Hi, and thanks for reading --

A few years ago I acquired an old Peavey KB-100 keyboard/vocal amp
(75w, 3 inputs) and I'm trying to refurbish it. Having successfully
replaced the frayed and broken power cord, I noticed that the main 15"
(8 ohm) speaker cone is torn near the edges. I'd like to replace the
speaker with something that will sound reasonably good for vocals.
Right now it sounds muddy and indistinct when sung through, despite
the fact that the tweeter seems to be working; I'm guessing it lacks
mids. I'd like to spend around $100, but could be convinced to spend
more if neccessary. Any hints about what to get would be very much
appreciated.

Thanks again in advance,

Dave

A few years ago I acquired an old Peavey KB-100 keyboard/vocal amp
(75w, 3 inputs) and I'm trying to refurbish it. Having successfully
replaced the frayed and broken power cord, I noticed that the main 15"
(8 ohm) speaker cone is torn near the edges. I'd like to replace the
speaker with something that will sound reasonably good for vocals.
Right now it sounds muddy and indistinct when sung through, despite
the fact that the tweeter seems to be working; I'm guessing it lacks
mids. I'd like to spend around $100, but could be convinced to spend
more if neccessary. Any hints about what to get would be very much
appreciated.

The speaker can be repaired, which is the best and least expensive solution.
A different woofer will have different requirements for the enclosure and
porting, which affects a lot more than just bass. Be sure to re-edge it
with the same suspension material, probably cloth.

And just because the tweeter works doesn't mean it's the proper sensitivity
to match the woofer. Often they just slap a piezo horn in. Not sure what
it's got for EQ, but for the typical dynamic mic you'll want to rail the
high treble (14+kHz) to the roof, about +12dB, bump up the 2.5kHz by 2dB,
drop the 4.5kHz by about 6dB, some extra bottom end usually helps (100Hz
+3dB), and if the treble horn lacks sensitivity you'll have to boost
everything above 2kHz accordingly. Then you've compensated for (most of)
the disproportions of the gear, now you can compensate for your voice and
how it interacts with the mic. You should really have at least a 9-band EQ
for the job, even a guitar stomp box. There's where your money should be
spent.

"Sugarite" writes:

Sug, thanks for the feedback

The speaker can be repaired, which is the best and least expensive
solution.

Reconing looks like a several-hour job for a non-expert like me from
what I can see on the web, and since I don't think I'm hearing the
tears (about an inch long each, oriented radially) yet, I was hoping
the sound could be improved by replacing the speaker. It looks like
I might be able to get some mileage out of plain Elmer's glue if I'm
going to try to salvage the existing speaker. Is that insane?

A different woofer will have different requirements for the
enclosure and porting, which affects a lot more than just bass.

Yeah, I figured that might be a factor.

Be sure to re-edge it with the same suspension material, probably
cloth.

If re-coning, I sure will, thanks.

And just because the tweeter works doesn't mean it's the proper sensitivity
to match the woofer. Often they just slap a piezo horn in.

I think that may be what it is. It looks a lot like
http://www.cybermarket.co.uk/ishop/i...23/900-299.jpg, at least
from the outside.

Do you think I can do better by replacing it?

Not sure what it's got for EQ

Some kind of 4-band.

but for the typical dynamic mic you'll want to rail the
high treble (14+kHz) to the roof, about +12dB, bump up the 2.5kHz by 2dB,
drop the 4.5kHz by about 6dB, some extra bottom end usually helps (100Hz
+3dB), and if the treble horn lacks sensitivity you'll have to boost
everything above 2kHz accordingly. Then you've compensated for (most of)
the disproportions of the gear, now you can compensate for your voice and
how it interacts with the mic. You should really have at least a 9-band EQ
for the job, even a guitar stomp box.

Just to be clear: you mean a 9+-band guitar eq stomp box would
probably suffice?

There's where your money should be spent.

Really? Wow, I wonder if my old QuadraVerb could be put to good use
here. I don't remember for sure but I think it has some EQ
capabilities. Can't stand the sound of the delay effects, but the EQ
might be OK.

--
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com

On Sun, 31 Oct 2004 17:38:44 -0500, David Abrahams
wrote:

Reconing looks like a several-hour job for a non-expert like me from
what I can see on the web, and since I don't think I'm hearing the
tears (about an inch long each, oriented radially) yet, I was hoping
the sound could be improved by replacing the speaker. It looks like
I might be able to get some mileage out of plain Elmer's glue if I'm
going to try to salvage the existing speaker. Is that insane?

I've always had good results by watering down Elmer's glue,
soaking a cigarette paper and applying like a patch. After it
dries, it's usually stronger than the original and with minimal
effect on mass.

