Musical Subs and Complete Bass - Page 10

Originally Posted by Auditor55


Firstly, you misunderstood me. Secondly, there's a difference from singling out a particular sub and brand and bashing it like the poster accused me of doing.

Originally Posted by dr_big

This topic currently interests me greatly. The general rule of thumb among audiophiles is that a small sealed sub is best for music, with the ideal system being something like two JL F113s.

The conventional thinking seems to say that two larger ported subs -- something like the ED A7-450 -- wouldn't sound as good, given that it's a big-ass driver and ported too.

You guys seem to be positing that this isn't in fact the case. That, all else being equal, the ported big sub should sound as good as the sealed smaller sub. Given the following parameters --
-- acoustic jazz music with acoustic bass
-- neither sub being overdriven (obviously not, given that we're talking acoustic music played at live levels)
-- both subs set up correctly
-- considering sound quality only, not overall output, not extreme extension (given that the acoustic bass doesn't drop down below 30hz)
-- crossover implementation aside

So given those parameters, are you guys saying that I wouldn't hear a difference between the two subs I mentioned? They'd have the same timbre, same crispness, detail, etc?

Thanks very much,
Jason

Originally Posted by dr_big

This topic currently interests me greatly. The general rule of thumb among audiophiles is that a small sealed sub is best for music, with the ideal system being something like two JL F113s.

The conventional thinking seems to say that two larger ported subs -- something like the ED A7-450 -- wouldn't sound as good, given that it's a big-ass driver and ported too.

You guys seem to be positing that this isn't in fact the case. That, all else being equal, the ported big sub should sound as good as the sealed smaller sub. Given the following parameters --
-- acoustic jazz music with acoustic bass
-- neither sub being overdriven (obviously not, given that we're talking acoustic music played at live levels)
-- both subs set up correctly
-- considering sound quality only, not overall output, not extreme extension (given that the acoustic bass doesn't drop down below 30hz)
-- crossover implementation aside

So given those parameters, are you guys saying that I wouldn't hear a difference between the two subs I mentioned? They'd have the same timbre, same crispness, detail, etc?

Thanks very much,
Jason

Originally Posted by ironhead1230

What is being said is if there is a sound quality difference between the two subs in your example, it is not because one has a smaller driver. Sound quality is dependent on the entire design of the sub, making sure it is not being pushed to its limits and its integration with the room and the rest of the speakers, not on driver size alone.

-Mike

Originally Posted by dr_big

I see. But can a big driver (15-18") in a ported configuration (I know this isn't part of the discussion here -- sorry!) sound as accurate with music as its smaller cousin?

Is there any truth to the "ism" that says a large ported enclosure is good for HT while a smaller sealed unit is better for music? Can a large box work well with small-scale, acoustic music? Measurements are one thing, and while they're a great guide and a wonderful means of trying to explain what we're hearing, listening is the final arbiter, in my opinion of course.

I know that I'm coming into the middle of a heated debate, but it seems as if you're already peripherally discussing this topic.

Thanks again,
Jason

Originally Posted by mojomike

The answer to your question is: Yes, a big ported sub with a big driver can sound as accurate as a smaller sub with music. Whether it actually will sound as accurate, or more accurate, or less accurate, is going to depend on many other factors beginning with how well the design of the sub is executed, how well matched it is for the room it's going into, and ultimately how well it is set up and adjusted by the user.

Originally Posted by dr_big

I see. But can a big driver (15-18") in a ported configuration (I know this isn't part of the discussion here -- sorry!) sound as accurate with music as its smaller cousin?Jason

Originally Posted by JHAz

group delay is arrival time, not settling time. See http://avtalk.co.uk/showthread.php?t=10999

:Group Delay

This is a measure of how the sub delays certain frequencies with respect to others. Typically the extreme bass will arrive at your ears (or our test mic) a few milliseconds after the rest of the frequencies and the extent to which this happens varies from sub to sub. The smaller and more consistent the group delay is across the frequency range, the better the sub should sound. If group delay becomes excessive it may be audible as 'slowness' in the bass or muddiness. For example, if the bass associated with a bass drum beat arrives after the 'thwack', it may sound ponderous and slow. If they arrive more or less in sync then it will sound 'tight'.

"How much group delay is audible? Opinions are divided, but a good rule of thumb is that a time delay of between 1 and 1.5 cycles is just audible. So at 50Hz, group delay should be kept below 20ms (1000/50) and at 20Hz, it should be below 50ms (1000/20) to guarantee inaudibility."

Originally Posted by Steve1981


An OT question (not that I'm worried about it on this thread):
Given that Audyssey is reputed to correct issues with phase & the time domain, are problems with group delay something that it could/would correct?

