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


EdmundGTP

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So as of right now, the electronic guts of my right side KSP-400 is on it's way back to an electronics repair facility to eliminate the dreaded hum/buzz.

I think it's safe to say that I've read just about every single thread on these forums regarding this problem, and have tried every single DIY Fix that
has been mentioned. All to no avail.

When the issue first came up, I contacted Klipsch Tech Support to get some more information on possible fixes. Obviously we're way past the time when
replacement parts for this speaker were readily available. And they had mentioned that they now farm out a significant portion of their electronics repair
work to a repair company, and suggested that I contact them for a repair estimate. Which I did. I sent them the unit about a month ago with a detailed
description of the issue. The unit returned with an invoice stating that a transformer capacitor was replaced. Hooked the unit back up. Hum was still there.
So today I called them back and they said to ship it back so they could take a look at it. As of now it's on its way back.

So now I have to ask myself. What happens if they cant fix the problem? I'd love to be able to keep and continue to use these speakers because frankly,
they kick ***. I love them.

So I wonder what the possibility is that these could be converted to Non-Powered towers, and if so has anyone here
attempted it? Obviously the midranges and horns can be driven directly without the subwoofer portion even being powered. Can anybody tell me what the
impedence ratings for the midranges and horns are, and in what specific configuration they're wired? And also what is the impedence value for the subwoofer
itself? If I can find that information, I'd like to at least try bypassing the sub amp all together, perhaps tapping off one of the main speaker input binding
posts to in effect bi/tri/whatever-wire the system, and running an in-line 80 hz low pass crossover directly to the sub. Obviously a more complex fix could be better such as a custom designed passive crossover. Any input on that would be appreciated as well. But, how horrible could it really sound?
What would be the harm in trying? These are awesome speakers, and it would be a total shame to see the lower half of them go to waste.

Thanks in advance guys!

-Ed

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  • 4 months later...

Yeah I actually just got the one back late last week. I installed it and its working perfectly. According to the work order sheets, the first time it went in, they replaced a power supply capacitor (didn't fix the hum) and the 2nd time it went in, they replaced the bridge rectifier. It took exceptionally long to fix the 2nd time because apparently the necessary transistors were on back-order.

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The repair company is I.A. Electronics. Phone: 1-800-748-0422. Located in Indianapolis Indiana. The repair cost for the amp was very reasonable. $125 flat fee with a $25 up-front payment by check, which I sent along with the amp. The $25 gets deducted from the $125 total once the work is complete. There were no extra fees or costs involved when it had to go back the 2nd time for additional work either; all else I had to cover was shipping to get it there. Turnaround time for the first repair was just a hair over 3 weeks I believe, and the 2nd time the amp was there from early December of '08 until just last week but the only reason the 2nd repairs took so long was that apparently the necessary transistors were on back-order. If my left speaker amp starts acting up, I will definitely go to them for repeat service.

Edit: here's their website http://www.iaelectronics.com/home.html

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  • 4 months later...

Well, looks like that amp is gonna be going back for repair a 3rd time.[8o|][8o|] After the 2nd repair it worked flawlessly for about 5 months. Now the problem is that it does absolutely NOTHING when plugged in. Fuse is good (not blown), tried multiple power cords, and multiple outlets, it simply does nothing; no lights, no noises, no clicks, no hums, no smoke, and no weird smells. Pulled the amp guts out of the speaker and gave them a once-over and I didn't come across anything glaringly obvious problems (i.e. disconnected wire(s), signs of damaged components), so back it goes. Feels like I'll never catch a break with these damned things.. [:(][:(] Hopefully it wont be too long before I have it back and have another update here..

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Did a little bit of experimentation last night. Wanted to see how easy it would be to run the internal subs of the KSP-400's with an external amplifier. Sort of an off-shoot of what I was thinking about in this thread: http://forums.klipsch.com/forums/p/117272/1188843.aspx

Basically turn them into Bi-Ampable non-powered towers. I did this on the one that stopped working in the post above, since it was already taken apart. I've taken these damned things apart so many times, I could probably do it in my sleep by now. First thing I found out is that with the amp section completely removed, the subwoofer disconnected, and with the lower control panel completely un-powered (i.e. no power cord), the upper portion (mids and horn) of the speaker worked perfectly. At first I was unsure whether or not the lower control panel would allow the mids and horn to play without having the circuitry of the amp and subwoofer connected. Turns out the mids and horn can be ran completely independent of the sub.

So next I decided to see how it would sound running a separate amp to the sub, using my receivers sub output, while playing the mids and horn using the right channel speaker output of the receiver. This is the odd looking rig you can see in the pic below. Notice the KSP-400 amp laying on the floor, and the power cord and signal cables removed from the lower control box.

IcdHzFJ.jpg

That piece of tupperware in the original amp cavity in the back of the speaker is holding all of the screws so they don't get lost, in case anyone was curious.

