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Recommendations for home passive subwoofer amplifier

lc6

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I am looking for a home (not car) amplifier for a passive subwoofer. Base requirements:
- To be placed on a shelf; rack-mountable acceptable (so no in-wall models)
- Built-in power supply (so, Aiyima, Acoustic Audio and similar models with external PS are no-go)
- Min. 150 W to max. 250 W into 8 Ohms with max. 1% THD; support for a 4 Ohm load preferred
- FR at least 20-150 Hz +/-1 dB
- Class D or at least G, but not AB (no fan cooling)
- LFE input (so models with only line inputs that do not bypass the internal crossover are not acceptable)
- Volume control either continuous or with max. 1 dB increments
- Phase control either continuous or with max. 45-degree increments
- Automatic activation and standby based on input signal (not just DC trigger input)
- Standby power consumption no more than 1 Watt
- Max. price $400
- UL certification preferred (CE is less meaningful because it is a self-certification by manufacturer).

I looked into the following makes and models:

AudioControl
RS 500 is too powerful and costs ~$1,500.
RS 1000 is an overkill.

Dayton Audio
SA1000 is too powerful and expensive, and Class AB (although it has a "patented tracking down-converter power supply for high efficiency").
APA1200DSP is an overkill.
BSA-200 has no LFE input.

HTD
SDA-200 is rated at 150 W but into 4 Ohms; also has only a 0/180-degree polarity switch.

Monoprice
SWA-200 does not have an LFE input.
SWA-400 has a volume setting only in 3 dB increments (too coarse).
DTA-100LF is not powerful enough and has no LFE input.

Nuvo
NV-SUBAMP200 underpowered, but otherwise OK (discontinued, so heavily discounted).
NV-SUBAMP500 adequate power, but also discontinued and heavily discounted.

OSD Audio
SAM500 DSP is too powerful and costs ~$650; also, it only has a Class D output stage and probably a non-switching PS with a toroidal transformer; it is fan cooled.
SMP500 DSP has the low end of FR at 30 Hz and costs ~$500.
SMP200 lacks a dedicated LFE input (although LFE is mentioned in the owner's manual) and there is no crossover bypass setting.
SMP300 may be suitable, although its phase control seems to be only a 0 or 180 degrees switch. I am not familiar with this brand. Any owners out there who could offer a first-hand opinion?

Polk Audio
SWA500 specific to Polk in-wall subwoofers (requires installation of one of the SPEX cards) and also too expensive at ~$650.

TDG Audio
SUBAMP-500 is too powerful and costs ~$1,000.

Does anyone have a recommendation for other suitable brands and models?
 
Last edited:

Sputnik

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Sound like you want every option you find in a plate amp, so maybe look at those? You can always make a simple wood enclosure if it has to be placed on a shelf or in a rack.

If you want a dedicated sub amp as a seperate, you're in custom install territory and that will cost more than 400$.
 
OP
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lc6

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What is a "plate amp"? Can you post links to some makes and models of those amps that meet my requirements? Thanks in advance.
 

Sputnik

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What is a "plate amp"? Can you post links to some makes and models of those amps that meet my requirements? Thanks in advance.
A plate amp is a subwoofer amp, for example from Dayton:


You want 250W? Get the SPA250. You want dsp with it? There's a SPA250DSP. You want class D? Get the SPA300D. Don't like the Daytons? There's plenty of other brands, and their features and specs are made for subs, so you'll have lfe, crossover, fase, often class D, FR for subs, auto on and internal power supply.

They also sell a frame, at the bottom of the linked page.
 

FrantzM

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Hi

I am on renewable 85% . Power consumption is an issue. I don't need fancy FR and THD figures.. 0.1% and 0 Hz to 1000 Hz plus or minus 1 dB, are good enough. I don't need DSP, it will be taken care by a miniDSP 2x4HD... So
300 to 500 Watts
less than $200.oo..
Class D Subwoofer amplifier ?

Peace.
 

kiwifi

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Hi

I am on renewable 85% . Power consumption is an issue. I don't need fancy FR and THD figures.. 0.1% and 0 Hz to 1000 Hz plus or minus 1 dB, are good enough. I don't need DSP, it will be taken care by a miniDSP 2x4HD... So
300 to 500 Watts
less than $200.oo..
Class D Subwoofer amplifier ?

