KSP-400 Hum Fix/Possible Non-Powered Tower conversion?

[EdmundGTP]

Haha, yeah that is a debatable point. However the amount of time that the one amp was out of my possession for repair ended up being a rough total of about 9 months between two repair trips.

Goodtimes: good luck with the fix! I hope it works out. If possible would you be able to forward me cutaway, schem, and instructions? I'd be interested to see them purely for curiosity's sake. Thanks. edmund(dot)alexander(at)gmail(dot)com

[stormwind13]

This was a very informative thread that steered me away from getting the amps fixed in mine to going with an external amp solution. I ended up using an altec lansing model 9444b amp, and using the internal crossover function on my integra dtr7.4 to feed it a nice <60hz signal. The main difference between my conversion and yours, is that I took and used the existing speaker level input posts and internally disconnected them- then connected the speaker directly to the posts internally. This eliminated the need to order custom plates to replace the heatsinks.

[fini]

I have KSP-400s and (knock on wood) have no hum problem, but ordered the pdf version of the KSP-400 service manual from Klipsch, just to have it on hand in the event I need it.

KSP400.pdf

[Travis In Austin]

The whole thread is incredible. I am worried a little bit, I got my amps back about a year or two ago and have not installed them yet. They just might not work. On the bright side, I have what looks like a great way around it.

Travis

[Trey Cannon]

I did not read the entire post...but there are ways to stop the hum that is in the amp of that speaker.

There is a bunch of wires/ cables that run from the preamp board at the botom of the speaker up to the amp unit at the mid back of the unit.

IF this bunch of wires is not tied tight in to a "single cable" it can pick up the RF noise from the transformer.

Bind them all together and pull them as far away from the xformer as you can. This may stop your hum.

IF not, look at the filter caps on the power board. Big caps and little ones. I think there are like 6 per side. I would have to look to remember.

Replacing them can have a good effect at times. A "cheater" plug on the power cable can also help.

As for making the speaker passive, it can be done. The HF of the speaker is in its own cabinet with its xover inside. Pulling the amp and using an external amp will work fine as long as you can tune the amp to driver the sub like it wants. A KSW-300 amp is the same amp....A KSW-15 amp would drive if as well.

[T2K]

I have KSP-400s and (knock on wood) have no hum problem, but ordered the pdf version of the KSP-400 service manual from Klipsch, just to have it on hand in the event I need it.

How did you go about acquiring the service manual from Klipsch. I haven't turned my speakers on in a year or two, I may need to get a service manual.

Trey, do you know of a service center that you could recommend/trust to repair these amps?

Thanks on both counts.

Keith

[fini]

I have KSP-400s and (knock on wood) have no hum problem, but ordered the pdf version of the KSP-400 service manual from Klipsch, just to have it on hand in the event I need it.

How did you go about acquiring the service manual from Klipsch. I haven't turned my speakers on in a year or two, I may need to get a service manual.

Trey, do you know of a service center that you could recommend/trust to repair these amps?

Thanks on both counts.

Keith

Keith, I emailed Klipsch Technicalsupport@Klipsch.com, they sent it for free. I attached the pdf in an earlier post above. If that doesn't work, I can forward the email they sent me. Shoot me your email address.

[EdmundGTP]

I did not read the entire post...but there are ways to stop the hum that is in the amp of that speaker.

There is a bunch of wires/ cables that run from the preamp board at the botom of the speaker up to the amp unit at the mid back of the unit.

IF this bunch of wires is not tied tight in to a "single cable" it can pick up the RF noise from the transformer.

Bind them all together and pull them as far away from the xformer as you can. This may stop your hum.

IF not, look at the filter caps on the power board. Big caps and little ones. I think there are like 6 per side. I would have to look to remember.

Replacing them can have a good effect at times. A "cheater" plug on the power cable can also help.

As for making the speaker passive, it can be done. The HF of the speaker is in its own cabinet with its xover inside. Pulling the amp and using an external amp will work fine as long as you can tune the amp to driver the sub like it wants. A KSW-300 amp is the same amp....A KSW-15 amp would drive if as well.

Appreciate the input Trey.

First thing I tried was bundling all of the low voltage signal cables. Didn't work.

Tried the cheater plug. Also didn't work.

I'm sure the issue with my amps was indeed the filter caps, but after multiple attempts to have them fixed I decided to say "screw it" and figured out my own work-around.

The speaker is now "passive" and driven with an external amp and EQ.

Works great!

[T2K]

I had just got up and missed the attached file Gregg, but I have it now. Thanks. Maybe I'll have time in the spring to listen to my speakers.[]

Sure wish there was a qualified service center, I might go ahead and have them checked/repaired since they're like you, getting on up there in age.[]

Keith

[fini]

Check and see what they'd charge to check me, would ya?

[T2K]

I spoke with a service tech at a local repair shop this morning and he could not help me with amp repair. However, he did say he could help you fini. He seemed like a sweet guy but he did have really huge fingers. Want me to make you an appointment?

Keith

[fini]

Thanks Keith, but I'm looking for a really huge guy with sweet fingers...

[Trey Cannon]

Ok Fini,,,that is just wrong.

