Fosi Audio CA30 4-ch power amp WITH HPF & LPF

[Mark185]

Close. I live in a 100 year old house with a detached garage 80 feet from the main house. It has a dreadful electrical system in the out building using knob and tube wiring. The second floor of the garage is a wonderful workshop space and I want music when I am working out there. The 1st floor looks like it was designed for Model T's and does not have a lot of work space but the second floor is great.

I will get around to rewiring the workshop/garage but that is far down the todo list. I am also installing some ground mount solar panels so DC power will be plentiful.

 

[Redacted]

There's a guy on here who can sell you 800kg of knotted cables and some pre-packaged dust to help out (and a dodgy rug to give you a migraine).

 

[xanalog]

Are you in a hideout in the woods?

I object to that line of questioning, your Honor!

 

[john61ct]

Wow what a fantastically detailed response, and good news to boot, thanks so much!

When mobile or otherwise off grid, my main banks are also LFP, at 48V nominal so I'll be looking at DC-DC chargers for the small 12V portapaks, need for other use cases anyway.

Can you suggest a CHEAP and QUIET (EMI/RF wise) grid AC charger from USA 110V for when using the rig inside a S&B location? Ideally with variable voltage output? Low amps is fine,

Actually a LINEAR PSU would be ideal, I could if necessary rig an HVD (high-voltage disconnect) relay cutoff with the variable voltage setting.

I'm looking at the miniDSP C-DSP 8x12 for some of the crossovers, but apparently it is super sensitive to PSU noise.

miniDSP's replacement wallwart for their 2x4 HD might be good enough...

I bought one for a 12 volt portable stereo rig

 

[john61ct]

My previous post also is relevant to this, and yes I hide out at sea and in deserts as well as in the wooded mountains.

LMK if you have further tech discussion, but let's set the personal-lifestyle questions aside here please.

There were various ones reviewed on here

BTW Amir apparently has one of these already on the way for testing!!

Here's hoping he can put the crossover functiins through the wringer not just SINAD...

 

[Ropeburn]

Wow what a fantastically detailed response, and good news to boot, thanks so much!

When mobile or otherwise off grid, my main banks are also LFP, at 48V nominal so I'll be looking at DC-DC chargers for the small 12V portapaks, need for other use cases anyway.

Can you suggest a CHEAP and QUIET (EMI/RF wise) grid AC charger from USA 110V for when using the rig inside a S&B location? Ideally with variable voltage output? Low amps is fine,

Actually a LINEAR PSU would be ideal, I could if necessary rig an HVD (high-voltage disconnect) relay cutoff with the variable voltage setting.

I'm looking at the miniDSP C-DSP 8x12 for some of the crossovers, but apparently it is super sensitive to PSU noise.

miniDSP's replacement wallwart for their 2x4 HD might be good enough...

If you don't mind a subjective experience without measurements, I've been using an "insular" (=off grid) 12V solar system for a few years now. Panel, charger, battery, inverter, the usual. Running everything "small" in house off it, except the hungry things like kitchen, warm water, heating.

It makes precisely zero difference. Not with playback, producing, recording. As always: competent devices assumed, your power source is a non-issue, stability assumed.

 

[xanalog]

Can a 48Vdc system (solar or otherwise) obviate the need (e.g.; FOSI ZA3 powerAmp) for conversion of 48Vdc-to-MAINS first, and ZA3's 48Vdc power-brick?
Sounds like the gains in efficiency may be countered by noise/EMI at ZA3's DC input.

 

[john61ct]

your power source is a non-issue, stability assumed.

I never claimed DC was superior, I only use it because I don't want to run the genset.

Of course when running native-DC audio electronics from grid AC, the quality of the PSU / charger can have a huge impact on SQ

 

[john61ct]

Can a 48Vdc system (solar or otherwise) obviate the need (e.g.; FOSI ZA3 powerAmp) for conversion of 48Vdc-to-MAINS first, and ZA3's 48Vdc power-brick?
Sounds like the gains in efficiency may be countered by noise/EMI at ZA3's DC input.

Yes, if you have any native-DC powered appliances with a battery bank already available, converting to AC power and then back to to DC would just be silly.

DC-DC conversion / charging is cleaner, more efficient and cheaper.

Running off battery by itself is actually RF noiseless, it's the electronic circuitry involved with power input (charging or maintaining the bank's level) that can get noisy

Some loads might not have a wide tolerance for voltage variability, so even 12V to 12V or 48-48 can be a thing.

My 48V bank (16S LFP) fully charges at 55.2V, and I don't usually shut thirsty loads down until it hits 46V.

Just as with automotive loads, 11-16V is the norm.

 

[john61ct]

Morel MW144 drivers for the low end

Can you point to reliable actual-measured specs for this driver?

TS seems highly variable from mfg docs, are they hand made?

Would you recommend it as clean between say 70-300Hz ? Does not need to be dead flat but would be nice.

