Does class D have the Heft of SS

[GreyBeard]

I don't recall the CA Series having a high-pass filter, other than the one built into the servo at about 2 or 3 Hz or thereabouts.

But, I bet any class D bass amp will have a high-pass filter at least at 30hz if not higher.

 

[Passinwind]

Betcha a dollar... if you took two identical amps, but disguised them to look different and added a 25lb weight inside one and did a shootout, the heavier amp would win every single time. Just a hunch

Heh, I'd buy that for a dollar. I took my first DIY rack mounted amp build to a big TB GTG in Seattle several years ago and quite a few people assumed it was Class A/B with a tube front end. Nope, Class D and opamps. Same with a local tech/engineer with very extensive experience designing pro sound gear. All my Class D builds until recently have tended to be a bit on the heavier side since I used big heatsinks in lieu of a fan.

 

[DavesnothereCA]

....I've found a balance between weight and a tone I like. I'll keep the heavy tube heads for the studio and an occasional special gig.

For my weekly gigs and sessions 15 lbs isn't killing me. I don't feel the need to ditch 6 more lbs.

As for the technical aspect of what out performs what and what is perception, etc...etc...I could care less. I know what makes me happy....

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I do not know yet what I think of Class D gear as I have not tried any (and some of the threads here have certainly already stimulated my thoughts and theoretical learning about Class D), but if choices for my next amp head conform to a weight which I feel OK lifting by myself, then saving any further weight - and/or spending extra money to do so - will be unnecessary/moot, unless there are OTHER benefits, including any which I may hear and/or feel while playing thru them.

While lifting a traditional all-tube SVT head of about 85 pounds is out of the question anymore, and a 44 pound SVT 350H or 450H solid state head is still more than I would feel comfortable lifting, once I reach the range of, say 25 pounds or less, it will still leave plenty of candidates for my next bass head.

And guess what ? - From what I have researched so far, some of those choices will be Class 'D' and some will be Class A/B.

Also, some of the Class 'D' heads weigh more than others, though all within that acceptable weight range, and I will need to investigate what technological differences are responsible for the range of weights of Class D gear of allegedly similar wattage ratings, and what the result might be in how a heavier weight Class D amp would perform, compared to a lighter weight one.

My objective will not necessarily be to buy the lightest choice available, and I have seen some which weight only 2 pounds - or even LESS - There is one 200 Watt Traynor model which is only a pound and a half.

At that point, it's overkill, and other factors matter more to me than featherweightedness.

Yes, it's a balance.
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[agedhorse]

But, I bet any class D bass amp will have a high-pass filter at least at 30hz if not higher.

Hopefully, somewhere between 25 and 35Hz.
One important reason why HPF's have become popular is that as class D amps have become bigger and more in reach of players trying to get more out of a speaker than physically possible, it simply became necessary for manufacturers offering both speakers and amps to protect the drivers from excessive power, especially when low eq is added.

I can't tell you the number of bass drivers I reconed due to players using all types of bigger amps as they became available. The CA9 (and other amps, especially bridged like the MA & MT series, PL/PLX series, etc) was responsible for me being able to pay off my student loans more quickly. That's where I got my appreciation for the importance of HPF's and the real world mechanical limits of drivers.

Since very few bass cabinets can reproduce 25-30Hz (at any meaningful level), there is usually little to no difference in tone/feel but a HUGE improvement in reliability and damage reduction with a steep HPF. All pro audio powered subs include such HPF's in their processing algorithms for exactly this reason.

 

[BurningSkies]

I carry my own HPF just in case. It's on my pedaboard and always on. That way even when I'm using someone else's backline, I have the benefits of it no matter what their rig.

 

[DavesnothereCA]

I personally would like to have an amp that had both old school and modern hi-fi voicing. Just put a toggle switch on front of it (left old school; right hi-fi). I know, I know, Fender Rumble already has it.

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Active EQ vs the traditional passive stack - Is that what you meant ?

