GK 400RB 4 vs 8 Ohm & HPF query ?

[acubass]

Although I really don't know if there is a difference In tone as much as feel. I like my 400RB II at 8 ohms. Anytime I have to push the master past 3 o'clock I'm less happy with the tone. I recently started using a Heritage SVT410HLF. That is a power hungry cab. I sounds so good though. I pull out -6d at 32 and -3db at 62 to keep some of the flabby lows which appear in certain rooms.

The HPF button pulls out way to much low end to be usable.

 

[sifi2112]

Thanks guys for all your replies .. Jason@GK says there is a HPF

Regarding 4 vs 8 Ohm cab, I agree that adding to an 8 Ohm cab seems the most practical but for stage volume I think the 400RB is already pretty loud, whether my thinking is right or wrong I'm still leaning towards a single 4 Ohm cab to get the most out of this amp.
If I need more I'll use my pa power amp & either use the RB's line out or get a RBI or similar & double up on the cabs I have.
It's all good lol .. I do like this amp

 

[jmlee]

The older 400rb heads don't roll off like the 800rb's.

Yes, that's correct. I've had the pleasure of A/Bing original series heads of both types (the 400RB is mine) with a 5-string and the lowest end rolloff difference is tangible.

Oh, and the 400 gets silly loud with two reasonably efficient 8 ohm speakers.

 

[Pocket4]

Last weekend was my first gig with this head. The volume demand was not huge in the small bar with my 5 piece band. Tone was awesome, but i ran into a bit of watt reality running into the single 8 ohm 210 Fender Rumble cab. There were moments when high preamp gain just seemed a tad weak. I would run this through a pair of cabs next time.

 

[AstroSonic]

I really think they do...

View attachment 3026493

My series II doesn't have a 4/5 string switch. The low cut switch cuts normal, 4 string bass response, causing it to sound a bit 'thin' on 4 string bass. The V 3 and 4 have an actual 4/5 string switch that, when set to '4' has a full tone on the E string, and when set to '5', extends the bass range to reproduce the lows on the B string. It seems confusing, but the switches, though both are low cut filters, impact different frequency ranges.

 

[Two Leggs]

Run that thing at 4 ohms and your amp will love you! 1 or 2 cabs that's up to you.

 

[Kro]

My series II doesn't have a 4/5 string switch. The low cut switch cuts normal, 4 string bass response, causing it to sound a bit 'thin' on 4 string bass. The V 3 and 4 have an actual 4/5 string switch that, when set to '4' has a full tone on the E string, and when set to '5', extends the bass range to reproduce the lows on the B string. It seems confusing, but the switches, though both are low cut filters, impact different frequency ranges.

Right, which is why my post in question read like this:

Hold on a sec, those 400RBs had a "lo cut" switch right? I'd expect that to be pretty potent... anybody know the specifics of what frequencies that affected?

This thread is about HPF capabilities on those early 400RBs. While I'm unsure of where exactly that lo cut filter rolls off when engaged, depending on its rate it may function like an even more extreme HFP than those 400RBs had otherwise.

 

[AstroSonic]

Right, which is why my post in question read like this:


This thread is about HPF capabilities on those early 400RBs. While I'm unsure of where exactly that lo cut filter rolls off when engaged, depending on its rate it may function like an even more extreme HFP than those 400RBs had otherwise.

The 400RB II has a bass roll off that weakens the fundamental of the low notes on the E string. When the Low Cut switch is engaged, the cut starts higher, causing the low notes on the E string to sound thin, which may improve the sound quality in some situations.

Low pass filters for bass guitar amplifiers are designed to keep the amp from reproducing frequencies below the bass guitar fundamentals. These amusical sounds do not contribute to the music being played, often consume substantial amplifier power and are potentially harmful to bass drivers (over excursion). The 400RB II has a low frequency rolloff that lightly touches on the lower E string fundamentals. The Low Cut switch on the Series I and II 400RB's cuts those amusical, ultra low frequencies, but it also substantially cuts the fundamentals of the low E string notes. That switch is really intended to address problems with the acoustics of the venue. The Low Cut switch on the 400RB II does cut the ultra low, amusical sounds, but that is inadvertent, and not its intended function.

The low frequency rolloff of an amplifier can be chosen to attenuate ultra low frequencies (as with the 400RB II), in an attempt to conserve power for the notes being played. Such an amplifier would be perceived as being louder than an equally powerful amplifier with extended low frequencies.

 

[Kro]

However, most high pass filters are set to attenuate the lows below the bass guitar fundamentals without impacting bass guitar fundamentals.

I mean, it depends on the note in question, but I'd dare say that most HPFs do in fact roll off above bass guitar fundamentals, even of the four-string variety (60Hz isn't exactly uncommon).

Anyways, I appreciate your additional description of how the lo-cut switch sounds to you when engaged. I don't want to steer this too far off topic.

 

[ljazz]

I've always thought the buttons on the old series were mimicked (yet with more variations) by the contour knob on the later rb's. In fact, I seem to recall Bob Gallien saying that years ago in another thread.

 

[Kro]

I've always thought the buttons on the old series were mimicked (yet with more variations) by the contour knob on the later rb's. In fact, I seem to recall Bob Gallien saying that years ago in another thread.

The high boost was transitioned to the variable "presence" knob, and the contour... well that functionality was transitioned into the variable contour knob - which I do think function similarly. It would appear that the lo-cut button likely was substituted for a different kind of "low-adjuster" with the 4/5-string button in later models though.

