) peak where the filter freq meets the resonant freq of the pickups.
I’ve used the ACG and Lusithand filter pres successfully with both passive and active pickups and I think they are awesome and would totally endorse both. I currently have one of the J-Tex filter pres ready to drop into something and hopefully at some point I’ll pick up one of the @bowthing ’s setups as well.

I would recommend grabbing one of the current single filter options with adjustable Q (for me having a significant Q peak available is key) and popping it into an external box to see what it can do for all your basses, then if you dig it you can configure something more versatile for an onboard filter pre (where you can have separate filters per pickup directly interfaced with the pickups).