Did I kill my QLS1's mids?

[Bucky Badger]

Well here's my story. Both speakers were playing fine yesterday and when I hooked up a Russound speaker controller, (I have 4 sets of speakers and wanted to control the volume of each set) and turned the stereo on I hadn't noticed that the volume on the selector was all the way up. I pegged the needles on my 700B and immediately turned down the volume. Now 1 of my QLS1's midrange bank isn't working. I kicked myself a few times and hung my head in shame. Lame of me I KNOW. So, what could I have done to my babies? I get nothing from the midrange pot and all mids are quiet. The Emits, mid-bass and Watkins are fine.The other speaker is fine and works well.
I have wanted to redo my crossovers and pots for awhile now but have been lazy.
So, did I kill my mids???
I kinda feel sick to my stomach. Crap.

 

[goodolpg]

If you have a multimeter you could take ohm/resistance readings on the dead drivers.
That would help troubleshooting a lot.
Not sure if the leads are push on or soldered on.

 

[Mark B]

Sounds like you might have blown the fuse to the mids.

 

[7.62]

Yep, check your fuses.

 

[chef free]

There's only one fuse for the EMITs, mid domes and mid bass, if the fuse was blown, they'd all be out.

It's hard to believe you could take out all six domes like that. Take out the woofer and check the wiring on the mid pot. When I got my QLS-1, one side had no mids working, one of the wires had somehow become disconnected from the pot.. The exact same place in the other crossover I bumped the same wire and it came off. It's a long shot but worth a look considering my experience.

 

[Bucky Badger]

Thanks guys for your ideas. Yup I checked the fuse and it's ok. I will pop off the Watkins and check out all connections. Thanks for your help. I hope it's just a wire........

 

[tubed]

I can see overpowering taking out one or two but the whole array?
My guess is the wire at the push on connector or one of the two at the potentiometer( or the pot itself?)

 

[goodolpg]

Appears to be a wiring problem if the whole array is out, hopefully it's as simple as a disconnected wire.

 

[okeeteekid]

I would bypass the pots in the mid section to see if you get sound.

 

[slimpikkins]

" I pegged the needles on my 700B" ouch! Hope everything is ok.
Jim

 

[chef free]

While you 're inside there, check the impedance of the dome wiring, it's the white wires.

 

[Bucky Badger]

All good ideas.

" I pegged the needles on my 700B" ouch! Hope everything is ok.
Jim

Me too.

 

[chef free]

Any news?

 

[Theother1]

I'm also curious as to how the entire array got taken out. The mid crossover?

 

[Mark B]

 

[7.62]

I'm not as knowledgeable as most of you, but this was one of my observations. When I was playing the Quantum 5's that I got with the QLS-1's and blew a fuse, somehow the power got to the mid and completely took it out. Maybe it fried the tinsil wire. I never investigated it. It did make me think the same could happen on the Ones. That's an expensive fix.

It's just my opinion, but due to age they are becoming pretty sensitive to any overdriving etc. one of the reasons I didn't mind letting mine go.

I'm curious to....

 

[cdfac]

you need to pull out each mid and check the resistance of the VC. if they all check out, then it's likely a blown cap, resistor, or inductor. i think besides at the drivers themselves, almost all wiring connections are soldered.

IIRC, the mids are wired in series pairs, that are then paralleled with either other. as such, you would generally need at least one bad mid in each pair to make all six go silent.

 

[slimpikkins]

Could have smoked the mid pot. They are only 25watt, probably rusty and 40years old...

 

[itsjim]

There's only one fuse for the EMITs, mid domes and mid bass, if the fuse was blown, they'd all be out.

It's hard to believe you could take out all six domes like that. Take out the woofer and check the wiring on the mid pot. When I got my QLS-1, one side had no mids working, one of the wires had somehow become disconnected from the pot.. The exact same place in the other crossover I bumped the same wire and it came off. It's a long shot but worth a look considering my experience.

^^^^THIS
I just rebuilt the crossovers in my Q2s. Those pots on the mid circuit seem to be the ones that take the most electrical abuse. One of mine was literally sprung open and useless, and the wiper wire was disconnected. The midrange circuitry for the QLS-1 looks to be functionally identical to the Q2, with slightly different cap and resistor values. But they use the same 5 ohm pot. Right off the bat I would consider replacing both mid pots with something like these:

http://www.tedss.com/2022000076

 

[HowardHudson]

Hey Y'all,

I just joined Audio Karma, so hello. I have two pair of QLS-Is but, more relevant to this thread, I have a ton of replacement parts. I bought about 16 Philips TW037YX 1.5" dome midranges when they went End-Of-Life. The stock tweeter has a circular plate, instead of the Infinity square, but I have some examples to measure out and fabricate, if there is some interest in replacement tweeters.

Because I will be moving to Holland next year, I will be selling off most of that gear, so if Bucky Badger, or anyone else, needs some replacements, hit me up. I am in Eugene.

I also appreciate the folks who share links to replacement parts. I will likely re-cap the crossovers I have and sell them off.

Pleased to meet you all and DELIGHTED there is a group as dedicated to these big, power-hungry speakers as I am.

Howard Hudson