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

[Mark185]

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.

No idea if RED series is as good. Always be suspicious of manufacturer's claims for SINAD. ARC and Helix are supposed to be some of the best but the amps I have bought and tested from them do not measure up to their claims. They do sound very good but my measurements do not match what they claim.

 

[john61ct]

amps I have bought and tested

I see a lot of folk putting down D-class amps in general.

Do you think it's worth investigating if there are similar good value DC-powered AB-class gear left over out there?

I will be comparing against GFA-555 and Parasound HCA when grid AC is available, not just max-safe SPL but subjective SQ qualities...

 

[john61ct]

linear power supply with a class D amp

My power source here is lithium battery banks, and I can build whatever size Ah at whatever voltage needed, certainly many times more robust than a vehicular lead battery and their usual anemic alternators.

TPA3255 is actually spec'd for over 53V, my understanding is that it's general design issues and other components's limitatiins that prevent most such amps from tolerating over 48V

3e Audio states that 52V is no problem with their A7 Mono amp. Of course with a battery sized too small, if a lot of surge amps are drawn, the source voltage will drop

unless there is a large enough (amps) charge source (DCDC converter from a larger "house bank") backing up the feed, certainly higher than the usual trickle.

Now in this scenario, the amp power supply is maybe more of a bottleneck for feeding short term dynamic current requirements?

Capacitors OTOH are helpful.

I am ignorant in the whole linear vs switched topic area, those who know more please help me learn how that factors into my system choices given the above.

Anyone please, not only kyuu and @Mark185

 

[john61ct]

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.

The Recoil DI series seems for whatever reason to be at least one major exception

 

[kyuu]

I am ignorant in the whole linear vs switched topic area, those who know more please help me learn how that factors into my system choices given the above.

Sorry, linear vs. switched is really tangential. It shouldn't make any difference to your setup really since you're looking to feed the amp DC directly via your batteries and therefore won't have a power supply of any sort.

 

[john61ct]

Alpine PDX-F6 yes looks great, but looks like not often that decent ones show up on the market. "Plugs" go missing?

 

[john61ct]

Sorry, linear vs. switched is really tangential. It shouldn't make any difference to your setup really since you're looking to feed the amp DC directly via your batteries and therefore won't have a power supply of any sort.

well not really directly I think?

Vehicle "12V" often ranges between 10-16V and is "dirty" power. I'm not intending to bypass the power input circuitry unless very good reasons, and with detailed expert guidance.

Or are you saying that "linear vs switched" only applies to the AC-DC transformer world?

 

[kyuu]

Or are you saying that "linear vs switched" only applies to the AC-DC transformer world?

Right, the "power supply" typically refers to the thing that is taking AC in and putting out DC to feed the amp circuitry.

 

[Mark185]

If you want to look for older Class A/B amps that perform well, I would suggest looking for older Alpine, ARC Audio, and one Rockford Fosgate mono amp that blew me away. Advantage of ARC Audio is that they support and repair their amps no matter how old they are. Their chief designer is Robert Zeff. If you don't know who that is, Google him. They are the only mobile audio company I know of who actually answer the phone when you call customer support and put you in touch with one of their engineers. No one else does that! Alpine made some great A/B amps but good luck getting support for one if you need it. Check out this RF 300 watt mono amp. It is a P300.1. You can find these for $100-130 on Ebay. I have one and am looking for another

 

[john61ct]

> one Rockford Fosgate mono amp

That whole series?

Do you agree with those that claim class A/B is generally better SQ than D? Setting aside factors subject to objective measurements...

 

[Mark185]

The only RF amp I have experience with is the P300.1. Back in the day when these were made, they had some pretty good design engineers. I suspect that is not true today. So many companies these days farm out the work or just copy the same basic design used by many other companies. That is part of what makes the Recoil surprising. This is just a clone of a design used my many. I do know the the quality of the output filters on a Class D have a lot to do with how clean they can sound and how low the distortion can be.

I do not agree that Class A/B is generally better then D with current designs. Good Class D amps are not distinguishable from good Class A/B amps in blind listening tests. Class A/B generally has fewer distortion harmonics at higher frequencies but in well designed amps those harmonics are well below the threshold of hearing. You can see them on an audio analyzer but you can't hear them.

 

[john61ct]

Excellent thanks, appreciate your taking the time

 

[Roland68]

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

I think you're getting carried away with something here.
The LS50 (Meta) is a small bookshelf speaker with a manufacturer-specified power handling of 100 watts at 8 ohms.

Just search the internet for defective KEF drivers of this type (there's a thread about it), then you can see what happens when inexperienced users overload such a small speaker with a 130mm mid/bass driver. And even worse, using it as the main speaker for movies without a subwoofer and/or without a low-pass filter for the LS50. That's obviously not covered under warranty.

