alexclaber

[quote name='pmjos' timestamp='1437584116' post='2827314']
I was trying to be helpful and didn't think explaining PWM would benefit most people. I still don't.

Your comment is correct but unintelligible. For reference I do not also fry eggs on my class A amplifiers or think that I need to become a Bat to hear the difference between Class D and other forms of amplifier.
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I don't think it's helpful to claim that class D amps are digital when they're not, they're just another analogue approach, albeit a far more efficient one. Get two equally well implemented amps of equal power, one class AB and one class D and run them so they never clip and you won't be able to hear a difference.

The sonic differences arise in how the amps clip or if one has deficiencies in its design or implementation.

[quote name='pmjos' timestamp='1437570139' post='2827130']
OK techy response for you guys.............

There definitely is a difference between Class D and other types of amps. A distinct technical difference, class D is [b]Digital [/b]and A A/B are analogue.[/quote]

Class D amps are not digital: http://www.hypex.nl/docs/papers/AES120_353BP.pdf

[quote name='Dan Dare' timestamp='1437333356' post='2825151']I think some lightweight amps suffer because they have switch mode power supplies, which are very susceptible to a poor quality mains supply. With no power reservoir, they cannot deal with voltage fluctuation (which is surprisingly common).[/quote]

But switch mode power supplies do have power reservoirs and are actually better at providing a solid stable voltage and current supply than traditional mains frequency transformer power supplies, if appropriately specified.

It isn't the topology that's the issue, it's the execution!

[quote name='nickhuge' timestamp='1437485703' post='2826411']
I've read really good things about these but would look dead weird with my amp flight/rack case on top at smaller venues!
[/quote]

Too tall?

From our range it sounds like you might be best served with a Retro Two10. It'll certainly be loud enough!

[quote name='MoJo' timestamp='1437245646' post='2824674']
It's one of those statements I've heard more than once, 'class D amps can be loud but they don't carry. You can't hear them at the back of the room'. Is this another urban myth. Volts are volts, right?[/quote]

Class D amps can certainly lack OOMPH when they fail to produce full power for the length of a bass note - it isn't because they're class D though, it's because many are built around modules which are made for typical program material which has a greater peak:average ratio than some bass sounds. But anyone claiming that:

[b]'class D amps can be loud but they don't carry. You can't hear them at the back of the room'.[/b]

isn't making much sense. The sound from a cab gets quieter the further you get from it and the amp driving it has no effect on that.

We definitely have to knock a load of these ideas up in photoshop - I can't help but think of your suggestion as being like a Big Twin 2 but with a megaphone bolted to each side and a big toggle switch labelled "drummer toasting direction" on top!

[quote name='Ghost_Bass' timestamp='1437128848' post='2823793']BTW. aren't we talking about a Behemoth design?
[/quote]

http://www.oxforddictionaries.com/definition/english/behemoth

We'd love to make a great busking amp but very few buskers seem willing to pay what something like that would cost to build let alone allow us to turn some kind of profit!

Maybe something for a Kickstarter?

The ELGEN will run perfectly happy with the Two10, just use the 8 ohm tap.

Remember, valve amps are the complete OPPOSITE of solid state amps when it comes to impedance. Too low doesn't bother them (though you'll get less power). Too high is what kills them - that's why you can't run them without a speaker attached because that would be an infinitely high impedance.

[quote name='Ghost_Bass' timestamp='1436458521' post='2818337']
I'm talking about having a real "PA-like" subwoofer there, not a bass cab that goes lower than the competition. [/quote]

So am I. Many PA subs don't go as low as a Big Twin 2.

So like a Big Twin 2 but quieter and more complicated?

Seriously though, if I could make a single driver that would do really clean full-range sound with tons of output, great dispersion, great transient response, then we wouldn't even make 2-way cabs. We made 3-way cabs in the past because we couldn't get a driver that could go high enough whilst going low enough.

Actually it looks like the new cab will be 2.5-way!

Just did some Behemoth concept testing - very pleased with the results!

[quote name='Phil Starr' timestamp='1436346731' post='2817241']You were looking for a Behemoth.[/quote]

We can out-Behemoth that!

I think all the cone drivers in there are ATC ones - it doesn't mention it on this image but I found an earlier version of the same cab and it's ATC throughout. I imagine this cost the same as a car!



Your DIY 1x12" looks a lot more sensible!

I just came across the specs sheet for a very fancy bass cab from the '70s and the speaker sizes in that were all in cm!

I shall see if I can post the image in here - it's a Zoot Horn FF1:

[quote name='Telebass' timestamp='1435994513' post='2814177']
You want bottom? LMIII with a Barefaced Super 15 will see to that. Despite being a 2x15, it weighs very little. Discontinued, though. ..
[/quote]

The Super Twin does as much bottom and the Big Twin 2 does more!

