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shoulderpet

Do active basses have the same mid scoop with both pickups on full as passive basses?

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Have pretty much always been a passive bass kind of person and was wondering, the passive basses I have played generally have a bit of a mid scoop with both pickups on, do active basses have the same mid scoop with both pickups on full? Thanks

 

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Assuming we're talking about an active bass with a preamp that has an EQ section then generally I would say you have much more control over how scooped or not the sound is than on a passive bass. 

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I'm not great with electronics, but I believe that in simple terms purely being active does nothing to address the natural scoop of a pair of pickups.

There are ways of creating a blend which doesn't lose volume compared to each pickup individually (it has something to do with 'loading', but as I say, I'm not great with electronics... and I don't know what loading actually is!)

I think the scoop really comes from phase cancellation as the two pickups 'hear' the same frequencies, but at fractionally different times and intensities. The parts of the signal which are out of phase with each other result in attenuation, or even full cancellation. Naturally this happens mainly in the mids where the voices of the pickups overlap the most, whereas the extended bass of the neck and the treble of the bridge tend not to interact so much.

Of course, as Cato says, with an onboard EQ you have the perfect solution to redress the balance to a degree!

Edited by Jus Lukin
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I don't know the answer to the specific question about a mid scoop, but an active pickup signal is "buffered" and doesn't interact with other signals when mixed. Two passive pickup signals will interact when mixed together, on the other hand. From the point of view of one pickup, bringing in the other pickup is introducing another coil in to the circuit. That changes the overall impedance of the circuit, which can change the frequency response.

Is it heresy to link to a post on Talkbass? If not, this is a decent explanation.

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4 minutes ago, bnt said:

I don't know the answer to the specific question about a mid scoop, but an active pickup signal is "buffered" and doesn't interact with other signals when mixed. Two passive pickup signals will interact when mixed together, on the other hand. From the point of view of one pickup, bringing in the other pickup is introducing another coil in to the circuit. That changes the overall impedance of the circuit, which can change the frequency response.

Is it heresy to link to a post on Talkbass? If not, this is a decent explanation.

Thanks for that, that link looks like interesting reading.  So what about a bass with passive pickups and an onboard active preamp ?

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19 minutes ago, shoulderpet said:

Thanks for that, that link looks like interesting reading.  So what about a bass with passive pickups and an onboard active preamp ?

I'd say it depends e.g. in my HB, before I rewired it, the pickups came together at a balance pot before feeding the active circuit, so it was still passive mixing, though the pot arrangement meant that there was always some resistance between them. Better preamp circuits such as the John East models buffer the signals before mixing them. EMG will sell you their Active Balance Control which does a similar thing for passive pickups. (I have some active EMG pickups on the way for my HB, as it happens.)

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Never noticed any mid-scoop on any of my passive basses.

I think a lot has to do with the pickups and the electronics involved.

YMMV

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Yep - one example would be the Fender Jazz with its VVT wiring. With both volume knobs on full, the two pickups are shorted together with no resistance between them. 

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Any mid-scoop is all to do with the position of the pickups. 

Change their positions either in relation to the length of the strings or the distance they are apart or both, and you will alter the scoop frequency and/or the amount of scoop. You may even find an arrangement where there is a mid-boost. The only way that active electronic can help is if the centre frequency of the mids control corresponds with the centre frequency of the scoop cause by the pickup positioning. Then you can boost that part of the signal to compensate.

Or you could wire them in series which will change it yet again.

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Non-loading preamps are EMG BTS/BTC, John East, and Audere. You can buy a separate mixer from Noll, called Mixpot. Practically all others have high-impedance (passive) mixing. Usually only the tone tweaking circuitry is low impedance (active).

Bourns has very functional blend pots, 250k / 500k MN, but as their type implies, they are high impedance.

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Most active electronics are done after the pickups are mixed together, so they are buffering the sound you would have anyway from the pickups in passive. However, with some preamps you can independently buffer each pickup and then mix them, which would change the loading and interaction between the pickups and change that scoop. The john east preamps do that, but most dont.

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On 25 February 2021 at 18:55, shoulderpet said:

Have pretty much always been a passive bass kind of person and was wondering, the passive basses I have played generally have a bit of a mid scoop with both pickups on, do active basses have the same mid scoop with both pickups on full? Thanks

 

In a word, yes - well all of mine certainly do. As others have said a mid control helps to adjust this.