This is a relatively small bookshelf speaker with good detail reproduction at lower power levels/volumes. And you want to run it with a completely overpowered amplifier that's anything but detail-oriented and can't possibly demonstrate what an LS50 is capable of.
The 3E Audio A7, on the other hand, is a perfect match for the LS50 and delivers 120 watts into 8 ohms, which is more than enough. It also handles the minimum impedance of 3.5 ohms without issue, as it's 2-ohm stable. In terms of measured performance and audible sound, it easily outperforms the Proton.

I know the Proton amplifiers quite well, as my first amplifier in the 80s was a Proton D540, which I later expanded with a D1200. I've also repaired a few D1200s in my time.
Where is the Proton D1200 supposed to be a DC amplifier?
The Proton D1200 is simply a Class A/B amplifier operating in Class G mode with an oversized filter capacitor. This higher dynamic power output is achieved simply by increasing the voltage through switching to a higher-voltage transformer tap. That's pure smoke and mirrors, because any amplifier that operates at the higher voltage is equivalent or better.
A NAD 2200, which works similarly, easily outperforms the D1200 in terms of performance. A NAD 2700 even more so.

 

[john61ct]

I think you're getting carried away with something here.

Yes I am aware

And I am sincerely grateful for your concern!

My goal is max safe SPL, HPF'd around 200Hz or even higher. Yes there will be MBM and/or true sub(s), those and the bass management details for discussion in other threads.

BTW mine are OG LS50, not Meta - but apparently no matter. That choice is the one fixed constant in the current discussion(s).

Excess headroom in itself is not a problem for me - I am aware of, and accept the risks of my testing.

As I stated above I realise 3E Audio A7 mono is a fine unit, certainly my first choice among the affordable chip amps,

but bottom line, I'll continue looking for just a bit more headroom, especially higher current, to keep voltage high when resistance drops at max-safe top SPL - apparently can even dip below 4Ω ?

As stated in my OP - let's just say I WANT that excess headroom for the ability to choose other current-thirsty speakers in future, without needing to upgrade the amp.

...

Lots of amps have been mentioned so far, I have just been seeking Education here, exactly so I avoid buying bad gear.

So, which above amp(s) specifically do you know/think are poor choices from a SQ POV? Just the Proton? or NAD also?

Surely not GFA-555 and Parasound HCA series?

I never considered buying any of those for my "mobile off-grid" usage, exactly because I realise they are AC only.

As per the title, I was hoping to find that "power dynamics" TYPE of tech implemented in DC-powered amps. Apparently that specific aspect was off track, but I have been learning lots here, and again, I greatly appreciate y'all's advice.

Can you suggest any other "good value" DC amps with more oomph than the 3e A7 even if not quite as meticulously measured SQ purity? High voltage is not a problem.

...

Could I also get your take on this question?

> I see a lot of folk putting down D-class amps in general. Do you think it's worth investigating if there are similar good value DC-powered AB-class gear left over out there?

 

[Roland68]

Yes I am aware

And I am sincerely grateful for your concern!

My goal is max safe SPL, HPF'd around 200Hz or even higher. Yes there will be MBM and/or true sub(s), those and the bass management details for discussion in other threads.

BTW mine are OG LS50, not Meta - but apparently no matter. That choice is the one fixed constant in the current discussion(s).

Excess headroom in itself is not a problem for me - I am aware of, and accept the risks of my testing.

As I stated above I realise 3E Audio A7 mono is a fine unit, certainly my first choice among the affordable chip amps,

but bottom line, I'll continue looking for just a bit more headroom, especially higher current, to keep voltage high when resistance drops at max-safe top SPL - apparently can even dip below 4Ω ?

As stated in my OP - let's just say I WANT that excess headroom for the ability to choose other current-thirsty speakers in future, without needing to upgrade the amp.

...

Lots of amps have been mentioned so far, I have just been seeking Education here, exactly so I avoid buying bad gear.

So, which above amp(s) specifically do you know/think are poor choices from a SQ POV? Just the Proton? or NAD also?

Surely not GFA-555 and Parasound HCA series?

I never considered buying any of those for my "mobile off-grid" usage, exactly because I realise they are AC only.

As per the title, I was hoping to find that "power dynamics" TYPE of tech implemented in DC-powered amps. Apparently that specific aspect was off track, but I have been learning lots here, and again, I greatly appreciate y'all's advice.

Can you suggest any other "good value" DC amps with more oomph than the 3e A7 even if not quite as meticulously measured SQ purity? High voltage is not a problem.

...

Could I also get your take on this question?

> I see a lot of folk putting down D-class amps in general. Do you think it's worth investigating if there are similar good value DC-powered AB-class gear left over out there?

What exactly do you mean by DC amplifiers? Car amplifiers?

The "Power Dynamics" technology is just a marketing gimmick, since nobody, especially audiophiles, wanted a Class G amplifier in the 80s and 90s. It simply switches to an additional transformer tap with a higher voltage when higher power is required. It offers (and technically cannot offer) absolutely no advantage in sound or performance measurements. It only serves to reduce heat generation, save a little power, and allow for cheaper amplifiers. It's simply a cheaper (stripped-down) version of a Class AB amplifier.

