Does the Mesa Big Block 750 have built in HPF?

[hamertek98]

Well, looks like my amps and cabs are just older. Or designed by some incompetent guys like David Nordshow or Steve Rabe ;-)



Or what we find just quite silly as a "main feature".



And actually this is the only answer that we all needed

You may want to quit now....
Rabe had some proven designs that did not help speakers. I still own and use Eden cabs.
And I actually loved some of his preamps. I've owned some SWR gear.
It was known not to be healthy for certain cabs..... even some he designed.
Nordschow made a lot of the cabs early on.

You don't believe in HPF's. I get that. But don't give advice for which you don't know. They are there for a reason.
I would not lend you equipment, nor want you to run sound (mix) for anything I didn't want messed up or blown...

Edit to add: ... Sorry if I came off rude. Not my intention. Learn more about things. I did....

 

[mazdah]

You may want to quit now....
Rabe had some proven designs that did not help speakers. I still own and use Eden cabs.
And I actually loved some of his preamps. I've owned some SWR gear.
It was known not to be healthy for certain cabs..... even some he designed.
Nordschow made a lot of the cabs early on.

You don't believe in HPF's. I get that. But don't give advice for which you don't know. They are there for a reason.
I would not lend you equipment, nor want you to run sound (mix) for anything I didn't want messed up or blown...

Edit to add: ... Sorry if I came off rude. Not my intention. Learn more about things. I did....

Proven by whom? Not healthy to speakers known by whom?
By people who don't know how to use their gear without damaging it?

I'm gigging regularly with SWR amp and preamps with original Goliath II Jr. 4ohm cab - stock speakers still going strong.
I've also used this cab with SVT-III, also without HPF as far as I know.
I'm gigging with WT-800 (800W bridged) and 540W Eden D410T - stock speakers still going strong, mind you - lows in WT-800 are centered on 30Hz.

I'm not as experienced as many here, BUT in my 20 years of regular and sometimes loud gigging I've never damaged a speaker.

That is why in my opinion HPF is in the same zone as "underpowering a cabinet".

 

[Drredplate]

HPF are a fad for those who have better things to do than recone and replace speakers. I’ve never been so shamelessly “trendy” except when I got my first pair of Docs in the early 90s.

I myself have now succumbed to using an HPF despite being a traditionalist.
I came to the conclusion that there was no point in heating my voice coils with frequencies that my speakers have little output at and I can’t really hear anyway

 

[deff]

I feel like arguing that a HPF is a fad or not useful is like shaking ones fist at the clouds. Even if it is there, it won't do anything but help the situation. It could hardly be construed as having any sort of deleterious effect.

 

[mcnach]

Why is a HPF a silly fad???

That's just what soem people with a misplaced superiority complex say, heed not and move along, don't make eye contact, that's what they want!

 

[mcnach]

That is why in my opinion HPF is in the same zone as "underpowering a cabinet".

oh dear

 

[40Hz]

Nope, no matter what the AI internet experts say

Thanks for putting it that way! Probably the best laugh I’m going to have all day.

 

[beans-on-toast]

HPF’s are in many amps, although not set at the frequency that a bass player might desire.

A HPF circled in a tweed Fender amp.

A first order HPF

Apply this formula.

C=0.1uF, R=220K

This comes out to around 7Hz. It always more complicated in the circuit. A little protection for the speaker but not removing low end like a player might want. Another HPF would come in handy.

 

[agedhorse]

HPF’s are in many amps, although not set at the frequency that a bass player might desire.

A HPF circled in a tweed Fender amp.

View attachment 7036810

A first order HPF
View attachment 7036813

Apply this formula.
View attachment 7036812
C=0.1uF, R=220K

This comes out to around 7Hz. It always more complicated in the circuit. A little protection for the speaker but not removing low end like a player might want. Another HPF would come in handy.

This is also in part to improve low frequency stability when feedback is applied around the output transformer, and to reduce the possibility of OT LF saturation.

 

[Thumpin6string]

I have had nothing but positive experiences with HPFs. I asked a simple question about a HPF in a BB750. Why do certain members come and make their derogatory comments that have nothing to do with my question? If you don't like HPFs, good for you. I didn't ask for your opinion. Opinions are like azzholes, everybody has one. Unfortunately, I'm not interested in yours. Thanks again, Agedhorse for your wisdom.

 

[jdjk7]

And in my opinion you don't need HPF - build in or in a pedal - for this, or any other head.

