overnight sensation - very bassy

Markgm

Member
2010-01-17 11:49 pm
VT, USA
Hi,
I have just put together my first kit speakers - the Overnight Sensations, as sold by Parts Express. I haven't yet screwed the drivers or port tubes in, but held in place with gorilla tape. I've made a couple of observations of the sound.

When I first built the crossovers, I put the drivers in the baffles and hooked up. I liked the tweet, mids and bass balance not too bad, but certainly lacking in low frequency extension.

Then I put the cabinets together. There came to be a lot of bass. I am missing the mids, particularly, and even treble, and this is more bass than I would like to have.
(Will screwing drivers and port tubes down noticeably affect this?)

Can I add stuffing, or seal the ports, or what can I do to tame this?

TIA-
Mark
 

Markgm

Member
2010-01-17 11:49 pm
VT, USA
Holy cow, bat farmer! I guess I wasn't treating these as I would speakers with full-range production. I started out with them sitting on the table. Now I have them on 15" stands on the table. This is much better. It seems they need it, as if they were bigger speakers.

Thank you, 5th Element, that is much better. I am still curious as to what effect stuffing has - my next experiment.
 

mayhem13

Member
2008-09-22 4:37 am
Stuffing will increase the volume 'seen' by the enclosure and for the most part produce more low freq content. The nice thing about DIY is the learning part. Add some stuffing and evaluate the sound just be sure there's none between the midwoofer and the port inlet.
 
I think it's likely your sensitivity to bass.

Most people don't consider a small cab 4" driver to be "bass heavy".

Also not a comment typically heard about the OS.

Neverless, if you think they're bass heavy, then they are.

Less stuffing = more bass not less. Also stuffing should be no more than fluffed handful of polyfill.
 
According to the website these are a full baffle-step compensation design. This means that for the best bass balance you should have them up on stands and free from any nearby walls, say at least 50cm away.

Baffle step compensation is used to correct for a gradual transition whereby you lose forward radiating sound pressure in the lower frequencies. This is a function of the cabinets smallest forward facing dimension, usually the width. As the width increases, when the transition occurs, decreases in frequency. Placing the speakers on a table effectively increases the cabinet width to that of the tables smallest dimension and as a result it pushes the BS frequency right down. Moving the speakers away from the table will reduce this effect, but any close proximity to walls or similar surfaces will have some effect on enhancing the lower frequencies.

I wouldn't expect stuffing to have too much of an impact on this, but if the port is augmenting the BS losses towards the end of the transition, then placing a little stuffing in the port might be a good idea.
 
Most people don't consider a small cab 4" driver to be "bass heavy".
:)

There came to be a lot of bass. I am missing the mids, particularly, and even treble, and this is more bass than I would like to have.

You may want to check the crossover wiring. If the tweeter components are wrongly terminated, it could lead to loss of mids and highs.
 
+1 to 5TH's suggestions of placement and trying a stuffed port.
I have built several of these and they have a tad of a laid back top end. I you are used to a brighter sound you could adjust the tweeter L-pad. Try reducing R1 to ~4ohms.
IIRC, I ended up with a small handfull lightly stuffed behind the woofer.

David
 
Fastbike1 said:
Most people don't consider a small cab 4" driver to be "bass heavy".

I didn't guess that would be possible, either, as I've said above. I have been accustomed to a pretty flat response from speakers costing 20 times as much, and which were noticeably larger. Sure, they reacted to walls and placement, but I just didn't guess this would happen here!

5th Element said:
According to the website these are a full baffle-step compensation design. This means that for the best bass balance you should have them up on stands and free from any nearby walls, say at least 50cm away.

Baffle step compensation is used to correct for a gradual transition whereby you lose forward radiating sound pressure in the lower frequencies. This is a function of the cabinets smallest forward facing dimension, usually the width. As the width increases, when the transition occurs, decreases in frequency. Placing the speakers on a table effectively increases the cabinet width to that of the tables smallest dimension and as a result it pushes the BS frequency right down. Moving the speakers away from the table will reduce this effect, but any close proximity to walls or similar surfaces will have some effect on enhancing the lower frequencies.

I am gaining huge respect for this by working with this speaker. They seem to respond to placement very much. Thank you for the additional understanding.

