Do all class D heads really lose their thud at volume?

[EBS_freak]

3 minutes ago, BigRedX said:

IME all the covers bands I have been in or seen in the last 10 years have their own vocal only PAs which would require me to still own a conventional bass rig.

This is pretty true. I think the more serious bands are slowly making the turn - but ultimately - the less you are relying on backline and letting the PA do the lifting, the better your band is going to sound.

I know lots of people will argue otherwise - but you aren't playing Wembley.

There's lots of other factors I know... shared ownership/sole ownership of PA, moving it, playing with other bands....

But ultimately, let bleed into mics, the cleaner your signal (hell, moving to a decent modelling setup with decent monitoring is probably the best move you can make right now (for getting a consistent tone at any volume).

[la bam]

29 minutes ago, EBS_freak said:

This is pretty true. I think the more serious bands are slowly making the turn - but ultimately - the less you are relying on backline and letting the PA do the lifting, the better your band is going to sound.

I get what you are saying, and see the benefits for everyone, and have played that way myself, but in my opinion, for the music I play (rock, indie etc)  having a fantastic backline sound really brings out the best in a rhythm section, and ultimately a band. Theres just something real about it. It's hard to raise your game with a quiet, small stage sound from a 1x10 cab. It's not just us as bassists, drummers feed off us too. The slam of a big amp and cab brings things to life. Just my experience though. It's all good.

[agedhorse]

On 14/09/2020 at 03:50, Dan Dare said:

I take it the commonly used module is from IcePower. It does seem to vary according to how it's used. 

This is true, there are good implementations of amplifiers using these parts and some that have suffered from the symptoms being described. Each designer is different, each has their own preferences, skill set and experience designing with these parts. 

My design experience with IcePower goes back almost 20 years, when I was also designing for the (touring) pro audio industry. When I started designing bass amps with these class D parts, I already had a 5 year advantage over just about every other designer so I wasn't affected by the learning curve nearly as much.

Also, this was the same time that players began demanding smaller, lighter weight cabinets, so some of the differences can be attributed to a general migration of demand and change in tastes rather than just the amps themselves. 

[agedhorse]

On 13/09/2020 at 03:50, Woodinblack said:

Im not blaming the amp, it is just a 100w amp, and the reason people say about 'valve watts' is that once a valve amp runs out of steam it compresses and distorts with even harmonics which are musically pleasant, so people are happy with that. a transistor based solid state A/B type will distort with odd harmoncs which aren't musically pleasant so people don't do it, so you get this idea of valves being louder, just that valves are more 'musical' when overdriven.

A class D will run out of power supply capability before anything else, so yes, the low end will go first because it is the bit which requires most power.

A solid state amp does not have to distort with odd order harmonics IF the designer chooses to manage HOW the amplifier clips. A tube amp, for example will NATURALLY distort with more lower level, even harmonics but this doesn't mean that a solid state amp (either linear class AB or non-linear class D) can not. In fact, one of the most important aspects of today's current digital based modelers (ie. AxeFx, helix, etc) is all about improving and perfecting what happens (in software) under modeled clipping conditions. Similar things are done by some designers in the purely analog world as well.

Often, the power supplies in class D integrated power amp modules with SMPS have GREATER capacity than their linear (class AB with ,line frequency power supplies) counterparts. Often by a great margin too.

Just providing some factual information here.

[agedhorse]

On 14/09/2020 at 05:08, EBS_freak said:

Nope - but the market is driven a lot around the B&O module. Small, affordable - enables for teeny tiny, lightweight - but oh so powerful heads... and that means that any amp that uses that module, is likely to exhibit similar behaviours. It's just whether you are willing to take that compromise. But the compromises are more about the module choice rather than the technology choice.

I'm going to disagree here as I have experience designing amps around different platforms. 

