Mini 0r Micro Amps.... I Must Be Missing Something?

[Munjibunga]

I understand the convenience of these small heads, TC, Ampeg, Aguilar, GK, GB, MB etc. especially if you ride a bicycle. I even ordered the PF-500, primarily looking for a small backup for tube amps.

I realized I have to carry it and whether it's on top of my cab or in a case, I still have to move it. A power amp (I'm using a Crown XLS1500) has way more power, ohm and cab options, these mini's just aren't worth the problems people are posting on TB. Yes, you need a preamp either racked or in pedal form, but it's worth it.

PF-500 cancelled. Call me when they have one the size of a pack of cards, that works.

Bizarre.

 

[Munjibunga]

Agreed. My ab of the th500 vs db750 concluded there is still a considerable gap the advantage going to the big head for dynamics, tone, tightness, lack of compression in the low end. The micro heads are great and if you don't ab gig both you will be happy with the micro. Once you try the big head at a typical medium gig you will feel and notice the difference. For super low volume coffee shops or in your basement at low vol not much difference. I dumped all micros accept a lm tube which I love and went back to a db751 for my main head. My bands I play with are happier now. 42lbs isn't going to kill me and I need the workout anyway. Now an 90 lb svt that's another story.

Hmmm ... the DB750 isn't exactly what I would call a "tight" amp, even with a Telefunken in V1. You want tight, get a Heart-Rock or, in the micro category, an MB800.

 

[joelb79]

Don't see how it's relevant to this discussion, though, unless all micros have that much built in grit, and all lead sleds don't.

This is certainly how the Bang & Olufsen ICEPOWER 125asx2 responds to signal; and I heard from the Aguilar TH500 shop tour/construction demo video that other amplifier companies are using this amp as well. Streamliner comes to mind.

I find that graph to be very revealing.

 

[joelb79]

They use the x250 ICE module (same

That unit is stereo only and not bridgeable unless its 8ohms. How are they using the 250asx if it doesnt even run bridged 4ohms?:

 

[joelb79]

That is not the power module used in the TH500. I'll not make a specific comment about the quality of your 'golden ears' on this one! You might want to remove that post, since that is the kind of stuff that perpetuates these type of beliefs.

Edit: +1 to your general point though. The higher end class D/SMPS bass amps, like the Glock, the Puma, etc., seem to use the 'monoblock' high powered modules from various companies, versus the 'bridging modules' at the lower end of the market (i.e. you can see the brand and model number of the Glock through the heat fins... that module is a monster!). I assume this at least somewhat impacts the overal performance of the unit in big, open, low end. Again, this has less to do with the topology of the power section versus the quality of component and the price point, like with any amp of any design.

Your right they use a 250ASX2

I know that he says that other amp manu's are using that same ICEPOWER unit. These guys seem more like preamp designers than amplifier technicians. These amps seem built strikingly like a lot of the computers I've built in my lifetime.

I'll keep my ear comments to myself tho JKung. I keep loosing that ability more and more with age anyhow.

Also, the distortion rate reported above regarding the TH500 is not correct. They use the x250 ICE module (same unit that is in the Genz 900 series amps), and then limit the output at 4ohms to the 8ohm spec, resulting in an uber reliable power source with very nice specs. Gockenklang does a similar thing, using a MUCH more powerful, uber high end class D/SMPS unit (1000 watt) than their specs would suggest, and then somehow limiting it to 650 watts, and keeping THD to a ridiculously low level.

The 8 ohm bridge specification is 10% THD, so again it is relevant. Thanks for explaining how they limit the amplifier current at 4 ohms; but the 8 ohm spec of 10% would apply as it comes on at a much lower power point; around 220w. Above that distortion flies off the chart; as referenced above.

I would think that glockenclang is using something similar to the ICEPOWER 1000ASP or something similar in specs. The ASP has far better THD specs than the ASX2 series.

 

[nostatic]

Funny, because at last night's gig I passed out spectrum print outs instead of playing (glad I brought a lot of copies - the dance floor was full). Then an origami flash mob broke out. It was crazy!

 

[KJung]

Your right they use a 250ASX2

I know that he says that other amp manu's are using that same ICEPOWER unit. These guys seem more like preamp designers than amplifier technicians. These amps seem built strikingly like a lot of the computers I've built in my lifetime.

