No bass with Scanspeak 26w8534g00

[cucicu]

Hi at all.
I write cause i am desperate.
I built a 3 way speaker with 26w on bass, reflex system.
Box is 110lt brutto volume (big I know) cause simulation with measured TS parameters suggested 110lt/ 26hz Qb3 alignement and also bigger volumes with Sb4 align.
Right now NearField response is really flat as predicted but bass is few and there is no impact/punch at all.
Someone would comment please and help me?
Thanks a lot

 

[TBTL]

Could be room effects. Does the bass return if you put the speakers in the corners of the front wall and sit near the back wall?
Another cause could be insufficient baffle step compensation. How did you design the crossover?

 

[cucicu]

No bass also with speaker placed in the corner.

What is missed much is the punch and the attack of the bass.

It goes quite deep but not punch.

Tried many filters but the problem is the same.

What about the volume? Could it be too big?

 

[bullittstang]

Need more information on your Filter, can you show a schematic? Different filters does not mean any of them had ample BSC built in.
Do you have a way to measure them, since you said they are flat nearfiled? If so post the FR too.

 

[Dave R]

What size is the port (diameter and length)?

 

[beardman]

I am not so sure those discovery w26 woofer can give the punch you hope for

i have tried the discovery 30w not much punch, but it plays a good clean bas,,

Scanspeak Revelator woofer give more punch,,they sound faster,,

Best bjarne

 

[Bill Coltrane]

Hi at all.
I write cause i am desperate.
I built a 3 way speaker with 26w on bass, reflex system.
Box is 110lt brutto volume (big I know) cause simulation with measured TS parameters suggested 110lt/ 26hz Qb3 alignement and also bigger volumes with Sb4 align.
Right now NearField response is really flat as predicted but bass is few and there is no impact/punch at all.
Someone would comment please and help me?
Thanks a lot

Could be lots of things.

Do you have sound when disconnecting the mid and tweeter?

Did you correctly asamble the crossover? (my main suspect atm)

Does the speaker itself work correctly?

We need the crossover schematic.
Foto's of the crossover, so we can check the connections.

Any frequency curve you measured.

 

[DonVK]

You probably have a leak somewhere (box, driver seal, etc) and the cabinet is not functioning as a resonator to provide those low freq via the port.

Take some measurements, near field at the woofer and the port. Do they look like your sims or what a BR should look like ?

 

[cucicu]

Please see attachments: first image is merged nearfield response of woofer and port.
Port is 100mm IDx200mmL for 26 hz tuning
second image is simulation with measured FR (FR; PHASE and IMPEDANCE)
third is obviously the xover.

Woofer box is very good and has no Leaks; volume is 110Lt as said before.
XOver is correctly assmebled

Thanks for the help

 

[beardman]

maybe you can get some hint here

DISC-4

 

[DonVK]

Are the midrange and tweeter backs sealed or separate chamber?

 

[DonVK]

A quick run through hornresp confirms your volume / port / tuning at 26Hz. However it also shows a response peak that you don't have. Does you sim include the box BR effect and baffle ?

How wide is the baffle?

 

[cucicu]

Yes mid and tweeter are in a totally apart box. Sealed

 

[cucicu]

Yes. Those posted before are real nearfield measurement nd there is no paek but also at the simulation. Baffle is 35cm wide

 

[cucicu]

this is also WINISD sim

 

[DonVK]

Is it possible this is a relative problem. The bass will sound weak if the mid and tweet are relatively too high. What is the measurement at 1m?

This is a baffle sim that predicts the near and far loss from the baffle.

 

[cucicu]

Mid and tw are damped. Rta seems logical but the punch of bass is lacking.

Looking at the MOL curve there is low spl under 50hz with this alignment. Maybe is that the issue.

Could I rise the tuning to lets say 35hz? This way is not qb3 anyway.....

 

[DonVK]

Stuff a rag in the port to seal it and temporarily make it a sealed enclosure. I suspect your problem will still be there.

 

[cucicu]

I tried and bass is weaker.

What do you suppose could be the problem?

 

[DonVK]

This is the the axial response of the sealed box (assuming you can seal the port securely).

If you have no leaks the BR will rolloff 4th order (-24db/oct), and the sealed version will rolloff 2nd order (-12db/oct). The sealed response is shown below. You can measure it to confirm no leaks. The sealed should still perform well.