In general, all of the MAJOR power amplifier platforms are really quite good and difficult to discern any real world differences when driven from an identical source. Most of the differences come from the designer's choices that typically reflect what the players are asking for as well as their own personal tastes)

The reason I (as a designer) have chosen IcePower is because of my 20 year history with the product back when I was designing touring level pro audio using the IcePower platform. In the industry, they are generally considered the "gold standard" module because of their reliability track record, their ability to supply defect free product without interruption, their product's safety and EMC certification, and the in-house engineering support capabilities. You might be surprised, but cost is actually pretty far down the list of priorities as they are not the cheapest supplier of these parts (not by a long shot).

[EBS_freak]

Quite happy to disagree. All good man!

[agedhorse]

10 hours ago, Chienmortbb said:

You are probably refering to ICEPower and if so that is an unfair jibe. The real problem is manufacturers overstating the power output of various ICEPower modules.

 

 

Actually, the bigger problem is the end users who think they understand what the data sheets mean without actually understanding the technical data behind the numbers and WHY they might be used in describing specific specs.

When an experienced designer learns all of the ins and outs behind the performance of the module and what is actually happening between the lines, it becomes apparent that there are additional performance gains present to those who understand how to exploit them. As a specific example, when I was designing around an earlier IcePower module, we used to get "armchair techies" who would insist that the module wasn't capable of driving 4 ohms BTL and that it was was only capable of 250 watts into 4 ohms therefore we were not being truthful. In fact, the amp could easily deliver 900+ watts RMS into 4 ohms BTL, and that the 250 watt single ended specification didn't even apply. This was such a valuable off sheet applications (that required specialized cooling and over-modulation management) that we received a patent for the techniques that we employed. 

It's very similar to what's happened in the automotive industry over the years. Power output per cubic inch (or litre) of displacement has increased greatly through the introduction of fuel injection, variable valve timing, variable ignition timing, stoichiometric fuel management through combustion products feedback, advanced combustion chamber design, tighter tolerances, lighter reciprocating mass, etc. 

The same applies to many of the successful applications in all industries. The more you know, the easier it is to be successful and deliver successful, reliable products.

[andy67]

Keep going agedhorse, it’s riveting reading because I’m now thinking about my Bugera Veyron BV1001T and the 2000w claim made by the manufacturer. Can you shed any light on where they get these numbers from? 
 

if you are unfamiliar with the BV1001T it has a valve (3 x ax7) pre into a class D out. 

Spec here: https://www.bugera-amps.com/product.html?modelCode=P0AED

Edited September 16, 2020 by andy67

[agedhorse]

1 hour ago, Woodinblack said:

Valve what? Class A/B what?

I mean a class A/B mosfet is going to be very similar to an all valve (apart from maybe one with a valve power supply regulation too, which is less common). A class A amplifier is going to always sound better than a class B or a class A/B regardless of power delivery. A class A mosfet will clearly sound better than a class B valve and when you are overdriving they will both sound better than a transistor (regardless of class). When you are not overdriving they are basically down to the power supply.

Often class D (which is very different) is going to fail because of a lack of power supply. So a class D with a big power supply (of the sort of the sort of power of any class A) will probably be very good, but you don't get them really in small heads (as its kind of not really the point).

Interesting perspective.

Would you care to give and example of a class A bass amp (power amp) that fits your above theory? From your description it sounds like you are unclear about what amp class actually means.

All class D amps have power supplies, and what may be surprising to you is that some of the power supplies used in class D amps are actually bigger (in capacity) than their line frequency brethren. Sometimes by a LOT. The physical size can't be used as a comparison because the SMPS that are most often used with class D amps operate at a higher frequency which requires smaller magnetics (transformer) and also recharge the supply bus at ~100,000 times per second rather than at 120 times per second (100 times per second in 50hz regions)

[agedhorse]

11 minutes ago, andy67 said:

Keep going agedhorse, it’s riveting reading because I’m now thinking about my Bugera Veyron BV1001T and the 2000w claim made by the manufacturer. Can you shed any light on where the get these numbers from? 
 

if you are unfamiliar with the BV1001T it has a valve (3 x ax7) pre into a class D out. 

Spec here: https://www.bugera-amps.com/product.html?modelCode=P0AED

This is a good question, and I believe it has been discussed before (maybe not here but on other forums).

