Thiele/Small Parameters, Tuning Frequency questions

[20ducks]

Through the power of Poker (5 card draw) I was able to win some items that I need some help with.

The ported sub enclosure has air space of 1.4 cu ft and a tuning frequency of 39Hz.

Mono amp will run 350 watts continuous @ 2 Ohm.

Sub is rated at 800 watts RMS with peak at 1600 watts at 2 ohms.


I have the Thiele/Small parameters for the sub but what do I do with them?
Sub enclosure is tuned to 39 Hz....okay, what do I do with that?

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[GTP]

What is Qtc for the sub?

 

[20ducks]

Doesn't show a Qtc. Shows the Qtp, Qms, Qes and Qts.

 

[GTP]

Sorry, I meant Qts.

 

[20ducks]

Parallel Coils: 0.761
Series Coils: 0.76

 

[GTP]

0.4 Qts is considered to be the transition between sealed box and vented box alignments. Smaller Qts is for vented and larger is for sealed.

I recommend you "put a sock in it" (the vent) to make the box sealed.
The good news is you don't have to mess with tuning the box by adjusting the vent (which is critical and requires measurement method).

Just put pillow stuffing in the box.

 

[GTP]

What size is the woofer?

 

[20ducks]

Box stuffing is no problem. The sub size is 10".

Looking at the T/S parameters I wonder what, as an average consumer, is the benefit of having them. I mean, electrical, mechanical, loss factors and other parameters do little to help me judge a speaker or should they? And, does the enclosure tune frequency have some sort of relevance?

 

[20ducks]

One last question: will using 8 ga power wire versus 4 ga have any effect?

 

[GTP]

Box stuffing is no problem. The sub size is 10".

Looking at the T/S parameters I wonder what, as an average consumer, is the benefit of having them. I mean, electrical, mechanical, loss factors and other parameters do little to help me judge a speaker or should they? And, does the enclosure tune frequency have some sort of relevance?

It is all a Greek alphabet soup for the average consumer. It is more meaningful to someone who has studied the mathematical electro-acoustic parameters/relationships for woofers in boxes. It is a very deep rabbit hole that I have spent years in practice (actually since 1971 when Thiele/Small published their papers).

You could probably find an online calculator with which to plug in your parameters and it will spit out a theoretical frequency response curve. I'm sure you will find that there is a significant 12dB/octave bass rolloff. Fortunately there is "cabin gain" which mitigates that somewhat, and perhaps your amp/head-unit has EQ controls. But unless you can measure with a microphone with a swept-sine technique (as a minimum) you are fumbling in the dark. Acoustic measurement is part of the deep rabbit hole.

Here is one I found via quick search. If you don't know certain parameters, use their defaults.
https://www.micka.de/en/#ideal

 

[S550HPP]

I would say the AMP is way underpowered for sub so need to change one of them to match up.

1000W+ @2 ohm amp or a sub rated to amp wattage range for best results.

Under powered sub will be a huge disappointment.

 

[20ducks]

I would say the AMP is way underpowered for sub so need to change one of them to match up.

1000W+ @2 ohm amp or a sub rated to amp wattage range for best results.

Under powered sub will be a huge disappointment.

After winning the items in a card game, why would I just spend money on a larger amp? I'm going to install these products and see if they are worth keeping. From all other accounts I made out on the spades I held. Thanks for your input though.

 

[McSkillet]

I would say the AMP is way underpowered for sub so need to change one of them to match up.

1000W+ @2 ohm amp or a sub rated to amp wattage range for best results.

Under powered sub will be a huge disappointment.

That 1000W+ amp will be pulling 60-70 amps on the power grid (if/when pushed that hard). A larger gauge power & ground wire will definitely be required to power that size amp.
Ported boxes are more efficient and don't necessarily/usually need an amp that pushes the wattage range the subwoofer is rated for to get good bass.

The site the12volt.com has a subwoofer box calculator. I haven't used it myself to know if it's any good, but you can give it a try with your T/S parameters. https://www.the12volt.com/caraudio/boxcalcs.asp

 

[S550HPP]

I would get get the cheaper of sub or amp that results in spec alignment, and sell the one don't use.

Can pull good money for top brand and amp model at diymobileaudio, which would be a good place to ask questions quoting amp and sub model #s.

 

[20ducks]

testing....also added filler to the sub enclosure, not too much, not too little. However, I am getting a small amount of stuffing blown back into the trunk through the port. What is a common method of preventing this?

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