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A flat line frequency response doesn't mean it will sound "tight and musical". Probably the best way to forecast musical quality is from past experience. It doesn't make sense to select a mushy driver just cuz a program will tell you the frequency is flat.

Solving the power issues at the expense of the music is not helping. That's not what the OP wants. The solution needs to be tight and musical in a small box with the Stryke amp and a $150 speaker. Focus.

Looking at the Qtc used by the folks posting graphs raises some questions. I see they range from around .6 to about .9. This is quite a range and may have quite a bearing on the quality of the sound.

I have read that .7 is about "normal" and that designs below .7 are tighter and more musical. I don't know if that is true, but if it is, it points out the folly of relying on a frequency data as the main design parameter.
 

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Heh thanks for helping get back on track jorge. However I don't actually know much about how QTC reflects on the actual sound or quality of sound. I'll have to look into it. However if that is the case then the SDX10 has the lowest QTC posted so far, and the Dayton HF 10 has a lower QTC in the 2 cu ft box than in the 1 cu ft box, so if that is true then its just another reason to go with a little bit larger box when possible.

I googled :thiele small parameters qtc: and followed the first link. I was giong to just paste in the pertainant information but its a few paragraphs so I'll just post the link instead.

http://www.members.shaw.ca/LoudspeakerBuilder.ca/thiele-small.html

To paraphrase tho he says that about around 7 you get natural sounding bass, as the qtc goes up you get louder bass but less low frequencies and as qtc goes down you get lower extension but less DBs leading to what he calls "tinny" bass, whatever that means.

I wonder if the QTC value is effected by the 30hz 6db boost because it certainly affects the overall frequency response.

Another thing that is somewhat debated regarding tight bass and musicality is the group delay, but then again most sealed boxes have very good group delay other than any that is added due to EQing trying to get them to play lower.
 

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I donno about the practical effects of Qtc with these sppecific components. One thing that changes a lot as you vary Qtc is the box size.

Looks like anything over .7 is going away from the goals and below that may help put the boost to good use.

It's gonna take someone with listening experience to put this in perspective. I expect some box size will emerge that will be the smallest that an experienced person believes will produce tight and musical sounds.

Hopefully that box will be small enough to suit costanza. If not, some rethinking of original objectives or components will need to happen. I suspect an equalizer would go a long way to making things happy, but that doesn't seem to be a current option.
 

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So how does one know what the Q of the flter is? Especailly on an older amp like the stryke where the specs are not easy to come by. Even on the newer Dayton and O-Audio amps don't give you a whole lot of information about their bass boost and cutoffs. What is the Q of the filter/eq and how do you know what it is?
 

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Here's a table for a Dayton 240. I am told that most of these plate amps have the same rumble filter circuits in them. The boost is part of the filter. The filter will start dropping off a few Hz below the boost setting.

I wouldn't be surprised if a little checking of the Stryke amp revealed that boost adjustments are possible as noted in the link. Maybe even with the values in the table.

http://www.parts-express.com/pdf/300-804boost.pdf
 

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What is the Q of the filter/eq and how do you know what it is?
Either you get the information from the manufacturer or you do a "best guess". Some time ago I asked about how to add filters in WinISD. The explanation I got was if it states boost at a single frequency (30 hz) then Change the Q to 1. If it states boost at a range of frequencies, (30 - 34 hz) add a filter at 32 hz and change the Q to 2.
 

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Discussion Starter · #28 ·
Okay, this has been so difficult! I have a Stryke Audio 350 watt plate amp (at 4 ohms) with a 6 db boost at 30 Hz. The amp will not be mounted in the box. I'm going with a 10", most likely the Dayton RSS265HF-4, since it has so many good reviews and is only $105. (If there is a "better" 10" out there for the same price, please let me know!) The maximum I want the exterior of my sealed box to be is 15" cubed (made from 3/4" MDF). I want tight/articulate/musical bass with as flat a frequency response as possible. I want it to sound as good at 80 Hz as it does at 30 Hz. I don't care about response below 30 Hz or high SPL's.
The question is, minus the space taken up by the driver, should I make the box smaller or leave it at 15" cubed in order to meet my goal?

