KLH Model 5

[LongPlay33]

Brought a nice pair of Model 5s that had just been gone through with new caps, In one of the speakers a woofer stopped working after listening to them at a pleasant high volume. I didn`t hear the woofer stop until turning on my receiver the next day. At that point I noticed the woofer not working and smelled a burning smell coming from it. It was then I read that I should not be using the loudness button when listening to my Sansui 9090db at a high volume. The bad speaker seemed to have froze up. Next I brought a replacement model 5 woofer for it. Once I replaced the bad speaker I again listened to music all night at a pleasant loud volume but this time I did not have the loudness button on. They sounded amazing. The next morning I turned on the receiver and noticed that both woofer speaker`s were not working and a burnt smell was coming from the recent replaced speaker. The woofer that had a burnt smell coming from it had a burnt spot on it where the wires enter it from the back side. Any idea`s what is happening here ?

 

[c5corvette]

Your problem is beyond my experience level, though I recently recapped two sets of Fives. IMO, the problem is not the loudness switch on the Sansui. My gut thinks you have wiring issues in the Fives. Has your Sansui affected other speakers?
I am sure others wiser than me will offer assistance. Once up and singing, you should be very happy with them.

 

[tyella]

I'm no expert on this level of diagnostics, but that doesn't mean I won't chime in!
Have you checked the DC offset of your Sansui? While I'd expect the tweeters to go first if you are putting to much DC current through your speakers, you still may have a problem with the receiver. It's an easy enough test if you have a multimeter.

 

[Vintage999]

It does sound like a DC related problem, I would check the DC offset on your amp. Another thing, in the crossover are 5 inexpensive resitors (cement types). They can go out of spec, start overheating and doing bad things. Lastly, the internal wiring on the 5s is somewhat complex. Its very possible that something wasnt wired right when the cap job was done.

Hang in there

 

[baco99]

If those are the older type crossovers with the alum plate, they use a common ground. Thew contacts of which can corrode over time, if the ground is flaky, or if there's a short somewhere (maybe where the speaker terminal posts hit the name plate (which is also alum and which also touches the crossover mounting plate and common ground, then you could be causing the amp to clip, and fry the speaker.

Or it could be the amp.

I'm working on a set of Fives now and the crossover is messy. Much better to rebuild it from scratch.

 

[c5corvette]

If those are the older type crossovers with the alum plate, they use a common ground. Thew contacts of which can corrode over time, if the ground is flaky, or if there's a short somewhere (maybe where the speaker terminal posts hit the name plate (which is also alum and which also touches the crossover mounting plate and common ground, then you could be causing the amp to clip, and fry the speaker.

If I recall, there are small black insulating washers on the backside of terminal post. Perhaps when recapped, they were damaged or compromised enough to cause problems??

 

[A400]

I think crossover caps can protect tweeters (and mids) from DC. It seems like the Sansui might be putting out some DC when you turn it on or off and affecting the woofers. I wouldn't connect any other speakers to it until you check it out. The other suggestions you've had seem worth pursuing too.

Good luck getting it resolved, nice gear.

 

[baco99]

If I recall, there are small black insulating washers on the backside of terminal post. Perhaps when recapped, they were damaged or compromised enough to cause problems??

That's what I was thinking. Either they wore down or they disappeared.

 

[dshoaf]

You need to immediately disconnect the speakers. If the woofers have frozen, it voice coil bobbins have likely deformed and locked into the magnetic gap. This is typical problem associated with the amp going "DC" on you.

I'm surprised that the Sansui's speaker protection relay allowed this to happen, though. Still, don't use that amp until it has been looked at. The amp sounds unstable.

Cheers,

David

 

[motorstereo]

I'm betting you had the volume knob past halfway and the bass knob adjusted for more than than those poor 5's were capable of handling. How loud was "pleasantly loud" and how much excursion were those old woofers doing?

 

[Vintage999]

The insulating washers can become compressed. I soaked mine in cleaning oil for a couple of hours which allowed them to expand and become more compliant. Also, the insulating washers must be reinserted in exactly the same way they were removed - the larger one on the inside and the flat insulator on the inside of the plate.

Check the crossover where the woofer wires are terninated to make sure no shorts exist, its kind of cramped.

Is your amp DC coupled? Alot of problems can arise there.

 

[audiomagnate]

One man's "pleasantly loud" is another's "OMG are you insane?" Check for DC on the Sansui,. Also, I'm pretty sure you would notice a turnoff thump loud enough to toast a Five woofer.

 

[LongPlay33]

Much thanks for ur input. I do also run klh model six`s without a problem , weird huh,I will check those insulating washers on the five`s. I then shall have the receiver gone over. And yes I do listen "pleasantly loud", I`ll be bummed if that`s the problem

 

[onplane]

Much thanks for ur input. I do also run klh model six`s without a problem , weird huh,I will check those insulating washers on the five`s. I then shall have the receiver gone over. And yes I do listen "pleasantly loud", I`ll be bummed if that`s the problem

You can measure DC offset when the amp is working hard. That is, with fairly loud sound coming from your speakers, you can test to see whether you have significant DC voltage across the speaker terminals.

The fact that the same amp works well on your model 6's, makes me think the amp is OK.

In the xover of the model 5, there is supposed to be a coil in series with the woofer and it protects the woofers from high frequency signals. If someone by-passed that coil (in hopes of increasing bass), that might explain your problem. There should be no other passive device in series with your woofers.

Now, there is a cap and resistor in parallel. You should check those as well.

Regards,
Jerry

 

[GD70]

When I forgot the insulating washers on my Six's, there was no sound. WTF?
Duh! I put them in and all was good.

 

[LongPlay33]

Well its taken me awhile to post these new facts...... unfortunately I have found that the klh model six`s woofers have gone out just like the model five`s too....so I guess pointing to the receiver should be my next step , right?

Can anyone recommend a competent service technician in the tri county Detroit area ?

 

[woodj]

May be missing something, but where in the OP is recapping mentioned?

 

[GD70]

May be missing something, but where in the OP is recapping mentioned?

The Fives were recapped.
Somethings up with that receiver. Don't know why another set of speakers was used with the same result.
Hopefully some AKers know of a good tech in their area, otherwise if you don't mind shipping to Brooklyn NY, AKer Tom B is an excellent tech.

 

[audiomagnate]

Well its taken me awhile to post these new facts...... unfortunately I have found that the klh model six`s woofers have gone out just like the model five`s too....so I guess pointing to the receiver should be my next step , right?

Can anyone recommend a competent service technician in the tri county Detroit area ?

I think you need to invest in some in line fuses with holders as well.

 

[audiojones]

Get that receiver OFF LINE! It definitely sounds like there is something amiss with the power amp section in it and the protection circuit may have been bypassed or is otherwise compromised. Do you hear silence and then a "click" a few seconds after you power up the 9090 or do you hear sound from the speakers as soon as you turn the power on? There's no way you should be burning out stoutly built voice coils like the ones used in KLH speakers with a properly functioning 9090 even at louder volumes (I've been driving mine with a 200 wpc power amp for years, and believe me I play them plenty loud). The protect relay should have kicked out or at least cycled on and off if you were driving them hard enough to melt the VC's.

I had a similar experience years ago with a Sherwood integrated amp. The protection relay never kicked out and it burned through speaker after speaker until I finally realized that it was sending D.C. directly to the speakers and burning up the voice coils while the protection circuit did nothing to stop it. I never even heard it when it happened, one day I had the grill off of the speaker and I saw the woofer cone push itself way out. Had I not noticed the cone pushing out the amp would have burned up another woofer while it was sitting there idling.