acme B2 vs GK 115MB, Question:

[HaphAsSard]

Kjung, if I were to use a High Pass filter, would I use it at the send/return, or further down the chain toward the power section (??)? If this low-signal generation is due to the power amp, is that to say the power amp is the source of these lows? Or are they provoked by the instrument or pre amp section- so that use of the High Pass filter would be inserted early in the chain- like at the input?

I believe bgavin's wonderings abold and KJung's comment below are on to something; or at least this is what I've seen discussed here in many a thread: subsonic frequencies are generated by player-string interactions other than ordinary plucking/picking. Or perhaps even then, in certain instances? Anyway, saying the SWR "produces" them only means it re-produces them, unfiltered-out.
I suppose the HPF could be placed anywhere in the signal chain before the power amp stage; there might be other considerations (gain, signal-to-noise ratio...and stuff) about which I defer to [del]more[/del] knowledgeable fellas; the filter would fulfil its filtering task regardless, I think.

I'm trying to understand where all this "sub-bass" signal is coming from.
(...) I'd like to understand where this very low frequency info is generated.
I doubt the SWR is generating something not in the signal chain... it would be broken if that is the case.

Is thumb-on-string motion responsible for VLF generation?

Unless the SWR is broken, it isn't generating spurious signal on its own.
It comes from somewhere, probably VLF from string movement over the pickups.

I have no experience measuring sub-harmonics, so can't comment.
What I can really see causing piston action, is moving the strings about over the pickup.
I always thumb-damp my B-string whenever I'm not playing that string.
I can see where motion would induce VLF signal.

Of course, the sub bass comes originally from the instrument.

 

[Count Bassie]

I believe bgavin's wonderings abold and KJung's comment below are on to something; or at least this is what I've seen discussed here in many a thread: subsonic frequencies are generated by player-string interactions other than ordinary plucking/picking. Or perhaps even then, in certain instances? Anyway, saying the SWR "produces" them only means it re-produces them, unfiltered-out.
I suppose the HPF could be placed anywhere in the signal chain before the power amp stage; there might be other considerations (gain, signal-to-noise ratio...and stuff) about which I defer to [del]more[/del] knowledgeable fellas; the filter would fulfil its filtering task regardless, I think.

It has happened in a big way before, and looked like it was really due to my actual playing. At any rate, I'm hoping the fDeckHPF is enough to really solve this issue... I'm not looking to change the flavor though, just the problematic part. But I think you've got it sussed there.

 

[KJung]

Kjung, if I were to use a High Pass filter, would I use it at the send/return, or further down the chain toward the power section (??)? If this low-signal generation is due to the power amp, is that to say the power amp is the source of these lows? Or are they provoked by the instrument or pre amp section- so that use of the High Pass filter would be inserted early in the chain- like at the input?

For the FDECK unit, which is a battery powered unit (i.e., a stomp box, not a studio grade rack unit), you would use it between bass and amp. Hi Passing works just as well in the effects loop, in general, but only if you have a unit that can handle the hot input post preamp.

Again, the power amp is not the SOURCE of the lows. Rather, the hi pass/low end management built into your particular amp does not filter out the sub bass that comes from your (or any) instrument (as stated in the post a few posts above this one).

I, again, am not one who feels an external hi pass filter is necessary with most amps or rigs, but you have a perfect storm there with the combination of the amp that literally allows the most sub bass to come through compared to almost any other amp, combined with a cabinet that, more than almost any other cab, is negatively impacted by sub bass

 

[Count Bassie]

For the FDECK unit, which is a battery powered unit (i.e., a stomp box, not a studio grade rack unit), you would use it between bass and amp. Hi Passing works just as well in the effects loop, in general, but only if you have a unit that can handle the hot input post preamp.

Again, the power amp is not the SOURCE of the lows. Rather, the hi pass/low end management built into your particular amp does not filter out the sub bass that comes from your (or any) instrument (as stated in the post a few posts above this one).

I, again, am not one who feels an external hi pass filter is necessary with most amps or rigs, but you have a perfect storm there with the combination of the amp that literally allows the most sub bass to come through compared to almost any other amp, combined with a cabinet that, more than almost any other cab, is negatively impacted by sub bass

Got it. I just needed to see it all in one place! Makes sense now, thanks. Thanks everybody!!