On an HH Stingray I tend to run the bass with all EQ flat whereas with the bridge H soloed I would probably boost the bass and treble a little and cut the mid. The tone with the HH selected provides a great slap tone and the finger style sound is also excellent - a fuller sound than the traditional Stingray H sound (although that's selectable at the flick of a switch). I use the HH setting most of the time. 

I have a Sabre with 2 band EQ - I rarely run it with both Hs selected and usually have the bridge H and one coil of the neck selected - mellows the traditional H sound. 

Edited by drTStingray

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Ibanez uses a A/C taper blend-pot to mitigate the mid-scoop.

Another, better way would be to incorporate an active blend, but most active basses have passive pickups with passive controls that feed a preamp.

 

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On my Passive Fender Jazz Bass(VVT) you can hear the difference when the pickups are both fully open or when one is backed up a tinny bit.
I personally like the scooped sound and especially the sound with the neck Pickup backed up slightly. 

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On 25/02/2021 at 17:31, bnt said:

circuits such as the John East models buffer the signals before mixing

A few months ago I had 'discussions' with two East users who swear that their BH2 Bartolinis sound better with the East preamps, even in Passive mode.

That makes zero sense, unless that buffer is still active even in passive mode, which would make the switch name a misnomer.

 

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17 minutes ago, Killed_by_Death said:

A few months ago I had 'discussions' with two East users who swear that their BH2 Bartolinis sound better with the East preamps, even in Passive mode.

That makes zero sense, unless that buffer is still active even in passive mode, which would make the switch name a misnomer.

 

I don't think all east pickups do that, and obviously they cant in passive. However, maybe they do have some additional resistors between the output and the mixing, which might prevent the scoop.

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That would dull them down, while the response from the two folks who make the claim is that the BH2 sound more open (more highs) than when in the Passive switch setting with the stock preamp.

This is the Uni Pre 4-knob, in Ibanez Ergonomic Headless basses (EHB). I do wonder why they didn't get the 5-knob & drill out the hole for the active/passive switch. As-Is they have a switch on there that has no function.

 

Edited by Killed_by_Death
spelling

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A resistor wouldn't dull them. It wouldn't brighten them either. Maybe it is what they had so why they installed it
I wouldn't replace the ehb pre with the east pre either, it's pretty good on its own - I have an east in my Shuker, only problem going between them is the knobs are the other way round.

maybe I could get an east for my SR5005 - not many companies do a 6 knob one though

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The Resistance becomes part of an R/C filter, & it definitely takes some edge off the high frequencies:

rc-low-pass-filter.jpg

albeit, the capacitance will be mitigated in an active system (cable Capacitance is not introduced), but still exists

 

If you read back in my thread that I linked to in the Ibanez club thread, both the East users with EHBs specifically purchased 4-knob Uni-Pre.

 

Edited by Killed_by_Death
fixed the graphic

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The r/c circuit doesn't have much added by the R given there is also an L and a R already in the circuit and quite a complex filter network presented by the lead.

but as I said I don't believe the east preamp has much of a passive filter network that would brighten the signal (if any).

I presume they didn't want to drill holes in the ehbs. A little puzzled though as to why you would buy a preamp like that for an ehb that already has something very similar. Also why you would spend that much on a preamp and comment on how much better it sounded when it was off!

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I've measured the A/C taper pots Ibanez uses & there's 50k Ohms of Resistance when they're centered, enough to take off some high-end, but not enough to make the output volume suffer.

Of course passive controls won't make anything brighter, they're meant to subtract, not add.

Those two East users kept flogging in the East pre instead of new pickups, that's how that started, because I always recommended Nordstrand pickups instead of a different preamp.

If you don't like the sound of the source (the pickups), tacking on a preamp to make it sound better is like adding a band-aid instead of solving the real problem.

That's when each of them commented that their BH2 pickups sounded better even passive, which I still fail to believe, unless...

 

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1 hour ago, Killed_by_Death said:

 

The Resistance becomes part of an R/C filter, & it definitely takes some edge off the high frequencies:

And note that a R/L filter is also a thing, & it definitely takes the edge off the low frequencies.

1280px-Series-RL.svg.pngPut that together with the R/C filter, and you can see why I think passive mixing of pickups could affect the tone a tad. 

 

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