Class D amps - do the manufacturers know what they are trying to do?

[Beer of the Bass]

The littler amp of the new Peaveys looks quite elegant really, with no flashy lights or knobs labelled "Kosmos", so I think they're aware that not everyone will love the one with the lights.

[Guest bassman7755]

[quote name='JPJ' timestamp='1390662335' post='2348071']
The main problem with the class D stuff is the lack of real umph. There is no other way of describing it but all the class D stuff I've tried is missing that real 'weight' to the sound.
[/quote]

Many of them have a high pass filter so are theoretically missing some fundamental on B and E strings in extreme cases. I think the importance of these frequencies is over stated though - using a 5 string I couldn't tell any difference in actual sound from my QSC PLX between the unfiltered sound and engaging the LPF at 50hz although you could see that the cone moved less with it on.

But then I cant hear any particular deficiency in the RH450 which is allegedly LPFed at 80hz even compared to the PLX which with its vast 1600 watts rms of headroom. Personally I think its psychological - if your thing you should hear a difference then you will.

Edited January 25, 2014 by bassman7755

[icastle]

[quote name='Beer of the Bass' timestamp='1390677003' post='2348283']
The littler amp of the new Peaveys looks quite elegant really, with no flashy lights or knobs labelled "Kosmos", so I think they're aware that not everyone will love the one with the lights.
[/quote]

That KOSMOS thing has been around on Peavey kit for a while now - it's truly horrid.

The lights can be any colour you like, or just switched off if you prefer - it's all user configurable.

[LukeFRC]

[quote name='Dad3353' timestamp='1390672850' post='2348226']
Apologies, Luke, if I've mis-represented your intentions. I wonder what bass player asked for programmable colour-changing lighting panel, though.
[/quote] I realised that my post seemed to contradict you- went to change it and the power went off. Let threads go off on any sort of tangent more interesting that way!

[Dad3353]

[quote name='LukeFRC' timestamp='1390679978' post='2348325']
I realised that my post seemed to contradict you- went to change it and the power went off. Let threads go off on any sort of tangent more interesting that way!
[/quote]

The beauty of t'web, eh..? (...[i]and yes, redcurrants are more prolific than gooseberries, depending on variety[/i]... )

Edited January 25, 2014 by Dad3353

[Roland Rock]

[quote name='bassman7755' timestamp='1390677092' post='2348284']

the RH450 which is allegedly LPFed at 80hz
[/quote]

Dubtastic!
;-)

[Bill Fitzmaurice]

There are two issues here. One is Class D amps. There is nothing about Class D that's inherently any better or worse than any other class. How well or how poorly the manufacturer makes it is the question, and where that's concerned you can make a really good or a really bad amp of any class. The worst amp I ever had was all valve A/B.
The other issue is DSP. You're seeing a lot of Class D amps using it, because that's what accounts for the majority of new amp designs. If DSP had been available when SET ruled the roost they'd have been in those as well. Here also implementation is the issue. Some are very good, some not so much. You can pretty much tell which came out of the minds of engineers who also happen to be bassplayers, and which from those who'd be more at home doing video games.

[LukeFRC]

[quote name='Bill Fitzmaurice' timestamp='1390687199' post='2348397']
There are two issues here. One is Class D amps. There is nothing about Class D that's inherently any better or worse than any other class. How well or how poorly the manufacturer makes it is the question, and where that's concerned you can make a really good or a really bad amp of any class. The worst amp I ever had was all valve A/B.
The other issue is DSP. You're seeing a lot of Class D amps using it, because that's what accounts for the majority of new amp designs. If DSP had been available when SET ruled the roost they'd have been in those as well. Here also implementation is the issue. Some are very good, some not so much. You can pretty much tell which came out of the minds of engineers who also happen to be bassplayers, and which from those who'd be more at home doing video games.
[/quote] Good distinctions Bill. (though no idea what SET is )
I agree there's nowt wrong inherently with class D, you rarely hear the "they lack punch" point of view when it comes to PA amps (mind you I haven't looked for that long)

You've hit it though with the DSP more than the added features - there's very little discussion explanation as to what they are aiming for and some things... well you can hear the compression - which is fine if that's what you want. Just lack of discussion.
The most surprising thing I found was when I took the top off my old Tecamp puma 1000 and found they hadn't used any DSP in it.