Making the port a bit longer might help. Just use a rolled up piece of stiff paper formed into a tube and slip it into the port to extend it. You can also put a sock in the port to plug it to see what that does.

Ron, I love your quotes. I am also having great success with your suggestions. I think socks in the tubes works, but may make the sound a little more sterile, overall, but paper tubes in the ports is giving me a sense of a more flattened out sound.

Between room placement and goofing with the tube lengths, I am honing in on the tonal balance I like best.

Thanks to everybody for your help. Again, I had no idea I would have this much bass from such a little speaker. I thought "-3 dB at 45 Hz" would mean lacking. HA HA HA HA HA
 

Jay

Banned
2003-02-11 9:02 am
Jakarta
Between room placement and goofing with the tube lengths, I am honing in on the tonal balance I like best.

Again, I had no idea I would have this much bass from such a little speaker. I thought "-3 dB at 45 Hz" would mean lacking. HA HA HA HA HA

You know what, you should really do your homework before building/buying anything. If you read the designer's comment about the bass, stand, etc., you won't be puzzled like that :D

With longer tube, the SPL will be slightly attenuated but the roll-off frequency will be lower. In small 2-way I prefer this "non-flat" setup than the simulator "flat" calculation result (I use longer tubes than calculated).

The crossover looks very bad. The woofer cut off looks to be 1.5 kHz and the tweeter 6 kHz. This is from just a glace. It gives me a head ache.

What, it is 4KHz. Research further if you want to give bad credit :D
 

strawberry

Member
2011-12-28 1:07 am
I've been looking at this a little bit. You will get better sound if you remove the 10 ohm from the tweeter and change place between the 6.8 uF and the 2.2 uF. You will get further better sound if you get another 2.2 uF for each woofer and make a 10 ohm + 2.2 uF link which you place in parallel with the 2.2 uF. Enjoy.
 

Jay

Banned
2003-02-11 9:02 am
Jakarta
I've been looking at this a little bit. You will get better sound if you remove the 10 ohm from the tweeter and change place between the 6.8 uF and the 2.2 uF.

No, strawberry, please believe me that speaker design is not as easy as it seems to the eyes of a beginner ;)

At "low level design" which is based mostly in trial and error, it probably works to design speaker "by feeling" or calculate "in head". But at higher level, which I believe Paul Carmody is at, it is not like that. You have to measure before you can make such comments.

Okay, yes, in general, a series resistor is better sounding than an L-Pad. But removing the shunt R may affect things which severity we don't know without measuring or simulating.

6.8uF can be placed in place of the 2.2uF, without affecting the design severly, but 2.2uF cannot be placed in place of 6.8uF.

But if you mean 2.2uF and 1.5uF then may be I understand where this came from. I myself have always tried to put the smaller caps closer to the tweeter (with 3rd order filter).
 

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You know what, you should really do your homework before building/buying anything. If you read the designer's comment about the bass, stand, etc., you won't be puzzled like that :D

I can't argue with that - I was just not giving enough credit to two things. One was the amount of bass this little speaker turned out to be good for, and the other was how much of an effect placement (and tube lengths) turned out to have.

Jay said:
No, strawberry, please believe me that speaker design is not as easy as it seems to the eyes of a beginner ;)

At "low level design" which is based mostly in trial and error, it probably works to design speaker "by feeling" or calculate "in head". But at higher level, which I believe Paul Carmody is at, it is not like that. You have to measure before you can make such comments.

Okay, yes, in general, a series resistor is better sounding than an L-Pad. But removing the shunt R may affect things which severity we don't know without measuring or simulating.

6.8uF can be placed in place of the 2.2uF, without affecting the design severly, but 2.2uF cannot be placed in place of 6.8uF.

But if you mean 2.2uF and 1.5uF then may be I understand where this came from. I myself have always tried to put the smaller caps closer to the tweeter (with 3rd order filter).

I think you both know more than me. I have been sanding, primering and painting since my last post here, so no listening tests going on, but I will be curious to learn more about the x/o as time goes on. I am curious about the comment Paul Carmody made about relaxing the mids a bit so as to not be fatiguing? Well, maybe I would feel the same way, but I might, for example, want to try the more fatiguing midrange at some point as well.

Cheers,
Mark
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