 

[steve_rolfeca]

That is a less than optimal head/cab combination. The old SM400 has virtually NO hi passing, so it is pumping massive sub bass into that cab.

One way or the other, that head has to go with that particular cab (or at least you need an external Hi Pass Filter like the FDECK III to eliminate that under 30hz nastiness coming out of that head.

IMO and a lot of IME on this one

I'm late to this party, but it's not just Ken's opinion- I've bench tested the power stage on a few older SWR heads, and even my Studio 220 was flat down to something like 10Hz. Needs a good HPF in the worst way...

 

[Count Bassie]

So you guys are of the opinion that the fDeck HOF-III will be sufficient to be able to make this head acceptable for use with the Acme? I have a 400s also, which has a good dash more power/headroom.

 

[KJung]

So you guys are of the opinion that the fDeck HOF-III will be sufficient to be able to make this head acceptable for use with the Acme? I have a 400s also, which has a good dash more power/headroom.

It will help for sure. Worth a try if you like the general tonality of that rig. You should be able to get more real volume, and with the variable control on the hi pass, take enough off the deep low end to balance the midrange and deep bass a bit better for more punch and articulation (doing that 'scoop filter' bypass would help also, but that would require a visit to a repair shop that knew how to do it).

Of course, there are SO many new amps that are 1/4 the size and weight, twice the power, and have no need for external hi passing (like the GK MB800/MBFusion800).

 

[Count Bassie]

It will help for sure. Worth a try if you like the general tonality of that rig. You should be able to get more real volume, and with the variable control on the hi pass, take enough off the deep low end to balance the midrange and deep bass a bit better for more punch and articulation (doing that 'scoop filter' bypass would help also, but that would require a visit to a repair shop that knew how to do it).

Of course, there are SO many new amps that are 1/4 the size and weight, twice the power, and have no need for external hi passing (like the GK MB800/MBFusion800).

I know there are more practical ways to go, and if I could get enough for the SWR I'd do the trade. I don't think that's a practical expectation though. And I do kind of like the voicing of the SWR stuff- but lately, I'll admit, I've been running a GK 400RB-III into the Bag End S-15s, and that is a revelation...

I could use the fDeck jig for upright anyway, as a buffering preamp, so I'm probably going to go that route.

Again, thanks for all the help here. Won't be wasted...

 

[KJung]

I know there are more practical ways to go, and if I could get enough for the SWR I'd do the trade. I don't think that's a practical expectation though. And I do kind of like the voicing of the SWR stuff- but lately, I'll admit, I've been running a GK 400RB-III into the Bag End S-15s, and that is a revelation...

I could use the fDeck jig for upright anyway, as a buffering preamp, so I'm probably going to go that route.

Again, thanks for all the help here. Won't be wasted...

The 400RB is VERY tight down low and somewhat bright. The 400RB and the small Bag End 15 cube is a CLASSIC rig from back in the day (I used that rig in the late 70's if I remember correctly).

I personally like the low end/mid range ratio of the Bag End 15s in a mix better than the Acme cabs, regardless of the head used. But, pure IMO there. Very different, and both do what they are designed to do, with the Acme's using a lot of power to generate impressive low end extension, and the Bag Ends needing very little power to produce a punchy, loud, articulate bass tone that sits in many mixes similar to where a mastering engineer would slot a bass in a good recording.

IMO!

 

[Count Bassie]

The 400RB is VERY tight down low and somewhat bright. The 400RB and the small Bag End 15 cube is a CLASSIC rig from back in the day (I used that rig in the late 70's if I remember correctly).

I personally like the low end/mid range ratio of the Bag End 15s in a mix better than the Acme cabs, regardless of the head used. But, pure IMO there. Very different, and both do what they are designed to do, with the Acme's using a lot of power to generate impressive low end extension, and the Bag Ends needing very little power to produce a punchy, loud, articulate bass tone that sits in many mixes similar to where a mastering engineer would slot a bass in a good recording.

IMO!

I've just gotten the Bag Ends back after having let them go 2 years ago, for the stupid reason of $$... I learned my lesson boy!! This rig is my favorite ever at this point.

