Please recommend an amplifier

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Hi all,

I would like a recommendation for my first DIY amplifier project to power a home cinema subwoofer I have built.

It is a sealed design with a JL audio 12W0 driver, built per JL’s recommendations.

I have hooked it up to a Toshiba M—15 power amp and a Sansui 9090 for rough testing before finishing the painting of the box and it sounds good in combination with my floor standers. There are some weird phasing effects which I think I will need an EQ to sort out but in the meanwhile I would like to build a dedicated amplifier to power it remotely from the main system, using some sort of wireless audio connection to avoid cables if at all possible.

The Toshiba apparently puts out 60 Watts into the 4 driver and very rapidly triggers its protection circuitry.

I’m not sure exactly how much power the Sansui puts out into 4 ohms but according to the meters it was putting at least “100w” in to 8ohms and so perhaps double the power the Toshiba was putting in to it. It certainly played louder and the excursion was much better but not wanting to fry one of my favourite vintage receivers, I didn’t push it.

The JL is rated for 125 w rms and based on my experiments can handle at least double that on the transients, with a sealed box excursion at the lowest frequencies ought not to be too much of a danger and so would like a recommendation for a suitable amplifier.

A question that I have from reading other posts here is would it be better to have an amplifier of ~125w rms with 3db headroom or a 300w rms amplifier or are they indeed the same thing?

With thanks,
 
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More headroom = higher power rating, whether it is only for momentary peak or continuous power demand. However, per watt, bass power is quite undemanding and cheap to implement, so the use of class D as adason suggests or even a more expensive class AB plate amp, is a smart one for several other reasons too, including the self-contained, easily adjusted level and upper roll-off controls, low cost and simple installation. The problem with using a regular stereo amplifier for a subwoofer, is the likely low peak power rating and complete lack of suitable bandpass/slope controls.

"Wireless" refers generally to RF digital signal and control systems. "Wireless speakers" still require a mains power source for the receiver, a DAC and the power amplifier, which need to be located inside or adjacent to the speaker(s). You would also need to program and incorporate the wireless transmit/receive devices, such as bluetooth or similar pre-built modules, with an associated remote control device if that's the level of convenience you want.

Anyway, I don't think wireless connectivity will do anything useful here. You have to accept that there is going to be at least a mains power lead or a speaker lead and once the crossover is adjusted optimally, there is no further need for a controller.

In the UK, these people sell apparently well regarded plate amps, similar to those stocked by several US distributors. This example is of the more expensive, class AB type: http://www.bkelec.com/MODULES/bsbp200.htm
 
would it be better to have an amplifier of ~125w rms with 3db headroom or a 300w rms amplifier or are they indeed the same thing? With thanks,

~125w rms with 3db headroom: is typically a short duration power "claim", and not an accurate spec

300w rms amplifier: is typically a continuous duty power spec

Look for a spec like: xxx-Watts rms continuous power into a x-ohm load, to get an honest rating.
 
More headroom = higher power rating, whether it is only for momentary peak or continuous power demand. However, per watt, bass power is quite undemanding and cheap to implement, so the use of class D as adason suggests or even a more expensive class AB plate amp, is a smart one for several other reasons too, including the self-contained, easily adjusted level and upper roll-off controls, low cost and simple installation. The problem with using a regular stereo amplifier for a subwoofer, is the likely low peak power rating and complete lack of suitable bandpass/slope controls.

"Wireless" refers generally to RF digital signal and control systems. "Wireless speakers" still require a mains power source for the receiver, a DAC and the power amplifier, which need to be located inside or adjacent to the speaker(s). You would also need to program and incorporate the wireless transmit/receive devices, such as bluetooth or similar pre-built modules, with an associated remote control device if that's the level of convenience you want.

Anyway, I don't think wireless connectivity will do anything useful here. You have to accept that there is going to be at least a mains power lead or a speaker lead and once the crossover is adjusted optimally, there is no further need for a controller.

In the UK, these people sell apparently well regarded plate amps, similar to those stocked by several US distributors. This example is of the more expensive, class AB type: http://www.bkelec.com/MODULES/bsbp200.htm


Thanks Ian I have struggled in deciding between class D and AB for this project. I appreciate that class d power is much cheaper but wonder if class AB wouldn't be more "dynamic"?

I was indeed referring to wireless signal transmission for this project reasoning I can plug the tx into the subwoofer output of the AV receiver and then put the sub somewhere unobtrusive with just a power lead coming from a handy socket.

Thanks for the link, that plate amp certainly looks good. I think I would prefer to use the filtering of the DSP or receiver before the signal is sent to the sub and just run it flat as the digital DSP or dedicated subwoofer channel output would be better quality than the filter circuits in the plate amp?
 
~125w rms with 3db headroom: is typically a short duration power "claim", and not an accurate spec

300w rms amplifier: is typically a continuous duty power spec

Look for a spec like: xxx-Watts rms continuous power into a x-ohm load, to get an honest rating.



Thanks LineSource, I had thought more power would have been preferable in the first place but thought I'd ask as I have a NAD 2200 power amp which despite having an identical RMs power rating of 100 to a Quad 405-2 that belongs to my dad, sounds a lot more "dynamic" on big orchestral blooms.

I understood that it was because the former has 6db of headroom whereas the latter has the lesser figure.
 
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