Bass Reflex full range?

Status
Not open for further replies.
Jump to Latest
JoeyAnchors

JoeyAnchors

Member
Joined 2015
#1
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:
#3
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?
 
#5
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
 
#6
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.
 
#7
zobsky said:
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
Click to expand...

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.
 
#8
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

http://www.diyaudio.com/forums/full-range/191302-dayton-8-fr-ps220-discussion-10.html

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/?set=a.645456515500837.1073741837.601735219872967&type=3
 
Last edited:
#9
freddi said:
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

http://www.diyaudio.com/forums/full-range/191302-dayton-8-fr-ps220-discussion-10.html

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/?set=a.645456515500837.1073741837.601735219872967&type=3
Click to expand...

Funny I was just researching into the Karlson design! Are there any plans around made for the Karlson/PS220-8 combo?
 
#11
xrk971 said:
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:
http://www.diyaudio.com/forums/full-range/256024-daytons-ps220-does-have-450hz-dip-not.html#post3921763
Click to expand...

Thanks xrk971! Those graphs do look interesting. I sent the Karlsonator8 plans to a few builders to get quotes.

It will be interesting to see how these sound with the PS220-8.
 
#15
go the link in this post - then look under "more" and save the large plan

http://www.diyaudio.com/forums/full-range/239386-karlsonator.html#post3565185

I did a crude guess of the Decware "Gizmo" which I think is used with a fixed resistor in the mod PS220. I used a 1K pot on the 120v winding of a 6.3vct filament transformer. Decware probably still sells the Gizmo transformers which are supposed to be air gapped.

just twiddle the pot - made a solid state amp sound kinda like a loose tube with my Heresy I - don't use the cap
- I just had that to see the reflected Z effects
An externally hosted image should be here but it was not working when we last tested it.
 
Last edited:
#17
seems like the full size (12" driver) Karlsonator might be too large - you probably want the Karlsonator 8 plan from that link - I think that's the dimensions X used in his PS220 simulation. I'd like to hear the 8 too.
 
Last edited:
#18
Freddi thanks. That is the plans I will be going with (K8).

Oh one thing I've been wondering that isn't talked about much with these cab designs..

How much damping/stuffing should I have done when I do have these built?
 
Last edited:
#20
If you will be building something as small as a K8, it might be worth your while to attempt a foam core prototype first before you commit $$ to the final build . You'll definitely learn a bit in the process and the cost and effort should be very minimal. xrk971 is the expert on foam core builds.
 
Status
Not open for further replies.
Top Bottom