One way to determine rated RMS power is to go to the AC power rating, which by safety agency standards must be a MINIMUM of what the amp draws from the source at rated audio power at the lowest rated impedance USING RMS metrics at a minimum of 1/8 rated power.

According to the published specs below, we can determine the likely power in RMS terms:

The calculation would be to assume an overall average efficiency of 85% for the power supply and amplifier, and run the following numbers using the published 110 watts input power:

(110W x .85%) /.125 = 748 watts RMS rated audio power as used in the safety certification. If the overall average efficiency was 80%, then the calculated value would be 704 watts RMS (both into 4 ohms). Under maximum power output, it's listed as 2000 watts peak, but without a concrete definition of peak being provided, no conclusions can be accurately drawn. Peak will always be less than when using RMS metrics however, usually twice the RMS value but sometimes more depending on the definition.

I hope this helps answer and clarify your question.

Edited September 15, 2020 by agedhorse

[Beer of the Bass]

Thinking about it, haven't there been a few cases where manufacturers have used a proprietary power module, run into reliability issues and discontinued support of them after a short while? That would make me lean slightly towards amps using ICEpower or modules from other large, established makers just because they're likely to be more of a known quantity and have continued parts availability.

[Woodinblack]

33 minutes ago, agedhorse said:

Interesting perspective.

Would you care to give and example of a class A bass amp (power amp) that fits your above theory? From your description it sounds like you are unclear about what amp class actually means.

I am not sure of any specific bass class a amp, and both class a amps I have here are fairly low power. I am fully aware what the class of amps is thanks, I was clarifying a confusion above that class a/b has anything to do with being a transistor amp vs a valve amp.

The class a amp I have is a hifi amp, and I have a small guitar one too (that I haven't used for a long time)

Quote

All class D amps have power supplies, and what may be surprising to you is that some of the power supplies used in class D amps are actually bigger (in capacity) than their line frequency brethren. Sometimes by a LOT. The physical size can't be used as a comparison because the SMPS that are most often used with class D amps operate at a higher frequency which requires smaller magnetics (transformer) and also recharge the supply bus at ~100,000 times per second rather than at 120 times per second (100 times per second in 50hz regions)

Of course it wouldn't surprise me?

but in the context of bass amps that we are talking about and specifically the tc rh amps, one of their weaknesses was considered their power supply.

Edited September 15, 2020 by Woodinblack

[Dan Dare]

I'd be very surprised if there was such a beast as a class A bass amp (apart from low power studio stuff). Class A amps are  very inefficient and produce large amounts of heat. For live bass use, you'd probably need something the size of a coal bunker, with truck cooling fans.

OK, maybe I'm exaggerating, but not that much.

[agedhorse]

1 hour ago, Dan Dare said:

I'd be very surprised if there was such a beast as a class A bass amp (apart from low power studio stuff). Class A amps are  very inefficient and produce large amounts of heat. For live bass use, you'd probably need something the size of a coal bunker, with truck cooling fans.

OK, maybe I'm exaggerating, but not that much.

Yes, you are essentially correct. I know of no practical examples of class A bass amps available.

[agedhorse]

1 hour ago, Woodinblack said:

I am not sure of any specific bass class a amp, and both class a amps I have here are fairly low power. I am fully aware what the class of amps is thanks, I was clarifying a confusion above that class a/b has anything to do with being a transistor amp vs a valve amp.

 

You made the claim that class A amps are always better than class B amps, yet in the bass amp world (this is a bass forum after all) class A amps of any practical power level simply do not exist. therefore a product that does not exist can't be better. That's why I wondered if you understood the nature of conduction angle as it applies to class A, versus AB, versus B, versus C.

[Woodinblack]

24 minutes ago, agedhorse said:

You made the claim that class A amps are always better than class B amps, yet in the bass amp world (this is a bass forum after all) class A amps of any practical power level simply do not exist.

Indeed, and I was referring to distortion in amplifiers not in specific bass amplifiers, as a clarification on classes.

