Deltalite 2510 in small box.

[Downunderwonder]

I've been shagging around all afternoon. I read someone put them in SWR JRIII and liked it so having acquired a couple I thought I'd give it a go. Result, not what I was expecting.

Tone generator and rice says 44hz tuning frequency.

I get crazy chuffing, sounds like something rattling inside, at moderate volume. It drove me nuts chasing down loose wire before I realised what it was.

WinISD gives port velocity 14.5 but doesn't give units. That is with 100w input, maxing out excursion at 36hz and 75hz.

I stuffed up the ports, all seemed well enough but by then I have exhausted my noise quota.

I think I may just build a sealed 2x10 after all, it's for lugging to practices.

 

[Arjank]

I've been shagging around all afternoon. I read someone put them in SWR JRIII and liked it so having acquired a couple I thought I'd give it a go. Result, not what I was expecting.

Tone generator and rice says 44hz tuning frequency.
Ugh, hit submit by accident. More coming...

How small is that box? I have owned a 2510 and know it doesn't like very small enclosures.

 

[Downunderwonder]

68,000 cm3 thereabouts.

 

[Downunderwonder]

2x10.

 

[Arjank]

68,000 cm3 thereabouts.

34liters per driver, thats appropriate for that driver, let me do some simulations.....

 

[Downunderwonder]

Might be a tad more, I measured the volume to the top of the shelf port, there's a divider about half depth between the drivers and the drivers themselves reducing that, but more volume behind the port unaccounted, to roughly balance.

 

[Downunderwonder]

The port is 20.5 wide by a bit over 1" but the carpeting restricts it 2 inches back into the port, to 1" high.

 

[Downunderwonder]

Damn, I got wrong, 66l new best guess of internal volume less port.

 

[Arjank]

The port is 20.5 wide by a bit over 1" but the carpeting restricts it 2 inches back into the port, to 1" high.

How long is that port?

 

[Arjank]

I used boxsim to calculate the tuning of that port.

Volume = 66liters
Port height = 1"
Port width = 20.5"

Port lenght = 6" tuning = 49hz
Port lenght = 4" tuning = 56hz
Port lenght = 8" tuning = 44hz

 

[Arjank]

Here the (half-space)simulation in AJhorn (just one driver, 33liters@50hz)

 

[Downunderwonder]

Awesome, thanks! That boxism programme is dead on what I measured, 8" shelf, 44hz. Is that P graph the max power to get to xmax? What does it say about port velocity?

 

[Arjank]

Awesome, thanks! That boxism programme is dead on what I measured, 8" shelf, 44hz.

Yeah, boxsim rulez

Is that P graph the max power to get to xmax? What does it say about port velocity?

Yes, thats the maxpower to get to the point where the driver exceeds xmax.
It doesn't say anything about port velocity, use WINISD for that.

 

[Downunderwonder]

Not much point if the power is limited to 80w.

I get numbers in the 14 m/s? range with 100w. I'm picking that's way too high as it sounds like it's the port doing the poppy tappity whistle noise. Weird or what?

 

[Arjank]

Not much point if the power is limited to 80w.

I get numbers in the 14 m/s? range with 100w. I'm picking that's way too high as it sounds like it's the port doing the poppy tappity whistle noise. Weird or what?

The slot port is probably the cause of the problem. The height of that port is only 1". A (flared)tube would be better in this particular case
For my cab with the Oberton 10B200 (which has a higher xmax then the 2510) I use flared tubes, even with a 3" tube I don't get any whistle noise.

IMO tubes are better then slot ports, I only use slot ports with my horn-reflex cabs and there it works because the port mouth is approx 1.5 times the cone area.

 

[gavinspoon]

I've been shagging around all afternoon

And then you started building speaker cabs?

I'm guessing shagging means something different in the states. In the UK that statement would mean that you'd spent the afternoon enjoying -- to the fullest extent -- the company of several lady friends

 

[Downunderwonder]

I tried bringing down the volume to 45L in winISD, brings the power handling up to 180w but I would need a hpf to keep out of trouble, tuning rises to 56hz.

Sealed looks like 25L takes the full 200w of my amp, can't be right?

 

[Arjank]

I tried bringing down the volume to 45L in winISD, brings the power handling up to 180w but I would need a hpf to keep out of trouble, tuning rises to 56hz.

Sealed looks like 25L takes the full 200w of my amp, can't be right?

AJhorn gives me something less optimistic....
Sealed (1driver)25liters approx 35watts below 60hz (Fb = 88hz)
Sealed (1driver)12.5liters approx 80watts at 80hz (Fb = 115hz)

Ported (1driver) 22.5liters approx 70watts at 90hz and below 50hz the powerrating drops rapidly.

 

[will33]

I'm thinking the port being so short (1") is contricting airflow at the higher power levels, that won't show up with a 1 watt test. It's a little like blowing through a whistle.

You could be fine with the same port area in a more symetrical shape to better allow airflow.

Any room to cut it taller and block off some sides to adjust it?

Or close it off and use a pair of 3" or 4" round pipes instead?

A rule of thumb is anything under 20 m/s shouldn't get noisy, but yours is so short, the air is getting caught up along the walls and may only have 1/2" of "free flow" down the middle.

 

[Downunderwonder]

I'm thinking the port being so short (1") is contricting airflow at the higher power levels, that won't show up with a 1 watt test. It's a little like blowing through a whistle.

You could be fine with the same port area in a more symetrical shape to better allow airflow.

Any room to cut it taller and block off some sides to adjust it?

Or close it off and use a pair of 3" or 4" round pipes instead?

A rule of thumb is anything under 20 m/s shouldn't get noisy, but yours is so short, the air is getting caught up along the walls and may only have 1/2" of "free flow" down the middle.

Handy rule of thumb. It's a tidy cab with its original drivers in it so I'm better not modding it and doing a couple of 1x10's.