Peavey kb 100 speaker replacement.

[captainlee]

I have a Peavey KB100 combo amp I want to put a sub woofer in it but most of the sub woofers on the market are 4 ohms while the stock speaker in the KB100 is 8 ohms I will be removing the 1 small tweeter in it.
this amp is 70 watts and will be fead a bass signal from a
Behringer SUPER-X PRO CX2310 Crossover so can I use a 4 ohms speaker??

Thanks in advance. Cap.

[Enzo]

This amp was designed for an 8 ohm load, and has just a single pair of outputs. I would not put a 4 ohm speaker in it, especially if you plan to use it for bottom.

[TomCarlos]

For those who come along....

I picked up an old Peavey KB100 for my music room. The speaker and tweeter where shot. So here is what I did...

Woofer - Eminence Kappa-15A - Not the "Pro" ... just the 15A. This is an 8 ohm speaker. It ran around $130. It might be an overkill for this amp, but boy it sure sounds great!! Anyone want an old 15" woofer?

As for the tweeters, I had a couple tweets from another project but they didn't see to put out much volume. So I bought a couple Motorola KSN1005A Replacement Piezo Horn Tweeters from ebay. The set ran around $12. Yes, I said a couple. I added a second tweeter by drilling a 3" hole and adding the second tweeter in a similar position to the first one. The KB300 uses a dual piezo into a horn assembly so I decided to mimic that setup. The end result sounds fantastic (for this old amp that I refused to trash).

See pics and thanks for visiting this thread.

Tom

[Dhg69]

Sorry I don't know where the Post new thread button is?
KB 100, Very very low volume turned up all the way on all three channels?
Any ideas ??
Thank you much, dave

[Enzo]

The new thread button is at the top of the menu page.


Poke a plug in and out of the patch jack/jacks, make any difference?

[Dhg69]

Yes , if i poke it half way i get some volume

The new thread button is at the top of the menu page.


Poke a plug in and out of the patch jack/jacks, make any difference?

Yes , if i poke it half way i get some volume

[TomCarlos]

I would like to add a footnote regarding adding an extra piezo to this cabinet as I have show in the previous posting.

The KB300 and other Peavey Dual Horns use 2 Piezo Tweeters connected in parallel. When you look at the wiring, it is a strange looking crisscross pattern where you will see two 51 ohm, 1 Watt resistors soldered from one Piezo to the other. The connections to the tweeters typically go like this...

Incoming Red wire goes to the (+) terminal of Piezo 1.
Incoming Black wire goes to the (-) terminal of Piezo 2.

If you redraw it, you have 2 Piezos in parallel. One Piezo has the resistor in series going to the (+) side and the other Piezo has the resistor going to the (-) side. I guess this crisscross is done so that you do not have resistors hanging off a terminal and bouncing around. It was confusing at first. But once you step back and draw it, it then becomes clear.

For my project, since the Piezos are on opposite sides of the baffle, I simply soldered a resistor to one of the (+) terminal and secured the incoming red wire through the other (+) terminal to act as a strain relief for the hanging resistor.

According to Peavey and other in these forums, "The resistors are provided to prevent the amplifier from oscillating because amps don't like a capacitive load that is presented by a Piezo element."

Thank you Enzo, thank you JMF.

[Enzo]

That is interesting, I would have thought the low impedance of the woofer in parallel with the piezos would have swamped the capacitiveness, if you will, of the piezo. I guess not.

[SWriverstone]

Hi TomCarlos and others...

I have a 15-year-old Peavey KB/A 100 keyboard amp with blown speakers...and I'd love to do the same thing you did above, TomCarlos. The same woofer and piezo tweeters you used are still available on eBay. Alas, I'm an electronics novice. I can solder reasonably well...but had trouble following the description of how to connect the tweeters and resistors.

TomCarlos, if you or someone else could clarify this (possibly with a small diagram?) for me, I'd be grateful! I'm confident in doing it...but only if I'm certain I'm connecting everything the right way! (Normally it would be as easy as replacing the single tweeter exactly the same way the current tweeter is wired...but I'd love to add the 2nd tweeter---I always felt this amp lacked a crisp high end.)

Thanks!
Scott

[TomCarlos]

Here you go !

[SWriverstone]

Awesome—thanks Tom! I appreciate it! (I'll post up once I've done the replacement.)
Scott

[SWriverstone]

Apologies Tom—but one more question (then I'm good to go!): should the resistors be soldered to wires that then run to the positive terminals (with wire between them as well)? Or do you solder the resistors directly to the positive terminals with wire between?

As I said, I'm an electronics newbie! thanks for tolerating my ignorance.

Scott

[TomCarlos]

Hi Scott...

There are a couple options here. I prefer to solder one side of the resistor to the (+) terminal and the other to the incoming lead (your positive signal). I would then use a long piece of heat shrink tubing over that entire connection. The idea is that you want minimal movement of the resistor leads. So see if you can rig up your connections so that the lead and resistor are stable and not wobbling around.

[Enzo]

Tom, you described earlier the way Peavey mounted the two resistors across the backs of the two piezos. I am not sure why we would now want to wire a resistor in air to a wire rather than on a terminal at each end. It surely doesn't matter which side of each piezo the resistor is, series is series. The cross wired piezo pair on that peavey dual horn I always thought was a clever and efficient wiring solution.

[TomCarlos]

Hi Enzo.... The difference here is because the tweeters are mounted with distance betwwen them (see photos of how I added a second piezo). I agree with you.... I don't like the idea of having hanging components. But in this case, we are not dealing with the dual horn setup. So the installer needs to use a technique that will prevent movement of the components. Other ideas are welcomed!!!