Dayton Audio SPA300-D Subwoofer Amp Review

[levimax]

And I explained why you are incorrect, explaining why Thiel Small parameters don't require high power for meaningful output at 20hz and provided a link to the Danley DTS-10 a production subwoofer that is 101db/watt efficient at 20hz. So unless you are arguing that a fair amount power means more than 1 watt, I have just provided you with a real word example that, 20hz at 100db is achievable without a fair amount of power.

I am not talking about the Danley I was talking about the example simulation given, sorry for any confusion.

 

[markk]

? The simulation shows that the output at 20 Hz is down 20 dB. The way I define a subwoofer is that it should be able to make audible amounts of 20 Hz output and preferably be flat or close to it at 20 Hz. Most commercial subs, even small sealed ones, accomplish this. In this case the current configuration is acting like a Mid Bass Module with lots of clean and high SPL output at 37 Hz and above and then rapidly then rolls off. You could add a -20dB shelf filter and flatten the response but you would give up a huge amount of headroom. The point of my comments was I was responding to a post that said that high power was not needed for a subwoofer and then showed an example of a Mid Bass Module to make his point. I would contend that you do not necessarily need high power for a Mid Bass Module but to get meaningful (100 dB+) output at 20 Hz a fair amount of power is going to be required even using large high efficiency pro drivers.

A bit of clarification is in order. For typical subwoofers, the power required to get to Xmax goes down in frequency. In a ported system, there is an area around port resonance where effectively the woofer sees a very low compliance and can generate high SPL's around port tuning with high power, but this is only in the region around the port tuning. Otherwise the same Xmax limits apply.

You should not add meaningful eq below a ported system's tuning frequency to attempt to get bass below this in the region where the response is dropping off at 24dB/octave. You will rapidly exceed xmax and you'll get >10% distortion from the driver by definition. Or, if you do this, you might as well use this 300 amp because the speaker distortion will exceed the amplifier distortion as you drive the unit beyond Xmax.

I will borrow a graph from Sigfried LInkwitz's page (all credit to him)

This is a graph of an older, but still solid Peerless sub, a 12" 830500..

It's for a sealed box system, but the results are instructive nonetheless.

Generally, below box tuning the maximum SPL drops at the Xmax limit. Power is not at all an issue. Box size affects this, but the general concept remains.
For a woofer in a ported box, below port tuning, the power needed to reach Xmax will be even less. That's because below box tuning, basically the driver unit "sees" a very high compliance. That is, it's acting like a big box and with dipole cancellation. This is why ported systems that have high port tunings (i.e. above 20-30) aren't very good. Low frequency energy rapidly causes the driver to hit Xmax without putting out much SPL. (but lot's of harmonics. You will hear bass. Just the wrong frequency.)

Your point that you'd need 20-30 dB of equalization to get 20 Hz of bass, though theoretically true, in practice means nothing. Using that much eq would drive the unit well past its Xmax. The only way to get high SPL down to 20 Hz is to have a lot of Sd. And, if you have a lot of Sd, unless you have a very small box, you won't need much power to get that bass. The key to low, low bass is Sd, not power.

The power is needed as you go up in frequency. Which is why pro subs are rated for so much power. unlike below port tuning, power requirements increase significantly as you go above port tuning. Most pro environments are not trying to generate 20 Hz bass. They are trying to generate 50-150 bass with very high SPL's. This requires power...


Now, as an aside, you can use a "reasonable" amount of EQ to lower the effective F3 of a sealed system, the so called Linkwitz transform. But that does not increase the SPL limit. I'm using an LT to add ~7-8 dB of gain to a sealed sub to effectively get an F3 of 30 out of a box that is naturally around 40hz to meet Dolby spec. But I don't have a higher SPL limit, just a flat FR curve to 30 Hz. I have a setting I can flip to for 20Hz at Q of 0.5, but I can't play at dolby reference levels because the problem is a deficiency of Sd, not power. Power and EQ cannot correct this. Small eq can be useful, but they do not allow your driver to exceed its Xmax limit.

 

[Count Dacula]

A limiter might help...?

 

[Nopiano]

Wait. Is this confirmed!? Wilson audio really uses this amp in the Loke sub? Sounds line neither Dayton nor Wilson tested the amp.

It was a supposedly better version, but still junk given the asking price. Lots here…

Wilson LōKē Subwoofer

Wilson has a new subwoofer. Darko says the 10" model was designed to match the TuneTot, includes internal DSP & amplification, and costs £9000. The plate amp appears quite similar to the Dayton SPA500DSP, available at P-E for $300. The overlap between new-Wilson shoppers & DIYers is probably...

www.audiosciencereview.com

 

[brendanheyu]

Ahh, this is a real shame.

