Rolls SX45 stereo two-way active xover.

BigElCat

Mmm Hmm
I bought one of these, they're not terribly expensive. My goal is vertical biamping of ADS L-1290/II speakers.

This thread isn't about those speakers, we have other threads about them. It's about the quality, my subjective impressions of the sound quality, of the Rolls Xover.

I'm integrating this little xover into a John Curl designed, Parasound system. I have a P/LD-1100 pre-amp, and two HCA-750A amps.

My source is all digital at the present time. I have a PC with a Paul Pang v2 card in it. A Pangea USB cable goes to a Singxer F-1, then a Belkin Pure AV digital coax cable goes to a MusicHall 25.3 DAC. The DAC has an upgraded buffer tube (Mullard CV2493).

So is the little Rolls up to the task ? Let's have a look.

First, it's made in the USA and it has a steel case. Surprising heft for its size.

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The chassis bottom is also steel, and the edges of the PC board sit on the folded edges of the bottom pan. Nice engineering.
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The pots were suspect by others in the Amazon reviews, because the center detent on the high gain is not exactly at 12 o'clock. My unit has the same quirk. However, the pots have a nice feel, and they are open to allow cleaning. The logo on the pots is a C with a reverse C nestled into it. I don't recognize the brand, but they rotate firm and smooth.
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It uses a 15vdc external power supply. It comes with a switching wallwart, I may get a better linear supply for it.

Rolls does not publish specs for it's performance.

My A/B comparisons are sort of curd, because so far I'm only using one amp. The variable crossover point adjusts from 50 Hz to 2.5K Hz. I leave it set on 50 when I swap it in and out.

I'm satisfied enough that I'm going ahead with my biamp project. My background remains black and deep with it in. Dynamic range remains the same, and I don't find any alteration of the sound stage. The resolution from the Singxer/MusicHall seems to get through just fine.

I hear demerits occasionally, a slight glare or harshness in the high end, but I can't attribute that to the Rolls. I should mention that my speakers have 30 year old ferrofluid in them, and the original caps.

I recently added the Singxer, and made tweaks to the software. I using MusicBee with WASAPI.

This system sounds better that it ever has before. The little Rolls is hanging in there. I'll update this thread when I have further impressions.
 
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I'm glad to see this thread. Poultrygeist turned me on to this little unit as a possible solution to my OB crossover issues. I'm seriously considering it. Keep your observations coming BigElCat.
 
I have 2 of these, one in a computer system and one in my workshop. Both units work very well, just need to tweak the crossover points and gain to get the best sound. Don't care about the high gain being off, the stuff works.
 
I'm glad to see this thread. Poultrygeist turned me on to this little unit as a possible solution to my OB crossover issues. I'm seriously considering it. Keep your observations coming BigElCat.

A couple of hours ago, I hooked up my second HCA-750A amp on the woofers. This is a horizontal bi-amp configuration, but my crossovers are hybrid active/passive. My mid-range domes and the dome tweeters are still affected by the passive xover. I can't change this, unless I un-wire the drivers from the crossover. And then I'd need a three-way active crossover and a third amp. The ADS crossover point between the woofers and the mid/tweets is 500Hz. Above 500, the original passive xover is still in use (redundant info). The woofers, however, can receive any frequency the Rolls sends to the woofer amp.
I guess I'm by-passing the electrolytic caps as well as the bass coil on the ADS crossover. I'm not sure about that.

Anyway....I'd definitely recommend the Rolls for a two-way OB system. It's not ideal for bi-amping the ADS L-1290s. My speakers sound quite different, sometimes in a positive way, sometimes in a funky way. I'll come back to this. I'm going to try vertical bi-amping, which was goal after all.

Vertical bi-amping, at least with my equipment, means a two channel amp will be dedicated to each speaker. One channel will drive the mid/tweet, the other channel will drive the woofers (2 woofers per speaker).

More later.
 
Vertical bi-amping, at least with my equipment, means a two channel amp will be dedicated to each speaker. One channel will drive the mid/tweet, the other channel will drive the woofers (2 woofers per speaker).
More later.

This is essentially what I'm looking to do. One solid state amp to drive 2 Eminence Alpha 15 drivers per side and a tube amp driving a single Audio Nirvana 8 in. FR driver per side. Even without using a crossover these speakers sound very good. I can't wait to hear them crossed properly and with tubes driving the AN's. I've been hesitant to pull the trigger on the Rolls unit only because it seems to good to be true. Guess I need to proceed.
 
The Rolls SX45 is not going to work for bi-amping ADS tower speakers. The active xover point can't be set to where it complements the built-in passive xover point. I really think it would be fine if you were working with raw drivers (without any frequency restricting components).
 
I made one last attempt by using both outputs on the pre-amp.

One set of outputs went directly to the amp channels drive the mid/tweets. I thought the passive xovers would just eliminate the unwanted lower frequencies.

The other set of outputs went to the input on the Rolls. I thought I could use the low outputs on the Rolls to adjust the roll off of the woofers.

