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fdecks HPF, Part II

#161
Anyone note any disadvantages to the 24 dB roll-off vs. the 12 dB, for either electric or upright? Is it always 24 db/octave below 35Hz, or will that vary depending on where the variable-frequency filter is set?

Also, if I'm reading the "tech" page right, the Series 3 will tolerate a significantly hotter input than Series 1 and 2, but clips hard when its limit is reached. Series 1 and 2 are "musically forgiving" in the way they clip... also might be simpler to use in, say, a junior high jazz-band setting. Thinking pros and cons, here.
 
#163
MarkA said:
Are you saying that a "bright cap"/treble-bleed not only preserves high end as the volume is turned down, but sucks out the low end? In the case of my friend's pre, it was a huge difference, requiring a significant boost of lows and low-mids at the amp to keep something like the same tonal profile. The resulting tone (through a Markbass f500 in this case) was actually really nice -- all the quickness and response of the F500 with a whole lot more detail and harmonic complexity -- I just didn't like that the sound varied so much with the level from the pre.
Click to expand...

Yes, depending on the value of components used. The classic example are the 1970s Fender Telecasters, which get VERY thin/bright with the volume turned down.
 
#164
MarkA said:
Anyone note any disadvantages to the 24 dB roll-off vs. the 12 dB, for either electric or upright? Is it always 24 db/octave below 35Hz, or will that vary depending on where the variable-frequency filter is set?
Click to expand...

This question is asking what the slope is from 35Hz on down, as a function of the variable knob. I believe the slope is always 24 dB / octave from 35 Hz on down (no matter where the knob is set).

tallboybass said:
The way I'm seeing it, as you bring the knee frequency up, the rolloff is greater for the subsonics below 35hz. True?
Click to expand...

However, I think this is what MarkA was really asking about. I.e. not the slope, but how much actual reduction there is. To my understanding, the variable knob controls the starting frequency of a 12 dB/octave slope. So, if that knob is set at 70 Hz (which is one octave above 35 Hz), then, the signal would be cut by 12 dB at 35Hz. And one octave lower, at 17.5 Hz, it would be cut by 36 dB. Whereas if the knob were set at 35Hz, there would be no cut at 35Hz (and 17.5 Hz would be cut by 24 dB, instead of 36 dB).

So, I believe tallboybass is correct. As you bring up the knee frequency, the amount that the lower frequencies is attenuated is increased. The slope stays the same. It's just that the attenuation already in effect at 35 Hz is greater, the more you roll the knee frequency higher.

But, I'm not electronics engineer, so I reckon I could be totally wrong.
 
#166
Hi. Probably the best way to explain is by example. Let's say the knob is set to 80 Hz on a Series 3. It will be:

Flat above 80 Hz.
12 dB/octave from 80 to 35 Hz
24 dB/octave below 35 Hz

In reality, the response graph isn't three perfectly straight lines, but is curved at each knee. But the above description is sufficient to gauge how the filter will behave. When the knob is set to 35 Hz, the preamp behaves as a single filter with 24 dB/oct slope.

Now I have to ask a somewhat loaded question, that I hope isn't against the rules. Series 1 and 2 come in a plastic enclosure, while Series 3 is in a metal box. Would people prefer a Series 1 / 2 circuit in a metal box? My thought is that while the plastic box is pretty rugged, the metal box is arguably more rugged.
 
#167
fdeck said:
Hi. Probably the best way to explain is by example. Let's say the knob is set to 80 Hz on a Series 3. It will be:

Flat above 80 Hz.
12 dB/octave from 80 to 35 Hz
24 dB/octave below 35 Hz

In reality, the response graph isn't three perfectly straight lines, but is curved at each knee. But the above description is sufficient to gauge how the filter will behave. When the knob is set to 35 Hz, the preamp behaves as a single filter with 24 dB/oct slope.

