how low should I go

[evanc]

I'm working on replacing my huge (think refrigerator) sized subs with something more reasonable. It seems my first decision should be how low the F-3 should be. Any thoughts? My current subs employ 18" cv drivers in a bandpass box. They do shake the house down to very low frequencies. Once I know what I'm shooting for as far as lower cut off I can move to picking drivers and designing boxes.

Thank, Evan

[magnoman]

Evan,
I too am trying to come up with my desired lowest frequency.
New to this forum and speakers in general, so I cant offer much advice, but it seems that since you can currently go quite low with a big driver, would it be possible for you to experiment with high pass filters (presumably in your low level signal) to determine where your taste lie?
It's likely difficult to do a true test given how many things will change with a filter in place but it might give you some "feel" for your desired threshold.

I live on a busy street with lots of these Shaker car bass bombs idling at the stop and so my taste for bass is certainly diminishing.

Looking forward to your selection
-Antonio

[weltersys]

Originally Posted by evanc

I'm working on replacing my huge (think refrigerator) sized subs with something more reasonable. It seems my first decision should be how low the F-3 should be. Any thoughts? My current subs employ 18" cv drivers in a bandpass box. They do shake the house down to very low frequencies. Once I know what I'm shooting for as far as lower cut off I can move to picking drivers and designing boxes.

Thank, Evan

How low you want to go depends on what you like to listen to, and how accurate you want the playback to the source to be.
If pipe organs are your bag, 16 Hz is required.
If you are listening to current pop music, an octave up, 32 Hz (the low B on a five string bass) gets you most of the action without as severe size/output level compromise.

If you are listening to pre-CD era pop, 40 Hz (low E on a four string bass) will suffice for most recordings.

The Eminence Lab 12 is a good choice to get down to the mid 20 Hz range without requiring huge cabinets.

[bentoronto]

Big, big, big gap between what people think their speakers are doing and what they really are doing in their listening environment. A lot of powerful-seeming bass is no lower than 80 Hz. Not saying your speakers are not capable of window rattling at 15 Hz, but may not be doing that except once a year.

Measure your present speaker performance. Eyeball the spectrum on your sources.

Shot-in-the-dark suggestion: if your 18 inch drivers actually have low resonance (many do not), just put them in any size box face down and drill holes (and re-fill these holes) in the box untill you can measure the sound your want.

[JLH]

In my case I looked when room gain started reinforcing the bass in my room. For me that is around 28Hz. A tapped horn tuned for 30Hz gives me all the bass I need for the music I listen to.

[Baldin]

On good recordings there will be room information below 30 Hz. I have built subs down to 20 Hz ... but my experience is that below 25 there is not much information to go for. If you want a resonable size and almost all information, go for around 25 Hz.

And it is a smaller size room, you need to do something to the room modes in the low end to get the benefit of the real low end (otherwise it will be masked, by the boomy upper bass).

[evanc]

good info..... thanks

[bentoronto]

At the risk of seeming peevish, I don't believe I have any idea what "room sound" could mean, except for music frequencies in the ordinary sense that loudspeakers make them.

There is pretty much nothing on music recordings that shows up on my spectrum analyzer below about 32 for the occasional bass drum and almost never even for big organs. If you can play their harmonics with authority you ear just can't tell the difference (even if your sternum can).

JLH - the room introduces a large number of distortions (both boosts and cuts) south of 250 Hz. Big ones. Lots of them. TERRIBLE ones below 100 Hz. There is no such thing as "room gain," at least as far as I can understand the term in acoustic theory, except for all those nasty resonances mentioned earlier in this paragraph.

[JLH]

Originally Posted by bentoronto

JLH - the room introduces a large number of distortions (both boosts and cuts) south of 250 Hz. Big ones. Lots of them. TERRIBLE ones below 100 Hz. There is no such thing as "room gain," at least as far as I can understand the term in acoustic theory, except for all those nasty resonances mentioned earlier in this paragraph.

Room gain is very real and is already well documented in acoustic theory. Room nodes (undesirable resonances) and room gain are two different things.

[bentoronto]

Originally Posted by JLH

Room gain is very real and is already well documented in acoustic theory. Room nodes (undesirable resonances) and room gain are two different things.

Well, JLH, I am always glad to learn and even to apologize for my posted errors. Soooo, I went looking for the "well documented" evidence of room gain* and all I found was a kind of circle of references and nowhere in the circle was any generally accepted standard source on acoustics.

Can you please refer me to these "well documented" references? BTW, since there must be pretty solid and varied sources, could you be so kind as to skip any that might be deemed "tainted" such as those by persons known to be committed advocates of OB, Stereophile authors, and kindred souls. I am certain that would be no constraint at all on you since you refer to presumably numerous "well documented" sources.

I could easily be very wrong. Ball's in your court.

*I did find people who were pretty confused about "room gain" and the radiation resistance of corner or wall placement, room modes, and familiar phenomena like that.