I ran my main receiver's sub output to ANOTHER receiver that I had laying around, and ran the output from that to the sub. The 2nd receiver was only good for about 100 watts and didn't offer as much actual gain as a standalone amplifier would but it worked!

So now I'm thinking, I'll have a pair of aluminum plates machined to cover and seal the amp cavities in the backs of the speakers, with provisions for binding posts which will have leads running to the subwoofer. Ill replace the lower control boxes as they are shown in the pic; no power connected, no sub connection, no signal wires. Just the 2 pairs of leads that run from the box to the mids and horns. Then buy a standalone 2 channel amp (Crown XTi 1000, or Samson SX1200). Run my sub output from the main receiver to the amp, then wire leads from the amp to the new binding posts on the backs of the KSP's. The loss of bass management controls on the lower box, I think could be remedied by the addition of the Elemental Designs eq.2 in the subwoofer pre-amp signal path (if that's even necessary).

 All of these changes would be 100% reversible to the speakers' original configuration if the results aren't what I expect. And worst case, if it doesn't work out, I can just sell the amp and eq.2 for at a negligible loss and send the KSP amp in for repair.

So I either do all that, OR JUST send the amp back for a 3rd time, and hope it can be repaired. I may be wrong, but I'm guessing theres only SO many times that a piece of electronics can be "operated on" and repaired before it's just no good anymore.

What would you folks suggest?

I really find it hard to believe that nobody has tried this sort of thing before.

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What about leaving the plates in and bi-amping the speakers-one amp to mid/hi, one to the bass. FYI, what I do is just run one wire to the speaker, with no LFE input at all. I let my SVS sub do the heavy lifting for really low frequencies. Spectrum Sound in Indy fxed my amp first time no problem for $130, but it'll take a while.....

Also, where did those feet come from, are they made for the KSP-400

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What about leaving the plates in and bi-amping the speakers-one amp to mid/hi, one to the bass. FYI, what I do is just run one wire to the speaker, with no LFE input at all. I let my SVS sub do the heavy lifting for really low frequencies. Spectrum Sound in Indy fxed my amp first time no problem for $130, but it'll take a while.....

Also, where did those feet come from, are they made for the KSP-400

Your first bi-amping suggestion, is (i think) very similar to what I'm thinking of doing, except I'm not sure what signal I'd use for the bass aside from the sub output on my receiver. In your particular setup, are the subs of the KSP's actually doing anything/are their amps being used? And aside from getting the original KSP amp fixed, I'm trying to determine a way to bypass it all together. In other words; remove the finicky piece of electronics from the equation.

This other guy you mentioned with the amps. Is he selling original KSP-400 sub amps? or remanufactured units? or what exactly?

Oh and I actually designed and had those feet made custom. I made a thread about that a little while back too, I think. Yah here it is: http://forums.klipsch.com/forums/p/117906/1191995.aspx

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I was wrong, I don't think the tri-amp thing will work, as that is only for the drivers. But what I said about not running an LFE is worth trying, if you have a small room and a big sub like I do.

There is a way to bypass it all together I believe. I was going to use my Hafler DH200 to power them.

HarryO is the member, I think that his log on. Last time we taked (a week ago) he said he had one NOS, and one used amp. He checks all his equipment before selling and knows quite a bit.

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Well presently I have no other sub besides the ones in the KSPs, so I was hoping to keep those functioning as such, and maybe at some point down the road, supplement the sub-30hz range with an additional larger sub.

Prior to all these amp problems I was simply running the KSPs off of my receivers speaker outputs alone, using the jumper bars to link the high, low, and mid inputs on the control box on the back of the speaker. So no LFE input usage there.

Getting back to the problem with the amp, I'm not even sure if the problem is with the amp itself, or with the control box. Being that the unit doesnt power on at all, or even make an attempt to do anything when plugged in, I think the issue could be in either of those two electronic parts.

Right now I'm really leaning towards pulling both amps out of the KSPs, and powering the woofers with an external amp, using my receivers LFE output, then I'll just split the LFE output to an additional sub when I get around to buying it.

My room is 13 X 19, with one end opening up to 9 X 10 room, so roughly 340 square feet to cover or 2700 cu. ft. to fill with sound. Not a 'small" room but not a HUGE one either I guess.

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Yeah thats true about the value without the orig. amps. Though I realistically plan on keeping these for as long as possible and am not terribly concerned with maintaining value. The other thing is, all the changes I have in mind right now are 100% reversible to bring the speakers back to OEM spec if need be. At this point I think I'm gonna proceed with trying out the external amp route. Though I think I'll still check with HarryO to see what exactly he might have available. Having spare parts never hurts! Thanks for the input!

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It strikes again!! [8o|] How frustrating eh? Think you'll end up sending the amp in for repair or try to work out a fix of your own like I'm about to? I can give ya the contact info of the place that repaired mine the past 2 times, though based on the fact that mine isnt working at all right now, that may sway your opninion on sending it to them.