Good fortune,

Chris Hornbeck

Dave wrote
Reconing looks like a several-hour job for a non-expert like me from
what I can see on the web, and since I don't think I'm hearing the
tears (about an inch long each, oriented radially) yet, I was hoping
the sound could be improved by replacing the speaker. It looks like
I might be able to get some mileage out of plain Elmer's glue if I'm
going to try to salvage the existing speaker. Is that insane?


Check with your local SR (sound reinforcement) companies, the biggest one
around here does a lot of reconeing. I had an older JBL 18" sub that had been
in storage for a while, the surround had decayed away. I think he charged me
about 75 bucks to replace it.

Sug, thanks for the feedback

The speaker can be repaired, which is the best and least expensive
solution.

Reconing looks like a several-hour job for a non-expert like me from
what I can see on the web, and since I don't think I'm hearing the
tears (about an inch long each, oriented radially) yet, I was hoping
the sound could be improved by replacing the speaker. It looks like
I might be able to get some mileage out of plain Elmer's glue if I'm
going to try to salvage the existing speaker. Is that insane?

I thought you said it was torn at the edge, the suspension alone can be
replaced, I get them done for $25. Reconing may not be necessary.

And just because the tweeter works doesn't mean it's the proper
sensitivity
to match the woofer. Often they just slap a piezo horn in.

I think that may be what it is. It looks a lot like
http://www.cybermarket.co.uk/ishop/i...23/900-299.jpg, at least
from the outside.

Do you think I can do better by replacing it?

Yeah, that's a piezo horn, worth about $3.50. Getting a compression horn
that is a reasonable sensitivity match and also fits into the cabinet will
be tricky. You shouldn't put them on an angle either, their rectangular
waveguide (plastic assembly) is designed to disperse the treble
horizontally. I doubt it will be worth the effort, cheap compression horns
are only marginally better than piezo horns, they can just take a lot more
power and drive longer distances, qualities you shouldn't expect from a
KB100.

Just to be clear: you mean a 9+-band guitar eq stomp box would
probably suffice?

That's pretty much exactly what's included on budget mixers, and there
should be an effects loop on the amp, best spot to put it.

Really? Wow, I wonder if my old QuadraVerb could be put to good use
here. I don't remember for sure but I think it has some EQ
capabilities. Can't stand the sound of the delay effects, but the EQ
might be OK.

I would want that EQ to be much more accessible than a clumsy GUI like that.
You'll want different settings for each room and speaker position relative
to the mic. Nothing like good ole faders. That's worth the $35 or so
alone.

"David Abrahams" wrote in message

"Sugarite" writes:

The speaker can be repaired, which is the best and least expensive
solution.

Reconing looks like a several-hour job for a non-expert like me from
what I can see on the web,

This is true, plus you may do the whole thing several times before you get
it right. Even experienced workers have a fair rate of rework if they want
the job done right.

and since I don't think I'm hearing the
tears (about an inch long each, oriented radially) yet, I was hoping
the sound could be improved by replacing the speaker.

The right way to replace a large driver is to discern the Thiel-Small
parameters of the existing driver by some means, and then obtain a
replacement driver with similar T-S parameters. You can find tables of T-S
parameters for a lot of drivers on the web. Plan B it to find the lab
procedures for measuring them on your own. Test equipment required is an
audio oscillator, an AC voltmeter that is reasonably accurate or a sound
card, and some resistors.

The tears in the surround probably don't change the driver's T/S parameters
that much, but they willprobably make the driver leaky, which can affect
your T/S parameter measurements. If you have a similar speaker with a good
driver, measure it.

It looks like
I might be able to get some mileage out of plain Elmer's glue if I'm
going to try to salvage the existing speaker. Is that insane?

AFAIK Elmer's Glue is technically a kind of glue that is widely used for
assembling speakers. Polyacrylic or something like that. But, it is not used
for glueing rips in the middle of a surround. It would be used to glue a
surround to a basket or a cone.

A different woofer will have different requirements for the
enclosure and porting, which affects a lot more than just bass.

Yeah, I figured that might be a factor.

See my former comments about matching T-S parameters.

Be sure to re-edge it with the same suspension material, probably
cloth.

If re-coning, I sure will, thanks.

Actually, the edge compliance is one of the less sensitive parameters.

And just because the tweeter works doesn't mean it's the proper
sensitivity to match the woofer. Often they just slap a piezo horn
in.

I think that may be what it is. It looks a lot like
http://www.cybermarket.co.uk/ishop/i...23/900-299.jpg, at least
from the outside.

See my former comments about matching T-S parameters. If you match the T-S
parameter's well, the efficiency is locked in someplace near right.

