Dual Showman Cab Tittification?

[wallyp]

Hello All

Purchased this beast from a shop that was closing down for the princley sum of £15. Nearly put my back out loading it into a pickup.

I bought the top speaker, an Eminence DELTALITE II 2515 NEO 8ohm 15" 300watt as the original was ripped.

I have a Dual Showman Reverb and a Fender J Bass I'd like to use with it. Mostly neck pickup with tone off.

 

My question, as a complete newbie to cabinet design, is can I get this to a useable state? And what should I be priortising? Its looks like somebody has closed a couple of the front open 'ports'. Should I be closing the rest off? Closed back? Acoustic matting? Create new ports? Seperate the two speakers with baffles? 

 

BTW low G to Open E farts like a good un. 

 

 

 

 

 

[Downunderwonder]

Option 1, sack the renaining OG driver and get another Deltalite. Port the cab to suit.

 

Option 2, put the OG driver up top in it's own enclosure. @Bill Fitzmaurice might design you a passive crossover to take weight off it and porting to suit

 

Option 2 would be putting basically a 8 ohm load to the amp.

[ajkula66]

Running the cab "as is" will most likely blow the JBL first so I would advise against that course of action.

 

These cabs were not the greatest design IMO since they're rather shallow so there is room for improvement...depending on how much time you want to spend rebuilding it to suit your needs...

 

Personally, I'd trash the cab and move the D140 - presuming that it's in good working order - into a smaller cabinet and enjoy the ride. The Showman will likely blow it with power above 6-7, so be mindful of that.

 

Good luck.

[Bill Fitzmaurice]

Add another Eminence, then it needs proper porting and damping. With the exact interior dimensions I can provide the porting information. There may be another issue as well. For a number of years their inputs were marked red negative, black positive, which is the opposite of how the Eminence are marked. If that's the case it would explain the farting. 

[Downunderwonder]

Option 1 it is then.

[ossyrocks]

That's a JBL E140, rated at 400w, will he really blow it with a Dual Showman?

 

I like the sound of the old D140F in my Bassman cab, but I will never run it very loud, and it is VERY heavy.

 

If the intention is to gig this behemoth, then Bill's advice to put another Deltalite in and port the cab accordingly is the best in my opinion. At least it will make the cab "slightly" more portable.

 

I would also get some new grill cloth, it's fairly cheap, and it's easy to install and it would smarten things up considerably.

 

I like your cab.

 

Rob

[Downunderwonder]

26 minutes ago, ossyrocks said:

new grill cloth.... would smarten things up considerably.

Meh, chicks dig mojo.

[wallyp]

Thanks Guys, loads of pointers there. In fact I like Option 1 AND Option 2. Not sure if we can have too many Cabs knocking about?

 

I'm handy with wood so will get some exact measurements of the present Fender Cab, which I do have the urge to tidy up, cosmetically and functionally.

 

i'll get another Deltalite Ordered and pop it in. I did try the 9 volt trick on the phase of the present cabs and matched them up. So I dont think the farting is that. Possibly pushing the mismatched speakers? Delta was 5.6 Ohm and the Fender/JBL 7.9 Ohm which I found odd.

 

"Eminence Deltalite II 2515 - 15" 300W 8 Ohm. Recommended Enclosure Volume: Sealed 42.5-48 liters, Vented 51-119 liters."

Rough dims for Fender CAB:

"The volume of an object measuring 45.5 inches by 30 inches by 11.5 inches is approximately 256.77 litres."

Such a thing as too much volume? Sould I seal up or go vented on the Fender Cab and what are the pro's and cons?

 

From googling the Dual Showman, its pushing 100watts ish so 'shouldnt' blow anything? But it does all feel a bit wonky and it doesnt inspire confidence to push the volume.

 

The speaker is for practice and recording so wont be humping the beast anywhere in a hurry. I've been playing with the crosssover in a Quad Cortex which is giving interesting results. Splitting the frequencies, high and low pass, to various amps. The flapping of my flares is an added bonus.

[Bill Fitzmaurice]

The E140 was rated at 200w. The problem with pairing it with the 2515 is that their T/S specs are wildly different. As for sealed versus ported, with sealed you give up about an octave of low frequency extension and take a huge hit on excursion as well. Besides that neither the JBL nor 2515 have specs that work well sealed. The net volume of the cab is probably closer to 200L, so by no means is it too large for two fifteens. 

[wallyp]

7 hours ago, Bill Fitzmaurice said:

The E140 was rated at 200w. The problem with pairing it with the 2515 is that their T/S specs are wildly different. As for sealed versus ported, with sealed you give up about an octave of low frequency extension and take a huge hit on excursion as well. Besides that neither the JBL nor 2515 have specs that work well sealed. The net volume of the cab is probably closer to 200L, so by no means is it too large for two fifteens. 

2nd Deltalite Ordered. Will measure up exact dims when I've fitted and would appreciate your help in porting dimensions. Whats your opinion on internal matting? Worthwhile?

[Bill Fitzmaurice]

Indispensable. 

[Downunderwonder]

The volume is the basic XYZ internal dimensions less the volume taken up by ports and the speakers' back space.

[Steve Browning]

It was an Ampeg (V4 I think) cab, very similar to this, that cemented my 2x15 love. I bet it'll sound wonderful.

[wallyp]

2 hours ago, Steve Browning said:

It was an Ampeg (V4 I think) cab, very similar to this, that cemented my 2x15 love. I bet it'll sound wonderful.

Thats encourging news. Any pics or a rundown of any setup you did?

[iainbass]

I had an original DS with two K140's and it was useless. I think they were originally guitar cabs.

[wallyp]

2 hours ago, iainbass said:

I had an original DS with two K140's and it was useless. I think they were originally guitar cabs.

Well, theres two sides of the same coin! 🤣

[wallyp]

16 hours ago, Bill Fitzmaurice said:

Indispensable. 

I spotted this:

https://www.thefoamshop.co.uk/Polyester-fiber-Dacron/POLYESTER-FIBRE-DACRON

Looks similar to this Barefaced Cab: Do the job do you think?

[Bill Fitzmaurice]

That's one option, but you don't need 50 meters. You should be able able to find the same polyester batting in a useful size at fabric shops, it's used for pillows and furniture upholstery.