Peace.
MiniDSP can take care of subwoofer volume and phase, so maybe this would fit the bill...
 

Jerry Sobel

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What is the difference between a subwoofer amp and a regular amp? In other words can I run a passive subwoofer off of a 7 channel 250W per channel amplifier or is a dedicated subwoofer amp the way to go and why?
 
OP
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lc6

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What is the difference between a subwoofer amp and a regular amp? In other words can I run a passive subwoofer off of a 7 channel 250W per channel amplifier or is a dedicated subwoofer amp the way to go and why?

You should be able to run the passive subwoofer through one the channels in your multi-channel amp. However, while (most likely) that channel would have a lower THD and higher SINAD than a dedicated subwoofer amp would, the latter would typically have an additional control for the phase (0-180 degrees) and low-pass filter (LPF) in additon to the volume. (The lack of of those controls is not an issue when a low-frequency effects [LFE] channel is the source of signal to the amp.) Those controls optimize the output of the subwoofer to be most in sync with the output of the other, and especially the main, speakers in your setup. Depending on your equipment, your AVR or pre-amp may have a similar phase control (and LPF), or even automatically compensate for phase differences after being automatically calibrated.
So, it all depends on what your audio scenario is: With the regular stereo music PCM, you do not have the LFE, but with multi-channel program material (DD or Atmos) you do.
 

Jerry Sobel

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Thanks for the reply. The reason I ask is because I recently had two in ceiling KEF Ci250RRb subs installed. I already have two floor based power subs. I was putting in atmos speakers and I wanted to try these in ceiling subs. I was running my first Dirac Live two nights ago and all of the frequency graphs looked correct except the KEF in ceiling subs. BTW I am running the subs on a McIntosh 7 channel digital amp and the subs are on the 250W per channels. The subs did not really come on until over 100Hz and then was a straight line to 3K and then it dropped. My floor subs were what you would expect. Up at 10-15 Hz and rolling off just over 300 Hz. So the KEF looked like a midrange driver. I called KEF and spoke to one of their specialists in the Ci and he said that I needed to run the KEF KASA 500 subwoofer amp and set the dip switches in the back and crossover in order to acheive the 25-30 Hz to 200-250 Hz frequency response. So I guess I do not understand what is the difference between a sub amp and regular amp except the crossover set point and why would a supposed in ceiling sub be running up to the 3K?
 
OP
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lc6

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Thanks for the reply. The reason I ask is because I recently had two in ceiling KEF Ci250RRb subs installed. I already have two floor based power subs. I was putting in atmos speakers and I wanted to try these in ceiling subs. I was running my first Dirac Live two nights ago and all of the frequency graphs looked correct except the KEF in ceiling subs. BTW I am running the subs on a McIntosh 7 channel digital amp and the subs are on the 250W per channels. The subs did not really come on until over 100Hz and then was a straight line to 3K and then it dropped. My floor subs were what you would expect. Up at 10-15 Hz and rolling off just over 300 Hz. So the KEF looked like a midrange driver. I called KEF and spoke to one of their specialists in the Ci and he said that I needed to run the KEF KASA 500 subwoofer amp and set the dip switches in the back and crossover in order to acheive the 25-30 Hz to 200-250 Hz frequency response. So I guess I do not understand what is the difference between a sub amp and regular amp except the crossover set point and why would a supposed in ceiling sub be running up to the 3K?

This sounds really weird. If your McIntosh amp is full-range (i.e. no filters), then it should easily handle frequencies down to tens of Hz. Try to temporarily switch the channels you intend to use for your ceiling KEF subs to the main speakers and measure the FR. If it is not cut off below 100 Hz, then you know the amp is not the culprit and a specialized subwoofer amp won't help; most likely something is wrong with the KEF subs themselves. You may also want to connect those subs to your subwoofer/LFE output on your AVR or pre-amp, do the calibration and see what the FR is.
I am sorry for your ceiling, though. You must (or soon will) have cracks in the drywall. :)
 
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