I may have been a little hasty.

[andreasmaaan]

Yes, the upper frequency roll off point can be set for the high level and LFE input

Are you 100% sure about this? Usually the LFE input bypasses the sub's internal filter. It's not impossible that this one works differently, but I don't read that obviously from the image you posted. Maybe just double-check that first?

 

[QMuse]

The LFE input does offer a lowpass filter?

LFE input on subs never involves any lowpass filtering as it completely relies on the AV processor to supply correct LFE signal to it.

 

[Soniclife]

Looks like you were destined to

LFE input on subs never involves any lowpass filtering as it completely relies on the AV processor to supply correct LFE signal to it.

That's often true, easy to test though by sending it a full range signal and playing with the settings. Who knows what to expect from REL.

 

[Soniclife]

If it does not offer a low pass a simple circuit could provide one.

 

[Certainkindoffool]

I know this is possible in the RME ADI-2 PRO, I am not sure about the non-pro.

Check to see if you can program your rca and ballanced outputs separately. It may be possible to set the RCA output to mono and use the parametric eq to simulate an LFE channel.

Edit: it should be possible to do this using a headphone jack as well...but exposed wiring sucks.

If i get some time today, I will try it on my unit.

 

[Count Arthur]

LFE input on subs never involves any lowpass filtering as it completely relies on the AV processor to supply correct LFE signal to it.

I think you may be right: https://relsupport.zendesk.com/hc/en-us/articles/115004487027-What-is-a-1-LFE-Connection-

The manual is a bit vague as to whether the LFE input on the Stampede bypasses the frequency roll off control; I've asked REL for clarification.

 

[Count Arthur]

Hmm, a somewhat inconclusive reply from REL:

"normally the AVR would determine the crossover settings and so its really just volume that you alter.
I would suggest that you try it as your system may well just output full range so you may well still have control."

I've ordered some 1kohm resisters, a length of suitable cable and some RCA plugs, so I'll make up a stereo to mono cable as described here and try it:

If that doesn't work, all may not be lost, there are dozens of these things on Ebay for about a fiver: https://www.ebay.co.uk/itm/DC-12V-2...087862&hash=item23d66c8594:g:cOYAAOSwq1NZiK5o

I could use it to control the cut-off frequency but run it at full volume and use the volume control on the REL sub.

 

[Soniclife]

Hmm, a somewhat inconclusive reply from REL:

"normally the AVR would determine the crossover settings and so its really just volume that you alter.
I would suggest that you try it as your system may well just output full range so you may well still have control."

I've ordered some 1kohm resisters, a length of suitable cable and some RCA plugs, so I'll make up a stereo to mono cable as described here and try it:

View attachment 85397

If that doesn't work, all may not be lost, there are dozens of these things on Ebay for about a fiver: https://www.ebay.co.uk/itm/DC-12V-2...087862&hash=item23d66c8594:g:cOYAAOSwq1NZiK5o

I could use it to control the cut-off frequency but run it at full volume and use the volume control on the REL sub.

"Don't ask us, we only made it."

You could build the low pass into your little box no doubt.

 

[andreasmaaan]

Hmm, a somewhat inconclusive reply from REL:

"normally the AVR would determine the crossover settings and so its really just volume that you alter.
I would suggest that you try it as your system may well just output full range so you may well still have control."

I've ordered some 1kohm resisters, a length of suitable cable and some RCA plugs, so I'll make up a stereo to mono cable as described here and try it:

View attachment 85397

If that doesn't work, all may not be lost, there are dozens of these things on Ebay for about a fiver: https://www.ebay.co.uk/itm/DC-12V-2...087862&hash=item23d66c8594:g:cOYAAOSwq1NZiK5o

I could use it to control the cut-off frequency but run it at full volume and use the volume control on the REL sub.

You may also consider one of these for the crossover. It's the same DSP unit (including the AD/DA stages, which are built into the ADAU1701 chip) as the MiniDSP 2x4, for a fraction of the price. Distortion performance was measured here. Far from SOTA, but very acceptable IMHO for something that will only process the signal going into your subwoofer.

And FWIW, I've used these extensively in budget systems and have never found anything to be audibly amiss. My (non-extensive) measurements also suggest the filters do more or less what they say they are doing. An added bonus is that you would also be able to set a number of PEQs for bass management, plus a high-pass filter if you need it. Of course, all of the above applies to the MiniDSP unit you linked earlier, too.

The precision of the digital XO filters will be vastly superior to a cheap analogue unit like the one you linked from eBay (which, concerningly, doesn't even spec the slope of the filter it uses).

EDIT: actually, you need to buy a separate board for around$25 to program it! Had forgotten this after using these for so long. Perhaps not as economical as at first claimed, sorry.

 

[Count Arthur]

I'm not really sure where to begin with that.

It strikes me that it's a bit of a free for all when it comes to subwoofer connection methods.