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Hmmm.. Anyway, I'm going to try the prong swap first. I talked to Harry (Bailey), he can't find the amp, even though he has one his inventory sheet. Anyway he mentioned that the amps did have quality issues, and some parts are not up to the task.

My only other thoughts are PartsExpress, as they have several plate amps for subs that might fit right in or could be swapped internally. And if the KSW 15" sub amp might be the same.

I will tell you that I've yet to see a KSP-amp for sale on ebay, and Ive had a saved search for a while now.

My local shop fixed the dead amp first time, so I will probably use them again. I did not fully removed the amp but took the whole speaker in. IS there any trick or tip to removal as mine seem to be boxed in pretty good with wood.

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Yeah trying the 3 prong to 2 prong plug swap is a good place to start. Though I suspect, that if you've been using 3 prong plugs so far, and havent had the hum previously, that just switching the plugs probably wont fix it. Then again, you never know. It really is the first and cheapest trouble shooting step to all of this. I had always been running my KSP's with a 3 to 2 prong plug converter to avoid ground loop hum, which coincidentally sounds EXACTLY like the hum you get when the amp fails.

Yeah, I looked around at some of the various plate amps that are on the market. Didnt seem like any of them would be either a direct or "easy" retro-fit. I'm sure the KSW amp would be up to the task, but they seemed rather pricey compared to some other simpler amplifiers.

There's three standalone 2 channel amps that I'm looking at right now.

Crown XTi1000 Those seem to run $350-400

Samson SX1200 $260-350

Samson PG2200 Also in the mid-high $200's

All have roughly the same output (200-300 watt range) into 8 Ohms per channel, which I'm fairly certain is the impedance of the sub itself.

Funny, you mention it; I too actually have a saved ebay search for Klipsch KSP parts that might come up.

Removing the amp from the speaker is actually very simple. If you look closely at the heatsink on the rear of the speaker there are 8 phillips screws situated between the fins along the periphery of the heatsink. Those are all that hold the actuall amp portion in. To remove it, you'll want to remove the lower six screws first, and the top three last. This is because the weight of the amp might actually cause it to fall out of the speaker while you're loosening screws, so be ready to catch it and support it when you're taking out the last ones. On the other hand, there is a thin foam type seal that goes between the heat sink and the speaker cabinet, and the amp may very well be "stuck" in place by that seal. If that's the case just remove all 8 screws and pull firmly but carefully at one of corners of the heatsink and it should separate itself from the cabinet. Again, be ready to catch/support it in case it breaks free suddenly.

Once the amp is detached youll notice a few wires making their way down a hole in the amp cavity. The 2 red ones are power wires. The green and black ones are the sub speaker leads. There is also a cable with multiple small guage wires bundled together which has a white plug on the end. Those are the low level signal, and control wires that go to the inputs and knobs on the lower control panel. That white plug can be removed from the circuit board. The 2 red power cables are attached to the amp by 2 white plastic screw down terminals. To remove those, just loosen the 2 small flat-head screws in the terminals and the wires should come free. The green and black wires are the tricky part. They are soldered directly to the board and from there go straight to the sub and are connected by spade connectors. To disconnect them without cutting them you have 2 options. Youll either have to remove the lower control panel, or remove the sub itself to get inside the cabinet and pull the connectors off of the subwoofer. Unless you're quadruple jointed, your hand cant reach them from the amp cavity.

The control panel can be removed by taking out the screws running along the edges of the panel. The other ones located slightly further "inside" the panel surface hold the control unit itself together, and dont need to be removed to get the unit free of the cabinet. Again, it may be stuck in place by the seal and you might have to gently pry at one of the corners to get it free. Same with the sub. If you decide to remove the sub, it's generally safest to remove the lower-most screw last, and be prepared to support the weight of the woofer as you loosen that last one. Also you may have to pry the sub free due to the same seal.

When you replace any of those items it will probably be worthwhile to replace the seals with something better. I've had really good luck using a "bead" of this Mortite Caulking Cord It's a putty or modeling clay-like seal which is easy to mold into place on the back of the amp, control panel, and the sub itself. If you look back at the pic I posted, it's that white stuff surrounding the cutouts for the amp and control panel. Though once you bolt those parts back to the cabinet using this stuff, it's CONSIDERABLY harder to pry them back off if you have to remove them again. I've done it a couple times now.

Sounds more complicated than it really is. And its way easier to move the amp and control panel by themselves, than moving the entire speaker around.

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Good thread, Edmund! Not relevant to a large percentage of members here, but to those of us with KSPs, it'll be bookmarked! Keep up the good work.

BTW, has anyone at Klipsch given you any guidance on this? There's gotta be someone there (these were made in Hope) who has something to add to your project.

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