 

[Count Bassie]

They'll not leave me again! If I have to live in a refrigerator box...

 

[bgavin]

The problem with selling off gear to pay bills... the money is soon gone, and the bills never stop.
One has to fix the revenue problem.

Count B, your problem is no different than anybody running a preamp + poweramp.
Your SWR head is equally as flat as my SVP-Pro, IOD, F1X preamp into a standard power amp.
I understand my Sansamp RPM and VTRM have a built-in rolloff, but I've not measured this yet.

The difference: bass heads give you no choice (except the GK with 4/5 string switch).
My QSC power amps give me the choice of None/30/50 Hz, but my Prolite2 = None.
More features = more $$$.

IMO, full range is not a defect in the SWR head at all.
It is designed for full range, and obviously delivers it.

 

[Count Bassie]

The problem with selling off gear to pay bills... the money is soon gone, and the bills never stop.
One has to fix the revenue problem.

Indeed. Work was not there for a minute and I panicked. Revenue problem fixed...

Count B, your problem is no different than anybody running a preamp + poweramp.
Your SWR head is equally as flat as my SVP-Pro, IOD, F1X preamp into a standard power amp.
I understand my Sansamp RPM and VTRM have a built-in rolloff, but I've not measured this yet.

The difference: bass heads give you no choice (except the GK with 4/5 string switch).
My QSC power amps give me the choice of None/30/50 Hz, but my Prolite2 = None.
More features = more $$$.

IMO, full range is not a defect in the SWR head at all.
It is designed for full range, and obviously delivers it.

Indeed again... More than the speakers want to see, apparently! SWR is the only integrated head I've heard of with this issue, though I'm sure it's for honorable intentions. The reality for many of us doesn't cater to it unfortunately however, I guess, but if I can remedy it with a simple box Velcro(TM)'d to the side of the rack case, happy am I.

But thank you for the enlightening note!

 

[KJung]

The problem with selling off gear to pay bills... the money is soon gone, and the bills never stop.
One has to fix the revenue problem.

Count B, your problem is no different than anybody running a preamp + poweramp.
Your SWR head is equally as flat as my SVP-Pro, IOD, F1X preamp into a standard power amp.
I understand my Sansamp RPM and VTRM have a built-in rolloff, but I've not measured this yet.

The difference: bass heads give you no choice (except the GK with 4/5 string switch).
My QSC power amps give me the choice of None/30/50 Hz, but my Prolite2 = None.
More features = more $$$.

IMO, full range is not a defect in the SWR head at all.
It is designed for full range, and obviously delivers it.

You still aren't quite understanding the issue here. No one is saying that the lack of normal hi passing on the SWR is a defect. It is a design mistake for the most part, since very few, if any cabs, can reproduce 40hz (much less 20hz!), and no other all-in-one bass head that I know of has this issue (at least anyway near this extreme).

+1 though that if you use a low end power amp designed for a PA/PA sub usage to drive a bass cab, and don't have external hi passing, you will have similar trouble. I would not recommend this either.

 

[bgavin]

I'm understanding what is going on just fine, thank you.
The SWR head is a design mistake in your opinion, only.
Steve Rabe felt differently, which is why he designed it full range.

The SVP-Pro, F1X, IOD are all full range preamps with no rolloff.
They are all designed to drive standard power amplifiers, which may/may not have a built-in roll off.
This does not make these preamps a "bad design".

It is all in how you use it.

 

[Count Bassie]

I'm understanding what is going on just fine, thank you.
The SWR head is a design mistake in your opinion, only.
Steve Rabe felt differently, which is why he designed it full range.

The SVP-Pro, F1X, IOD are all full range preamps with no rolloff.
They are all designed to drive standard power amplifiers, which may/may not have a built-in roll off.
This does not make these preamps a "bad design".

It is all in how you use it.

I'd be interested in knowing- seriously- what is a scenario in which this is not an issue? Not trying to be a wise-guy here, but this does seem to be an issue in every circumstance for me. The thing is a 400w power section fronted by a very flexible eq, except for the bass shelving pot, which tops off at 31 Hz. Right?

The 400s is a 500w power section... if it were a low-volume amp I could see it, like the Studio 220, for instance. Help me out here...