Originally Posted by JHAz

Not afaik. Would be a complex delay line to make all the frequencies line up with the most delayed frequency.

Originally Posted by Steve1981

An OT question (not that I'm worried about it on this thread):
Given that Audyssey is reputed to correct issues with phase & the time domain, are problems with group delay something that it could/would correct?

Originally Posted by JHAz

Not afaik. Would be a complex delay line to make all the frequencies line up with the most delayed frequency.

Originally Posted by ironhead1230

Actually audsyssey can correct problems with group delay, but so can anything else that smooths the frequency response. Group delay is directly related to frequency response. Any peaks or dips in the frequency response will relate to a sharp change in group delay.

Originally Posted by mojomike

The fortunate thing about group delay is that the frequencies in which it rises (the deeper frequencies) also happen to be where our hearing becomes less sensitive to it.

Originally Posted by DonH50

I was under the impression Audyssey handled time and FR in which case it would correct group delay. Pioneer's MCACC does correct group delay across frequency. Hard (but not impossible) to believe a modern DSP solution would not deal with phase and group delay over frequency.

The relationship between group delay and frequency depends upon the type of filter. In a room, I can see where group delay would impact the FR by changing the nodal points, but AFAIK there's no fixed absolute general relationship between FR and group delay.

Group delay is the derivative of phase.

Originally Posted by mojomike

That's an interesting point about Audyssey. I'd like to know if it does indeed correct group delay.

Originally Posted by JHAz

I'm not sure that group delan and FR are necessarily tied together. For example, the RELQ200 has almost uniform group delay, but ther is not a flat spot anywhere in its frequency response. http://www.avtalk.co.uk/showthread.php?t=10953

At least that's how it looks to me. I'd expect group delay to relate closely to phase (seems to me they're two different ways of saying the same thing).

Originally Posted by DonH50

I was under the impression Audyssey handled time and FR in which case it would correct group delay. Pioneer's MCACC does correct group delay across frequency. Hard (but not impossible) to believe a modern DSP solution would not deal with phase and group delay over frequency.

The relationship between group delay and frequency depends upon the type of filter. In a room, I can see where group delay would impact the FR by changing the nodal points, but AFAIK there's no fixed absolute general relationship between FR and group delay.

Group delay is the derivative of phase.

Since group delay is directly related to acoustic phase, we can actually make one further leap: group delay is
related to frequency response. The Hilbert transform is a method of deriving the acoustic phase from the
acoustic magnitude (the typical frequency response curve shown in most all literature and design programs).
There is one caveat: the Hilbert transform is valid ONLY for what is called a minimum phase system. What is
a minimum phase system? The actual way to calculate one is also beyond the scope of this paper; however,
for our purposes, a subwoofer driver operating in a box, in it's linear mode is a minimum phase system.
Operate beyond the linear limits of the driver (where distortion, power compression, suspension compression,
and other nonlinear issues come into play) and the system is no linger minimum phase, and hence cannot
use the Hilbert transform.
With the Hilbert transform, we can directly calculate the acoustic phase from the frequency response. That
is, given the acoustic magnitude frequency response of the subwoofer system, we can transform the data into
the acoustic phase frequency response, via the Hilbert transform. And, as we have seen above, we can use
the derivative of the acoustic phase to calculate the group delay. Hence, group delay is related to magnitude
frequency response for minimum phase systems (linear subwoofer systems).

I just wanted to point out that (for a minimum phase system) frequency response, phase response, and group delay response are simply three different views of the same physical 'delay' phenomenon. Change one of these responses an the other will change accordingly (remember, it's a minimum phase system).

For example, given only the frequency response of a system the phase response and group delay response can be calculated. This implies that the frequency response curve contains all the information concerning both phase and group delay. So frequency, phase and group delay are really just different takes on the same information.

Originally Posted by dr_big

I see. But can a big driver (15-18") in a ported configuration (I know this isn't part of the discussion here -- sorry!) sound as accurate with music as its smaller cousin?

Is there any truth to the "ism" that says a large ported enclosure is good for HT while a smaller sealed unit is better for music? Can a large box work well with small-scale, acoustic music?

Originally Posted by pokekevin

You said the ref 12 is more musical but not by much. Yet you haven't heard one? Reserve judgement?

Originally Posted by Steve1981

Well then, I'll ask Chris K!

Chris Kyriakakis, Mar 05 05:37 pm (PST):

Yes, the time domain filter correction includes magnitude and phase across frequency.

Best regards,
Chris Kyriakakis
Founder and CTO, Audyssey

Originally Posted by Auditor55


I don't think I was referring to the ULS-15. Anyway, that's a far difference from saying that ULS-15 is no good for music. I have my gripes about HSU, however not enough to belittle their products.