Amplifier for passive subwoofer

[Buffalo]

Ok guys, more subwoofer help please.

Thinking about buying a passive sub and need something to power it. The sub manufacturer recommends a pro amp (Alto Mac) which is a nice price but it's huge. They also recommend the Vincent power amps as an alternative but would prefer something cheaper.

So looking for an alternative which is more akin to domestic hifi and fits in a rack. The cheaper the better and secondhand/old is not a problem and preferably something easy to find.

Any thoughts ? Many thanks.

Steve

 

[russ abbott - royds broth]

Why can't you use the amp you have?

 

[Buffalo]

Hi Stu. The NAF will still be driving main speakers full range - I doubt it's up to the task of driving the 12" drivers of the sub aswell.

 

[Tenson]

Is this a sealed or ported sub? The answer will decide whether you need lots of current or voltage from your amp.

 

[rocky raccoon]

Do you already have the filter & controls upstream? If not, check out the plate amps at Wilmslow audio. They have a 500 watt jobby with all the knobs on.

 

[Tenson]

Or get a digital crossover like MiniDSP or DCX2496 that can also do real time delay and other bits to help integration as well as high-pass your main speakers. Did it with Rob's ESL63s and some sealed subs last weekend. The result was totally transparent integration. Just ESL63s that have crazy deep bass and slam capability.

 

[sunbeamgls]

Suggest a nice big ole Rotel power amp in bridged mono. RB850, RB970 etc.

sent from a different Galaxy

 

[tomart]

I second that, I have an old Lux amp I was thinking of using for the same purpose. However I am not sure about using a filter as mentioned previously.

 

[Buffalo]

Cheers chaps, plenty of options to investigate.

The sub is a WLM Duo 12 which is sealed. They also sell various controls and filters to go with them but I guess I'm not tied to those - quite like the idea of the digital crossover

My thinking was something like a Rotel too - any alternatives ?

 

[Tune]

One area often ignored when using subs is damping factor.

Using a solid state bass monster on a sealed cabinet next to your single ended valve amp can produce a noticeably different quality to the bass IME.

My subwoofer allows me to adjust the output impedance of the amp to subtly alter the tonality of it's output. A few power amps will allow the same. I believe the Marchand sub amp does but it's pricey. You might well also find such a facility on some guitar amps as well as old Jap crap like the Technics 9600 which I had back in the day.

Now measurements would suggest it makes little or no difference but given the high output impedence of your main amp, I would suggest that it will and it's worth investigating.

Failing that, I really cannot recommend the Linn sub highly enough at today's used prices.

 

[Tenson]

You need to get an amp with a lot of voltage then, not so much current. Sealed subs don't damp the drivers resonant impedance peak like ported ones do. So you need a lot fo voltage to drive power into the high impedance.

The Rotel mentioned above for example runs of 30V rails.

Bryston amps like the 3B (doesn't need to be ST / SST stuff) runs on 55V rails. The Alesis RA500 runs on 55V rails too (I love this affordable amp) and you can even bridge it for twice that!

 

[Buffalo]

Got to say Mike, the combination of chiselled solid state bass sitting underneath the slightly more rounded sound of the SET is something I've wondered about. WLM seem to swear by it though for their ethos.

Thanks Tenson. After a bit of research earlier, the Rotels all seemed bridgeable but only into an 8 ohm speaker or more - the sub is 4 ohm. I'm no techie but assume kind of bares out what you say ?

The Alesis looks good. Do you know of any current UK dealers ? A quick google suggests it's not that readily available here.

Cheers

 

[Tenson]

The Alesis is sold online. You shouldn't expect to hear it in a hi-fi store. Buy on credit card and return if not satisfied. Get the RA500 not the RA300.

 

[vacdac]

Got to say Mike, the combination of chiselled solid state bass sitting underneath the slightly more rounded sound of the SET is something I've wondered about. WLM seem to swear by it though for their ethos.Thanks Tenson. After a bit of research earlier, the Rotels all seemed bridgeable but only into an 8 ohm speaker or more - the sub is 4 ohm. I'm no techie but assume kind of bares out what you say ?

The Alesis looks good. Do you know of any current UK dealers ? A quick google suggests it's not that readily available here.

Cheers

If you use a bridged amp to power speakers the load it will actually see is a halving of the load the speakers present. This is why sometimes using some amps bridged can cause problems with certain speakers.

So a four ohm speaker will present as a 2ohm load to a bridged amp. What is needed is a more powerful amp that is stable into a 4ohm load or if using a bridged amp it will need to be stable into a load of 2ohms or less.

 

[Buffalo]

Sorry, meant online. Still available in the States but seems whole of Europe has stopped stocking it? Bugger !

 

[vacdac]

I think the Behringer A500 is stable into loads of under 2ohms & can also be bridged if even more grunt is needed.

Plenty of these have been sold so they should be easy to find s/hand & they're cheap to buy new too.

 

[Buffalo]

Thanks Chris, will check them out.

 

[vacdac]

Thanks Chris, will check them out.

Yeah Steve do check the specs to double check. I'm reasonably sure I've seen this stated though. Lots of pro kit sellers sell em so try DV247 & Thomann in Germany. I've bought plenty of stuff from both & they're both good to deal with.

Reviews for the Behringer are easy to find too. :^

 

[Tenson]

Yeah Steve do check the specs to double check. I'm reasonably sure I've seen this stated though. Lots of pro kit sellers sell em so try DV247 & Thomann in Germany. I've bought plenty of stuff from both & they're both good to deal with.Reviews for the Behringer are easy to find too. :^

Note I recommend the Alesis RA500 not Behringer A500. They are quite different.

There are couple on eBay but from the states. They have a voltage switch on the back though.

Get an impedance plot for the passive sub. See what it really does over the range you will use it. I bet it will be far higher than 4 ohm over the range below 100Hz. Look at the impedance plot for this 4 Ohm subwoofer for example. Below 100Hz it quickly rises to well over 10 Ohms. Depends how you will use it, you could bridge.