Yes, it might be a decent starting point for a head or preamp to offer that sort of choice.
~

 

[Mike Arnopol]

I agree 100%. I played a new class D amp from a small manufacturer. Pretty well known. We were playing through it a just watching the cone going nuts. No HPF .We then switched to an amp with a built in 30hz HPF. The cone looked like it was barely moving. And it sounded better. Some of the outboard HPF's ---to me-- squashed the dynamics. I think that Josh Broughton makes one. He's really smart and I bet it's nice. Without one---even on electric (DB is much worse---piezos have a ton of info below 30hz) I can see you wasting maybe 25% of your power and if the cone is bouncing around like that---anything above that is compromised sonically. You are wasting all of your Xmax (excursion) trying to reproduce stuff that you don't want. It's even worse with reflex cabs. They are typically tuned between 45 and 50 hz. Anything below that the speaker is bouncing around as in free air. They really go nuts will all of that subsonic junk.

 

[DavesnothereCA]

....Sorry, but I hear a difference that's common to all micros I've played, a difference that's common to all rigs with trad solid state power amps I've played, and a difference that's common to all rigs with tube power amps I've played. And I honestly don't think it's because of different preamps, because I hear these commonalities with each format every time....

....But if there are micro [Class D] power amps out there that sound just like trad SS power amps, then I think we as bass players are getting lowballed because I've yet to hear them, and I scarcely think the technology has changed so much over the last year or two that something revolutionary has happened since then.

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I for one would like to know which makes/models those are too, as it would help me make a shortlist of which to consider for my shortlist of next bass head candidates (as stated in my thread about the RMS watts), and to determine whether I can already afford any of them, or whether I need to keep saving.
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[DavesnothereCA]

....One of these days I'm gonna hook up that Yamaha p2500 power amp from out in the shed and drive it with the pf-500's preamp and just see if I can hear any difference. ...

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Yes, please do !

We need to hear more opinions of the results of such tests.
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[ThisBass]

But, I bet any class D bass amp will have a high-pass filter at least at 30hz if not higher.

Which totally makes sense. We don't want to waste power for none musical sounding transient noise that covers a frequency range down to DC in theoretical consideration. In practice transient noise (that's noise that comes naturally along with any stringed instrument) does easily underrun the lowest tuning of the instrument and thus can harm any ported cabinet if there was no (cab) protection done like implementation of a proper designed HPF.

A HPF also helps to prevent from port "chuffing". Remember that port chuffing is mainly caused by transient noise rather than any swing of a string nor "highish" initial signal peaks on its own.

In the very past the meaning of transient noise was hardly understood even by engineers.
Time periods of decades is a factor that even improves knowledgement of engineers.

 

[DavesnothereCA]

I've played the following:

B15 based preamp -> Carvin DCM1000 (transformer power supply, Class AB, 700W) -> fEarful 15/6
B15 based preamp -> QSC PLX1602 (SMPS power supply, Class AB, 1000W) -> fEarful 15/6
B15 based preamp -> Crown XLS1500 (SMPS power supply, Class D, 1050W) -> fEarful 15/6

... and I can't tell a bit of difference between the power amps.

~
Thanks for posting your findings.

And do they all please you by having this 'HEFT' factor, or do you feel that they all could do better ?
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[ThisBass]

I've played the following:

B15 based preamp -> Carvin DCM1000 (transformer power supply, Class AB, 700W) -> fEarful 15/6
B15 based preamp -> QSC PLX1602 (SMPS power supply, Class AB, 1000W) -> fEarful 15/6
B15 based preamp -> Crown XLS1500 (SMPS power supply, Class D, 1050W) -> fEarful 15/6

... and I can't tell a bit of difference between the power amps.

Which one protects the cab by HPF implementation at which number of f3?

I'd not claim that the presence of a HPF (if any) was an totally "inaudible" feature. Personally I claim that the presence of a HPF helps to improve the total sound by remove some "mud" that does not contribute to the total sound in musical meaning. Other players who are used and biased to vintage designs may claim that the presence of a HPF may suppress at some content a little bit some musicality they are used to in long term consideration of listening and playing.

 

[agedhorse]

I'd not claim that the presence of a HPF (if any) was an totally "inaudible" feature. Personally I claim the presence of a HPF helps to improve the total sound remove some "mud" that does not contribute to the total sound in musical meaning. Other players who are used and biased to vintage designs may claim that the presence of a HPF may suppress at some content a little bit some musicality they are used to in long term consideration of listening and playing.