[BassBunny]

[quote name='JPJ' timestamp='1390662335' post='2348071']
The main problem with the class D stuff is the lack of real umph. There is no other way of describing it but all the class D stuff I've tried is missing that real 'weight' to the sound. I do want to try the Aguilar Tone Hammer as allegedly this amp suffers least from this issue, but until someone brings out a class D module that sounds the same to my knackered old ears as a good old a/b design with huge transformers, then I'll keep the SWR and continue to be on first name terms with my chiropractor
[/quote]
Couldn't agree more. Have tried most Class D amps and actually owned 2x RH450's, as I really wanted it to work. Loud, yes, but lacks "balls". If it wasn't for a problem with my back, (and I am on first name terms with my Chiropractor), I would still be using my Eden WT550. Loads of natural tone and tons of clout.
So will stick with MarkBass, either my SA450 or LM2 and job done.

[mcnach]

[quote name='Beer of the Bass' timestamp='1390677003' post='2348283']
The littler amp of the new Peaveys looks quite elegant really, with no flashy lights or knobs labelled "Kosmos", so I think they're aware that not everyone will love the one with the lights.
[/quote]

I rehearsed for a while at a place in Edinburgh where they provided the Peavey Tour 450 amps with the Cosmos control.
Sometimes I'd turn around to look at it, and I liked to think that if I used it it might just take me on a trip around nearby galaxies. That and the blue led made me feel happy. I never used it 'though, as I wasn't sure I'd be back in time for dinner...

[BassTractor]

Yeah! Never noticed it before, but strangely it does seem to lack a Return Time knob.

[discreet]

[quote name='JPJ' timestamp='1390662335' post='2348071']
The main problem with the class D stuff is the lack of real umph. There is no other way of describing it but all the class D stuff I've tried is missing that real 'weight' to the sound. I do want to try the Aguilar Tone Hammer as allegedly this amp suffers least from this issue, but until someone brings out a class D module that sounds the same to my knackered old ears as a good old a/b design with huge transformers, then I'll keep the SWR and continue to be on first name terms with my chiropractor
[/quote]

That's just it - no huge transformers - no oomph. Physics!

[Bill Fitzmaurice]

[quote name='discreet' timestamp='1390781290' post='2349552']
That's just it - no huge transformers - no oomph. Physics!
[/quote]Class D is about the power amp, not the power supply. No one who owns one of these complains about lack of oomph.
https://www.djdeals.co.uk/prod-details.asp?AID=3067

[discreet]

[quote name='Bill Fitzmaurice' timestamp='1390789004' post='2349587']
Class D is about the power amp, not the power supply. No one who owns one of these complains about lack of oomph.
https://www.djdeals.co.uk/prod-details.asp?AID=3067
[/quote]

I don't want to disagree with you Bill. I suppose it's what you perceive 'oomph' to be. I've gone backwards technologically for what I believe to be very good reasons. What it actually is that's making that difference for me, I admit I don't know. But a difference there certainly is.

[wateroftyne]

The currently-available micro-heads that I've tried just don't have it. They have to do all sorts of nonsense to 'sound' loud, which isn't quite the same as 'feeling' loud. IMO.

Give me a lump of iron, please.

[Happy Jack]

[quote name='Bill Fitzmaurice' timestamp='1390789004' post='2349587']
Class D is about the power amp, not the power supply. No one who owns one of these complains about lack of oomph.
[url="https://www.djdeals.co.uk/prod-details.asp?AID=3067"]https://www.djdeals....ls.asp?AID=3067[/url]
[/quote]

I'm on my second Powersoft at the moment, Bill.

The first was my main bass power amp but it was overkill in terms of output (2000W for pub gigs - I think not!) and it was utterly clean ... it just made everything louder.

Bear with me.

My current Powersoft is a 4x700W unit and it's my PA power amp. I keep one channel free so that, should my bass rig crash and burn, I can simply run my Sansamp through the spare channel and there you are - 700W of uber-clean power to my Barefaced cab. That's more than enough power, but it also just makes everything louder.