Not so. The amps temporarily went into protection mode. Fortunately no harm was done.

My bi-amp experiment is over.
 
I'm glad to see this thread. Poultrygeist turned me on to this little unit as a possible solution to my OB crossover issues. I'm seriously considering it. Keep your observations coming BigElCat.
Thanks for the post BigElCat. And to Ross, it does look like an easy way to tune a set of OB's. I just finished, finely, my jeep and cleaned up my shop two days ago and found the 15" drivers and horns from a Maggie console. Now I have the room to build some OB's with them.
 
Sorry to hear it didn't work out for you. I'm hoping my project will go better.

I had to console myself by bridging the HCA-750As and running them as mono-blocks. 150 watts RMS gets the L-1290s into their power band nicely.

For good measure, I introduced my Atlantic Technology PBM 172 sub-woofer into the system. It's a sealed cabinet 12"er...it blends well with the L-1290s.

I have the Hi Pass set at 55 Hz....taking the very bottom off the L-1290s cleared up the upper bass and mid-range.
 
Of course I can't feel too sorry for you Bret. You, after all, own a pair of L-1290s and I do not. For that I console myself with the lowly, [but oh so nice], l-710s. I've never even heard any ADS larger than the L-810. Maybe, hopefully, I will some day.
 
The Rolls SX45 is not going to work for bi-amping ADS tower speakers. The active xover point can't be set to where it complements the built-in passive xover point. I really think it would be fine if you were working with raw drivers (without any frequency restricting components).

I wouldn't expect it to work all that well for any situation that overlays existing passive crossovers. Seems like you'd get a hole/dip in response at some point regardless where it's set.

For overlaying existing passives, separate high pass and low pass is the ticket. Active HPF would be set about an octave below the passive HPF and active LPF about an octave above the passive LPF. I'm sure there are some exceptions but that's the generality of it.
 
I wouldn't expect it to work all that well for any situation that overlays existing passive crossovers. Seems like you'd get a hole/dip in response at some point regardless where it's set.

For overlaying existing passives, separate high pass and low pass is the ticket. Active HPF would be set about an octave below the passive HPF and active LPF about an octave above the passive LPF. I'm sure there are some exceptions but that's the generality of it.

Can that be done with an active 3-way xover ?

There would be no middle band width, so the mid output would not be used.
 
Can that be done with an active 3-way xover ?

There would be no middle band width, so the mid output would not be used.

If you want 3-way then you have to get a device having 3 way adjustable capability; LPF, bandpass, HPF. Of course, you'd also need speakers having the suitable input connections.

Example here from the config utility for DCX2496. It has 2-ch, 3-way capability.

The low end is not filtered, although you could add a high pass there too if you wanted to limit the low end for some reason. Same with the high end, you could also add a low pass filter there if you wanted to limit the high end for some reason.

With something like this you can also change the slope type, Linkwitz-Riley, Butterworth, Bessel; the slope rate, 6, 12, 18, 24, or 48dB/oct, or mix and match to your hearts or ears content. Plus, as you see, many other things like delay, gains, etc. etc.

Of course, something like this costs more but the flexibility is there.

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In the case of what I think you were trying to do with your speakers would be something like this.

Assuming for discussion the speaker's crossover for low to mid/high is 500Hz, I set the high pass filter to 250Hz and the low pass filter to 1kHz both with steep slopes (in some case more shallow slope could be better here, but this is just example). This allows the speaker's crossover to be predominant in regard to the actual crossover point, while the active crossover limits the work/frequencies the amplifier has to deal with.

Generally, you wouldn't want this type of setting for a pure biamp because there would be a big peak in the overlap region of HP and LP. But, in the case of overlaying with the speaker's crossover, the speaker's crossover will take care of that.

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My short search for a L-1290/2 owner's manual was not fruitful. I'm assuming you have the switches on the speaker's connection plate set correctly? And that you were using one amp for both speakers/channels woofer connections, and the other amp for both channels mid/tweets? If so, I don't see why it wouldn't work. From what I have read in my short perusal of ADS engineering on these, I would not have attempted to better it myself. Maybe just be glad that your pair works correctly, and that you didn't bust them, or your amps? :)

Thanks for posting, and sorry it didn't work out.
 
My short search for a L-1290/2 owner's manual was not fruitful. I'm assuming you have the switches on the speaker's connection plate set correctly? And that you were using one amp for both speakers/channels woofer connections, and the other amp for both channels mid/tweets? If so, I don't see why it wouldn't work. From what I have read in my short perusal of ADS engineering on these, I would not have attempted to better it myself. Maybe just be glad that your pair works correctly, and that you didn't bust them, or your amps? :)

Thanks for posting, and sorry it didn't work out.
http://sportsbil.com/ads/l-1290_and_l-1290_ownersmanual.pdf

I had the switches set correctly. You described horizontal biamping, I tried that first. Then I tried vertical.

The active crossover slopes did not overlay the passive crossover points. It was supposed to cross-over at 500 Hz. I could not dial in a crossover point that would sound good with the passive xover.
 
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