Any DC-powered amps work like Proton "Dynamic Power on Demand"?

[john61ct]

DL1200 came up here:

Budget tall mid-bass to sub speaker, to act as stand for LS50s

For speakers I'm not going to power via Wiim Amp Ultra, I'm looking at true "dumb power" amp 3e A7 Mono I'm also trying to understand taking 4ohm speakers already reco'd, wiring in parallel the pair is now 2ohm? Dayton apparently designed for this with the RSS210HO-44 To get 4 OHM from two 4...

www.audiosciencereview.com

My top priority is SQ into nom. 8ohm but I need DC-powered.

Looking for something with dynamic handling of current/power like this.

Plain stereo is OK

but better would be 4+ channels, maybe bridgeable to 2 or 4ohm, maybe a sub channel

ideally with built-in bass management BPF Xover or even full fledged DSP

 

[john61ct]

@EJ3

For reference, also some of the following posts as well

Why are active crossovers uncommon in home audio?

Welcome to ASR. I think you are right, most home audio customers don't want to design their own speakers. Active crossovers are almost universal in pro-PA sound, and are common in pro studio monitors. On ASR, if you go to Review Index > select Speakers > search for Powered, you will find many...

www.audiosciencereview.com

I realise my OG LS50's don't "need" the kind of current / power at this level, but my benchmark is GFA-555 and I'm sticking to it.

The goal being, get every dB "safe maximum" SPL out of LS50 including a nice high HPF

If it prevents quibbling, let's just say I want the headroom, and the ability to choose other inefficient / current thirsty speakers in future without needing to upgrade the amp.

On the Class D cheap chip amp front, so far leading contender is 3e Audio A7 Mono, Fosi V3 Mono close behind. But I personally suspect these will not touch the SQ delivered by GFA-555 much less this new-to-me Proton / NAD category.

 

[Mark185]

Class D amplifiers do not have ability to deliver 'dynamic power on demand'. That requires either a 'loosely' regulated power supply with enough energy stored in capacitors for the dynamic peaks or a sophisticated power supply design that can switch between different power rails. I believe it also requires a Class A/B amplifier design. Class D depends on a stable regulated power source because it's basic function is rapidly switching the supplied power off and on to reproduce the music signals.

Class D 'headroom' comes from a design with multiple high current output switching MOSFETS and a power supply with ability to deliver massive amounts of current at the regulated voltage level. It is not 'dynamic power on demand'. It is just massive overkill in terms of output transistors and power supply capability.

The requirement for DC powered and large headroom does not come cheaply. There are many DC powered amplifiers in the mobile car audio world that can pump out hundreds of watts that are also considered serious sound quality amplifiers but they are not cheap. There are also a select few Class A/B DC powered amps that do have serious headroom capability. One example is the Copper Amp from ARC Audio but you are looking at $2K for one of them.

FWIW, I have an Adcom GFA-5500 amp in my home system so I know what you are aiming for. I also have an Apt Holman One amplifier that is probably the first serious design that had 'dynamic power' headroom. If you are not familiar with it, Tomlinson Holman is a legendary designer that is also known for the THX specification. He also worked for Skywalker Studios and Apple before finally retiring a few years ago. Apt Holman preamps and amps are still sought after > 40 years after they were made. Proton and NAD came after the Holman design.

Is your DC application for a boat or RV? If so, it is probably better to buy a good inverter that can supply 110 V AC at the current level you need. You can actually find them used on Ebay for not a lot of money. Look for Xantrex brand inverters. i just bought a 1000 watt unit that was taken from industrial mobile equipment and paid $100.

 

[mhardy6647]

Not to be, you know, that guy, but to the best of my knowledge, all amplifiers are DC powered. If they plug into the wall, that's what their power supplies do -- provide DC for the amplifiers to use so that they can... umm... amplify.

 

[Mark185]

I sure hope that was tongue in cheek.

 

[mhardy6647]

... but true.

 

[wwenze]

Not to be, you know, that guy, but to the best of my knowledge, all amplifiers are DC powered. If they plug into the wall, that's what their power supplies do -- provide DC for the amplifiers to use so that they can... umm... amplify.

Someone just thought "challenge accepted" and is currently building a modulation scheme that runs on mains AC.

 

[john61ct]

Thanks SO much for that generous response.

I am not interested in using inverters for high amp loads that run for hours, would rather just do without mod cons.

In this case, just sacrificing some dB of SPL out of the LS50s is NBD, if necessary I'll use the big amps only while at home then.

If you can reco some DC-powered amps that CAN deliver more headroom than those cheap chip amps I mentioned above, at good value pricing,

ideally with bass management included,

I'll put them on my secondhand watch list.

So far from the "car audio" world, Polk Audio PA D5000.5 and PAD4000.4 seem OK SQ, nice BPF features but maybe a bit underpowered even bridged.

Class D amplifiers do not have ability to deliver 'dynamic power on demand'... just massive overkill in terms of output transistors and power supply capability.

The requirement for DC powered and large headroom does not come cheaply.

 

[john61ct]

Yes in fact I've had engineer level smart folk talk about bypassing the AC transformer and feeding those DC rails directly.

Bit above my skillz paygrade, I prefer keeping my battery banks and DCDC converter gear under 80V, 60V even better.

But if I get into EV transport one day I might get braver.