Superior good value driver suggestions 8" maybe up to 10" would be welcome

 

[Mark185]

My Morel MW144 drivers are at least 15 years old and specs have changed over the years with different production. runs. Fs is typically in the 45 Hz range and Qts is around 0.5-0.6. In a small sealed box, my Fb is 100 Hz with a Q=0.85. This gives a bump in response between 100-120 Hz and -3 dB around 75 Hz. I can use EQ to extend that a little but these drivers should not see anything below 50 Hz and I have a steep 50 Hz high pass filter in my DSP. This is after all, a portable stereo. I do not expect deep bass response. I can always add a subwoofer in my garage if desired. IMO this driver is very clean 70-1000 Hz and has good power handling with its 3" voice coil. I am experimenting with crossing it over between 250-800 Hz with different drivers. I actually have an old pair of Bohlender Graebner Neo 8 PDR planar magnetic drivers and think I may try pairing them with the Morels. Advantage there is the Neo 8 does not require much in the way of enclosure volume and can play up to somewhere in the 12-15 kHz range with good EQ. EQ is essential to flatten a rising response with the Neo 8. These have been out of production for many years. Parts Express sells a similar driver made by a different company. The Neos are very efficient and do not require a lot of power.

If you want good value drivers in 8" range, I would look at Parts Express offerings. They have a 7" 4 ohm driver that is very good but it starts to have cone breakup around 1500-2000 Hz if I remember and needs to be crossed over lower or be equalized to compensate or both. If you want high efficiency and excellent frequency response, you have to pay more. Scanspeak is probably the best but they are $$$. It is possible that SB Acoustics makes something in this size range that is good value and I have been impressed with the drivers I have seen from them.

 

[john61ct]

At PE I see RS180-4 in aluminium, and RS180P-4 which is "paper" composite

As stated, I am here only asking about the 70-300Hz range, aka MBM coupler nothing to do with deep bass just to "augment" in between bookshelves and trueSubs.

Besides clean flat bandpassed response in that range, efficiency would be nice but strong power handling more so, 4Ω is good.

Lower Qts, high Bl, stiff Cms.

And budget, yes Scanspeak is pricey, so is the Satori line at SB.

I will try to find accurate TS specs for the Morel MW144 as currently sold.

 

[Redacted]

Not sure about all the "going round the houses" on here, but when I did my electronics degree, it was generally accepted that in a system, "active" meant "powered", and "passive" meant "unpowered", c.f. crossovers, but now that it's generally believed that men are also women if they say so, perhaps I'm just falling behind with current terminology!

 

[Head_Unit]

I think high-power car amps use internal DC-DC converters to get the power

Yes they do, hence all head units only output maybe 2 actual unclipped watts regardless of lying specs. Head units are too small to fit the hot and electromagnetically radiating DC-DC converters.

 

[Mark185]

Yes they do, hence all head units only output maybe 2 actual unclipped watts regardless of lying specs. Head units are too small to fit the hot and electromagnetically radiating DC-DC converters.

Yes they all lie about power specs but 2 watts is not realistic either. I refer you to this:

He is measuring about 13 watts at about 1% distortion. Looks like 0.1 % at 10 watts. Nothing to get excited about but 2 watts is too pessimistic.

 

[john61ct]

He is measuring about 13 watts at about 1% distortion. Looks like 0.1 % at 10 watts. Nothing to get excited about but 2 watts is too pessimistic.

Let's stick to Fosi Audio CA30

Other units with similar crossover features, ideally to make direct comparisons.

Pending Amir's review how do you think the Fosi Audio CA30 ACTUAL power output compares to their claims?

Do you know other 4+ channel units just as clean and with similar built in crossover features, that put out similar or higher output power into 2-4Ω in a similar price range per channel?

 

[Redacted]

Nobody doing reasonable power in a car relies on what the head unit can do. AFAIK, no need for DC-DC converters in a typical OEM head unit, as 12V is enough to be audible with 4 ohm speakers. Cars with good stereos all have separate power amps, and yes they get hot from DC-DC converter (hence big heat-sinks cases). All car amps are Class D AFAIK, for obvious reasons..

I did have friend keen on car audio (for sone reason) and it had multiple power amps, but could not be used unless his engine was running so as not to drain the battery flat in seconds.

My cheapo car has only a weak head unit, but has a DC-DC converter for it, under the passenger seat, purely to keep the stereo working fine when the stop-start kicks in!

 

[john61ct]

I am not planning on using this in a car as such, but many contexts will be off grid.

Running PCs, screens, fridges other kitchen appliances much less aircon generally are thirstier than most audio gear

and running a genset for hours per day gets very expensive, so efficiency becomes important.

The main banks being at nominal 48V is a good balance between safety and efficiency.

I can DC-DC convert up or down to any desired setpoint, to feed loads directly

or charge sub-banks at lower "standard" voltages 12/24/36V

With exact hi/low cutoffs depending what sort of chemistry used, e.g. LiPo vs LFP vs lead vs NiMH.

Solar if course is ideal when possible.

While running engines for propulsion, can opportunistically also charge the main banks, but that might only be a few hours per weeks if you're traveling smart.

 

[john61ct]

Not sure about all the "going round the houses" on here

wut?

> it was generally accepted that in a system, "active" meant "powered", and "passive" meant "unpowered"

Yes true, but with crossovers a more stringent aspect has taken over, active implying bi- tri- amping, and xovers are DSP at line level before the power amp

whether the speakers themselves include those powered components physically or not within the enclosure.

Active non-DSP "electronic crossovers" are old tech, considered lesser than, not part of modern "active systems".

 

[Redacted]

FTAOD, by "powered", I just meant the general act of "applying a voltage and having current drawn, to get a certain behaviour", i.e. it needs to be plugged in, if you will, and nothing to do with the narrower context of say, powered speakers or various crossover implementations.