Blog: Old gig Returns; A Reunion of Gear & request for help w/ Speaker/Cabinet design

[78pbass]

Wow, that's a mouthful! Read on for explanation

Old Gig Returns

So, I send an email to my old band leader Jason early last year. I was reminiscing about hell-shows and thought he'd enjoy the mention. After more than a year of non-response, his reply was:

Sorry it took me so long to respond.

 

Call me ASAP

(***) ***-****

 

Thanks

So we talk and basically, he's ending a self-imposed 2 year hiatus. We haven't played together save for one show, in more than 5 years. As you all know, I hung it up last year because I just havent had the want to do it any more. Jason and I alwasy had such a good time, and the music's great as well as his voice is so good, it was a no-brainer. Kinda one of those 'if he ever asks, I'll jump on it' kinda things.

 

A Reunion of Gear

Since I hung it up officially, I sold off my gear. Well my favorite combo was my ATK (which never left) into my GK 400RBIII (which never was reliable) into my trusty Nemesis 112p with the Eminence KappaPro 400w.

 

I started Craigslisting only to find a Nemesis 112p for sale last month. I contact the guy. Its rare to find one in this town, or anywhere for that matter. It was a killer tiny cab. We speak and he mentions the upgraded speaker.

"Did you get this cabinet from Steve B*** of *** Band?"

He replies "why yes, how do you know"

"I traded him for a Dr Bass 210 two years ago; I owned that cabinet for 10+ years""consider it sold"

 

I picked it up and apart from him relocating the handlestrap, its my old cab. That makes me happy!!!

 

I then went out and got a GK BL600 to replace my less-than-trusty 400rb. For what I paid, I like it alot. I just didnt want to spend much until I'm sure I still want to do this again.

 

 

...which brings me to...

A request for help on Speakers

Originally I had replaced the 12" with an Eminence KappaPro 400w. It was immense! Talk about perfection in a single cab!!! Then after about 600 shows or so, the speaker just got old and the surround created a mechanical failure (i believe). I contacted Eminence and it was still under warranty so they sent me a new one.

 

Only, it was the 500w version and from then on, never sound good. It was really breathy but couldnt keep up with the lows of a bass rig. It was farty and without the low-mids of before. I called Eminence back and they assured me it was the same design with better materials. Not to my ears.

 

So, my request is, can someone with a designer tell me what I can expect if I swap the KappaPro with the Delta 12A?

 

here are the details to consider:

2.7 cu ft box (outside dimensions: 24"x16"x16", .75" ply)

4"dia x 6" port and 2" of stuffing

 

Kappa Pro 500w:

Nominal Basket Diameter ----------------------- 12", 304.8mm

Impedance ----------------------- 8 W

Power Rating ----------------------- 500Wrms

Resonance ----------------------- 37Hz

Usable Frequency Range ----------------------- 57Hz - 2.8kHz

Sensitivity ----------------------- 97.1

Magnet Weight ----------------------- 80oz.

Gap Height ----------------------- 0.375", 9.52mm

Voice Coil Diameter ----------------------- 3.0", 76.2mm

 

Thiele-Small Parameters

Resonant Frequency (fs) ----------------------- 37Hz

DC Resistance (Re) ----------------------- 5.46

Coil Inductance (Le) ----------------------- 1.22mH

Electromagnetic Q (Qes) ----------------------- 0.25

Mechanical Q (Qms) ----------------------- 6.93

Total Q (Qts) ----------------------- 0.24

Compliance Equivalent Volume (Vas) ----------------------- 121 liters/4.27 cu. ft.

Peak Diaphragm Displacement Volume (Vd) ----------------------- 249cc

Mechanical Compliance of Suspension (Cms) ----------------------- 0.32mm/N

BL Product (BL) ----------------------- 17.3 T-M

Diaphragm Mass inc. Airload (Mms) ----------------------- 59 grams

Efficiency Bandwidth Product (EBP) ----------------------- 148

Voice Coil Overhang (Xmax) ----------------------- 4.8mm

Surface Area of Cone (Sd) ----------------------- 519.5cm2

Maximum Mechanical Limit (Xlim) ----------------------- 14.8mm

http://www.partsexpress.com/pdf/290-424s.pdf

 

Delta 12A

Nominal Basket Diameter ----------------------- 12

[james on bass]

I can't help you with your tech question, but I'm glad to see you excited about music again. You seemed so down and bummed out when you started the fire sale.

[78pbass]

I can't help you with your tech question, but I'm glad to see you excited about music again. You seemed so down and bummed out when you started the fire sale.