There are many hifi amps run as Class A to a reasonable power, and many small class A guitar amps, certainly in the 5W group, such as the small fenders. I have played a 5w bass amp (made by a friend). Personally I think 5w is the perfect size for a guitar amp, the bass amp was too underpowered to work well though. I note there are many people on this thread (and the valve amp thread) that seem to rate low powered valve amps, I suspect they are A/B like the smaller ashdown.

24 minutes ago, agedhorse said:

That's why I wondered if you understood the nature of conduction angle as it applies to class A, versus AB, versus B, versus C.

Yes thanks, but cheers for asking.

I didn't notice anyone on here had suggested using a class C amplifier for bass. Maybe for radio!

 

[la bam]

1 hour ago, Dan Dare said:

I'd be very surprised if there was such a beast as a class A bass amp (apart from low power studio stuff). 

Yes, sorry, when I say class a/b I'm actually meaning solid state type amps. Or the traditional amps inbetweeners class d and full valve.

[agedhorse]

5 hours ago, Beer of the Bass said:

Thinking about it, haven't there been a few cases where manufacturers have used a proprietary power module, run into reliability issues and discontinued support of them after a short while? That would make me lean slightly towards amps using ICEpower or modules from other large, established makers just because they're likely to be more of a known quantity and have continued parts availability.

Yes, there have been quite a few cases of designers underestimating how much effort goes into a successful design. This is especially true where the SMPS and the amplifier work together to improve performance even more as a pair. 

I know how difficult it is to design reliable SMPS and class D amps, I've done it a few times and it took longer and cost more than I expected every time. Ultimately, even though I have the background and education to do so, I simply couldn't compete with the depth of highly specialized talent that IcePower has in-house. The smart decision (IMO) was to partner with the best designers in the world and exploit their strengths as well as have input into their evolution of new products. Sometimes it better to put ego aside and keep your strengths for where they can make the greatest contributions.

[BigRedX]

17 hours ago, la bam said:

I get what you are saying, and see the benefits for everyone, and have played that way myself, but in my opinion, for the music I play (rock, indie etc)  having a fantastic backline sound really brings out the best in a rhythm section, and ultimately a band. Theres just something real about it. It's hard to raise your game with a quiet, small stage sound from a 1x10 cab. It's not just us as bassists, drummers feed off us too. The slam of a big amp and cab brings things to life. Just my experience though. It's all good.

I have found that playing music that I absolutely love is more than enough compensation for any perceived shortcomings (loss of "vibe") caused by not running a conventional rig on stage. 

[Jus Lukin]

-

Edited March 8, 2022 by Jus Lukin

[Alec]

Just stop and consider the PA systems you find in A-list gigs these days, in theatres/arenas/stadia/festivals - pretty much all of them (D&B Audiotechnik, L'Acoustics, Clair Bros and so on) are powered by Class D amps.  And I don't think you can ever claim they lack grunt...

[wateroftyne]

12 minutes ago, Alec said:

Just stop and consider the PA systems you find in A-list gigs these days, in theatres/arenas/stadia/festivals - pretty much all of them (D&B Audiotechnik, L'Acoustics, Clair Bros and so on) are powered by Class D amps.  And I don't think you can ever claim they lack grunt...

This has been covered earlier.

[pete.young]

1 hour ago, wateroftyne said:

This has been covered earlier.

 

With the honourable exception of @agedhorse excellent contributions, everything in this thread, and probably everything on the entire forum has been covered earlier, where do you stop?

[wateroftyne]

6 minutes ago, pete.young said:

 

With the honourable exception of @agedhorse excellent contributions, everything in this thread, and probably everything on the entire forum has been covered earlier, where do you stop?

He made a (valid) point. I merely said it’s been mentioned and discussed earlier in the thread.
*shrugs* 

Edited September 16, 2020 by wateroftyne

[EBS_freak]

33 minutes ago, wateroftyne said:

He made a (valid) point. I merely said it’s been mentioned and discussed earlier in the thread.
*shrugs* 

 

https://www.basschat.co.uk/search/?q=*shrugs*