Open baffle with Pyle PPA12

Eldam

Banned
2012-09-13 12:25 am
France
Hello Andrea,

90 dB efficienty is maybe a little low for an OB used in the bass ? But if true the Fs is impressive: 27 Hz and the price is staying nice !

Despite the stiffness of the suround/spider, the motor seems weak (but 800W peaks allowed). The PA 18 should be better with 94 dB and more Sd, just two cents, don't know where you want to go exactly.

Imagining the Xmax is not more than 8 mm for instance, it's maybe short for EQ or very wild bafle could be needed... (or low spl programms)

I don't know if that helps: Had you already a look at the OBL15 project here : OBL-15 ? some nice subwoof reference as well (with measurements)

see you,
 
Last edited:
Hello Andrea,

90 dB efficienty is maybe a little low for an OB used in the bass ? But if true the Fs is impressive: 27 Hz and the price is staying nice !

Despite the stiffness of the suround/spider, the motor seems weak (but 800W peaks allowed). The PA 18 should be better with 94 dB and more Sd, just two cents, don't know where you want to go exactly.

Imagining the Xmax is not more than 8 mm for instance, it's maybe short for EQ or very wild bafle could be needed... (or low spl programms)

I don't know if that helps: Had you already a look at the OBL15 project here : OBL-15 ? some nice subwoof reference as well (with measurements)

see you,

Hi Eldam,

I'm planning to use 4 speakers per channel in series to reach 32 ohm, crossed around 230-250 Hz, because the OB will be powered by an OTL amplifier. So the total sensitivity will be around 96 dB. This is a budget speaker for a friend, so the Pyle seems the right compromise. But I cannot find any plot for this driver.

Instead of the OBL 15, I have to build something similar to the OBL 11 for a friend. It will be a little different about the speaker: I will use an L Cao FA8 in place of the JA8008 and an Aurum Cantus G2Si in place of the Audax tweeter.
 

Eldam

Banned
2012-09-13 12:25 am
France
I just have been finding that : Base de données : Catalogue haut-parleurs

15" & 18" : look at the Xmax ! Very low ! The 18" sems a better choice and just few money more ! 250 Hz is possible as well... 24 ohms is enough if 3 in serie? (total 84 dB sensivity into 24 ohms!* if you choose the 93/2.83v - 18") hope your OTL to be a monster :D in power!

if you make a U shape bass bafle with one driver per side, bafle length will stay short and you should have the floor level help (but a little loss due to the U-shape, but also a better waf !). If having already 8 x PPA15, maybe better to try serie-parralel conf (16 ohms/87 dB/2.83V too low for the OTL?) or directly jump to cheap class D : Below 200 Hz, ears is less hard with electronics behavior ! And stay with the OTL for the range above ?!



*: in serie efficienty decreases from 3 dB per driver added ?!
 
Last edited:
I just have been finding that : Base de données : Catalogue haut-parleurs

15" & 18" : look at the Xmax ! Very low ! The 18" sems a better choice and just few money more ! 250 Hz is possible as well... 24 ohms is enough if 3 in serie? (total 84 dB sensivity into 24 ohms!* if you choose the 93/2.83v - 18") hope your OTL to be a monster :D in power!

if you makes a U shape bass bafle with one driver per side, bafle length will stay short and you should have the floor level help (but a little loss due to the U-shape, but also a better waf !)



*: in serie efficienty decreases from 3 dB per driver added ?!

The sensitivity decreases in series if you keep constant 2.83V rms, but applying the same 1W on a 32 ohm load ( or 5.66 V rms) the sensitivity increases by 3 dB doubling the number of the speaker. OTL likes voltage rather than current, the higher the load the better the performance.
 
I have just seen, the Pyle is a cheap driver, but limited in excursion. I think I have to turn to a more expensive driver, at least the Peerless SLS 12 830669.

This is the simulated frequency response of the entire system using the Peerless.
 

Attachments

  • OB_SPL.jpg
    OB_SPL.jpg
    67.8 KB · Views: 124
How about using 16-ohm woofers, like:

- Eminence Delta-15B 15" Driver 16 Ohm (but the Fs is 45Hz)

- Hammond 15″ Woofer (16 ohm) (no idea of specs)

Four of them would make for a nice 64-ohm load, and the Eminence have decent X-max specs.

The Delta 15 B has limited excursion, datasheet says 1.6 mm.
About the Hammond, without any specs, is difficult to evaluate.
 
The Delta 15 B has limited excursion, datasheet says 1.6 mm.

True, but look at the X-mech. Eminence rated X-max at a certain distortion level. And to add to that, with four woofers in series, I doubt you will exceed 1.6mm, unless you go for serious party levels.

About the Hammond, without any specs, is difficult to evaluate.

True, but it is a woofer meant for organs, so it is used in a semi open baffle application. And these woofers are made to work with valve amps (or rather I think those old organs used valve amps). I would suggest e-mailing them and asking for specs.

That said, getting back to my point on X-max, if you are going to use four 15" woofers, I doubt that you will have trouble with X-max unless you want party levels, and then the fullrange driver might not keep up. The advantage of the Eminence is higher efficiency, at the cost of higher Fs. The Hammond is an unknown, but due to it's intended application, it might be worth investigating.
 

Eldam

Banned
2012-09-13 12:25 am
France
Hi Andrea,

The SLS are good too. A bit off topic, but you should find this interresting because it's stay cheap and easy to do. Well it's a // with two SLS but Nothing stop you to try in serie in the spirit of the OTL use (16 ohms enougn for the OTL ?) : Jazzman's DIY Electrostatic Loudspeaker Page: Ripole Subwoofers: Mostly, the design helps to enlarge the choice of the drivers to explore the lower end.

Jazmann is a member here from the ESL section...