 

[ljazz]

The high boost was transitioned to the variable "presence" knob, and the contour... well that functionality was transitioned into the variable contour knob - which I do think function similarly. It would appear that the lo-cut button likely was substituted for a different kind of "low-adjuster" with the 4/5-string button in later models though.

I don't believe that's correct..... You have the same filters on the 800rb which is already rolled off on the lows. The presence on the newer rb's is at 10k.... No way the hi button on the older ones is that high.

Here is where the contour knob and filters adjust on the new rb's (from the 700rbII manual) .....
4/5 String Bass +11dB@20Hz
Contour +2dB@50Hz /
-10dB@500Hz /
+3dB@7kHz
Presence +9dB@10kHz

 

[Kro]

I don't believe that's correct..... You have the same filters on the 800rb which is already rolled off on the lows. The presence on the newer rb's is at 10k.... No way the hi button on the older ones is that high.

Here is where the contour knob and filters adjust on the new rb's (from the 700rbII manual) .....
4/5 String Bass +11dB@20Hz
Contour +2dB@50Hz /
-10dB@500Hz /
+3dB@7kHz
Presence +9dB@10kHz

I'm not saying it's an exact 1:1, just that they do similar jobs. I still think that's a better approximation than stating that the older buttons are just mimicked by contour, though I could be wrong.

Also, just because the presence is set at 10k doesn't mean it's just a big spike there. I've tested it. Presence, while being set at 10k, definitely affects lots of highs under that frequency. If I can find them I'll post some pics of the presence response on my 1001RB-ii (or maybe make new ones at some point).

 

[Kro]

The presence on the newer rb's is at 10k.... No way the hi button on the older ones is that high.

Those posted frequencies can be misleading.

I'll replace these with one single overlayed version if I have a chance, but this is my usual ENTIRE signal chain through my 1001RB-ii preamp (so nothing else about this really applies to these amps except for the relative presence boost as a reference). It has an effect all the way down to like 1k.

Presence Off

Presence 9:00

Presence 12:00

I think this was Presence 3:00 (I had it mislabeled in my files)

 

[AstroSonic]

My guess is that the 4/5 button was added in response to the rise in popularity of 5 string basses. It is not a transitional control (not just another flavor of 'contour' or anti-boom), but quite distinct in function - it extends the bandwidth at the bass end of the spectrum to accommodate 5 string basses.

 

[Kro]

My guess is that the 4/5 button was added in response to the rise in popularity of 5 string basses. It is not a transitional control (not just another flavor of 'contour' or anti-boom), but quite distinct in function - it extends the bandwidth at the bass end of the spectrum to accommodate 5 string basses.

I think that you have to look to the market that GK and other MI manufacturers were catering to at that point of time, and what rock styles were becoming popular when the 4/5 string button was introduced. IIRC it was a time of down-tuned everything, including bass, and lots of low frequency content.

Part of me feels like GK went straight from targeting 80s hair-bands to nu metal.

I personally fell like the button was introduced to better serve certain styles of music than really a 5th string per se, and that it was just easier to label it a 4/5 string button from a marketing standpoint than try and sell it in any other way. I have no proof to back it up, but it's my personal take.

With that being said, I'm more than happy to be given the option to go the "5-string" route, and then control those lower frequencies through other means.

 

[AstroSonic]

I think that you have to look to the market that GK and other MI manufacturers were catering to at that point of time, and what rock styles were becoming popular when the 4/5 string button was introduced. IIRC it was a time of down-tuned everything, including bass, and lots of low frequency content.

Part of me feels like GK went straight from targeting 80s hair-bands to nu metal.

I personally fell like the button was introduced to better serve certain styles of music than really a 5th string per se, and that it was just easier to label it a 4/5 string button from a marketing standpoint than try and sell it in any other way. I have no proof to back it up, but it's my personal take.

With that being said, I'm more than happy to be given the option to go the "5-string" route, and then control those lower frequencies through other means.

I don't know of any musical genre that is clearly dominated by bass players using 5 string basses, but who knows. In any case, GK was likely addressing a need (musical or instrumental) by the market they serve.

I too prefer to have the options needed to adjust/sculpt the tone as needed, but understand why others would prefer to just have that tone baked in. Trouble is that I would need to have several heads. LOL, I do, and I still sculpt.

 

[Kro]

I don't know of any musical genre that is clearly dominated by bass players using 5 string basses

Well, I guess that was my point - but there are definitely some musical genres that focus on down-tuning and rely on very low bass notes... there was definitely a trend right around when the 4/5-string button was introduced...

 

[BogeyBass]

The Lower watt GK grind is fun and reliable.

But they really shine with enough speaker efficiency. And a standard like a good old 2x15 or a 4x10 or 4x12

If your looking for one speaker solution id shoot for a efficient 2x12.

Likewise feel a 4ohm faital is waste of time. Good tone maybe. Just not enough efficiency. Better off with 2

 

[Kro]

Likewise feel a 4ohm faital is waste of time. Good tone maybe. Just not enough efficiency. Better off with 2

I would of said similar, but:

I've used a single Bagend 112 @ 8 Ohm in practice & had to turn down lol

If a 112 works for his purposes, then I'd bet that a 115 would as well. Just my thinking as to why it just might work in his case.