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Sub setup: High level differing from low level

2652 Views 7 Replies 4 Participants Last post by sivadselim, May 22, 2007

mpc7488

Discussion Starter · May 21, 2007

Posted this in the Sub section but it probably belongs here in the Setup section. I have read through the stickies and some of the links, but couldn't find any answers to my problem yet (other than a potential at this article: http://www.hometheaterhifi.com/volum...es-6-2005.html ).

Hi all,

I've been tinkering with my system the last few days and it's driving me crazy!! I could use some advice on how to get the best sound quality out of my setup.

I've had my subwoofer hooked up for the past couple years on the high level inputs. This is the recommended setup in the manual, and it always sounded great for music but I regretted not being able to use the LFE channel from my receiver. At the recommendation of a coworker I switched over to the low level input this week to try it out. The improvement with movies is quite noticeable, quite a bit more depth on the bass, and effects like thunder are better. However, the sound quality with music degraded quite a bit - the blending is way off, it sounds like there's a noticeable gap between where my speakers roll off and the sub picks up. I cannot for the life of me figure out how to eliminate this gap when hooked up on the low level input.

My equipment:

Receiver is a Yamaha HTR-5830, which has a 90 Hz internal crossover according to the manual.

My speakers are Paradigm Cinema 90s, with a Mirage PS12-90 sub.

Setup 1: High level input to sub, front speakers set to Large, Center Small. Sub crossover set to 100 Hz.

Sound Quality: Great for music, decent for movies.

Setup 2: Low level input to sub, front speakers set to Small, Center Small. Sub crossover raised to maximum (150 Hz, receiver is handling crossover).

Sound Quality: Great for movies, noticeable degradation in music quality, blending sounds off like there is a gap between where the speakers drop off and the sub picks up.

I set everything up this evening and used the same track to do a listen comparison every time I made a change. I surmised that setting the Front speakers back to Large might correct the problem. Tested low level, then high level, still a big difference. Then I thought, aha! The 90 Hz cutoff of the receiver was too low for my little speakers, and I was getting a gap that the subwoofer used to cover. So I tested low level, then high level with my subwoofer crossover set to 80 Hz to mimic this situation. The music still sounded great and well-blended, guitar sounded as it should, etc. As far as I can tell, that setup should sound *exactly* the same as the low level setup, but it doesn't at all.

Sorry for the length, I wanted to include as much information as possible. Any suggestions? Thoughts/input is appreciated.

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sivadselim

· #2 · May 21, 2007

A few thoughts:

In Setup 1, I presume you set your receiver up as having NO SUB, correct?

How are your speakers connected in Setup 1? Are they connected to the sub's high-level outputs or are they connected to your receiver's ouputs?

Regarding setting your subwoofer's crossover to 100 Hz in Setup 1; the term "crossover" can be a bit misleading when it comes to most subs. Most subs do not really have a continuously variable crossover, but instead have a variable low-pass filter (the "crossover" knob) and a fixed high-pass filter. So, if your speakers are connected to the sub's high-level outputs, you really don't know what they're being sent unless you know what your sub's fixed high-pass filter value is. So, it may be a good idea to try and see what this value is, either via the sub's manual or by contacting the manufacturer.

Now, there is also probably a difference between the slopes of the sub's high and (variable) low-pass filters relative to the slope of the receiver's digital crossover. Most likely the receiver's crossover slopes are much steeper. Many people DO find that the shallower slopes of a subwoofer's filters, when sub and speakers are connected via the high-level inputs and outputs, blend much better, especially for music performance. So, your impression that Setup 1 sounds more well-blended may be spot-on.

Lastly, how do you calibrate your system for Setup 1? And for Setup 2?

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WallyWest

· #3 · May 21, 2007

N/M.

Should have read the thread first, lol. I agree with what sivadselim said.

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Teran

· #4 · May 21, 2007

In setup 2 did you try switching the phase on your subwoofer? If the phase is reversed on a properly aligned system you would have a null at the crossover frequency. This would cause the separation you are noticing.

Set your receiver's crossover. Set your subwoofer's crossover to its highest setting. Adjust the phase switch on the sub until it sounds loudest (not necessarily the best). Adjust the sub's crossover down until a gap appears in the bass and then adjust it back up until it sounds the best.

