Speaker question for experts

Ricky Davis · Post by **Ricky Davis** » 28 May 2000 10:12 pm

Ok I've tried alot of different speakers now in my twin; just basically to satisfy a couriousity of mine. I've come up with the perfect match for a "15 and it's a D-130F from the '60s.
My question is; while going through this I've notices some of the speakers had quite a jump to them. What I mean is when I have the volume pedal on I can hit down on the strings with my right hand and some of the speakers had quite a bit of pop or jump to them>are ya getting my drift?
Some seem so much more responsive to that than others and almost too much sensitivity in that area; So what causes it? I know each speaker is diff. but some speakers were dang near identical and one was much more jumpy than the other.
What are causes and fixes and/or solutions or whatever else someone can knowledge me about this.
Thanks ya'll.
Ricky

Donny Hinson · Post by **Donny Hinson** » 29 May 2000 12:08 am

Well Ricky, I'm no expert, but those qualities that you don't seem to like are exactly what I look for in a speaker!

Those "cone jumps" show that the speaker is both efficient and low-end capable. When you tap the strings above the pickup, and get that "whump" sound, what you're doing is setting up a very high amplitude, low-frequency wave. Big speakers (that have big cones that can move a lot), and big magnet structures (that add to the efficiency, or sensitivity of a speaker) will accentuate this characteristic.

If you want to avoid this characteristic, stay away from efficient speakers, and large, modern, bass-type speakers. The old D130-F JBL speaker is not much more efficient than the average stamped-steel factory speaker (it doesn't have a huge magnet structure), and has a bottom end that rolls off rather smoothly. Couple this with the fact that JBL put a pretty stiff cone in these speakers (which doesn't move a lot, compared to modern speakers) and you see why the JBL has the sound that you like.

All other things being equal, a massive magnet structure means the speaker is going to be more efficient in the low and mid-range frequencies. My 15" EV-SRO speaker weighs over 30 pounds! [This message was edited by Donny Hinson on 29 May 2000 at 01:09 AM.]

Ricky Davis · Post by **Ricky Davis** » 29 May 2000 5:50 am

Hey Donny thanks for the reply and it does make since. I have a D-130F in there now and no way I'll take this one out>it sounds better than anything I've put in there. I will say this though; this speaker has a "whump" to it though. It is not as much as some I've tried; but it is more than some others.
Thanks.
Ricky

b0b · Post by **b0b** » 29 May 2000 8:06 am

I'm moving this to Electronics, where the "experts" hang out.

Brandin · Post by **Brandin** » 29 May 2000 9:28 am

Ricky, be careful "whumpin'" on that JBL. You can knock the voice coil out, and the speaker will have to be reconed. These old JBL's don't grow on trees. =:^)

I have a JBL D-130F in my silver face Vibro-
sonic that sounds great (lots of high mids.).
I have another JBL D-130 that has been reconed with the E-130 kit, and does not sound as good.[This message was edited by Brandin on 29 May 2000 at 10:32 AM.]

Jerry Gleason · Post by **Jerry Gleason** » 29 May 2000 10:54 am

It's interesting that you mention the "whump" with certain speakers. When I first got my Stereo Steel rig, I was using JBL K-130 speakers, which have the same alnico magnet as the D series. With these speakers, I noticed that as I used the heel of my hand on the strings for palm blocking, the cones moved back and forth (a lot!) in response. You couldn't hear it, but you sure could see it, and feel the breeze it created if you were close. The Stereo Steel is supposed to roll off at 30 hz, but this subsonic wave was definitely there, so I learned to be careful.

I'm still using the Stereo Steel amp, and I don't have the whump problem anymore, but I've been through so many changes in speakers, cabinets, pickups, and preamps that I can't say exactly why.