Now I have to ask a somewhat loaded question, that I hope isn't against the rules. Series 1 and 2 come in a plastic enclosure, while Series 3 is in a metal box. Would people prefer a Series 1 / 2 circuit in a metal box? My thought is that while the plastic box is pretty rugged, the metal box is arguably more rugged.
Click to expand...

Were I looking for one of the others, yes. You may remember that I have one of the protos of the Series 3 (with the original chrome jacks) that came by way of Dave Green as a wedding gift. I've loved it to death since I've had it. My wife not so much. ;) I like the fact that it CAN just be put in my gig bag without special consideration.
 
#168
Did a gig with the HPF-3 on Saturday night, and about to leave to soundcheck for another gig with it tonight. The Saturday gig was on an elevated stage that sounded hollow judging by the sound of walking around on it. Medium to large bar that was about half full (attendance around 150 with the people relatively spread out across the bar) with a decent PA, and surprisingly good stage monitoring. I was using my GK MB800 through an LDS nEarful 15/6/1. The room was boomy in the upper bass and lower mids. Using the HPF-3 and rolling the second filter up to the point of it just being audible sounded great at low volumes, but still boomed in the room at full volume. Rolling it all the way up (135hz if I remember correctly...?) fixed the boom at full volume, but was a little thin for my taste. I decided to just live with it, and once the band got going I really didn't mind the missing bottom end. My amp needed more gain to get the clip light to come on, and my compressor wasn't overreacting to low frequency transients.

All in all, my experience was very pleasant. Tonight will be using a provided backline (SVT-4Pro, and an Ampeg 610HLF), so I'm hoping the HPF-3 will do a good job of dealing with the crazy low end of the HLF series cabs. I've heard the 610HLF is more balanced than the 410HLF, but regardless I've got the secret weapon to cure the bottom end mud if it mirrors my experience with a 410HLF.
 
#169
fdeck said:
Hi. Probably the best way to explain is by example. Let's say the knob is set to 80 Hz on a Series 3. It will be:

Flat above 80 Hz.
12 dB/octave from 80 to 35 Hz
24 dB/octave below 35 Hz

In reality, the response graph isn't three perfectly straight lines, but is curved at each knee. But the above description is sufficient to gauge how the filter will behave. When the knob is set to 35 Hz, the preamp behaves as a single filter with 24 dB/oct slope.

Now I have to ask a somewhat loaded question, that I hope isn't against the rules. Series 1 and 2 come in a plastic enclosure, while Series 3 is in a metal box. Would people prefer a Series 1 / 2 circuit in a metal box? My thought is that while the plastic box is pretty rugged, the metal box is arguably more rugged.
Click to expand...
Thanks for responding, Frances!

Just to give you some different feedback (as per my PM to you), I would like the opposite of what you mentioned, a Series 3 HPF in a Series 1 enclosure...without volume control or external 9v power capability. In my case, the HPF gets velcroed to the top of my MB212, so small and light is a bonus. Can't imagine needing the bigger metal enclosure unless it was for use on a pedalboard, but you already make that!
 
#174
I've used a HPF-1 on a few gigs with both an upright and electric and a couple different rigs. Works great to tighten up the bottom, particularly with my old SWR Bass 750/GIII.

Personally I prefer the simplicity of the Series 1; I definitely don't need another volume knob, and don't particularly see the need for -24 db below 35 hz, -12 seems to be enough. Also, I'm assuming the battery will last quite awhile. I wouldn't pay extra for a metal box either.
 
#176
I too like the simplicity of the S1, and it sounds good enough to not sweat upgrading for now. With a 9v battery terminal adaptor it connects to my voodoo pedal power so I don't have to use a battery. works gud.
 
#179
Yeah, the phase switch is probably most useful for acoustic instruments. It 'flips' the signal phase (think of a sine wave where the curve is reversed), thus decoupling an acoustic top from a loudspeaker.

Phase reversal is also useful when recording an instrument through two sources: say for example, a di and a mic'ed cabinet. If the signals sound thin when combined, flipping the phase on one of the signals usually solves the problem. This has to do with frequency cancelations.
 

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