Not to be, you know, that guy, but to the best of my knowledge, all amplifiers are DC powered. If they plug into the wall, that's what their power supplies do -- provide DC for the amplifiers to use so that they can... umm... amplify.

 

[Mark185]

Thanks SO much for that generous response.

I am not interested in using inverters for high amp loads that run for hours, would rather just do without mod cons.

In this case, just sacrificing some dB of SPL out of the LS50s is NBD, if necessary I'll use the big amps only while at home then.

If you can reco some DC-powered amps that CAN deliver more headroom than those cheap chip amps I mentioned above, at good value pricing,

ideally with bass management included,

I'll put them on my secondhand watch list.

So far from the "car audio" world, Polk Audio PA D5000.5 and PAD4000.4 seem OK SQ, nice BPF features but maybe a bit underpowered even bridged.

Look at Recoil amplifiers. Inexpensive and higher power rating than the 'chip' amps. I have this model:

https://www.amazon.com/DI800-4-Full-Range-4-Channel-Amplifier-Bridgeable/dp/B0BZ4JS2Y1/ref=ast_sto_dp_puis

Operate it in bridged mode for stereo. Plenty of power and the sound quality is good. Not on a level with $1000-$2000 amplifiers like ARC Copper series but very good for the money. I bridge mine.

 

[john61ct]

Wow that is worryingly cheap

If you're right about SQ that would be FANTASTIC value, thanks so much!

I wonder if @amirm would be willing to test?

 

[Mark185]

Here is a test by a fellow that tests many mobile audio amplifiers.

 

[mhardy6647]

Wow that is worryingly cheap

If you're right about SQ that would be FANTASTIC value, thanks so much!

I wonder if @amirm would be willing to test?

Drop ship one to him and I reckon he would be thrilled to. Not being facetious, either!

 

[john61ct]

Yes done it before - I pinged him now will just wait. If the queue's too long maybe I'll try it out first

 

[john61ct]

Here is a test

Seems to imply not the greatest SINAD-wise as output rises into tweeter range, the most enthusiastic reco is as a MBM amp?

Is 85dB very clean in the world of high power car audio amps?

I don't want to spend a grand, but I do want to do justice to the LS50s...

 

[Mark185]

85 dB is clean in mobile audio. Background noise levels in mobile environment is in the 75 dB range in cars that are considered quiet. I have Class D amplifiers from Helix and ARC Audio that each cost more than $1000 and they are no better. RAWCat is comparing the Recoil to Alpine Class A/B high end amplifiers that cost a great deal more than $100. I do not recommend JL Audio since they have been purchased by Garmin.

The cleanest Class D mobile amp I have tested to date is a 15 year old Alpine PDX F4. It is the second generation PDX amplifier. First gen was not so good and had noise problems. Amir tested a PDX F6 some time ago and gave it a strong recommendation. The problem with PDX amps is if they break, it is very hard to find someone that knows how to fix them. I own 2 PDX F4 models. The F6 is very hard to find on the used market. F4 has 4 100 watt channels and is bridgeable. F6 has 4 150 watt channels and is also bridgeable.

 

[john61ct]

Super stuff, thanks

 

[john61ct]

mobile audio amplifiers.

Any idea if Recoil's RED series is as good? Their SPL series is crazy pricey and physically huge.

Some lines they claim >95dB SINAD - I hate to assume the company is honest across the board!

I think the DI series is getting cleared out by Recoil direct only

There are DII series now as well going for relatively more.

https://smscaraudio.com seems the only source to carry the newer lines, ofc at higher prices.

 

[kyuu]

Class D amplifiers do not have ability to deliver 'dynamic power on demand'. That requires either a 'loosely' regulated power supply with enough energy stored in capacitors for the dynamic peaks or a sophisticated power supply design that can switch between different power rails. I believe it also requires a Class A/B amplifier design. Class D depends on a stable regulated power source because it's basic function is rapidly switching the supplied power off and on to reproduce the music signals.

AFAIK this is incorrect. There is no technical reason you cannot use a linear power supply with a class D amp. It just generally isn't done, as if you aren't interested in space and power efficiency designers typically go with a class AB design. Pairing a class D amp with a linear power supply just doesn't normally make design sense.

 

[Mark185]

I believe the issue is that with Class D amps, the power delivered is a function of the current capacity of the power supply and the duty cycle of the output mosfets if it is a discrete design. Switching to a different power supply rail for dynamic power probably introduces distortion with Class D in a way that does not happen with Class A/B amps. I will caveat this by saying although I am a EE, I have not done analog or digital circuit design in many years. I am more of a software engineer and have been for some time. I know enough to get into trouble and do not claim to be an amplifier design expert - but I do understand most of the basic concepts. This thread has me curious so i just bought what is supposed to be the definitive amplifier design book by Bob Cordell. Now I have to find time to read it.

In the mobile audio world, designers get headroom with many many parallel output mosfets and power supplies with massive current capability. They also have large heatsinks and are in no way compact or light. But there are no design tricks in the power supplies like the classic amplifiers from Holman and Carver. I do not recall how NAD and Proton did their designs. With the Adcom amps, it is just a very large transformer and equally large capacitors.

I believe with chip amps like the current ones using TPA3255, thermal considerations prevent designs with dynamic power on demand. Using 48 volt power supplies with these amps already puts them on the ragged edge of thermal stability - a lesson I have learned the hard way. Maybe the chip amp designers will take a page from the PC world and come up with water cooled heat sinks. No reason why that can't work other than size and weight.