High or low level sub inputs?

I recently read on the REL and/or Sumiko website that REL recomments
the high(speaker level) connections. Using the speaker level connection helps preserve the flavor of the amp's output. I think it may all be system dependent, because I also recently read that a user of Definitive Technology says that low level(pre-amp) was preferred.

Happy Listening!

You will only tell which is better by, posted on May 9, 2007 at 18:20:00

GGA
Audiophile

Posts: 297
Joined: December 4, 2001

listening but here are some pros and cons:

When a high level signal is given to the sub amp the sub amp actually lowers the signal back down to line level, thus creating an extra step in signal processing.

Plus the distortion (or more kindly, the "signature") of the main amp is added to the distortion of the sub amp. The sub driver is not seeing the pure signal created by the main amp but the signal as modified by the sub amp, not to mention the changes caused by the crossover or low pass.

The purist will object to adding another box and cables for the main amplifier to drive, even one with high impedance.

A drawback to the low level signal is that the preamp must drive both the sub and main amps. If the two amps have fairly low impedances they will be even lower when hooked up in parallel. If the preamp does not have a good output stage or the distances are too long for it, the sound may suffer.

Still the only way to tell is by listening.

Best way to Bi-amp, posted on May 9, 2007 at 19:21:09

Craiger56
Audiophile

Posts: 5574
Location: San Jose CA
Joined: April 3, 2002
Contributor
Since: December 29, 2003

High-pass stereo subwoofers

By relieving your amp and speakers of bass below 80hz by 6 db their performance potential is enhanced above 80Hz.

The signal attenuation is a very transparent kind of processing and places a specialized solid state amp where all but the very best, work best, in the bass.

At least one subwoofer manufacturer offers both types, a high-pass for music systems and a low-pass for home theaters.

Cheers

"You're pretty good"

-Albert King to Stevie Ray Vaughan

GGA's advice, posted on May 9, 2007 at 22:55:44
soundbound Audiophile Posts: 135 Joined: November 8, 2004	Makes a lot of since to me. Try both and see which sounds best to you.

Low level sub inputs, of course..., posted on May 10, 2007 at 01:03:19

Lowrider
Audiophile

Posts: 1924
Location: Riga
Joined: April 30, 2002

The main amplifier and the speakers dont have to play low frequencies, less power uded, less driver strain, and I dont understand why sending distortion to the subwoofer could sound better...

Less distortion in general...

Antonio Melo Ribeiro

Re: High or low level sub inputs?, posted on May 10, 2007 at 07:40:17

JerryS
Reviewer

Posts: 2026
Joined: February 24, 2001

I prefer high for these reasons:
The sub and main speakers are usually easier to integrate.
If you change amps, you don't have to reset the subs.
Eliminates the need for dual outputs on a preamp.

Happy listening.

Regards,
JerryS

Re: High or low level sub inputs?, posted on May 10, 2007 at 09:47:17

Dawnrazor
Audiophile

Posts: 12592
Location: N. California
Joined: April 9, 2004

I have had a similar experience. High level was the best blend with my sub and Maggies.

I never could get a good blend with low level, even though it would make things easier for my tube amp (at the time) to drive. Some of that is that the crossover points IMHO were a bit high at 80hz or 100hz. If it was at say 50hz, it may have worked better.

One kind of HAS to try it both ways though to know.

sub amp changes the sound of main amp, posted on May 10, 2007 at 10:15:33
Jon L Audiophile Posts: 6065 Joined: April 6, 2000	which is my main gripe with speaker-level inputs. Even when the sub amp is turned OFF(!), the main amp's character changes, probably b/c of the impedance of the sub amp the main amp's speaker outputs are "seeing."

Re: High or low level sub inputs?, posted on May 10, 2007 at 12:38:14
MylesJ	Some digital amps don't like it when you hook the sub to the high level outputs. Been there and had my HCA-2 go into oscillation a few times. I contacted PS audio and they said don't do that.

If you change amps, you don't have to reset the subs. WRONG... NT, posted on May 11, 2007 at 23:34:12
Lowrider Audiophile Posts: 1924 Location: Riga Joined: April 30, 2002	... Antonio Melo Ribeiro

Re: If you change amps, you don't have to reset the subs. WRONG... NT, posted on May 12, 2007 at 10:15:56

JerryS
Reviewer

Posts: 2026
Joined: February 24, 2001

Hi Antonio,
I change amps quite often, and I think my comment is correct. When you change amps using the high-level sub input, even for one of significantly greater or lesser power, the volume of the subs changes proportionally. The crossover frequency of the sub is dependent on the main speaker, so no change there is needed.

There may be some minor tweaking if you change from a soft and flabby tube amp to a way-tight and controlled solid state amp, for example, but the settings should stay almost completely unchanged.

Please tell us why you think this is incorrect.

Thanks,
JerryS

How was that constructive?, posted on May 12, 2007 at 10:18:44

Craiger56
Audiophile

Posts: 5574
Location: San Jose CA
Joined: April 3, 2002
Contributor
Since: December 29, 2003

Obviously it wasn't and that's a shame because JerryS is an extremely knowledable and helpful member, not someone that should be discouraged from posting.

It appears to me the original post was interested in opinions and experiences on the subject of high-pass vs low-pass subwoofer connection and it's unfortunate anyone would use it for chest beating, something I'd like to discourage.

JerryS has a wealth of good info and advise at his site linked below.

Cheers

http://www.10audio.com/

Re: sub amp changes the sound of main amp, posted on May 12, 2007 at 15:45:10

JerryS
Reviewer

Posts: 2026
Joined: February 24, 2001

Hi Jon,
I'm not saying you're wrong, but I have never noticed this. Very interesting! Can you tell us on what model(s) of sub and main amp you heard this?

Maybe the sub is relatively lower impedance and the amp is higher? Just guessing, but worth trying to understand. In my system, the amp would be <1 Ohm and the sub 20k Ohms, which should minimize any interaction.

Thanks,
JerryS

And yours ? NT, posted on May 12, 2007 at 23:37:01
Lowrider Audiophile Posts: 1924 Location: Riga Joined: April 30, 2002	... Antonio Melo Ribeiro

Re: If you change amps, you don't have to reset the subs. WRONG... NT, posted on May 12, 2007 at 23:48:37

Lowrider
Audiophile

Posts: 1924
Location: Riga
Joined: April 30, 2002

Hi Jerry,

You have a very good point, it would be absolutely correct if amplifiers where wires with gain...

Even though the volume of the signal changes proportionally, amplifiers react differently to the load of the speakers, again, with easy speakers the difference would be negligible...

Antonio Melo Ribeiro

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High or low level sub inputs?

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