Why's that?

 

[Thumpin6string]

Why's that?

Obviously not based on facts.

 

[hamertek98]

I have had nothing but positive experiences with HPFs. I asked a simple question about a HPF in a BB750. Why do certain members come and make their derogatory comments that have nothing to do with my question? If you don't like HPFs, good for you. I didn't ask for your opinion. Opinions are like azzholes, everybody has one. Unfortunately, I'm not interested in yours. Thanks again, Agedhorse for your wisdom.

Sorry for the derail.

 

[Thumpin6string]

Sorry for the derail.

You have no need to apologize. You were responding to the biggest derailer.

 

[agedhorse]

Well, looks like my amps and cabs are just older. Or designed by some incompetent guys like David Nordshow or Steve Rabe ;-)



Or what we find just quite silly as a "main feature".



And actually this is the only answer that we all needed

Proven by whom? Not healthy to speakers known by whom?
By people who don't know how to use their gear without damaging it?

I'm gigging regularly with SWR amp and preamps with original Goliath II Jr. 4ohm cab - stock speakers still going strong.
I've also used this cab with SVT-III, also without HPF as far as I know.
I'm gigging with WT-800 (800W bridged) and 540W Eden D410T - stock speakers still going strong, mind you - lows in WT-800 are centered on 30Hz.

I'm not as experienced as many here, BUT in my 20 years of regular and sometimes loud gigging I've never damaged a speaker.

That is why in my opinion HPF is in the same zone as "underpowering a cabinet".

Ok, it's time to set the facts apart from the fiction:

1. SWR did indeed have some serious issues with speaker damage with their earlier amps and cabinets. The PAS drivers that were used in the earlier days turned out not to be mechanically robust enough to be used without failure when played hard, This was one of the motivating factors for Fender's acquisition of the brand. (the other was heat management issues combined with the need to meet international safety regulations). The PAS drivers were chosen because of their unique and fairly transparent mid voicing which did originally contribute to the SWR sound, but ultimately (and unfortunately) contributed to the pre-Fender failure. Had the earlier SWR amps included a more sophisticated HPF, this might have been avoided.

2. The later SWR products, such as the Spellbinder Blue, HeadLite and Working Pro, did include HPF's, this is a natural evolution. The same applies to the later speakers, they became more robust out of necessity as the costs of warranty replacements became unacceptably high.

3. The entire Eden WT series included a HPF, as did the WTX series. The low frequency band is not fixed at 30Hz, but sweeps from 30Hz to 300Hz, but with the included HPF, this effectively shifts the 30Hz calculated point upwards somewhat.

4. The SVT-III (and SVT-III Pro) does have significant first order HPF, not as aggressive as many of their later products like the PB series, PF series and SVT-7 Pro. Again, designs evolve.

 

[Rip Van Dan]

Well, looks like my amps and cabs are just older. Or designed by some incompetent guys like David Nordshow or Steve Rabe ;-)
***SNIP***

Actually with the David Nordschow's Eden amps his Bass EQ, which is a shelving EQ set at 30Hz, acts as a bit of a de facto HPF. His DNA amps have it set at 35Hz. Also you have to remember that David was always designing and manufacturing his own speakers and cabs as well as for speakers and sometimes cabs (SWR Goliath I) for other manufacturers. So nothing he designed sounded boomy or muddy so they weren't really needed for his speakers. Adjustable HPF's are most effective at cleaning up muddy and boomy speakers, of which David never had the problem with in his designs. He had complete control of the speakers and the cabs they were used in, and designed them to have what he called, "High-Fidelity for the Low End". So his speaker designs were not boomy or muddy.

For about 7-years, I was using a GK115bpx cab (bottom of GK's line and a terrible cab) with an acoustic B410. That GK115 was the boomiest, muddiest cab I ever used and using my first Eden amp, (Nemesis RS400), I had to turn the Bass EQ down to 10 o'clock to tame that boomy sound. Then it was no longer mud although the acoustic B410 was starved for bass frequencies. Since the Bass EQ was a shelving EQ, it basically cut everything below 30Hz, which is similar to an HPF set at 30Hz. With the Bass EQ cut like that, it produced a significantly better sound than trying to run it flat.