In any case, I think whatever I end up with regarding the REL sub, it may be a bit of a stop gap solution and I will look towards a getting a sub that works better with active speakers. Dynaudio have range that ought to work well and are pobably superior to the REL in any case.

 

[andreasmaaan]

I'm not really sure where to begin with that.

It strikes me that it's a bit of a free for all when it comes to subwoofer connection methods.

In any case, I think whatever I end up with regarding the REL sub, it may be a bit of a stop gap solution and I will look towards a getting a sub that works better with active speakers. Dynaudio have range that ought to work well and are pobably superior to the REL in any case.

Fair enough If I could get a final word in, don't take REL's advice to run the sub full range. It will not only fail to integrate properly with your speakers, but it will also mess up your lower midrange. You need some sort of low-pass filter on the sub, whether via the power amp and the high-level inputs, or via some sort of external DSP or analogue crossover. Judging by their website and the advice they've given you, REL seems to be full of BS, truth be told. Ridding yourself of the sub is likely to be a good decision in the long-term, I reckon...

 

[Count Arthur]

As I will have the bits on hand and it will only take me a few minues to cobble together, I will try the stereo to mono cable into the LFE input. If the REL subs built in frequency cut-off no longer works and the sub is trying to operate full range, then as you say, it's probably a no-go and will likely sound awful. Especially as with my current set up, with speakers that don't go as low as the Core 7s, I already have the sub set to cut-off at 45Hz, so it's only filling in the bottom 20 or so Hz down to somewhere in the 20s.

That being the case, I'll have a think about whether I want to look for another solution that will work with the REL, or look for a different, more suitable sub.

 

[pjug]

The issue I see with using an amp, and if it works, I already have something suitable, is that without speakers attached, one of the outputs will have no negative connection. There are three conductors to the speakon connector, left +, right + and one -ve which is connected to one of the negative connections on the amp. If there is no negative connection to one of the amp outputs, surely there's no circuit and that channel, either left or right, whichever has no negative connection, will be innoperative:

View attachment 85311

That diagram assumes the amp's negative speaker outputs are grounded. But if you get a cheap amplifier to do this they might not be. My cheap T amp is bridged so that it can put out reasonable power from a 12V DC supply.

 

[sfdoddsy]

I'm a little confused by the problem.

Sure a receiver or prepro would be easiest. One with good EQ would be even better.

A MiniDSP doing crossover and EQ would be better still if you are the nerdy type.

And there are certainly much better subs than your REL (I'm an ex-REL owner).

But hooking up what you have now is easy.

Your Core 7 speakers have an 80Hz high pass filter when you set them to HP.

Your REL sub has a selectable low pass filter via the remote.

Get a Y splitter for the pre-amp outputs and you are good to go.

 

[Count Arthur]

The problem is:

My DAC/Preamp has both XLR balanced and RCA single ended outputs, which can be used simultaneously.

The Core 7s willl use the XLR input, no problem,.

However, other than the high level/speaker input the REL Stampede sub only has an LFE (Low Frequecy Effects) input. This is for use with A/V type amps/processors, with a dedicated mono subwoofer channel and bybasses the frequency cut-off adjustment available on the sub. As such, even if I take the stereo line level output from my preamp and make it mono, I will have no control over the upper frequency cut-off point and the sub will try and produce the full 0Hz to 20kHz+ frequency range. I haven't tried it, but I imagine this will sound awful. There's no way the subwoofer will reach up into the kHz frequency range but it may well produce sound into the frequency range where it becomes directional and you will be able to locate the sub as the source of the sound.

Other subs, even some in the REL range, have stereo line level inputs which, which presumably are downmixed to mono by the sub and allow adjustment of the upper frequency cut-off. These would work just fine, but the Stampede doesn't have this feature.

 

[sfdoddsy]

Ah. In that case get rid of the sub.

 

[pjug]

Or if you want to keep the sub get a miniDSP. The cheaper 2x4 will do. You don't have to even use it a a crossover, just have the miniDSP do the LP filter and summing before sending the signal to LFE. But also you have the option to play around with a crossover.

 

[Count Arthur]

Ah. In that case get rid of the sub.

That's kind of what I'm thinking:

5 times the amplifier power and twice as many drivers.

 

[NTK]

Looks like sensitivity of the sub high level input is pretty high. May worth to experiment driving the sub high level inputs with the RCA outputs from your RME.

 

[Count Arthur]

Please let us know how those Core 7s sound, when you get a chance.

Pretty good.

I haven't got them set up properly yet, I have them plonked on the desk on some pieces of foam and they're probably a bit too low at the moment, but first impressions are excellent.

I'm missing the added punch from the subwoofer, but the clarity and imaging are a big step up from the 52SE; I've had multiple eargasms this morning.

I'm thinking of adding the 9S: https://www.dynaudio.com/professional-audio/subwoofers/9s, the larger 18s and Core Sub are probably overkill for my room.