I have a Krix Seimix 3 subwoofer (a brand from Australia) that has had a major failure in the amp section of the plate. I was looking at this plate and a little woodworking to get this sub back up and working. The current plate outer dimensions is around 185mm square, at 300w or so. It will cost about $800 to replace this plate in a $1400 sub. The local price for a DA SPA300D delivered is about $440.

Is it just that bad that it isn't even worth considering?

 

[mocenigo]

Hypex FusionAmp - not explicitly measured here, but they use the same nCore amp modules with PSU that have been measured when put in cases by Buckeye and others. The assumption is that the Hypex DSP boards are up to the same standard as their amps and preamp kit. Unlike many plate amps they have ventilation slots, and a fan in the high power ones, so you can't use them to seal the back of the speaker.

They're used in the Ascilab C8C and there were no signs of bad behaviour in the review.

I am not sure they are on par with the other modules. I have Hypex Fusion plate amps, use their DSP function, and there is a bit of hiss through the subwoofer (!!!). However, as soon as I am half a meter from the sub that noise is unaudible. And the sub is not very sensitive, it is at about 87dB/W/m. The other Hypex amps I had in the past, NC500 modules, were dead silent with 96dB/W/m speakers.

 

[Zinda]

I am not sure they are on par with the other modules. I have Hypex Fusion plate amps, use their DSP function, and there is a bit of hiss through the subwoofer (!!!). However, as soon as I am half a meter from the sub that noise is unaudible. And the sub is not very sensitive, it is at about 87dB/W/m. The other Hypex amps I had in the past, NC500 modules, were dead silent with 96dB/W/m speakers.

Hiss through a sub? Sounds like the DSP is causing that, have tried bypassing the DSP? The sound has to be introduced after the DSP or it would be filtered out? I not a fan of DSP myself only heard loss in articulation and fine details, eqing with DSP has shown spikes appearing in upper octaves while setting low frequency corrections. MiniDSP set to zero changed the sound so drastically I removed it after 30 minutes of testing. I guess the more Chinese tech added to any system will result in some unheard of side effects.

 

[Dave TR3A]

I not a fan of DSP myself only heard loss in articulation and fine details, eqing with DSP has shown spikes appearing in upper octaves while setting low frequency corrections. MiniDSP set to zero changed the sound so drastically I removed it after 30 minutes of testing. I guess the more Chinese tech added to any system will result in some unheard of side effects.

That doesn’t accord with my experience. with DSP. Do you have any measurements to support your contention?

 

[aktiondan]

I bought this amp several years ago when it first came out and measured the same thing with regard to increased distortion with the bass boost off. I had designed a sealed 10" sub around the bass boost circuit so I had no intention of turning it off, and since the distortion was better with it on, oddly enough, I didn't complain too much. The bass boost on this amp is not for every type of sub though, and the high-pass filter is set quite high, (it's about -6 dB at 20 Hz) which means it works best combined with smaller subwoofers in sealed enclosures. You can see the measured near-field response of my sub with the bass boost produces a near-flat response down to 30 Hz, something you don't get without the bass boost. It rolls off really quickly after that however, so getting any kind of subsonic bass out of this amp is just not possible. Not an issue for my setup as I use it mostly for music which I think for that purpose it works out great. It basically meets its rated power, it's nice and compact, the bass boost works great for increasing the low-end extension on smaller sealed subs, it's got no turn-on/off thump, it's priced well, and has worked just fine for me for the last 4 years.

Still, I was bothered by the increased distortion, so I reached out to PE and eventually did hear back from them. They sent me the data from their test sample which showed no appreciable increase in distortion with or without the bass boost. Makes me wonder if they had some kind of pre-production unit and something got screwed up in the final design or manufacturing. They had no explanation for my results. I thought maybe it was something in my measurement setup, but then I just came across Amir's review today and when he measured the same thing I immediately thought, I knew it! There's definitely an issue with the bass boost circuitry, in the weird way that turning it off makes it so much worse. I actually tapped into the line-level stage of the amp, before the actual amplification stage, and this is what I measured. So it's not an issue with the Class D amp itself, it's definitely originating in the filter stage. I thought the performance was just fine with the bass boost on in the end so I kept it. And yes, the bass boost looks awful if you take it on its own, but I think if you design this thing with a specific sub response in mind, namely a smaller sealed sub, it does a fine job of complimenting the natural speaker enclosure's roll-off to buy you just a bit more extension, without going to a larger box, or to a vented design.

You can read more about this sub on my site at https://www.danmarx.org/blog/the-co...d-of-a-300w-sealed-subwoofer-with-bass-boost/