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Old 10th March 2015, 04:12 PM   #1
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Default Bass Reflex full range?

I'm looking at building BR boxes for a pair of PS220-8 full ranger drivers for my hifi system.

I was thinking of an external size of 27"H x 10.5"W x 16"D using 3/4" plywood. Given this size what should the port be tuned to?

These will be used without the help of a subwoofer and I'll be happy with port tuning in the 40-50hz range if possible.

Any help?

Last edited by JoeyAnchors; 10th March 2015 at 04:24 PM.
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Old 10th March 2015, 04:21 PM   #2
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Try a 3in diameter x 3.625in long vent based on the published data for a ~42Hz tuning & a lightly damped alignment.
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Old 10th March 2015, 04:57 PM   #3
IG81 is offline IG81  Canada
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I agree with Scott, with a little addition, see below.

Using the PE data...

Dayton Audio PS220-8 8" Point Source Full-Range Neo Driver

... and your Vb of ~54L, I'd use a 3" diameter port with length between 4" and 3.75", resulting in Fb between 40Hz and 45Hz. The small extra I propose: this driver really seems like it wants ~2ohm of drive impedance for the enclosure volume you propose, which can come down to the amplifier you plan to use. Anything specific?
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Old 10th March 2015, 05:10 PM   #4
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I plan on using it with a SX450.
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Old 10th March 2015, 05:12 PM   #5
zobsky is online now zobsky  India
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The big issue I've observed with running full ranges in bass reflex boxes is bass roll off, and a resultant thin sound. Not because the bass isn't being produced, but rather because there is often no attention paid to baffle step compensation (BSC). This can be addressed in several ways. For example:
1. Not building a bass reflex, and investigating back loaded horns etc (which have their own special set of concerns)
2. Implementing an inline BSC circuit
3. Running each channel as a bipole (2 drivers per cabinet)
4. Corner loading the cabinet (helps to an extent, at the risk of sounding boomy if you are unlucky)
5. Implementing the system as a FAST (full range + seperate powered woofer cab)

2 and 5 are probably the easiest to try if you experience the issue I've described.
Hope that helps
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Old 10th March 2015, 05:31 PM   #6
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Zobskyy idealy choice would be. A pair of ZOB open baffles. Second being the Singularity cabs, but they are both much out of my price range. I have a local bass speaker cabinet builder (who specializes in bass reflex) who can build be a pair for $500.

I'm looking for a balanced sound with tight bass and don't need tons of lowend that shakes windows by any means.
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Old 10th March 2015, 08:37 PM   #7
IG81 is offline IG81  Canada
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Quote:
Originally Posted by zobsky View Post
The big issue I've observed with running full ranges in bass reflex boxes is bass roll off, and a resultant thin sound. Not because the bass isn't being produced, but rather because there is often no attention paid to baffle step compensation (BSC). This can be addressed in several ways. For example:
1. Not building a bass reflex, and investigating back loaded horns etc (which have their own special set of concerns)
2. Implementing an inline BSC circuit
3. Running each channel as a bipole (2 drivers per cabinet)
4. Corner loading the cabinet (helps to an extent, at the risk of sounding boomy if you are unlucky)
5. Implementing the system as a FAST (full range + seperate powered woofer cab)

2 and 5 are probably the easiest to try if you experience the issue I've described.
Hope that helps
All good points, allow me to comment on them.

1. Basically an acoustical solution for an acoustical problem, I like this. Often more complex and higher material cost. Sort of ruled-out by the OP here.
2. What I would recommend here. Line-level is preferable, but OTOH, a small-gauge inductor's DCR could compensate for what I assume is fairly low-impedance drive from the SX-450.
3. Interesting solution, at the cost of double driver cost and cabinet size and possible need to have the speakers a bit more out in the room.
4. As with the first item, I like that it's an acoustical solution. I'd suggest a different bass alignment if the OP were to do this though, or risk boominess as you say.
5. Possibly one of the best ways to take this system to a higher performance level, at the cost of more drivers and cabs and possibly amps.
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Old 10th March 2015, 08:46 PM   #8
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they would probably be good in either GregB's Karlsonator8 or a classic Karlson 12 - suspect the Karlsonator will measure flatter and perhaps the original will have more "hit" - I would have tried PS220 but Dayton's funky graph was confusing as to whether some sort of "built in BSC" existed or not.

here's mention of PS220 in the K12 designed in 1954

DAYTON 8" FR PS220 Discussion

here's a Karlsonator 8 build - the aperture could be extended higher up to the lower edge of the mass load vent
giving better looks and perhaps sound.

https://www.facebook.com/media/set/?...9872967&type=3

Last edited by freddi; 10th March 2015 at 08:53 PM.
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Old 10th March 2015, 09:01 PM   #9
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Quote:
Originally Posted by freddi View Post
they would probably be good in either GregB's Karlsonator8 or a classic Karlson 12 - suspect the Karlsonator will measure flatter and perhaps the original will have more "hit" - I would have tried PS220 but Dayton's funky graph was confusing as to whether some sort of "built in BSC" existed or not.

here's mention of PS220 in the K12 designed in 1954

DAYTON 8" FR PS220 Discussion

here's a Karlsonator 8 build - the aperture could be extended higher up to the lower edge of the mass load vent
giving better looks and perhaps sound.

https://www.facebook.com/media/set/?...9872967&type=3
Funny I was just researching into the Karlson design! Are there any plans around made for the Karlson/PS220-8 combo?
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Old 10th March 2015, 11:55 PM   #10
xrk971 is online now xrk971  United States
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I think you want a Karlsonator and not a Karlson proper. Possibly an XKi could work even with the PS220. I must have simulated a PS220 for a Karlsonator at some point. Let me dig it up.

Ok, found it:
Dayton's PS220 - does it have that ~450Hz dip or not?

Last edited by xrk971; 10th March 2015 at 11:57 PM.
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