As far as the high end response ( 1 KHz) its helpful to match things like
whether or not there is a whizzer cone, and whether the basic cone material
is the same. IOW replace drivers with paper cones with drivers with paper
cones, etc.

On 30 Oct 2004 20:55:57 -0700, David Abrahams
wrote:
Hi, and thanks for reading --

A few years ago I acquired an old Peavey KB-100 keyboard/vocal amp
(75w, 3 inputs) and I'm trying to refurbish it. Having successfully
replaced the frayed and broken power cord, I noticed that the main 15"
(8 ohm) speaker cone is torn near the edges. I'd like to replace the
speaker with something that will sound reasonably good for vocals.
Right now it sounds muddy and indistinct when sung through, despite
the fact that the tweeter seems to be working; I'm guessing it lacks
mids. I'd like to spend around $100, but could be convinced to spend
more if neccessary. Any hints about what to get would be very much
appreciated.

Thanks again in advance,


I successfully patched speakers and they remained Good Enough until the
speaker blew outright. The suggestions here are roughly equivalent to
mine.

With the Peavey speaker, check whether or not it's a "Replacable Basket"
model. If your amp is a Black Widow variant (BW Equipped) it probably
is--and I'm pretty sure the Scorpion speakers are as well.

My biggest complaint with my KB-100 is the weight, but it was unbeatable
at the price point when I bought it--at least locally.

Do you know what model speaker is in the amp? The Peavey Scorpion and
Black widow speakers are easily repaired. The basket/cone comes off
the magnet with three allen screws and you can buy a replacement.
Takes all of 5 minutes to replce and as long as your pretty careful
with drooping the magnet over the voice coil it's a breeze. Even if
you fix it you're not going to get a great vocal tone out of the amp.
The tweeter is just a piezo, it'll work but not like a proper horn
driver in a cabinet made for vocals. Also, what kind of mike are you
plugging into it? Low-z or high-z?

Hi, and thanks for reading --

A few years ago I acquired an old Peavey KB-100 keyboard/vocal amp
(75w, 3 inputs) and I'm trying to refurbish it. Having successfully
replaced the frayed and broken power cord, I noticed that the main 15"
(8 ohm) speaker cone is torn near the edges. I'd like to replace the
speaker with something that will sound reasonably good for vocals.
Right now it sounds muddy and indistinct when sung through, despite
the fact that the tweeter seems to be working; I'm guessing it lacks
mids. I'd like to spend around $100, but could be convinced to spend
more if neccessary. Any hints about what to get would be very much
appreciated.

Thanks again in advance,

Dave



Which speaker is in it. I suspect that it is the lower end stamped frame
speaker that Peavey puts in their least expensive cabinets. Upgrading to a
Scorpion or a black Widow would make a fair amount of difference.

If you just want to fix the radial tears, I have had good results with Silicone
seal.

Richard H. Kuschel
"I canna change the law of physics."-----Scotty

David Abrahams wrote:

Hi, and thanks for reading --

A few years ago I acquired an old Peavey KB-100 keyboard/vocal amp
(75w, 3 inputs) and I'm trying to refurbish it. Having successfully
replaced the frayed and broken power cord, I noticed that the main 15"
(8 ohm) speaker cone is torn near the edges. I'd like to replace the
speaker with something that will sound reasonably good for vocals.
Right now it sounds muddy and indistinct when sung through, despite
the fact that the tweeter seems to be working; I'm guessing it lacks
mids. I'd like to spend around $100, but could be convinced to spend
more if neccessary. Any hints about what to get would be very much
appreciated.

15" + piezo is unlikely ever to sound great for vocals.

If you want to replace the speaker - a basic Eminence model will probably
do fine.

OTOH - when being cheap - I've used gaffer tape to patch cone tears with
resonable results ! Stick it on the rear of the cone.


Graham

Chris Hornbeck wrote in message . ..
On Sun, 31 Oct 2004 17:38:44 -0500, David Abrahams
wrote:

Reconing looks like a several-hour job for a non-expert like me from
what I can see on the web, and since I don't think I'm hearing the
tears (about an inch long each, oriented radially) yet, I was hoping
the sound could be improved by replacing the speaker. It looks like
I might be able to get some mileage out of plain Elmer's glue if I'm
going to try to salvage the existing speaker. Is that insane?

I've always had good results by watering down Elmer's glue,
soaking a cigarette paper and applying like a patch. After it
dries, it's usually stronger than the original and with minimal
effect on mass.

Papier mchè is more familiar to me than reconing.
I used rice paper, and it seemed to work out just fine. Thanks!

-Dave

"Arny Krueger" wrote in message ...
"David Abrahams" wrote in message

"Sugarite" writes:

The speaker can be repaired, which is the best and least expensive
solution.

