Of the lightweight heads available... Class AB

[Dood]

Just out of interest really, I'd like to know which of the lightweight (or indeed small form factor) bass heads feature Class AB power amplifiers instead of D Class?

I think certain MarkBass models do? What about the likes of the Eden Traveller heads? I feel some tests coming on!

[LukeFRC]

for the stupid amongst us... can you explain the difference? I know that AB or D (or H i've seen somewhere) is one bit they can save weight on, along with the power supply... but apart from that I'm a bit uneducated

[Sean]

The awesome Mesa Walkabout is AB. Small amp, huge heft. I've run mine through a Barefaced BT2 and it's incredible, it has so much heft.

[wateroftyne]

[quote name='Sean' timestamp='1399772062' post='2447547']
The awesome Mesa Walkabout is AB. Small amp, huge heft. I've run mine through a Barefaced BT2 and it's incredible, it has so much heft.
[/quote]

Yeah. Once you've tried a Walkabout, the others feel a bit 'diet'.

[PauBass]

[quote name='wateroftyne' timestamp='1399791780' post='2447575']


Yeah. Once you've tried a Walkabout, the others feel a bit 'diet'.
[/quote]

I've always read really good things about these amps and many times I've thought about getting one but I'm worried those 300 watts are not enough, I play in rather loud band
Any ideas on how it compares, volume and tone wise, to heads like the Aguilar TH500?
I'd run this amp through a Barefaced Super Twin

Edited May 11, 2014 by PauBass

[warwickhunt]

[quote name='PauBass' timestamp='1399795535' post='2447615']
I've always read really good things about these amps and many times I've thought about getting one but I'm worried those 300 watts are not enough, I play in rather loud band
Any ideas on how it compares, volume and tone wise, to heads like the Aguilar TH500?
I'd run this amp through a Barefaced Super Twin
[/quote]

WoT is the man to 'subjectively' answer that.

[wateroftyne]

[quote name='PauBass' timestamp='1399795535' post='2447615']
I've always read really good things about these amps and many times I've thought about getting one but I'm worried those 300 watts are not enough, I play in rather loud band
Any ideas on how it compares, volume and tone wise, to heads like the Aguilar TH500?
I'd run this amp through a Barefaced Super Twin
[/quote]

I have no experience with the TH500 so I can't comment on that,

Most of my bands are pretty controlled volume-wise, but I've done deps in loud bands with the Walkabout, and as long as I've brought enough cone area along (2 x Bergantino 2x10s at the time), it's never struggled. It's just given out an honest, fat, analogue punch with a proper backbone.

Don't forget it's a conservative 300 watts - it's 340w into 4ohm. It'll also put 480w into 2ohm.

That said, it you crave clean headroom, don't bother.

[warwickhunt]

Did you not own the Aggie amp Michael? [size=4] [/size]

[warwickhunt]

Aaaah just spotted 'TH'... you had the AG! [size=4] [/size]

[PauBass]

[quote name='wateroftyne' timestamp='1399796863' post='2447626']


I have no experience with the TH500 so I can't comment on that,

Most of my bands are pretty controlled volume-wise, but I've done deps in loud bands with the Walkabout, and as long as I've brought enough cone area along (2 x Bergantino 2x10s at the time), it's never struggled. It's just given out an honest, fat, analogue punch with a proper backbone.

Don't forget it's a conservative 300 watts - it's 340w into 4ohm. It'll also put 480w into 2ohm.

That said, it you crave clean headroom, don't bother.
[/quote]

Thanks for the advice.
Might not be enough for me as my cab is 4 ohm... The TH500 is loud little amp, it would be interesting to hear from someone that has used both.

[BassBunny]

MarkBass LM 2/3, LMK and SA450 are all Class A/B. Not sure about The Eden Traveller, (even though I have had one), but wouldn't exactly call it lightweight.

[JapanAxe]

[quote name='LukeFRC' timestamp='1399758636' post='2447465']
for the stupid amongst us... can you explain the difference? I know that AB or D (or H i've seen somewhere) is one bit they can save weight on, along with the power supply... but apart from that I'm a bit uneducated
[/quote]
You can find an explanation [url="http://en.wikipedia.org/wiki/Class_AB#Class_AB"]here[/url].

The practical benefit of Class D is the lack of big heavy mains transformers.

[Guest bassman7755]

[quote name='JapanAxe' timestamp='1399799719' post='2447672']
You can find an explanation [url="http://en.wikipedia.org/wiki/Class_AB#Class_AB"]here[/url].

The practical benefit of Class D is the lack of big heavy mains transformers.
[/quote]

In point of fact you could use a transformer PSU with a class D amp but it defeats the point somewhat since the primary design objective is light weight and efficiency.