The tech support guys should have a place to send the amp for repair.

[fini]

Ok Fini,,,that is just wrong.

Yeah, but that's where I have to go to get a response from you!! Merry Christmas, DUDE!

[Trey Cannon]

Right back at ya...

I am not on here much anymore...work keeps getting in the way.

[sfatula]

So, i have a newbie question here. I am doing this same thing, but, don't know the answer to this. So, I have an external amplifier driving the pair of KSP-400 speakers. The amplifier is hooked to my sub output on my home theater receiver. So, when not using the system, it is off. When I turn it on, say I find an amplifier with a locked on button. So, home theater receiver comes on, and, triggers the amplifier driving the subs to come on, maybe via some sort of trigger the amp might support, or, maybe via a power sequencing sort of device. Won't there be an enormous thump on the subs, since, I have to leave the volume level somewhat high on the amplifier ti put out the required power?

I want to make this as automatic as possible. How to avoid that if so?

[sfatula]

Also, will it matter on the sub which is positive and negative now? So, do I need to mark the connectors on the outside of the KSP-400's? If so, is the larger connector on the sub positive, and the smaller negative?

For wiring inside the box, do I need some sort of shielding wiring, or, is it largely irrelevant since there is no longer any electrical inside? Not sure if the subs themselves can interfere with the signal.

[EdmundGTP]

In Florida at the moment. Once I get back to Arizona later tonite I can check back thru my notes and pics and follow up on your posts.

Ahh, what the hell. I have my laptop and a few extra minutes; I can probably cover at least one of your questions.

In order to avoid loud turn-on thumps, all you have to do is make sure that the amplifier powering the KSP subs is the LAST component to turn on, whether it be by trigger or by power sequencer. I have additionally signal processors in my subwoofer pre-amp signal path which further complicates the issue. I leave those signal processors turned on all of the time and when I want to use the KSP subs, I turn on their power amplifier by hand AFTER turning on my receiver. Also, from what I've seen, most power amplifiers don't start outputting signal the second that you turn them on. Typically there's a delay of a few seconds while the internals of the amp power up, and THEN it starts passing signal to the speakers.

It's kind of funny that I went through all the work to get the KSP towers fully functional, and now 90% of the time I don't even use the subs in them because I have an additional third powered sub that turns itself on and off by signal sensing and is more than big and powerful enough to cover the duty of the KSP subs.

Anyway moving on. You will want to keep your subs wired in-phase with the rest of the system so it is important to know which lead going to the speaker is positive and which is nevative. Those binding posts which I linked to you earlier are distinguishable from eachother by different colored plastic rings on them (red for positive, black for negative) so you shouldn't have to make any additional markings on the KSP's. All you have to do is connnect the proper sub wire lead to the proper binding post. If you have un-mounted the sub from the KSP enclosure, its terminals SHOULD be labeled somehow. I don't specifically recall which size spade terminal goes with positive or negative though. If I recall correctly however, the two wires which run from the sub to the amp are green and black in color, and I'm almost 100% sure that the black (as it usually is) is the negative lead. As far as sheilding is concerned, you dont need any, becasue at this point you no longer have any low-level/voltage audio signals passing through the KSP enclosure. Those low-level/voltage signal wires (i.e. RCA type signal path) are the ones most succeptible to RF interference, hence the reason sheilded RCA cables are so important.

A side note. Another thing you might find when taking the KSP's apart, are some screw holes that may be a bit stripped out from previous over-torquing. I know at least a few of the holes in my speakers were wallered out to the point that they barely held the screw in. While, the speakers are apart I'd try to fix these holes by pressing a couple of tooth picks into them until they fit tightly, then snap off the excess. Then you may or may not want to push a drop of wood glue into the hole and let it set up for a day before trying to re-insert a screw. That way when you go to put everything back together all of the screws can be properly tightened and you eliminate some possible air leakage points.

Also, if you take the subwoofer out of the enclosure, pull out some of the foam as well and have a look at all of the internal corner joints. You'll notice that they used some really thick glue to seal all of the joints, but there may be some spots where the glue is lacking or doesnt form a continuous bead along the inside corner. While mine were apart, I re-caulked all of the areas that looked like this just to be on the safe side.

I'll be trying to think of some other tips and info from when I worked on mine, while I fly back west. Good luck on it and post back with pictures/updates/questions if you can.

[Trey Cannon]

The larger connector is pos. +

[sfatula]

I had thought the magnets might add some noise to the speaker wire inside. Perhaps they are magnetically shielded somewhat.

Anyway, I think I am going to go with this wire, cheap, and, I can color it properly:

http://www.apexjr.com/wire.html

Top one, mil-spec.

I am also thinking of using the Crown XLS 1000 since it doesn't have the fan noise of previous versions. Read lots of good and bad things vs other brands/models, and, the good seems to outweigh it to me. Found it for $250 shipped, new. Seems like a decent price.

I'll be sure and seal any spots I find. The taking apart wasn't bad at all. When I got to your step that said I can remove either the sub, or, the control panel, I chose the control panel, but, there is no possible way my arm fit into the hole to reach that far! So, sub turned out to much not so bad as well.

I got the caulking cord as you recommended.