Reconing looks like a several-hour job for a non-expert like me from
what I can see on the web,

This is true, plus you may do the whole thing several times before you get
it right. Even experienced workers have a fair rate of rework if they want
the job done right.

and since I don't think I'm hearing the
tears (about an inch long each, oriented radially) yet, I was hoping
the sound could be improved by replacing the speaker.

The right way to replace a large driver is to discern the Thiel-Small
parameters of the existing driver by some means, and then obtain a
replacement driver with similar T-S parameters. You can find tables of T-S
parameters for a lot of drivers on the web. Plan B it to find the lab
procedures for measuring them on your own. Test equipment required is an
audio oscillator, an AC voltmeter that is reasonably accurate or a sound
card, and some resistors.

The tears in the surround probably don't change the driver's T/S parameters
that much, but they willprobably make the driver leaky, which can affect
your T/S parameter measurements. If you have a similar speaker with a good
driver, measure it.

Thanks for a very educational response! That said, it looks like more
trouble than this cheapo used amp is worth. The glue-and-paper
technique seems to be working out fine for now.

"Sugarite" wrote in message ...

I think that may be what it is. It looks a lot like
http://www.cybermarket.co.uk/ishop/i...23/900-299.jpg, at least
from the outside.

Do you think I can do better by replacing it?

Yeah, that's a piezo horn, worth about $3.50. Getting a compression horn
that is a reasonable sensitivity match and also fits into the cabinet will
be tricky. You shouldn't put them on an angle either, their rectangular
waveguide (plastic assembly) is designed to disperse the treble
horizontally. I doubt it will be worth the effort, cheap compression horns
are only marginally better than piezo horns, they can just take a lot more
power and drive longer distances, qualities you shouldn't expect from a
KB100.

Just to be clear: you mean a 9+-band guitar eq stomp box would
probably suffice?

That's pretty much exactly what's included on budget mixers, and there
should be an effects loop on the amp, best spot to put it.

Really? Wow, I wonder if my old QuadraVerb could be put to good use
here. I don't remember for sure but I think it has some EQ
capabilities. Can't stand the sound of the delay effects, but the EQ
might be OK.

I would want that EQ to be much more accessible than a clumsy GUI like that.
You'll want different settings for each room and speaker position relative
to the mic. Nothing like good ole faders. That's worth the $35 or so
alone.

Well, it's not a big improvement in the GUI department, but I was
having feedback problems so I picked up a used Behringer Feedback
Destroyer Pro, which I'm sure can handle most of my EQ requirements.
I note that the manual says emphatically that this unit is not
intended for mics to be connected directly, but I'm wondering just
what the downside could be. For my particular cheapo setup, it could
be ideal as one of the mics really could benefit from having the
preamp.

Any clues?

Thanks again for your very generous help.

David Abrahams wrote:

Well, it's not a big improvement in the GUI department, but I was
having feedback problems so I picked up a used Behringer Feedback
Destroyer Pro, which I'm sure can handle most of my EQ requirements.
I note that the manual says emphatically that this unit is not
intended for mics to be connected directly, but I'm wondering just
what the downside could be. For my particular cheapo setup, it could
be ideal as one of the mics really could benefit from having the
preamp.

Any clues?

The downside is not having any sound.
The output from a microphone is maybe 40 dB or so too low to go into a
line level input. Imagine putting a flashlight battery across the terminals
of a 120V lamp...
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On 5 Nov 2004 11:26:03 -0800, (David
Abrahams) wrote:

Well, it's not a big improvement in the GUI department, but I was
having feedback problems so I picked up a used Behringer Feedback
Destroyer Pro, which I'm sure can handle most of my EQ requirements.
I note that the manual says emphatically that this unit is not
intended for mics to be connected directly, but I'm wondering just
what the downside could be. For my particular cheapo setup, it could
be ideal as one of the mics really could benefit from having the
preamp.

Probably the downside is simply that the unit has line level
connections. A directly-connected mic won't work.

As always, when using this sort of gear, remember that your first
priority is to get the sound GOOD. Getting it LOUD is secondary.
Other things can often be quieter. The most general complaint from
today's audiences is of over-amplification.

Many times I've walked in to a theatre which has been comprehensively
tweaked for feedback rejection. I ask the operator to play his
favourite CD through the system. If it sounds terrible, I suggest he
switches out that 1/3 octave graphic eq that's looking like a relief
map of the Himalayas. Having got the quality back, we can think
about a volume structure for the show.

Sometimes, when an operator's got ears, you see channel EQ doing it's
best to negate the main EQ :-)

CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm
"Possibly the world's least impressive web site": George Perfect