Axiom Home Page Forums General Discussion Technical Questions 3dB frequency point of my M3's?

Hello, how can I find out what that would be?
Was recommended as a starting point for setting my sub.

thx!

I would guess that could be derived from this graph:

This is from Axiom's product page for the M3s.

From looking at this graph, I would say that 150hz would be the best choice.

I would never cross a sub that high.

And I don't see 150Hz as being a -3dB point in that graph anyway...

Looking at the specs the +/- 3dB point is 60hz, however, I would follow normal practices and start around 80hz or possibly a bit higher.

OK, thanks - I had it set around 70 anyway...so I guess I was in the ballpark.

150 still looks like where +3db starts. I would try here to see what it would sound like to eliminate that bass hump. Then adjust downward if it didn't help. This would make the subwoofer reproduce directional bass though.

80hz or 100hz is ideal. The M3 connoisseur (2X6spds) on these forums likes his crossed at 100hz used with a subwoofer.

I was assuming he wanted the MINUS 3Db point, as you would normally crossover to the sub where the main speaker is rolling off (if you didn't want to use the 80Hz standard, at least).

I have to confess not seeing anything on the graph that corresponds with what has been posted.... but then I don't really know what I'm looking at, exactly.
The thing is the frequency knob on my sub only controls the sub.

The specs for the M3 is -3db at 60HZ. I would set the sub at 80HZ, that should be a pretty good spot for the setting.

Using the control on a subwoofer makes it a lot harder to have a smooth transition from the mains to the sub, than it is when using a receiver's crossover setting.

Most of the time the sub's control is a low-pass filter, and not an actual crossover (a crossover being a low-pass paired with a high-pass).

I find it much easier to set up the subwoofer, by totally disregarding the numbers, and doing it by ear (or SPL meter). You'll need to find a low frequency sweep sound. Play that on a loop. Start with the subwoofer's filter setting rather low. There should be a dropout in sound pressure level between the filter point and where the main speakers take over. Gradually raise the setting on the sub until you get a smooth frequency response through the whole transition range. That's where it should be set regardless of what the number says.

When you say "the receiver's crossover setting".... you mean the tone control? i.e. "bass" knob? (I'm using a very vintage receiver btw..)

thx

Yeah, if you're using a vintage receiver, you won't have a crossover in it.

Em, newer receivers split out the bass frequencies and send it out to a "Subwoofer Out" jack on the back...

You have control at which frequency this split happens in a receiver.

You were doing it the only way you can. The knob on the subwoofer that is probably labeled Crossover (even if it isn't technically that).

Oh, the volume of the subwoofer should also be set when the filter point is low, so the output of the sub, and the output of the main speakers is equal. So when you start to raise the filter frequency the two will meet at equal levels.

What subwoofer model do you have, by the way?

it is an Infinity SSW 10.
$$ extremely limited at the moment...someday I'll buy one from Axiom. Actually, I glad I got the M3's when I did.
But this sub isn't bad by any means...its just I have not much control over the whole deal.
I got to wondering about the whole thing while trying to decide whether to even use the sub for turntable listening or not.
We'll see! lots to think about and the music is sounding good!

again, thanks to all who piped up with info.

Does your receiver have an infrasonic or rumble switch?

No gang references, Bob!

I don't think we can stop Bob from saying anything at all today. Must have been discount day at JP's Drug Emporium.

nope!

Em, you may want to just switch off the sub for LPs if you start getting and low-level rumble (feedback) issues with your turntable. Receivers with a rumble or infrasonic filter cut out the VERY low frequencies for that reason.

Ooh! Mark goes all techno like. St. Patty's day is a month away. So, waz wit da "Em?"

The instruction manual for setup isn't bad. It has you adjusting things by ear. And judging if there is too much mid-bass (indicated by having the Frequency setting too high, and causing a large overlap between the sub and mains). And quickly covers the interplay between the Frequency and Level controls.

you know, I was thinking that very thing. It just doesn't seem to require it.
But then I've only very recently started using my TT again.
Got a nice new stylus coming today, so I will revisit this whole issue.

I hate to think the only reason I feel I don't need the sub with LP's is that I'm getting some kind of "rumble" which is fooling me into thinking I'm feeling deep bass! ha! could be...

For the most part, subs and turntables didn't exist at the same time.

When TT were popular, subs hadn't entered the picture yet for most people. Yet, electronics manufacturers were still offering those infrasonic filters for people who had problems with rumble due to speaker/TT positioning or speaker systems that offered pretty low bass. Now, those switches don't seem to exist anymore, even though TT have made a bit of a comeback and people are using them in systems with subs.

I don't think you'll be missing out on any actual music info if you simply switch off the sub when listening to the TT. I don't remember what speakers you have (M22s or M3s maybe?), but certainly if they are floorstanders, you could run those full-range and get all the bass you'll extract with your TT!

pssssst....Mark, read the title of the thread...

oh.

Thanks for looking out for me Adrian! How long do I getr to use this freakin' cold as an excuse?

You can use the meds as an excuse, lol.

Hi Mark and Aunty Em,

Yes, you are correct. Moreover, the vast majority of LPs had no really low frequencies below 30 Hz on them because most modest or inexpensive commercial phono cartridges wouldn't track the frequencies. It was common in the mastering of LPs to roll off lower frequencies sharply below 30 Hz. The exception were some half-speed mastered LPs and a few audiophile labels like Telarc.

Also, a subwoofer used with any turntable will tend to reproduce sub-sonic tonearm/cartridge warp frequencies, generating "woofer flap"--the woofer visibly going in and out trying to reproduce the ultra-low resonances, at 12 to 15 Hz, wasting amplifier power and creating a type of Doppler distortion.

Heavens, when I get into describing all the things that are wrong with analog vinyl playback, I can scarcely believe how we put up with it! Of course, the only alternative back then was tape, preferably open-reel. Even the cutting lathes used to master LPs had audible rumble components.

I recall a few audiophile LPs that had huge groove excursions, frequencies to 20 Hz and lower, which we used for phono cartridge tracking tests: the "1812" Overture (Tchaikovsky) on Telarc. The canon shots would literally cause most cartridges to skip out of the groove.

Cheers,
Alan

thanks for chiming in, Alan. I simply won't worry about using the sub while listening to LP's.

Oh, sure, I enjoyed writing about vinyl again and all the technical details of vinyl playback.

Alan