So I lug around my Matamp 100W head. It makes everything [i][b]better[/b][/i].

[Beer of the Bass]

[quote name='mcnach' timestamp='1390779741' post='2349540']
I rehearsed for a while at a place in Edinburgh where they provided the Peavey Tour 450 amps with the Cosmos control.
Sometimes I'd turn around to look at it, and I liked to think that if I used it it might just take me on a trip around nearby galaxies. That and the blue led made me feel happy. I never used it 'though, as I wasn't sure I'd be back in time for dinner...
[/quote]

It's a good thing you never turned the knob! I can just picture you preparing for liftoff, then being underwhelmed when instead of being transported to the planet Gong on a flying teapot, you just got a sort of not very good octaver effect.

Edited January 27, 2014 by Beer of the Bass

[JTUK]

[quote name='wateroftyne' timestamp='1390811407' post='2349650']
The currently-available micro-heads that I've tried just don't have it. They have to do all sorts of nonsense to 'sound' loud, which isn't quite the same as 'feeling' loud. IMO.

Give me a lump of iron, please.
[/quote]

This....

[Alec]

[quote name='LawrenceH' timestamp='1390675542' post='2348271']
A PEAVEY! Look at the Peavey logo, for Chrissake! When have their aesthetics ever targeted any sector other than that in the USA which wears naff 80s mullets? It is for this reason that I could score an all-valve high plate voltage 1u rack preamp for less than 50 quid, whereas if it didn't say 'Peavey' on the front in hairdressing scissor font and have a stupid double X in the name it would have cost me about 400 quid
[/quote]
I think this pic from the Peavey stand at NAMM reminds you where Peavey are coming from (clue - a couple of decades ago)

[dincz]

I was a believer but after trying various power amps I now have my doubts - not so much about class D - but about the switch-mode power supplies that (usually) feed them. I think it's all about having the headroom (and the power supply is part of this) to deal with the initial attack of a note. Class D/SMPS can handle it provided the amp has available clean power way in excess of what you might think you need - that is, lots of headroom.

It's significant that amps are no longer rated for continuous power but for burst power, i.e. power that can be maintained for only a few tens of milliseconds. In fact, it seems from tests I've read that most SMPS powered amps will shut themselves down if you try to get their maximum rated power for several seconds continuously.

If you want "oomph", which I take to mean the clean power to deal with attack , then stick with iron or choose a class D/SMPS amp with several times the power rating of a conventional amp that would do the job. That's where multiple kilowatts of Powersoft amp comes in handy. On the other hand, there's no reason at all why a SMPS couldn't be engineered for the purpose if some of the size/weight advantages were to be sacrificed.

I'm not a design engineer so this is more gut feeling than anything else, although I was a maintenance tech in broadcasting for 20 years in a previous life so it's not a totally uninformed gut feeling.

Edited January 27, 2014 by dincz

[flyfisher]

De gustibus non est disputandum.

[discreet]

[quote name='flyfisher' timestamp='1390824216' post='2349848']
De gustibus non est disputandum.
[/quote]

Obviously there can be... especially on BC...

[flyfisher]

Sure, we can argue preferences but let's not forget that's all they are. There are no rights and wrongs.

[Bill Fitzmaurice]

[quote name='discreet' timestamp='1390810749' post='2349643']
What it actually is that's making that difference for me, I admit I don't know.
[/quote]The power supply. The main deficiency of most Class D amps is that they lack sufficient capacitive storage capacity. Manufacturers in their zeal to make the amp as small as possible don't put in enough capacitors to do the job. If you look under the hood of a really well made Class D you'll find half the chassis filled with storage capacitors.

[LukeFRC]

[quote name='Bill Fitzmaurice' timestamp='1390832913' post='2350002']
The power supply. The main deficiency of most Class D amps is that they lack sufficient capacitive storage capacity. Manufacturers in their zeal to make the amp as small as possible don't put in enough capacitors to do the job. If you look under the hood of a really well made Class D you'll find half the chassis filled with storage capacitors.
[/quote] as show by the inside of one of those powersofts....