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High-level input to sub

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Posted on November 1, 2020 at 10:49:25
dbphd
Audiophile

Posts: 1666
Location: Montecito, CA
Joined: September 6, 2006
I'd like to use a Velodyne HGS-15 with an Ayre A7e integrate amp that has no provision for a sub, but would that by pass the high-again servo and other electronics of the sub?

 

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RE: High-level input to sub, posted on November 1, 2020 at 11:39:21
Kal Rubinson
Reviewer

Posts: 12430
Location: New York
Joined: June 5, 2002
It will definitely not bypass the servo and there's no distinction in the manual between what happens with each of the inputs.

1.
"High pass crossover switch- 80Hz (THX)/100Hz
This switch selects the frequency for the high pass crossover outputs. This crossover is functional on both line and speaker-level outputs. Smaller speakers with limited low frequency ability may prefer the higher 100Hz setting which will reduce the low frequencies sent to them. Larger speakers with greater low frequency output may be able to handle the 80Hz setting without strain."

2.
"Inputs
Your new subwoofer is equipped with speaker-level, line-level and balanced (XLR) inputs. Use the LINE LEVEL jacks when connecting your subwoofer to a pre-amp, signal processor, line-level crossover, or receiver with pre-amp level outputs. The SPEAKER LEVEL jacks connect directly to the speaker outputs of any amplifier, integrated amplifier or receiver. Your amplifier section will notice no additional loading effects when you use
these inputs due to their very high impedance."

 

RE: High-level input to sub, posted on November 2, 2020 at 12:43:34
dbphd
Audiophile

Posts: 1666
Location: Montecito, CA
Joined: September 6, 2006
Thanks for the reply, Kal. I had proposed to use the subs with an Ayre A7e integrated amp and a pair of LS50s. The A7e has no line output and I was reminded again that connecting the fully balanced amp to a sub via speaker leads is likely to lead to ground problems.

The unaided bass of the LS50s is fine for the jazz and baroque music I listen to in the living room, and the media room has KEF Reference 1s supplemented by Velodyne HGS-15s with SMS-1 acoustic room correction for large orchestrations and pipe organs. A local (Santa Barbara) has a recently serviced HGS-15 for sale that I might buy as a backup.

db

 

RE: High-level input to sub, posted on November 2, 2020 at 13:14:45
Kal Rubinson
Reviewer

Posts: 12430
Location: New York
Joined: June 5, 2002
"I was reminded again that connecting the fully balanced amp to a sub via speaker leads is likely to lead to ground problems."

Possibly but not usually. It will depend on what else is connected to that source and how the sub handles the ground. I am using mix of balanced and single-ended input subs from a "fully" balanced source at the moment.

 

RE: High-level input to sub, posted on November 2, 2020 at 13:53:18
Posts: 1253
Location: Maine
Joined: August 16, 2011
Dbphd, I use an old Heathkit Aa32 integrated tube with a Bash sub amp. With no sub output I use a Y cable as the BASHSub amp has the crossover and controls all contained within. I found most sub amps have the same features as BASH with adjustable volume and frequency as well as a cut off frequency. I hope that's what you were asking, hi Kal....Mark K.

 

RE: High-level input to sub, posted on November 4, 2020 at 02:04:47
dbphd
Audiophile

Posts: 1666
Location: Montecito, CA
Joined: September 6, 2006
I think the admonition was about fully balanced output to high-level input via speaker leads. The Ayre A7e has no other outputs.

In my primary setup I use balanced output from the Ayre KX-5/20 preamp to Velodyne SMS-1s and balanced from the SMS-1s to HGS-15s because all connections in that setup are balanced, but I doubt single-ended connections would put the preamp at risk.

Ayre stuff can be tricky. Even though Charles Hansen told me not to insert anything between the preamp and amp, I tried two high-pass filters, one active the other passive. I removed both after a day of listening.

db

 

RE: High-level input to sub, posted on November 4, 2020 at 05:17:33
sbrook
Audiophile

Posts: 230
Location: Florida
Joined: November 3, 2004
Is your original question meaning if you use the speaker level network to integrate the sub would it provide a clean unprocessed (but high passed) signal to your speakers? Other than the signal being bw cut (at 80 or 100hz)I would rate that as yes and no.