Specs for the RSS265HF-4:
Power handling: 350 watts RMS/600 watts max * VCdia: 2-1/2" * Le: 1.05 mH * Impedance: 4 ohms * Re: 3.3 ohms * Frequency range: 22 - 1,000 Hz * Fs: 26 Hz * Magnet weight: 100 oz. * SPL: 87 dB 2.83 V/1m, 84 dB 1W/1m * Vas: 1.59 cu. ft. * Qms: 3.26 * Qes: .51 * Qts: .44 * Xmax: 12.3mm * Dimensions: A: 10-1/2", B: 9-1/4", C: 5".

THANKS!!!!!!!!!!!!! :)
 

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Well costanza basically you need to figure out how many cubic inches are taken up by the driver and however much bracing you are going to have and then figure out how many cubic inches you need to have one foot after subtracting the bracing and driver from the total volume. How close you want to get to exactly 1 cu ft is up to you. Deviations up 5-10% probably wont matter to most people.

As for figuring out the volume of your bracing thats pretty easy. How much volume does the Dayton 10" take up inside the cabinet. I'm not really sure, but hopefully there is an easy way to approximate it, or maybe one of the gurus here knows a good way to get that info.

If you're talking about a 15" cube then inside is going to be 13.5x13.5x13.5 or something after taking into account the thickness of the box, It'll be more like 13.5x13.5x12.75 if you go double thick on the front.

One cubic foot is 1728 inches, so if you have 13.5x13.5x12.75= 2323 cu in or 1.35 cu ft. Now if your bracing and driver take up about 1/3 of a cubic foot you're great. But you'll have to design and figure out the volume of your bracing your self and hopefully someone else here can help you with the space displaced by the driver on the inside of the box.

Hopefully that was helpful to you.
 

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Discussion Starter · #31 ·
Thanks for all your help! Does the boost play any part in the size of the box? In other words, if the speaker is designed for 1 cu ft without boost, wouldn't the boost allow you to make the cabinet smaller with the same output from the speaker?
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As for making the box smaller, no not really, not without losing output in the 30-40hz range. I tried explaining it several times but every time I read what I wrote I saw that it could be confusing. If you want to see one of us could post some graphs or try to explain it but basically, no. If you make your box any smaller than 1 cu ft you will start losing bass below 35-40 hz in relation to the rest of the frequency range that the sub is playing.
 

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Does the boost alter the design of the box from no boost? Does it allow you to make the box smaller with the same speaker output?
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The boost affects the output and the frequency response. The box size stays the same to maintain a Q of 7.
Yellow - 1 cu.ft with 6 db of boost.
Green - 1 cu.ft. wiyh no boost.

Both models assume a subsonic filter at 18 hz, which could probably be verified by contacting A.E. Speakers. (formerly Stryke)

Text Green Line Font Design
 

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Discussion Starter · #35 ·
The boost affects the output and the frequency response. The box size stays the same to maintain a Q of 7.
Yellow - 1 cu.ft with 6 db of boost.
Green - 1 cu.ft. wiyh no boost.

Both models assume a subsonic filter at 18 hz, which could probably be verified by contacting A.E. Speakers. (formerly Stryke)

View attachment 12804

Wow! I was a little hesitant about the boost, but it looks like a requirement in this application! I'm going to get started on this, this week :)
 

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I have a duel 10" Dayton set-up and am happy with the results.My old cabinet was 1.2 cf on each side,but on a sealed unit the volume is not as critical,so it works fine for me,and yes for $105 they are a great deal.


 

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Why does the boosted signal produce less SPL? Is the output adjusted to remain within Xmax? How many watts to reach Xmax boosted and unboosted? I would try to figure it out myself, but can't find a way to do it with UniBox.
 

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If you haven't decided yet, you might take a look at my 10" driver thread and (upcoming) build pics. I am using a 2.2 ft3 tube that cost $12 @Lowes, along with scrap mdf and an aurasound driver from madisound (would've strongly considered the exodus 10", now). The tube will take little floor space and be about 42" tall.

It should be a good sub for music, decent down to 28hz...
 
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