Analog Crossover/High Pass Filter reccomendations for Using Subs with Sierra LX

[reforminded]

I love my Sierra LX but was looking for a little more full low end sound in my room, and as much as I want to upgrade to ELX Towers, WAF doesn't currently allow that. I picked up a used JL Audio Dominion D108 Sub and plan on adding a second--they have very clean bass and enough for my needs (music only). I had read that when adding subs like this, there will be a marked improvement if I also add an active crossover/high pass filter to limit the signal going to the speakers, letting the subs handle everything below the crossover. Can anyone a decent one that is XLR and RCA compatible (XLR from preamp to crossover, XLR to amp, RCA to subs).

Price is certainly a factor, so to borrow a line from the Simpsons, "I would like your finest, cheapest cigars".

[curtis]

I love my Sierra LX but was looking for a little more full low end sound in my room, and as much as I want to upgrade to ELX Towers, WAF doesn't currently allow that. I picked up a used JL Audio Dominion D108 Sub and plan on adding a second--they have very clean bass and enough for my needs (music only). I had read that when adding subs like this, there will be a marked improvement if I also add an active crossover/high pass filter to limit the signal going to the speakers, letting the subs handle everything below the crossover. Can anyone a decent one that is XLR and RCA compatible (XLR from preamp to crossover, XLR to amp, RCA to subs).

Price is certainly a factor, so to borrow a line from the Simpsons, "I would like your finest, cheapest cigars".

What kind of low end room response are you getting from your LX's? I get down the the mid-30hz in my room.
As for an active crossover, miniDSP products seem to be very popular and effective, but they seem to be RCA only.

[racrawford65]

The minidsp Flex is available as RCA In/RCA Out or TRS In/TRS out. TRS is balanced so essentially the same as XLR. When I had a 2 channel preamp in my system, I used a Flex for this exact purpose - LR outs from preamp to Flex, Flex out 1 & 2 to speaker amp, Flex out 3 & 4 to subs. Worked great. One of the cool features with the Flex (and other miniDSP products) is you can set up 4 configurations. I had 4 set up. Don't recall exactly but think they were 2.0 (no EQ), 2.0 (with EQ on the bass), 2.2 (flat EQ), 2.2 (house curve). EQ was done with REW + UMIK. You can also add a DIRAC license to the Flex for room correction if you don't want to mess with REW. I have no experience with the DIRAC upgrade.

Alternate to the Flex, is their 2x4HD model, but it's RCA only. It's also not as good spec wise as the Flex although fine for sub only applications. I've used this previously. The Flex is much better and more feature rich (on-screen display, includes a remote, and the in/out connections are all on the rear for a cleaner install).

OP - does your amp have both XLR & RCA inputs? Similarly, do your subs have both? If not and you have to connect as posted, go with the Flex TRS In/Out. You'd need XLR --> TRS cables for preamp to miniDSP, TRS--> XLR cables for miniDSP to amp & TRS --> RCA cables for miniDSP to subs. If so, probably some other cable options. Alternately, you could probably find the necessary adapters and use those instead of different ended cables (eg XLR to XLR cable + XLR to RCA adapter for the subs).

https://www.minidsp.com/products/minidsp-in-a-box/flex

An alternate to the Flex could be the dSpeaker X2. It's in the same price range as the Flex and is equipped with their room correction technology. It's not as "tweakable" as the miniDSP from what I understand. That said, it's a press a button and calibrate for room correction (so, really pretty automatic). Their products are pretty good, also. I've used their 8033-SII before on subs only. It did a good job EQ'ing the subs.

https://www.dspeaker.com/products-1

[reforminded]

Please correct me if I am misunderstanding, but wouldn't any DSP essentially be adding an Analog to Digital Converter into the chain, which would then process the signal, run it through a Digital to Analog converter, then output? I would definitely like to avoid adding all those conversions if possible and was hoping for an all analog device--but again I may be completely understanding how these work. Since my subs have their own low pass filters and I have the hooked up to "Output 2" on my amp, so they have their own dedicated line level signal to the low pass filter, I think I only need a high pass filter for the "Output 1" going to my Sierra LX.

I found an older NHT X2 crossover which is meant to seperate output into high and low for subs and mains, and I wonder if that would work if I only used the high pass part of it? It has XLR in and out and selectable high pass settings of 50hz/80hz/110hz. I think this means I could use it for just the mains, set to 80hz, then set the integrated low filters on the subs to cross over at 80hz, and all would be hunky dory?

[Mag_Neato]

You can certainly give that a try. Maybe it will cover your application.

I have always wondered why more manufacturers don't include Hi & Low pass filters in their gear. I have a Parasound Halo P6 preamp that has those filters in the analog output. I Hi-pass my Siera-2EX V2's at 80hz using the hi pass filter. I don't use the low pass for the 2 Rythmik subs, but rather have those being EQ'd with a MiniDSP 2x4HD that is connected to the sub out connections on the P6. This way the 2EX's do not have that additional A/D & D/A conversion in their path.

[racrawford65]

Agree with Ed in that you can try that. I'm not familiar with NHT X2 but a quick google search seems to have sufficient controls to integrate subs & mains.

Also, I understand not wanting the extra conversions, but, at least for the miniDSP Flex, it's transparent (I couldn't detect any negative impact on sound quality). The advantage is being able to EQ the outputs. For me, the trade off to incorporating the Flex was worth it.

[James]

I had a similar concern when using room correction software and an equalizer.

The DAC in our CD player, which we use for streaming, is very good. When I used the equalizer, there was a slight but noticeable decrease in sound quality. But the improvements in frequency response outweighed that for me.