External crossover good next move?


Hello Audiogoners, budget-minded post

I have an NAD C320BEE amp with a basic Velodyne subwoofer (CT-80) inserted between pre and amp sections (per Bob Reynolds suggestion--thank you). Source is a Lite DAC-AH, fed by an NAD CD player.

The problem is the cable runs to and from the subwoofer need to be quite long (at least 6 feet). I have a DH Labs cable from the DAC to pre, but cables running to the sub and back, I am ashamed to say, are $29 Monster cable. So I wonder how much I am losing in the Monster cable. Also I wonder about the quality of the crossover in my sub: this is an 80-watt HT-oriented sub I got for $300 new in 2001.

I am considering an external crossover, like Paradigm x-30 or Outlaw ICBM. Could I expect a real improvement through this upgrade? Does anyone have a sense of quality of the crossover in a sub like mine, versus those products?

I like the sub-monitor arrangement, and am not quite ready to buy a new amp, although I would not be surprised to hear that is best route. Any ideas appreciated
abarnett
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Thanks for your response. The Outlaw ICBM is advertised as having a "2nd-order Butterworth" high-pass and low-pass. I don't understand the terms and need to do some reading.

Part of the reason I like the external crossover idea is so I can have short cables between pre and power amp sections. I get the impression this is important if I end up with a passive preamp (e.g., Creek integrateds)

I'm guessing a passive high-pass filter, like this ACI product, leaves something to be desired?

http://audioc.com/accessories1/misc/hipass.htm

Otherwise, couldn't this could be combined with a Y-splitter?
Can you tell us about your speakers and how they are crossover over/hooked up?

-Rob
Also- why do you need to cross over in the first place?
I have the AR.com kit speakers (Ed Frias design). It has a 6.5" Peerless woofer. I don't know about the speakers' crossover. I see someone on an audio chat site saying he thinks the crossover for the speaker is at 2300 Hz.

The sub has line in/line out jacks. I have the subwoofer between the pre and power sections of the NAD for the biamping effect. The NAD is 50 wpc, and I notice an overall improvement using the sub (with the NAD not amplifying bass). Also, as I understand it, the monitors do a better job if they aren't receiving bass. I set the crossover on the sub at about 80 Hz.--Thanks
Well, my second question alluded to my reccomendation.

But if you like the sound that is all that matters.

However, it is somewhat atypical to do what you are doing and it opens up multiple cans of worms like this.

9/10 people are simply going to use parallel speaker level runs straight off the NAD and dial in the sub where the speakers naturally roll off. This avoids your very fragile low voltage line signal from having to unneccessarily traverse long IC runs and an additional crossover that might not be well enough engineered to provide pure transparency.

YMMV though.

-Rob
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If you were bypassing the passive xo in the speakers than your point would be better taken. But your not.

Also, the distortion/noise added at the line level is completely different than what is created by the transducer. It is far more audible and nasty.

Finally, if you were talking about relieving a tiny amp of a horrendous bass load than it may make sense. But the NAD is more than adequate to drive these relatively efficient speakers.

But again, if he likes the sound that is all that matters.

But there is a reason why hardly anyone utilizes this approach.

-Rob

Rob, thanks for your comments, this is helpful.

The other day I took the sub out and reconnected the pre and power sections with a decent cable (DH Labs BL-1). Without the sub, it sounded kind of flat and drab compared to what I'm used to. It seems to me the extra power from the sub is a net plus for this kind of budget system.

Are there good active (external) crossovers that can be used at the speaker level?
The comparsion should not be done with and without the sub.

You can still run the sub. By all means you should if you like it. All I am saying is get the signal to the sub via speaker level. Cheap speaker wire is all you need. 1 pair going to the sub, and another going to the AEs on each side. 4 leads coming off the amp.

You have a nice little speakers, and a well built intelligently designed amp. I just do not see how running your sub in the preout/main in loop is going to help anything. I dont believe it is helping the AEs in any way.

-Rob
Rob, thanks for your post. I will try it!
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Your missing the point. This is not a line level vs speaker level debate.

The issue is running it in the preout/main in loop. In this case line level forces it to be in the loop, which is why speaker level makes more sense to me.

Simple logic says that adding 12ft of ICs and an additional crossover to your signal chain is not ideal. If you are going to do it, it better have a big sonic payoff. This is where we disagree.

His speaker is efficient and represents a benign load to the amplifier. In addition, the amplifier has a respectable power supply. The NAD does not need to be relieved of the load.

If you are looking for a 75hz wallop, than okay. But if you are looking for flat response you are better off letting the speakers roll off naturally and filling in with the sub at this point. That 6.5in Peerless woofer is going to do far more justice to an upright bass than the sub.

Finally, due to this config the OP is asking about buying an external passive XO as an upgrade. His money is much better spent in other places. Why force yourself down this road when you can simply work this need out of the design?

There is no right or wrong. Just opinions- ours differ. Im suggesting he try speaker level. I see it as sonically superior and more simple.

-Rob
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Thank you both for your suggestions. What is an OP?

I don't want 12 feet of ICs--that's why I'm considering this. I can connect an external XO with two short ICs of decent quality (which I have) and run less-good cable to the sub. My thinking is, if I can pick up a decent external XO for <$200 used, I can clean up the signal path compared to what I have now and avoid long IC runs. I guess I will try both approaches and see which sounds better.

Bob, if the more expensive SVS sub is a good idea, then why isn't a good external crossover also a good idea? It's the same approach, right?

What about a good-quality, external crossover designed to work at speaker level? That would avoid the objection about distortion in the woofers. Does anyone make that?
OP is original poster.

Why dont you run a search for "subwoofer line level speaker" at audioasylum? Might help.

Here is something from www.rel.net

<<
A2. Agreed, most do. However, REL sub-bass systems use the unique REL ABC, which circumvents this problem completely. The ABC is part of the electronics of the sub-bass system and as such does not interfere with the main signal route between pre amp, power amp and the speakers of the main system. For hi-fi use, the signal for the REL is taken at high level via the main speaker terminals on the main amplifier. The impedance of the REL’s high level input (100,000 ohms) has no adverse effect on the main system whatsoever. >>>
Here is the questions; it didnt post initially.

Re; issues with subwoofer integration.

Q2. They either need a crossover hanging on the end of the power amp or an active filter between the pre and power amps, aren't both likely to ruin the sound from any carefully chosen system?

Answer in post above.

Generic, yes.

Search in the speaker asylum for more info.
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A follow-up. I went ahead and got an Outlaw ICBM on Ebay. This device was mainly built for DVD audio/SACD players, but can be used as a stereo crossover and got good reviews. So now I have good quality ICs from source to main amp, and a much shorter trip.

I'm happy with the effect. Definite improvement in detail, clarity, e.g., I can hear nuances in vocals I haven;t before; things seem a little better sorted out. Not night and day, but appreciable. I have not yet tried the two sets of speaker wire approach Rob recommends, but will.

Only complaint is I'm noticing the sub more on certain song, a little thuddy. This may be a matter of tuning things. Or I'm just turning on it now that I have started to imagine better! Thank you all for your suggestions