You may want to try this procedure with the receiver's crossover set to different values as you may be able to work around room modes in your final alignment.

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mpc7488

Discussion Starter · #5 · May 21, 2007

Thanks for the replies, here's some responses:

Quote:
Originally Posted by sivadselim /forum/post/0

In Setup 1, I presume you set your receiver up as having NO SUB, correct?

Actually, it's set to have a sub, and only pass bass to the sub (not the fronts). It's a separate setting from the Large/Small speaker setup.

Quote:
Originally Posted by sivadselim /forum/post/0

How are your speakers connected in Setup 1? Are they connected to the sub's high-level outputs or are they connected to your receiver's ouputs?

They're connected to the sub's high-level outputs for Setup 1.

Quote:
Originally Posted by sivadselim /forum/post/0

Lastly, how do you calibrate your system for Setup 1? And for Setup 2?

For levels, nothing fancy - original setup was with a test tone from the receiver, and I recently used a calibration disk from Sound and Vision that had a few additional tests. (No SPL meter or anything like that.) Is that the question? I listen to a CD track with one, then switch to the other and immediately play the same track. I hesitate to say the difference is 'drastic', but it's very noticeable.

Quote:
Originally Posted by Teran /forum/post/0

In setup 2 did you try switching the phase on your subwoofer?

Yes, I did - this was part of the S&V disk procedure, bass was way off when the phase was switched to 180. The receiver crossover is not adjustable, it's fixed at 90 Hz (cheap one).

My worry is that sivadselim is right about the slopes on the crossover, and I'm not going to be able to match the sound with the low-level arrangement.

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sivadselim

· #6 · May 21, 2007

Quote:
Originally Posted by mpc7488 /forum/post/0

Actually, it's set to have a sub, and only pass bass to the sub (not the fronts). It's a separate setting from the Large/Small speaker setup.

That doesn't make sense.

If you are connecting the sub to the high-level L+R speaker outputs of the receiver, then you must set the receiver up as having NO SUB so that the info that would normally be sent to the low-level subwoofer output of the receiver will be, instead, re-routed to your front L+R speaker outputs and hence, your subwoofer.

With your subwoofer connected to the high-level speaker outputs, but your receiver set up as having a sub, with LARGE front speakers, there is no info lost when you play music, because 2-channel music doesn't have an LFE track. But the LFE track of movies will be completely lost in that configuration, and you'll only get the bass of the LARGE L+R front speaker channels to your subwoofer.

Capeche?

If there is something I "don't get" or am missing here, please clarify it for me.

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mpc7488

Discussion Starter · #7 · May 22, 2007

Understood, sivadselim - the LFE info. *was* getting lost previously, that's why I noticed such a difference for movies when I switched. If I were to go back to using the high level inputs, I would do exactly as you suggest and correct the problem by setting the receiver up as having no sub.

The problem is that my current setup, which I believe to be "correct", sounds noticeably worse for music.

Low level setup:

Basic Menu -> Setup -> Room: S, Sub: Yes, Speakers: 5

Sound Menu -> Speaker Set -> Center: Small, Front: Large, Surround: Small, Bass: Subwoofer (other options are 'Front' or 'Both')

This sounds great for movies, but bad for music. From this setup, all I did was disconnect the low level input and re-connect the high level input (receiver to sub, sub to speakers) to listen to the difference, no setup changes otherwise. Movies sound worse (as you describe they will), but music sounds quite a bit better.

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sivadselim

· #8 · May 22, 2007

Quote:
Originally Posted by mpc7488 /forum/post/0

Low level setup:

Basic Menu -> Setup -> Room: S, Sub: Yes, Speakers: 5

Sound Menu -> Speaker Set -> Center: Small, Front: Large, Surround: Small, Bass: Subwoofer (other options are 'Front' or 'Both')

This sounds great for movies, but bad for music.

Based upon your description of your front speakers, you should set the fronts up as SMALL, too, with this setup. Bass set to "Subwoofer" would be correct; the other bass choices shouldn't be available with the fronts set to SMALL. Then you need to properly calibrate the system with either a calibration DVD or the test tones in the receiver.

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