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redbandit599

Active Pre Amps - bass mostly 40hz?

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Just an observation really  but it seems that most on board active pre amps have the bass control centred at 40hz.

I know there are exceptions to this, but 40 hz seems bordering on the fringes of muddiness. 

Obviously everyone has a different idea of the perfect tone, but it seems quite a few of us regularly reduce or cut frequencies that low.

Just seems that 40hz seems to be 'standard' - am I missing something?

Edited by redbandit599
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Agree, I’d have thought 60 or even 80 a bit more use. 

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3 minutes ago, Lozz196 said:

Agree, I’d have thought 60 or even 80 a bit more use. 

Exactly my thoughts. My Dingwall has a Darkglass Pre which I think is at 70hz and that adds plenty of useful bottom, but there doesn't seem many that aren't 40hz.

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No idea what the bass frequency is set to , on the 3 band EQ's in my Stingray and Bogart , but it's higher than 40 , and very useful .

I had a SEI Jazz years ago with an Aguilar 2 band that had the bass set at 40 hz , and it was utterly useless .

Lots of people like these Aguilar 2 bands , and the Sadowsky one which is similar I believe , so what do I know - all taste as per normal .

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The bass control in the Sadowsky preamp I've got in a jazz is apparently centred at 40hz, but then I guess it affects a wider range and the low centre affects the shape of the curve in a way that's good for the "naturalness" of tone when boosted. It is a very audible control, affects and thickens all notes on the neck and doesn't get too muddy unless boosted stupidly high. 

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Yeah I could never get my head around the EQ section on Aguilar heads, where the bass control is centred at 40hz.  IMO this is much too low to be usable, and anything past around 10 o'clock on the Bass dial causes some seriously weird sounds out of 10" drivers.

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I've got a Bartolini NTMB in my Lakland 5501, and the bass on that is centred at 30hz. I've never found a need to boost it - it does seem a little muddy. However,  I often cut it a little - particularly when I boost the mids at 250hz.

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On a side note, I quite like the EQ on my TC Electronic BH550 head - it boosts and cuts at different frequencies. The bass boosts at 80, but cuts at 50. It'd be interesting to see this type of thing on an on-board preamp. 

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2 minutes ago, geoham said:

On a side note, I quite like the EQ on my TC Electronic BH550 head - it boosts and cuts at different frequencies. The bass boosts at 80, but cuts at 50. It'd be interesting to see this type of thing on an on-board preamp. 

That sounds ideal.

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2 hours ago, Baloney Balderdash said:

Is there such a thing as a passive preamp? :crazy:

The simple answer is no, because the "amp" bit means some sort of amplification is going on and thus batteries are required. That said, "Tone Controls": You can still use a passive tone stack network, like a modified Baxandall type or even the tone stacks used in valve amplifiers as a set of tone controls and it would work.  Fender's own TBX Tone Control is an example of a passive tone control network.

Edited by Dood
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Doesn’t “centred” mean you can boost and cut to the desired tone? So it’s only a starting point.

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6 minutes ago, chris_b said:

Doesn’t “centred” mean you can boost and cut to the desired tone? So it’s only a starting point.

How I understand it, is that you don't boost of cut at a single frequency - it could be an octave or two each way from the centre point for example. But the boost or cut peaks at this centre frequency.

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24 minutes ago, chris_b said:

Doesn’t “centred” mean you can boost and cut to the desired tone? So it’s only a starting point.

Technically the center frequency it is the middle, and therefor top point, of the (kind of bell shaped triangular) curve that the boost/cut effects, so the more you boost or cut the broader a frequency spectrum will be affected around the center frequency, how broad determined by the bandwidth (or steepness/angle) of said curve (which will vary depending on the specific equalizer's circuit, and as far as goes fully parametric equalizers will be adjustable), either measured in dB/Oct (dB per octave) or as the Q value. 

Edited by Baloney Balderdash
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34 minutes ago, geoham said:

How I understand it, is that you don't boost of cut at a single frequency - it could be an octave or two each way from the centre point for example. But the boost or cut peaks at this centre frequency.

Yes, that's my understanding too. 40hz centre is probably fine for cutting. But, should a song call for a bit of extra 'on the fly'bottom then it would probably be better to lift centred in the 'useful' range of the curve, centred a bit higher, with the deeper 40hz being down the bell curve a bit.

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Don't forget shelving eq - Ampeg for example use james or baxendal looks like this:

baxabass.gif

Much nicer sounding to my ears - though I agree putting it at 40hz is limited!

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MM SR preamp is NOT boost only. (corrected by @drTStingray)

I had a MG Quantum with bartolini preamp. The capacitors could be changed, and they don't have to be similar. This means that boost and cut frequencies could be different.

Edited by itu
correction

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11 minutes ago, Dood said:

John East's Uni-Pre offers extensive frequency selection too, anther great suggestion.

Ooh - that's sexy - in a wires and knobs kind of way 😉

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On 19 October 2020 at 15:56, itu said:

MM SR preamp is boost only.

If you mean the 2 band Musicman circuit, then that is boost and cut (but doesn't have a centre detent).

Ive also seen it described as a Baxendall type circuit. 

Edited by drTStingray
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2 minutes ago, drTStingray said:

If you mean the 2 band Musicman circuit, then that is boost and cut (but doesn't have a centre detent).

Ive also seen it described as a Baxendale type circuit. 

It’s a Baxandall circuit (sometimes called a James eq), named for James Baxandall who invented it.

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1 hour ago, drTStingray said:

If you mean the 2 band Musicman circuit, then that is boost and cut (but doesn't have a centre detent).

Thanks, I stand corrected. It seems to be an old rumour, that is misinformation.

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Doesn’t the Stingray boost more than it cuts though? Although I’ve heard the actual frequencies have changed a lot over the years. 

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Setting the bass peak at 40hz seemed bonkers to me. Do most active circuits do that? Seems unlikely. Thought I’d have a look at my Audere preamp’s spec... I do love how that preamp sounds!

 

Quote

In the Pro JZ3 preamps you can select either a 2, 3 or 4 band tone controls.

 

All active tone control pots contain a center detent where the response is flat, giving you the uncolored bass voice.

Our tone controls are different than most preamps in the following ways:
1) The boost/cut amount changes slowly at first off the center detent and then the action speeds up as the knob is rotated farther from the detent.
2) Mid-range controls use wide bandwidths - the issue with narrow bandwidths is the phase shift changes too fast vs. frequency and they sound artificial while our wide frequency mid-range controls makes them sound more musical.
3) The Bass and Treble controls are shelving which extend to lower and higher frequencies than other preamps. The shelving control makes our specs look very different than most preamps. Our spec is at the 1/2 boost or cut frequencies. You can think of our specs as all the frequencies below 180 Hz or above 3.2KHz (for a 4 band example) have a significant level of boost or cut range.

The frequency response points:

  4 Band 3 Band 2 Band

Bass shelving Hz - dB

180 +/- 16 dB 200 +/- 16 dB 200 +/- 18 dB
1st Mid Peak Hz - dB 250 +/- 10 dB 500 +/- 10 dB  
2nd Mid Peak Hz - dB 750 +/- 10 dB    
Treble shelving Hz - dB 3.2K +/- 18 dB 2.5K +/- 16 dB 2.0K +/- 17.5 dB

 

In summary, we design very musical tone controls that are easy to use and give you lots of control of your sound.

 

Edited by TrevorR
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