MTH30 Questions : Complete Noob!

[sebDIY]

Measurement (calibrated) from one of my MTH:

[tb46]

Hi sebDIY,

Thanks for that. It basically confirms the Hornresp simulation (real life smaller peaks, etc.). How high up do you use it?

Regards,

[weltersys]

Originally Posted by sebDIY

Measurement (calibrated) from one of my MTH:

Thanks for posting the chart, what were the measurement conditions?
What drivers did you use in your cabinets?

Looks like a classic example of Hoffmann's iron law, low, loud, small, pick two.

In your example of the MTH, the lower octave of typical pop musical bass is sacrificed for small and loud, response is 25 dB down around the low B (31.5 Hz) on a bass guitar.

As usual, smoother than Hornresp would predict.

[Brian Steele]

Originally Posted by weltersys

As usual, smoother than Hornresp would predict.

I want to see the impedance response curve. That will show how close the sim matches the actual design.

[sebDIY]

Looks like a classic example of Hoffmann's iron law, low, loud, small, pick two.

In your example of the MTH, the lower octave of typical pop musical bass is sacrificed for small and loud, response is 25 dB down around the low B (31.5 Hz) on a bass guitar.

For my use it's perfect. I was searching a light cabinet (mine is 23Kg with ferrite driver, this is the lightest of all cabinets I've tried), searching also clean sound, and it is, with ability to make strongest level in this size. I have compared with some 18" bass reflex. The 18 BR goes lower, but MTH-30 makes more level and is more dynamic, also lighter and smaller.

The loudspeaker is LF12G301 RCF, measurement groundplane 2 meters without any wall into18 meters perimeter

Without any any eq, you can cross at 110/120hz without hearing any ugly resonance, but I think it is usable above 120Hz with Eq cutting peaks. I know some people cross it 150Hz. I use most of the time for wedding: 2 MTH-30 and 2 ZX1 EV. I have made 200 people without any problem in this configuration and I think it can do even more.

[weltersys]

Originally Posted by Brian Steele

I want to see the impedance response curve. That will show how close the sim matches the actual design.

Oliver's (TB46)Hornresp FR peak and dip locations matching senDIY's measured peak and dip locations indicate the sim matches the design very closely.

I find it interesting that most in the DJ and PA business are perfectly willing to trade LF extension for SPL.

Art

[turbodawg]

Originally Posted by weltersys

Oliver's (TB46)Hornresp FR peak and dip locations matching senDIY's measured peak and dip locations indicate the sim matches the design very closely.

I find it interesting that most in the DJ and PA business are perfectly willing to trade LF extension for SPL.

Art

Lots of small pa setups don't use subs, so in comparison this is very good.

[weltersys]

Originally Posted by turbodawg

Lots of small pa setups don't use subs, so in comparison this is very good.

"Very good" is a relative term, like "good enough".

The Mackie HD1502, a fairly small speaker on a stick using a 15" and 1" exit HF driver drops off only 1/6th octave above the MTH30.

[sebDIY]

I find it interesting that most in the DJ and PA business are perfectly willing to trade LF extension for SPL

Most wedding rooms I work got reverberation, and can sound "whaouwhaouwhaou" in the infrabass range, espacially with very compressed music, so I prefer, from far away, a truncated and dynamic bass cabinet, more listenable, than a slow sub.

[ghettosynth]

Originally Posted by weltersys

Oliver's (TB46)Hornresp FR peak and dip locations matching senDIY's measured peak and dip locations indicate the sim matches the design very closely.

I find it interesting that most in the DJ and PA business are perfectly willing to trade LF extension for SPL.

Art

Well, for me at least, I'm not "in the business", so to speak, it's a hobby. I specifically need something "one man" portable." If it's not easy to grab and go, I just won't take it. No 18" sub, and most 15" subs are not just grab and go for me.

Well, I'm still debating on what exactly that I'm going to do here, I'm fairly certain that I'm going to build at least one pair of small 12" TH subs.

I have some more pedestrian questions.

First, does anyone have any specific recommendations for the following items:

1) Connector plates, I want to use speakons.
2) Finish, I'm leaning towards some sort of paint, but I want to know what people like and use, and what's cost effective.
3) Handles and pole mounts.

Given the simulation results and measurements here, I'm not seeing a lot of difference between the low frequency extension of the MTH30 and the THAM12, which is a bit smaller. I also notice that hornresp really considers only the dimensions of the horn and the properties of the driver, and how the horn is folded, holding all else constant, doesn't come into play in the sim. I have no sense of how the quality of the horn fold impacts real results, but, given what I've read elsewhere on this forum, performance is relatively insensitive to small deviations holding all else constant.

Consequently, it appears that I can trade off some SPL for LF extension in the THAM12 by just making the cabinet about 3 to 4 inches taller. After that, it appears to be diminishing returns for additional length. I simed this using the 12PS100. Looking at the design, it seems that I could scale the height in the build plans fairly easily without dramatically affecting the taper of the horn or any other critical dimensions. Anything that I'm overlooking here?

Finally, I haven't sim-ed it yet, but, I'm leaning towards the B&C 12NDL76 for weight reasons. Any thoughts on this, are there any other good choices of driver in the 10 pound range that I should consider? In particular, is there anything less expensive that would work almost as well?

tnx,
gs