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High Pass Filter for Stereo Speakers in 2.1 System?

M

malcesine

pfm Member
I need to limit the frequency to my stereo speakers at >= 80Hz in a 2.1 setup but I can’t use an AVR and my SVS sub does not have a high pass filter for the high level outputs so looking for other solutions.

Ideally the solution would utilise as simple a signal path as possible, all in the analogue domain.

I would like to avoid buying a very expensive sub with high pass filter or changing my source/amp etc so thinking perhaps a standalone HP filter / crossover would work well?

Source is SBT, amp is integrated, speakers = Quad ESL63

Any thoughts or specific kit you would recommend?
 
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An active crossover for PA use would do what you want, they start at about £75 for a Behringer one.

The DBX 223XS is an industry standard unit and is what I use in simple PA systems, sounds good, works reliably and costs about £140... it uses XLR connections so you’ll need some suitable adapters.

The next thing I use up from this is the DBX Driverack Venu360... but that’s digital... and around £1000.
 
William said:
Hi

I’m not sure if this is what you are looking for but I hope it helps in some way.

http://www.troelsgravesen.dk/High-Pass-Filter.htm

Regards

William
Click to expand...

Troels's solution would be an excellent one - except for the fact that the high pass filter needs to go between pre and power amps - but the OP has an integrated.

Edit: Actually, if your SBT is your only source, and you use analogue out from it, you might be able to put a filter between it and the integrated amp.
 
irb said:
Troels's solution would be an excellent one - except for the fact that the high pass filter needs to go between pre and power amps - but the OP has an integrated.

Edit: Actually, if your SBT is your only source, and you use analogue out from it, you might be able to put a filter between it and the integrated amp.
Click to expand...
Bugger, missed that... needs a pre-power or an integrated where you can split the pre and power sections to use what I suggested.
 
Actually, if the SBT is your only source, I’d use a MiniDSP 2x4HD. You could still use your integrated amp but you could swap it for a power amp.

The MiniDSP is digital, but it would take the digital output of the SBT, filter the sub and main speakers in the digital domain and then convert to analog, it can even do room correction. You can get a remote control for the MiniDSP. I think it’d offer the best bang for buck in your situation, plus loads of flexibility.
 
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malcesine said:
I do exactly that, so could treat my SBT as preamp?
Click to expand...

Well you could perhaps put a first order passive high pass (i.e. a series capacitor) between the SBT and the integrated. So yes, you'd be treating the SBT as the preamp and the integrated like the power amp in Troels's scheme.
You'd need to know the input impedance of your integrated amp. And you need it to be a steady figure. (i.e. this wouldn't work if the volume pot in your integrated amp is the first thing the input sees, as the input impedance would vary depending on the volume.)
Of course, this strategy isn't very flexible. It only gives a first order roll-off. The Quads will have a third order roll-off, inherently, so the combination gives you fourth order, which is good for matching a sub - except that the Quads' own roll-off probably begins a bit lower than 80hz. So it may not match perfectly. But it's definitely the least invasive way if doing it. Fairly cheap to try, if you're ok with the DIY.
A minidsp would be a lot more flexible. And maybe you could feed it a digital signal from the SBT?
 
Does the SVS sub have pass through line level outputs? If so, could you run the SBT direct into the sub and then take the line level output from the sub to the integrated? That way you could feasibly experiment with the Troels solution above, unless my thinking is screwy!

Failing that, I would think the dac in the minidsp would probably best the SBT anyway.
 
malcesine said:
Thanks both on suggested mini DSP
How would the mini DSP DAC stack up against the SBT?
Click to expand...

I’ve got the DDRC -24 which is essentially the same as the 2x4 but with Dirac Live.

I use it as follows

Pre main left and right out splitter > miniDSP > active subwoofer
> active left and right speakers

So basically using the miniDSP to cut the hi frequency information going to the subwoofer (I don’t bother with Dirac live for now).

Now I know different to what you need but my point here is that I once ran the miniDSP direct to my active left and right speakers acting as a pre/DAC. It was a quick trial but I was not overly impressed, there was a lot of ‘noise’ and some hum from memory, this could purely be an unfortunate coupling/mismatch with the single ended outs of the miniDSP going to the balanced ins of the active speakers. Nonetheless you’ve got a great pair of resolving speakers in the Quad 63’s so just wanted to flag. On the other hand I could be raising something that would not be a problem at all for you.

I agree with others that overall the miniDSP is great, I have no issues with it currently with my sub.

Depending on budget you could look for one of their newer models like the SHD but that will likely at least twice as much as the 2x4, depending on which version you go for. I do though think there is a solution for you!
 
Update....

I emailed SVS and they got back to me impressively quickly confirming that my sub indeed did not have any filter on high level outputs but (surprisingly - and not in manual) had a fixed 12dB/octave 80Hz high pass on the RCA/line level input to output.

I got some cheap 5m RCA’s and connected SBT -> Sub line level input and Sub low level output back to Integrated amp.

Worked a treat with a bit of volume tweaking on source, sub and amp to balance it up.

There defo more adjustment required and it only works with single source but the principle seems sound.

Thanks all for suggestion and input :)
 
Nice solution misterdog
As much as I’d like to, I can’t run the Quads full range due to bass boom/room issues and from previous experience I’m not a fan of digital room correction :-(
 
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