The D1200 actually only delivers 100 watts into 8 ohms, even less than the A7.
After that, the D1200 uses tricks and high capacitor capacitance. This means that any power above 100 watts is only available from the capacitors and only in the millisecond range. Furthermore, distortion and noise levels increase dramatically when high power is drawn from the capacitors.
Another point is that this power can only be used in the lower bass range, precisely what an LS50 doesn't have, can't do, and what will damage it.

And that's exactly where we arrive at a crucial point. With a low-pass filter at 200 Hz, the LS50 can't draw 30-40 watts; that's physically impossible.
Even a 3E Audio A5 or Topping PA5 II/Mini300 would be overkill and more than sufficient. Furthermore, the TPA3251 used in the listed amplifiers is even slightly better than the TPA3255 in the A7.
The next step up would be the B100.

 

[Mark185]

I think this week, the best value and performance you are going to find are the Fosi V3 Mono amps that Fosi is selliing direct from their Ebay site. With a discount I have only seen on Ebay from Fosi, these amps are ~$75 each. They will work best on 48 volts DC so you will need some form of power supply that steps 12 VDC up to 48. They are not hard to find. My suggestion is buy them and try them. There's not anything I am aware of that can approach their performance for $150 for 2 mono blocks. I just ordered 2 - and I already own a 3e A7, Adcom 5500, Apt Holman One, and a Hafler XL280 which is another amp known for having dynamic reserves.

@Roland68 is correct. You do not need massive power for satellite speakers crossed over at 200 Hz. Even these Fosi V3 monos are overkill but at $150 for a pair, you are not risking much and can always sell them without losing a lot of your investment if you decide you want something else. You do have to consider how you are going to power them but solutions are out there. You never really described your use case but if you are wanting to power audio amps because you are off grid and using solar with battery storage, most of those battery banks are easily able to provide 48 volts DC.

 

[john61ct]

What exactly do you mean by DC amplifiers? Car amplifiers?

I mean power amps with DC power input. That can include equipment designed for mobile use, or pro or audiophile gear so long as they can be powered via DC as many external PSUs supply.

Whatever the voltage is OK.

> it offers (and technically cannot offer) absolutely no advantage in sound or performance measurements.

It did offer much more headroom for transient power demands far above the RMS rating, hence caught my interest. OK, I understand not relevant to my use case

> cheaper (stripped-down) version of a Class AB amplifier.

Do you consider Class AB superior to Class D for high SQ? Taking a poll...

> With a low-pass filter at 200 Hz, the LS50 can't draw 30-40 watts; that's physically impossible.

Interesting, I did not realize that.

BTW a HPF (min Hz) but I bet you knew that. I will not use any LFP on the front/main pair nor any of the other full-range speakers, only on MBM/subs.

> Moreover, the TPA3251 used in the LS50

Wut? mine are OG passive as I stated, do you mean an active variant?

 

[john61ct]

Fosi V3 Mono

Yes that has been my #2. I think the extra price for 3e A7 is likely worth it, if I truly have no use for the extra power at 52V, maybe the stereo rather than Mono for future flexibility.

There are TPA3255 amps with a HPF function built in too, but I think they are inferior to those two, e.g. no PFFB circuit to help with the load dependance.

> you will need some form of power supply that steps 12 VDC up to 48.

Actually the battery power side of things is much more within my wheelhouse

The main House bank voltage in all scenarios is nominal 48V, but charges much higher, so a buck DCDC will be needed to prevent the amp(s) seeing that. True for 3e's 52V also.

 

[Mark185]

The TPA amps with high pass filter built in are not worth the expense. I have tested both the Douk A5 and Aiyima A20 high pass filter implementations. I own an Aiyima A20 that I bought just to test. I have posted measurements elsewhere on this forum. Turning on the high pass filter on the A20 causes a significant rise in third harmonic distortion. Odd order harmonics are associated with fatiguing harsh sound at higher volumes. I will not use the built in HP filter if I keep this amp. I will use a separate DSP unit for filtering and parametric EQ. The A20 without using the filter is a very good amp that approaches the Fosi V3 Mono and 3e audio in terms of sound quality. I bought the Douk A5 for one of my kids to use as a dorm room stereo. It is great for that use case but the HP filter on that is nothing to write home about.

PFFB is overrated IMO. If the output filters are optimized for the speaker load you intend to use (ie. 4 or 8 ohms) there is no need for PFFB. Nice to have but you can get very good performance without it.

 

[john61ct]

PFFB is overrated IMO. If the output filters are optimized for the speaker load you intend to use (ie. 4 or 8 ohms) there is no need for PFFB. Nice to have but you can get very good performance without it.

I dunno what "output filters" are.

Since LS50s can drop below 4ohm my intention is to test with amps stable down to 2ohm.

Of course if power rating is 300W there and 150W at 4ohm, then tops is likely 75W most of the time.