I'll keep my ear comments to myself tho JKung. I keep loosing that ability more and more with age anyhow.

Both amps that use this module (the TH500 and the 9 series Genz amps) use different circuitry to get to 4ohms... the Genz uses lots of power management circuitry to make the increase distortion at 4 ohms bridge sound 'tubey and musical' and some very sophisticated heat reduction mechanics. The TH500 somehow limits the bridged output of that power unit to put out only 500 watts at 4ohm bridged, which sounds massive, clean, punchy and tight! So there is nothing on the basic specs of that ICE Modules homepage that really gives you a picture of what is going on with those two unique executions (other than it is a bit different from some other class D applications that use pure and simple 'non bridged' designs... or at least different internal bridge designs.. that is a bit over my head).

However, compared to a Puma900 (I believe that head uses the monoblock 1000 watt version of the ICE module that is listed under a different product line name) and Glock Blue Soul (which uses a very impressive 1000 watt monoblock class D module from another manufacturer), and even the Markbass SD1200, that uses internally produced power modules, there is definitely a difference down low. Every SMPS and/or class D amp sounds quite different, and not surprisingly, just like their heavier brethren, the quality/heft of components does make a difference.


Again, these are the only two heads I am aware of that use that ICE module. The TH350 and Shuttle 6 use the module you described earlier. The Aguilar 'method' for using this module at 4ohms sounds fatter, more open, less compressed. The Genz version sounds louder, but they have it hi passed at a high enough level that it definitely doesn't sound as big. I assume this was a design goal just as much as a power/distortion level limitation, but just guessing there.

 

[Rune Bivrin]

Most of the time we wrestle with psycho-acoustics. Since for many years a more powerful amp would have to be bigger, we sub-consciously infer that a bigger / heavier amp has a bigger / heavier sound. Getting rid of that association isn't easy.

Me, I'm rid of the amp completely right now. I have a Zoom B3 and DI to the board. Guess what topology the power amps in the PA is...

 

[KJung]

I would think that glockenclang is using something similar to the ICEPOWER 1000ASP or something similar in specs. The ASP has far better THD specs than the ASX2 series.

To be specific, I wanted to +1 this. There are many, many executions of class D/SMPS bass amps (even among those that happen to use the ICE modules), and the top of the line models compare VERY well to the top of the line 'big iron' heads.

Like with most amps of any design, the expensive ones do seem to perform better. That doesn't mean that you will like it better, or even that they will sound 'better' or get 'louder', but they will look better on the scope, for the most part.

That is why it is key to stay away from 'all class D/SMPS' sound like 'x'. VERY different stuff going on under the hood.... just like with every amp brand using similar topology power amps and supplies.

 

[Jarrett]

Whenever I start doubting my micros, I haul my old Trace Elliot AH350SMX out of the closet and A/B it with whatever micros I have at the time. After 30 minutes or so, I lug the Trace Elliot back to the closet and continue to gig happily with my micros

 

[Russell L]

Love my Little Mark III. Why the hell would I want to haul a big heavy thing instead?

 

[Groovy_Gravy]

Sorry, I'll stick to my SVT. All 80lbs of her.....

same here..Ill keep my 75 pound V4B and my 90 pound trace elliot 410

 

[seamonkey]

The Demeter - 600w is B&O Ice, the Kemper 600w - I suspecting that just about everyone is using a B&O Ice
This is good because it's power supply SMPS + Amp, and B&O knows how to manufacture reliable amps. If you look, you'll probably see most of any problems with Micro heads are from manufacturers who have tried to build their own. There's nothing wrong with the technology. There's a learning curve for every amp maker who decides to make their own.

 

[KJung]

The Demeter - 600w is B&O Ice, the Kemper 600w - I suspecting that just about everyone is using a B&O Ice
This is good because it's power supply SMPS + Amp, and B&O knows how to manufacture reliable amps. If you look, you'll probably see most of any problems with Micro heads are from manufacturers who have tried to build their own. There's nothing wrong with the technology. There's a learning curve for every amp maker who decides to make their own.

Again, Markbass is not, Glockenklang is not, Walter Woods is not, Puma just recently moved to ICE, I don't believe GK uses ICE modules either (not sure there).