Yes, you'll be fine! The two best rules of thumb are:

1. PA use - amp has twice the power output of the cab's power handling
2. Guitar use - amp has half the power output of the cabs's power handling

For bass guitar? If you're Anthony Jackson (super clean uncompressed high accuracy reproduction of the instrument's sound) then the PA use approach is spot on. If you're Lemmy (heavily overdriven valve amps) then the guitar use approach is the one. Everyone else sits somewhere in between, which why it's so bloody confusing!

If you're near us you're welcome to borrow a demo cab for some gigs - they get on very well with Markbass heads!

[quote name='Chienmortbb' timestamp='1435674584' post='2811284']I am not sure of the quality of Chinese ply but the point about voids is an urban myth. When ply is made, adhesive is used to glue the layers together but it is kept under enormous pressure until the adhesive is set, the excess adhesive is squeezed to wards the edge but any knot holes or gaps are filled by the adhesive[/quote]

I'm not sure how much ply you've seen but I can assure you that categorically isn't true! The phenolic adhesive which holds ply together does not fill the voids.

[quote name='PauBass' timestamp='1435649435' post='2810877']We always record rehearsals when we are writing new songs, the difference from when I was using my DB750 to the recordings with Class D amps, confirm it for me, there's something missing, and I'm not talking volume.[/quote]

I bet it's that same thing I referred to earlier, about many lightweight amps not being able to deliver full power for long enough. So you get the attack of the note at full loudness but you don't get the WEIGHT of the note because the amp has run out of power by the time that comes through. Do you want to borrow our prototype power stage and see how it compares to the DB750's using the DB750 preamp to drive it?

[quote name='Ghost_Bass' timestamp='1435333716' post='2807852']Sorry but no, it's not placebo. At gig levels you can notice that the 4ohm cab "breathes" more. Mind you that this may come from the lower impedance on the amp and not from the cab itself. I'm not saying that a 4ohm cab is "louder" than a similar 8ohm one, just that there's more headroom at hand using [u]the same amp[/u] with a 4ohm cab [/quote]

But what were these identical 4 and 8 ohm versions of the same cab? Without knowing that then it doesn't stack up. And what was the amp?

I'd bet that on many of the 4 ohm version the sonic difference is because the speaker has surprisingly different T/S parameters to the 8 ohm one...

And you said "more clean headroom at lower volume" in the previous post whilst now you're saying that "at gig levels the 4 ohm cab 'breathes' more". That's a completely different thing!

[quote name='Ghost_Bass' timestamp='1435328693' post='2807785']
More that i can name, and i'm not takling about BF in particular (only played a MidgetT, Super12T and Big Twin, so, not comparable). I've had and tried a lot of cabs in the past and the general ideia i got from them is that at 4ohms i can get more clean headroom from the amp at lower volume. You know as well as i (even better than me) that if you have two identical cabs, one at 8ohm and another at 4ohms the drivers won't be quite identical and the sensitivity of the cabs will also be diferent.
I find that these diferences were more noticeable when using class-D amps where the bass had to be turned up a notch when running at 8ohms to give more "weight" to the low end. I know, the physics say one thing, but my ears hear another I still prefer using a class-D amp with a Neo cab though
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I'm 99% certain that what you've experienced is subconscious user bias. At lower levels you won't hear any difference if the 4 and 8 versions are essentially identical. It's placebo effect.

Yes, speaker and instrument jacks are almost always just tip-sleeve like the lower one in this pic whilst balanced ones for mics and feeds you'd usually use XLR for are tip-ring-sleeve, as are stereo ones like on old school headphones like the upper one in the pic:

[quote name='Conan' timestamp='1435326544' post='2807747']Having had all the "experts" convince us that lightweight Class D is the way to go, they are now all saying that the only way to get proper "heft/slam/thump/(insert adjective here)" is to go back to bulky, heavy amps with big manly transformers in them... [/quote]

It isn't - it's just having an amp that can do the amount of power you need for a full note length. With some of the optimistically specced Class D amps you might need a '900W' amp whilst a Class AB that can do its 300W continuously might have similar heft and loudness. But it isn't the Class D or Class AB thing that makes the difference, it's the power supply. The iAmp 800 was Class D with a traditional power supply. The Markbass LM2 was Class AB with an SMPS.

[quote name='Dan Dare' timestamp='1435323109' post='2807695']
Not a behemoth, but a 1x15. I love the tone of 15s for bass. Appreciate all the technical arguments about 12s being as good, but they just don't sound the same for me.
[/quote]

There isn't such a thing as "the tone of 15s". They all sound different! Same with 12"s. In fact there are plenty of 12"s which many would think sound like 15"s and vice versa. The one thing you can definitely say about 12"s vs 15"s is that the latter look bigger. Incidentally we started out making 15"s!

You're quite right about the 2 ohm thing - something we're working on though...