 

Thanks! I should say that I'm entering this with trepidation and caution. We'll see, but who knows; this music thing could be catching...

[78pbass]

Bump for Burdi, Isaac, and/or any other cabinet/ WinISD geniuses

[isaac42]

Using your parameters, here's what I got:

Yellow is the Delta 12A, green is the Kappa Pro.

 

In both cases, I'd say that the tuning is lower than it needs to be, and the port is too small. You might hear "chuffing" at high volumes. Still, too low is usually better than too high, in my opinion.

[fretless]

 

big +1

[lug]

If you want to borrow any gear, let me know. I got a Avatar compact 15" whose box is too small for the speaker but will do in a pinch. It handles 500 watts. I got's lots and lots of bigger stuff if you are a weight lifter.

[78pbass]

Using your parameters, here's what I got: Yellow is the Delta 12A, green is the Kappa Pro. In both cases, I'd say that the tuning is lower than it needs to be, and the port is too small. You might hear "chuffing" at high volumes. Still, too low is usually better than too high, in my opinion.

 

So, does it seem worthwhile? I know its in the eye of the beholder, but the 500w just doesnt sound very good whereas the 400w sounded great. I tried finding its specs, but came up with nothing.

 

I may try it anyhow, worst comes to worst I can either return the Delta speaker or sell the Kappa. and still be right side up.

 

What are your thoughts?

[isaac42]

Seems to me that either one should sound fine, and neither is particularly preferable. If the 500W sounds terrible, then there are a few possibilities.

 

The problem isn't in the cabinet or the cabinet/driver match, but in the midrange response.

 

The driver is not properly installed.

 

If neither of those is the case, then you probably won't like the Delta 12A, either, because the response isn't all that different on the low end in that cabinet.

 

For the midrange response, here are the spec sheets. Look at the response curves:

 

Delta 12A: http://www.eminence.com/pdf/delta-12a.pdf

 

Kappa Pro-12A: http://www.eminence.com/pdf/kappapro-12a.pdf

 

Looks to me as though they'll sound rather different because of the large response peak of the Delta-12A above 1.5KHz. Since we don't have any information on the Kappa Pro-12 as opposed to the Kappa Pro-12A, I have no idea which would sound closer to it.

[78pbass]

 

If neither of those is the case, then you probably won't like the Delta 12A, either, because the response isn't all that different on the low end in that cabinet.

 

true, but per my first reponse, I may be looking for something inherently not there in the first place. Interestingly enough in the spec sheets I found this distinction within the descriptions:

 

Kappa: Recommended for professional audio in a vented mid-bass, and vented bass enclosure incorporating a high-pass filter.

Delta: Recommended for professional audio as a mid-bass or woofer (with high-pass filter) in vented enclosures.

 

Perhaps I'm running more full range than the Kappa can deliver?

[78pbass]

oh, and thank you very much; I really appreciate it.

[isaac42]

 

So you think that it possible because the midrange response is so different, I may be driving the speaker too hard to make up for lost volume in a different area? I've tried different EQ with less than great remarkable results.

 

 

Hard for me to say. Both drivers seem to be pretty flat across the band at about 97dB. then the Kappa has a relatively small, narrow peak at about 1.8KHz, and its response falls off above that. Call it a 2KHz top end.

 

On the other hand, the Delta has a comparatively large and wide peak in its response from about 2K to 5K. That's going to be very audible if you're running it full range. It's going to sound louder and brighter.

 

 

Please elaborate on this.

 

 

If there's a leak around the driver frame, it could be radically changing the tuning of the speaker.

 

 

true, but per my first reponse, I may be looking for something inherently not there in the first place. Interestingly enough in the spec sheets I found this distinction within the descriptions: Kappa: Recommended for professional audio in a vented mid-bass, and vented bass enclosure incorporating a high-pass filter. Delta: Recommended for professional audio as a mid-bass or woofer (with high-pass filter) in vented enclosures. Perhaps I'm running more full range than the Kappa can deliver?

 

 

Quite possible. The Kappa tops out around 2KHz, like a JBL D140. It's hard to get a bright sound out of it, if that's what you're looking for. It's intended as the bass section of a full range system, not as a full range driver itself. It should be crossed over to a midrange driver no higher than 800Hz, even 500Hz. That doesn't mean that it can't be used by itself, full range, if you like the sound it gives you, but it's going to be lacking over an octave of response, from 2KHz to 4KHz and higher, that other drivers have. Like the Delta.