My experiences with using speaker level crossover networks in an active sub have always led me to prefer something else. It may be the limitations of the active subs I have played with but it seems, at least for critical 2 channel listening, that this always introduces some sort of artifact I don't like. Part of this of course is the general lack of flexibility in the crossovers in most sub plate amps.

Outside of a fully bass managed HT setup I prefer to not high pass the mains. This has held true for me with bookshelf and nominally full range speakers. Whether with line level or speaker level connections (depending on what is available) I set the sub LP to its min and the gain barely in. Using familiar test music (we all have our favorites) I adjust lp and gain settings until it sounds right, to me, at my normal listening volumes. I find that good quality smaller speakers (such as your L50's) are not improved by being high passed but rather that it generally messes up their tonal qualities. Better to let proper placement and the designer's intent govern the sound and LF roll off.

This is not terribly scientific, perhaps even heretical, but I've spent too much time over the years obsessing over sub integration. Bottom line, if it sounds good to you then you are done.

 

I think the admonition was about fully balanced output to high-level input via speaker leads.?, posted on November 4, 2020 at 06:14:16
Kal Rubinson
Reviewer

Posts: 12430
Location: New York
Joined: June 5, 2002
No. That is not, and should not be, under anyone's consideration. Not possible.

Sorry. I was thinking about a fully balanced line level source. What you suggest should work.

 

RE: I think the admonition was about fully balanced output to high-level input via speaker leads.?, posted on November 5, 2020 at 03:10:11
dbphd
Audiophile

Posts: 1666
Location: Montecito, CA
Joined: September 6, 2006
Ayre suggested I might try the speaker-level connections proposed by REL for a differential amp, i.e., let the ground float. If that results hum, try connecting the ground to an unused RCA receptacle.

I'm inclined to skip the idea of adding a sub. The combination of A7e and LS50 sounds excellent to me, and with most jazz recordings even the bass seems well portrayed.

db

 

OK., posted on November 5, 2020 at 05:22:35
Kal Rubinson
Reviewer

Posts: 12430
Location: New York
Joined: June 5, 2002
I have edited my preceding posts. I had been thinking (in error) about a fully balanced line level source. What you suggest might work but I've never dealt directly with the issue.

 

RE: High-level input to sub, posted on November 6, 2020 at 16:24:23
John Elison
Audiophile

Posts: 23874
Location: Central Kentucky
Joined: December 20, 2000
Contributor
  Since:
January 29, 2004
I agree with leaving the main speakers playing full-range, eg., no high-pass filter. However, this requires the ability to adjust the phase of my subwoofers to correspond with the phase of my main speakers. I'm using Rythmik servo subs with continuously variable phase. I adjust phase so that bass is loud and full. Then I turn down the volume on the subs so bass blends perfectly playing at the same volume as the rest of the frequency range. I have a few LPs with a string bass going up and down the scale and I adjust the subs' volume so the string bass volume is the same up and down the scale.


 

RE: High-level input to sub, posted on November 8, 2020 at 14:06:21
John Elison
Audiophile

Posts: 23874
Location: Central Kentucky
Joined: December 20, 2000
Contributor
  Since:
January 29, 2004
I have fully balanced PS Audio monoblocks, but they also include a ground lug in addition to the red and black speaker outputs. I connected my main speakers to the red and black speaker outputs and I connected the speaker level inputs on my subs to the red speaker output and the separate ground lug. It worked just fine.

Best regards,
John Elison

 

RE: High-level input to sub, posted on November 10, 2020 at 23:22:10
KanedaK
Audiophile

Posts: 2515
Location: Brussels
Joined: April 27, 2010
Well I do not completely agree.
High-passing the mains has numerous advantages and I think should be done if possible. The main culprit being the generally lousy quality of the circuitry that does the high-pass filtering (most times, in the sub itself) ...only way to do it successfully is via a proper, high quality active crossover IMHO.
If you don't have access to, or can't justify the expense for such a crossover, then indeed it is much better to leave the main speakers full range.

Just my opinion, of course.

 

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