Conversely you can use a switched mode PSU with a class A/B/AB with some additional trickery that allows them to vary the supply voltage in line with the signal thus overcoming the inherent inefficiency of A/B/AB designs operating on a fixed voltage. This is the so-called "class H" design used in earlier light weight PA amps such QSC PLX range but this design seems to be losing ground to class D designs these days.

Edited May 11, 2014 by bassman7755

[Beer of the Bass]

[quote name='JapanAxe' timestamp='1399799719' post='2447672']
The practical benefit of Class D is the lack of big heavy mains transformers.
[/quote]

The power supply and associated mains transformer are a separate issue from the type of power amp used. Usually Class-D amps and switch-mode power supplies are used together, but there are exceptions. The older Acoustic Image heads had a linear power supply with a toroidal mains transformer powering a Class-D power amp and were surprisingly weighty for their size. The Markbass LMII uses a lightweight switch-mode power supply with a class-AB power amp.

[LukeFRC]

[quote name='JapanAxe' timestamp='1399799719' post='2447672']
You can find an explanation [url="http://en.wikipedia.org/wiki/Class_AB#Class_AB"]here[/url].

[/quote] thanks!

[Sean]

The WB through my BFBT2 is way louder than I would ever need and would be too loud for an unmic'd drum kit to compete with but as WoT points out, it's not about clean headroom, it's a filthy little amp. The WB is a different animal completely to the TH500, it's actually more comparable to valve amps in the way it behaves and sounds. I absolutely love it. Almost as much as my 400+.

[molan]

I had a Walkabout for while - didn't get on with it at all and sold it very quickly. Sounded a bit flat and wooly to me, especially in combo format

Conversely I've had a TH500 more or less since they came out. Have tried a lot of other heads along the way but keep coming back to the TH

[wateroftyne]

[quote name='molan' timestamp='1399819825' post='2447971']
I had a Walkabout for while - didn't get on with it at all and sold it very quickly. Sounded a bit flat and wooly to me, especially in combo format
[/quote]

Yeah - the Walkabout doesn't really shine in the Scout combo.

[Merton]

Stop all this positive Walkabout talk, they sound like a fine back up for my valvey goodness and I can't afford one

[Prime_BASS]

Having owned a variety of lightweight heads some AB and some class D I can't say I've ever heard a significanyou noticeable difference in sound or performance.

A lot of heft IMO in the small lightweight stuff comes from the preamp voicing and EQ stack not much else.

One amp I am totally blown away with is the car stereo GK MB200. Massive sound and volume came from that and my super compact at the bass bash, just a shame it's missing an actual master volume.

[Musicman20]

The pre amp and overall design/limiting will have a much larger impact on tone and volume over the difference between two similarly rated, but different class, power amp sections.

Edited May 12, 2014 by Musicman20

[wateroftyne]

[quote name='Musicman20' timestamp='1399883201' post='2448491']
The pre amp and overall design/limiting will have a much larger impact on tone and volume over the difference between two similarly rated, but different class, power amp sections.
[/quote]

Yep - I think you'll be pushed to find any Class D that doesn't have some sort of limiting circuit in place to 'simulate' a louder amp.

[Muzz]

[quote name='Merton' timestamp='1399831674' post='2448135']
Stop all this positive Walkabout talk, they sound like a fine back up for my valvey goodness and I can't afford one
[/quote]

If it helps, I wasn't blown away by the Walkabout either. I A-B'd against my Streamliner, and though there wasn't tons in it, I kept the Streamliner and the Walkabout went back (to WoT! ). Having said that, I guess 900 Class D against 300(ish) Class AB is different numbers, but the Streamliner was smaller, lighter and cheaper, which were factors for me. I didn't notice any difference in 'heft', either. Cabs could be a big factor here, too...

[Musicman20]

[quote name='wateroftyne' timestamp='1399883431' post='2448494']
Yep - I think you'll be pushed to find any Class D that doesn't have some sort of limiting circuit in place to 'simulate' a louder amp.
[/quote]

Aye I agree, but I think all of the modern amps, in fact all amps (?), have limiting circuits of some sort. I'm not an expert, but I know the limiter on the class A/B Markbass LM3 was pretty harsh...clamped down when the master volume was just over 12 o'clock, (more so at 8 ohms).

Limiting circuits have come a long way, more so in the modern lightweight amps.

You then have something like the TC amps, which is going in a completely different direction.

I imagine the magic of the WA is a sum of all the well designed parts of the amps getting that 'right' tone at a pretty decent volume, in a small package.

As one of the ex Genz guys is now working for Mesa, who knows what we might get!

[Muzz]

[quote name='Musicman20' timestamp='1399885407' post='2448512']
As one of the ex Genz guys is now working for Mesa, who knows what we might get!
[/quote]

Oooo, now that's interesting news...