In 2010 I bought my WT500/800 directly from David and like all his dual powerblock amps it has a "balance" knob on the front. By turning that knob a 4 to 6 clicks towards the 410 channel, it sent more power to the 410 than the 115 and that cleaned the boom from the 115 up nicely without cutting the bass EQ, but by lowering the level of that cab in the mix of the two. It also made that poor acoustic B410 a lot happier because it was finally being fed the normal Bass EQ level it had been starving for.

The adjustable HPF's that you find on Mesa and some other amps allows you to use it if you need to - your speakers aren't handling those low frequencies well - or not us it if your speakers don't need it. I would hazard a guess that the adjustable HPF's on Mesa amps aren't needed with the Mesa Subway speaker cabs because @agedhorse designed them to work well and sound good together. So you can get a nice amp that has that adjustable HPF and make your current "not as good " speakers sound better if they are boomy or muddy, until such time as you can get the cabs designed to work with that "better amp".

When I got my Eden WT500/800 in 2010 that "better amp" made my speaker cabs sound better because of the balance control on it. In 2015, when I bought my DNS-410 cab by DNA (David Nordschow Amplification), I no longer needed that option because my new 410 sounded loads better by itself than my previous 410+115 stack had. Plus it was an order of magnitude LOUDER as well as delivering clearer, cleaner, and more articulate sound. It also handles more power than my 800-watt amp can deliver, so I run my WT500/800 bridged at 800-watts into it. You could say, I grew into the capabilities of my Eden amp and the sound that an amp and speaker system designed by the same superb designer could deliver from that amp. It made my existing speaker cabs sound better and then really shined with speaker cabs that could deliver virtually everything it could provide. That may very well be the reason that Mesa and some others include it in some of their amp designs.

 

[agedhorse]

The WT series amps do have a fixed 2nd order HPF.

 

[micguy]

Since HPF is a pretty new silly fad and Big Block is a pretty old school hefty amp - i'd say no. And in my opinion you don't need HPF - build in or in a pedal - for this, or any other head.

I've been playing bass for well over 40 years, and designed a lot of pro audio equipment for a living. I know of one line of bass amps (made decades ago, very few were sold, long since discontinued) that was DC coupled - meaning it had no high pass filter. They made a big deal bout DC coupling, and when you played through one, the thing wasted a LOT of power moving the cone of the speaker it was attached to at the start of every note - it was the stupidest thing, and it should never have gotten out of the lab. When I heard about it, I went down to a local store and stride on - "damn!!! they actually were stupid enough to do that!!!"

Every bass amp has some sort of high pass filter, even if it's just a DC blocking capacitor or two somewhere. Most amps have an intentionally designed high pass filter in them - it may or may not not be a block you can see easily on a schematic, it may just be a careful choice of capacitor values.

Short answer: Your "no" answer was a shot from the hip - those of us with some knowledge of the topic know that's not the right answer.

 

[Wasnex]

I know of one line of bass amps (made decades ago, very few were sold, long since discontinued) that was DC coupled - meaning it had no high pass filter.

...it wasn't just an obscure line of bass amps.

From the Crown DC-300A II OM:

Using innovative circuitry, the DC-300A II yields ultralow distortion through a wide range of frequencies from DC (0 Hz) to 20 kHz.

Crown did acknowledge and address the resulting issue:

SOLVING INPUT PROBLEMS
Sometimes large subsonic (subaudible) frequencies are present in the input signal. These can damage loudspeakers by overloading or overheating them. To attenuate such frequencies, place a capacitor in series with the input signal line. The graph in Figure 3.4 shows some possible capacitor values and how they affect frequency response. Use only a low-leakage paper, mylar or tantalum capacitor.

 

[micguy]

...it wasn't just an obscure line of bass amps.

From the Crown DC-300A II OM:

Using innovative circuitry, the DC-300A II yields ultralow distortion through a wide range of frequencies from DC (0 Hz) to 20 kHz.

Crown did acknowledge and address the resulting issue:

SOLVING INPUT PROBLEMS
Sometimes large subsonic (subaudible) frequencies are present in the input signal. These can damage loudspeakers by overloading or overheating them. To attenuate such frequencies, place a capacitor in series with the input signal line. The graph in Figure 3.4 shows some possible capacitor values and how they affect frequency response. Use only a low-leakage paper, mylar or tantalum capacitor.

View attachment 7037302

That’s a PA amp - not a bass amp. It’s not what we were talking about here. Bass amps (save the one I’m talking about, which was obscure enough that you don’t know about it) have high pass filters.