Matching Subwoofer Plate Amp and Drivers

[Solar Paul]

Hi, I'm planning for a subwoofer build for the LFE channel of a 5.1 surround system:

• We are more interested in drama than slam bam action pics, so we are probably more at the musical end of the spectrum and there won't usually be very high volumes
• Plan is for a dual opposed 10 inch sub. Current leading contender for the drivers is SB Acoustics SB29SWNRX-S75-6. These are rated at 200wrms (86db sensitivity) with an impedance of 6ohm, so wired up they would be 3ohm in parallel or 12 ohm in series
• Cost is a factor, so I'm considering a cheapish plate amp from Aliexpress https://www.aliexpress.com/item/1005002806616053.html This is rated at 350w (max400w) and advises suitable impedance: 4-8Ω

Will this be a good match of the plate amp and drivers? Am I thinking correctly in how I am looking at this?

Thanks in advance
Solar Paul

 

[ppataki]

Hi, I'm planning for a subwoofer build for the LFE channel of a 5.1 surround system:

• We are more interested in drama than slam bam action pics, so we are probably more at the musical end of the spectrum and there won't usually be very high volumes
• Plan is for a dual opposed 10 inch sub. Current leading contender for the drivers is SB Acoustics SB29SWNRX-S75-6. These are rated at 200wrms (86db sensitivity) with an impedance of 6ohm, so wired up they would be 3ohm in parallel or 12 ohm in series
• Cost is a factor, so I'm considering a cheapish plate amp from Aliexpress https://www.aliexpress.com/item/1005002806616053.html This is rated at 350w (max400w) and advises suitable impedance: 4-8Ω

Will this be a good match of the plate amp and drivers? Am I thinking correctly in how I am looking at this?

Thanks in advance
Solar Paul

What cabinet size did you have in mind?
Placing two of these SB drivers in a sealed cabinet of 25 liters (Vb) and drive them with 350W of power you will get this output curve (SPL at 1 meter):

This might be enough for your needs; I am just not sure if the plate amp you linked is stable at 3 ohms.....probably not but you can ask the seller about it

If you want to be on the safe side: go for two 8 ohm subs (Dayton Audio for example) and connect them in parallel to get to 4 ohms or you can stay with these drivers and probably choose another amp that is stable down to 2 ohms.

 

[DVDdoug]

I always recommend modeling/optimizing cabinet design with speaker design software. It will help you decide between a sealed or ported box for a particular driver (depending on the Thiele/Small parameters) and optimize cabinet size and port dimensions if ported. WinISD is free.

This is rated at 350w (max400w)

Many amplifier specs are not honest and personally I don't trust stuff sold on AliExpress. The 1st customer comment says 50W but I don't necessarily trust that either.

 

[Solar Paul]

Hi DVDdoug and ppataki,

Thanks for your responses. Well the 6 ohm drivers are proving problematic so I'm reverting back to plan A which is to use 2 x SB Acoustics 10" SW26DBAC76 3 Dual Voice Coil drivers (4 ohms and 4 ohms). These 2 drivers are rated at 300w each and I've modelled a 50L box - ie 25 L per driver in WinISD. That will give me a lot more wiring freedom and a better choice of amplifier, although the drivers are a little pricier.

I've had a suggestion elsewhere to use multiple channels of amplification for a mono sub (a channel per driver). Taking this idea a bit further - I see that Tinysine (which reviews ok on Audio Science Review) and includes DSP capabilities for a reasonable price have an amp, model TSA8804 V2 (4 x 100w into 4 or 8 ohms), which theoretically offers 400w. I'm thinking of wiring each channel into a voice coil into .

Any thoughts on this scenario?

 

[Keith_W]

I would be concerned that a dual opposed 10" sub would produce enough SPL. It might work for small rooms, but in my large-ish room (6m x 7m), two 10" subs really struggled.

 

[Solar Paul]

Hi Keith_W,
Well, that's a good point but there are a number of factors at play. Our current audio system bottoms out at 80hz (although we've previously had systems playing nicely down to the mid 20hz region) and this new system I am building (literally) will be our best (most full range) yet. But my wife is concerned about too much bass and disturbing our neighbours, so I think softly softly will be a good start. TBH we are both more interested in drama than sound effects so there is a good possibility that we will find the level of bass sufficient. If not there is always the possibility of a 2nd unit

 

[ppataki]

I've had a suggestion elsewhere to use multiple channels of amplification for a mono sub (a channel per driver). Taking this idea a bit further - I see that Tinysine (which reviews ok on Audio Science Review) and includes DSP capabilities for a reasonable price have an amp, model TSA8804 V2 (4 x 100w into 4 or 8 ohms), which theoretically offers 400w. I'm thinking of wiring each channel into a voice coil into .

Yes, that will work out nicely indeed
When powering each VC with a separate amp, the important point is that the amps shall be exactly the same - which is fine in your case

 

[Kalasbarnet]

Hi!

I Have resesrched exactly what you have researched for the past month! Dual opposed 10 inchers, was also looking at the sb acoustics and was also looking at plate amps and then looked at the tinysine haha! Exactly the same thought process!

In the end i was thinking the tinysine 4x100w powering 4x grs 10SW-4HE but modeled it all and was not content (i wanted a probably unrealistic f3 around 20hz with a max spl around 105db for apartment listrning at max 85db but enough headroom for dynamics etc).

The grs are only 100eur a piece and model really nice (if u are in the usa they are even cheaper).

Anyways i also researched china plate amps because of price and found a solution.

The solution which meets my aim is 2 subs, each with 4 grs drivers each (the 10 or 12 inch) and each sub driven by "sinbosen DM30" a china 2 channel plate amp available for 308eur that they say can output 1500w x 2 into 8 ohms, so would drive 2grs 4ohms in series.

I am seriously considering this option but am very skeptical of the china amp...

i forgot to mention i had size constraint aswell with max 30liters per 2 drivers, so max 60 liters per sub of 4 drivers.

Anyways with this setup it actually modeled really good and could achieve around 105db with an f3 of 20hz. And the price is reasonable, drivers are 100eur each and plate amp is 308eur each so that's 708 eur per 4 driver sub. With one of these you could get 100db with an f3 of 20hz for 708 eur or less (less if going for the 12 inchers which are cheaper aswell for some odd reason and give slightly higher spl) and this would probably be enough for apartment listening with decent dynamic headroom

The reason for looking at extremely overpowered china amps is that i read they always output a lot less than advertised. Had to use LT-transform so alot of power was needed for my aims