The only two companies I know of that make their own are Markbass, which is reliable as all heck, and Walter Woods, who has a bit of a mixed record there, but he kind of invented the darn stuff in at least some ways, so I'll cut him some slack

 

[KJung]

Anyway, fun thread focused on one of my favorite topics! I enjoyed it!

 

[Mark Reccord]

The 8 ohm bridge specification is 10% THD, so again it is relevant. Thanks for explaining how they limit the amplifier current at 4 ohms; but the 8 ohm spec of 10% would apply as it comes on at a much lower power point; around 220w. Above that distortion flies off the chart; as referenced above.

I think you're looking at the wrong graph. The one I looked at for the 250ASX2 in the link you posted has THD+N under 1% at 500W/8Ohms in bridge mode. As for running it bridged into 4 Ohms, if they're setting the limiting circuitry up to kick in at 500W when the module is driving a 4 Ohm load, they're not operating it outside of its design specifications. It doesn't care about the load impedance per se, it just cares about the amount of current it has to deliver to that load. As long as that's artificially limited there aren't any issues with running it into a 4 Ohm load.

I'll bet dollars to donuts that's what's inside the GK MB500 as well, probably set up that way. I'll pop the cover off mine tonight and have a look-see.

In over a year of gigging with the MB500 and doing some comparisons to the non-class-D GK heads, I don't think the MB500 gives up anything in the tightness/punch department to them or any other amp for that matter. Even at gig volume. I will admit to liking how the 800rb hits its limits better than the same behaviour from the MB500 but it's hardly relevant as I'm not reaching them often enough to worry about it. The MB500 doesn't sound like my SVT but it definitely sounds great and I don't think I've used the SVT on a gig since I bought the MB.

So, yeah, I'm missing something with my micro: About 85lbs that I don't have to drag to gigs.

 

[Mark Reccord]

Again, Markbass is not, Glockenklang is not, Walter Woods is not, Puma just recently moved to ICE, I don't believe GK uses ICE modules either (not sure there).

The only two companies I know of that make their own are Markbass, which is reliable as all heck, and Walter Woods, who has a bit of a mixed record there, but he kind of invented the darn stuff in at least some ways, so I'll cut him some slack

GK might be a good example of what you are talking about (and also Ampeg) if they do make their own. They were also pioneers in class D/SMPS, starting with one of the very earliest bass amp executions... the GK1200 (that blue and pink medal thing). It was pretty bad, but it was quite something in its day. They moved the MB150 combo's to class D/SMPS VERY early on also, although they too blew up by the dozen for the first couple years of manufacture. Again, not sure what GK is using inside their micro's now.

GK is using ICE. The MB200 is for sure and I'll find out this evening what the 500 uses.

 

[KJung]

I think you're looking at the wrong graph. The one I looked at for the 250ASX2 in the link you posted has THD+N under 1% at 500W/8Ohms in bridge mode. As for running it bridged into 4 Ohms, if they're setting the limiting circuitry up to kick in at 500W when the module is driving a 4 Ohm load, they're not operating it outside of its design specifications. It doesn't care about the load impedance per se, it just cares about the amount of current it has to deliver to that load. As long as that's artificially limited there aren't any issues with running it into a 4 Ohm load.

Yeah, something doesn't seem quite right with that chart, but that is over my head (based on the performance of that amp when pushed). Maybe he is posting the 'each side' sort of thing versus bridged.

The TH500 is a clean machine down low, and huge (even compared to some other class D amps) if you don't dial the gain up. Again, though, that particular preamp has a lot of hair voiced in it.

The Genz execution is a bit different, since they really are allowing it to reach 'maximum power' at 4ohms, so I can see where the THD would increase there. But even in that case, you would rarely push that amp into full power, and their power management sounds amazing.

 

[KJung]

GK is using ICE. The MB200 is for sure and I'll find out this evening what the 500 uses.

Cool. I'll delete that part of my post, since I was purely guessing. I thought they might be doing their own, since they kind of pioneered the technology in the late 70's/80's with the GK1200 and the MB150 (second generation).

 

[Mark Reccord]

Hmm, the 115V BTL graph shows THD at about 2%, 500W/8Ohms. A bit higher but not 10%. Given that most places in North America would show 120V+ I suspect those numbers would come into line with the 230V ones (higher mains voltage = high rail voltage = higher knee for THD jump). If they spec 8 Ohm operation at 350W, then THD is going to be way down at that level even at a lowish 115V mains.