 

[KJung]

I'm understanding what is going on just fine, thank you.
The SWR head is a design mistake in your opinion, only.
Steve Rabe felt differently, which is why he designed it full range.

The SVP-Pro, F1X, IOD are all full range preamps with no rolloff.
They are all designed to drive standard power amplifiers, which may/may not have a built-in roll off.
This does not make these preamps a "bad design".

It is all in how you use it.

You are again confusing preamps with power amps. Most preamps are 'full range'. The hi passing is at the power amp stage. Again, if you feel a head that you need to buy an external hi pass for (MANY of us did that back in the day) is a good design, then OK.

Again, you are confusing preamps and power amps (you keep mentioning preamps!). If you hook up almost any preamp to a PA power amp with no hi passing, and drive the typical bass cab, that will be a very inefficient rig that can cause some serious damage to many speaker cabs (especially the Acme, which has, from what I understand, massive xmax, and normal/limited xlim). That can REALLY get you into trouble!

Again, preamps... that is one thing, power amps, that is another thing. Again (again), most bass cabinets (99%+) are tuned to roll off somewhere between 40 and 60hz.

The SWR SM400 is UNIQUE (in the true sense of that word... not very unique, but literally unique!) all in one bass head, and the idea of running a ported cab tuned in the 40's (or 50's) with a wide open amp putting out significant power was, quite frankly, one of the dumbest design decisions in the history of bass amplification.

Again (again!) MANY of us had relatively good success with the SWR SM400 by using an external hi pass set, depending on the cab, between 30 and 40hz.

I know the OP gets this, so I'll drop out of the thread.

 

[Count Bassie]

My GK 400RB produces a more useable signal into my Bag Ends. The SM400 works, and I love the sound, but I have to deal with it to make sure I'm not getting blurry/woofy.

 

[bgavin]

You are again confusing preamps with power amps. Most preamps are 'full range'. The hi passing is at the power amp stage. Again, if you feel a head that you need to buy an external hi pass for (MANY of us did that back in the day) is a good design, then OK.

Again, you are confusing preamps and power amps (you keep mentioning preamps!). If you hook up almost any preamp to a PA power amp with no hi passing, and drive the typical bass cab, that will be a very inefficient rig that can cause some serious damage to many speaker cabs (especially the Acme, which has, from what I understand, massive xmax, and normal/limited xlim). That can REALLY get you into trouble!

Again, preamps... that is one thing, power amps, that is another thing. Again (again), most bass cabinets (99%+) are tuned to roll off somewhere between 40 and 60hz.

The SWR SM400 is UNIQUE (in the true sense of that word... not very unique, but literally unique!) all in one bass head, and the idea of running a ported cab tuned in the 40's (or 50's) with a wide open amp putting out significant power was, quite frankly, one of the dumbest design decisions in the history of bass amplification.

Again (again!) MANY of us had relatively good success with the SWR SM400 by using an external hi pass set, depending on the cab, between 30 and 40hz.

I know the OP gets this, so I'll drop out of the thread.

I am not confusing anything. Why are you so damn condescending? Knock it off.
What is coming across is YOU think full-range is a bad design, and YOU dismiss it as such.
Maybe you should call Bob Gallien and tell him his RB series running full range is also one of the dumbest design decisions in the history of bass amplification. Such unbelievable arrogance.

My entire point is there is a whole line of products that does not conform to your version of a "good design", because they are full range.
Yes, nearly all the "heads" are built with roll off.
No, nearly all the preamps do not value this feature sufficiently to include it in their designs. Sansamps being the exception.

If a player has bad string movement technique or other bad habits that piston his cones, this is his problem.
Fix the technique, add more speakers, filter the electronics.
And don't apply 400 watts to a speaker capable of 20 watts RMS at 31 Hz.

especially the Acme, which has, from what I understand, massive xmax, and normal/limited xlim

You don't understand much then.
Save the pontification for areas of your expertise, because speaker design is evidently not one of them.
Making statements like the above, just makes you look stupid and reduces your credibility.

 

[Mystic Michael]

Geez Bruce, what da hey? You've been spoiling for a fight ever since you entered this thread. Take a laxative already.

As an impartial observer, I'd say there's reason to believe that you in fact don't get the point that Ken was making. But there's no need to go to war over it.

MM