Correct, when I said that the HPF didn't result in a change of tone or feel, I should have been more clear in that the tone or feel of the bass itself BUT by removing all the extraneous sub-audible content the reproduction by the speakers could certainly improve the sound quality by removing the negative artifacts like chuffing, excessive IM distortion, doppler distortion, etc.

Thanks for bringing this up.

 

[DavesnothereCA]

Just curious: have you ever tried a Class D lead sled?

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Forgive my ignorance, but which makes/models might some examples of those be ?

EDIT :

I see you later mentioned the Crown K2.

Other than the 62 or so pounds each, were you pleased with it ?

Any other examples ?
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[redneck2wild]

But, I bet any class D bass amp will have a high-pass filter at least at 30hz if not higher.

The Peavey MiniMega & MiniMax might have a high-pass filter set lower than 30hz due to this post:

It does, but it is set much lower than the FDeck box and probably doesn't have as steep of a roll-off.

Nearly every Peavey bass amp since the early 90's had an infrasonic HPF. The Mini Mega is one of the first to not have it. Why? If you look at nearly every highly regarded bass amp made since the 70's, they don't have them. There are certainly multiple benefits to using a HPF, but there are certain types of sounds and feel you can't get with one. As I have posted before, I was chasing a tone with the mM, and I realized that I needed to lose the HPF to get the lows like I wanted, and how I know the majority of bass players want.

I could see how some players may benefit from using a HPF. FDeck is good people, so I hope he sells a million of those things.

The Headliner 1000 has a HPF built in. It's kind of interesting to listen to the mM and Headliner side by side because they have the same power amp module and very similar overall preamp designs, but the HPF in the Headliner is one of the main reasons why the two amps sound so different.

 

[DavesnothereCA]

The Peavey MiniMega & MiniMax might have a high-pass filter set lower than 30hz due to this post:

It does, but it is set much lower than the FDeck box and probably doesn't have as steep of a roll-off.

Nearly every Peavey bass amp since the early 90's had an infrasonic HPF. The Mini Mega is one of the first to not have it. Why? If you look at nearly every highly regarded bass amp made since the 70's, they don't have them. There are certainly multiple benefits to using a HPF, but there are certain types of sounds and feel you can't get with one. As I have posted before, I was chasing a tone with the mM, and I realized that I needed to lose the HPF to get the lows like I wanted, and how I know the majority of bass players want.

I could see how some players may benefit from using a HPF. FDeck is good people, so I hope he sells a million of those things.

The Headliner 1000 has a HPF built in. It's kind of interesting to listen to the mM and Headliner side by side because they have the same power amp module and very similar overall preamp designs, but the HPF in the Headliner is one of the main reasons why the two amps sound so different.

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Thanks - I was considering some of those models, and/or some of their smaller siblings.

This is good info, and from a 116 page thread, to boot !
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[GreyBeard]

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Yes, please do !

We need to hear more opinions of the results of such tests.
~

I think it all has to do with high-pass filters. That extra THUMP (heft) you feel from an amp that doesn't have a HPF, compared to one with a 30-50 hz HPF.

 

[murphy]

I think it all has to do with high-pass filters. That extra THUMP (heft) you feel from an amp that doesn't have a HPF, compared to one with a 30-50 hz HPF.

Perhaps we have hit the nail on the head....Question answered

 

[DavesnothereCA]

I think it all has to do with high-pass filters. That extra THUMP (heft) you feel from an amp that doesn't have a HPF, compared to one with a 30-50 hz HPF.

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Possibly, but whether the filter is at 30 or at 50 would make a significant difference alone, as well as the order (steepness) of the filter.

Is it not the Mesa Subway D-800+ which on the front panel lets us continuously adjust the frequency point of the HP filter ?

I have a standalone graphic EQ (ART) which also contains such an adjustable filter.
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[DavesnothereCA]

Perhaps we have hit the nail on the head....Question answered

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In only 29 pages ?

Let's wait and see what Andy thinks about this.
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