My PMC IB1 is buzzing???Wowww is me..................

xsparky · « **on:** 22 Dec 2005, 07:45 am »

Hi,
Just a few days before Christmas and my speaker decides to crap out.I have spent several hours pinpointing the problem.At first I thought it was a bad tube in my preamp,but not the case.Darn!
These speakers are only about 9 months old.I listen to them at moderate levels,but not excessively loud and I have never pushed them.I have a McIntosh C2200 tube preamp feeding a 6BSST power amp.I have checked all wiring and swaped amp channels.I finally swapped left right speakers and narrowed it to the midrange driver of one speaker.If I hold the diaphram gently,the buzzing stops.As soon as I let go,it returns.This calibur of speaker should not do this.
Off to the dealers tomorrow.I think they will have to replace both mids as they are a matched pair.
I was about to order a IB1 center,about $5000.00 Cdn.We shall see.

Jason Nugent · « **Reply #1 on:** 22 Dec 2005, 03:00 pm »

As a suggestion, I don't suppose any of the bolts holding the driver in the cabinet are loose, are they? I had a pair of old Mirage M-1's that needed tightening every once in a while.

xsparky · « **Reply #2 on:** 23 Dec 2005, 12:18 am »

Thanks for the suggestion,but I checked that.
I talked to my dealer and they are in contact with Bryston for a replacement driver.

HPower · « **Reply #3 on:** 23 Dec 2005, 12:37 pm »

I had a simular, but not as obvious a buzzing coming from one of my OB1's.
The buzz only happened at certain frequences, and I also thought it was a bad driver.
Then as I am packing the speakers up to take them into Bryston I notice a rattle type sound coming from inside the same speaker, hmm.

When I got to Bryston the technician ( Cam, great guy and very helpfull ), opens up the back panel where the terminal posts are and we have a look at the x-over.
As it turned out, one of the coils had come loose and was hanging just by it's wire and was resinating against the cabinet. Cam re-secured the coil, replace a
couple of the caps that got dinged up by the coil and the OB1's sound perfect agian.

I don't know if this your problem, but it might be worth looking into.

xsparky · « **Reply #4 on:** 24 Dec 2005, 01:47 am »

Hmmm...
I took out the driver and had a look inside.All seems ok.I have not opened the back area where the terminals are.The buzz definately only comes only at certain volumes and frequencies.Again when I gently touch the diaphram,the buzzing stops.
The driver itself only costs aproxamately $50.00.Really not that much to it.I suppose it is how it's implemented with the crossover and cabinate.
If I can only swap this 3" for the driver that comes with the IB2.I better not even go there................

http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=264-550&DID=7[/url]

Dokter_doug · « **Reply #5 on:** 28 Dec 2005, 07:02 pm »

This post is almost too funny...quotes around "funny".

Three days before Xmas the midrange speaker on one of my IB1's just stopped working altogether. Panic! My solution...cannibalize the midrange speaker from my CB6 centre channel box and stick my old LB1 classic centre back into the system while PMC sends me another midrange speaker for my IB1.

Doug

xsparky · « **Reply #6 on:** 28 Dec 2005, 07:27 pm »

Hi Doug,
Thanks for the reply.I feel I know you indirectly.I beleive you and I purchased our speakers from Pat.I beleive we actually spoke with each other when I was originally considering this speaker.(with no regrets)Pat has been very helpfull with getting my driver replaced through Bryston.Must be a bad batch.
I am now about to purchase the IB1 center to match my front left and right.It should be awsome when together.How do you like your CB6.I keep thinking it will be over kill with the IB1 center,but that is such an Important speaker.
The Vifa mid reproduces voices extremely well.
Cheers.

Dokter_doug · « **Reply #7 on:** 30 Dec 2005, 09:45 pm »

Indeed we did speak. And Merry Xmas and Happy New Year to you.

I love the IB1's! Pat has certainly been helpful with solving this particular problem. I too would like an IB1 for a centre channel but currently have no place to put it aside from on top of my TV...which really would warrant a WAF of approximately negative 400. The CB6 was a nice upgrade, although it took a while to break in. It integrates better with the IB1's insofar as it is a more full range speaker than the LB1. It makes for very "present" dialogue when watching movies, but I have found that for SACD or DVD-Audio playback I have had to trim back ther centre speaker volume a bit. But this is no problem as I just purchased a McIntosh MX119 pre-amp-processor which tracks trim levels very nicely and automatically.

Doug

KUB3 · « **Reply #8 on:** 2 Mar 2006, 08:10 am »

I hate to say it, although I'm now of the opinion that this must be a bit of an issue with pmc mid range drivers. Before I bought my new IB2 speakers I knew a guy who had a few sets of midranges replaced on his IB1. I thought it was due to the lower ability of his midranges, or just bad luck. Anyway he tired of the hassle and sold up to get some active ATC monitors.

After six months with my brand new IB2 I had the same buzzing problem. I only ever ran my system sensibly, using a BP25 pre and 7B SST mono's. Luckily the pair of mids were replaced under warranty. So now I'm thinking it's a bit of a coincidence mine went wrong too. Low and behold I see some of you guys have had midrange issues also. Not sure a dome midrange is a good idea anymore!

(I'm shortly getting some AML1 speakers instead, due to moving to a small listening room).

Jason Nugent · « **Reply #9 on:** 2 Mar 2006, 05:21 pm »

You guys are talking about the larger mid frequency soft dome and not the 27 mm tweeter, right? Just curious. My AB2S monitors don't have the midrange dome. I haven't had any problems up to now with the HF dome.

Alfalfa · « **Reply #10 on:** 2 Mar 2006, 07:20 pm »

That's probably because it's not the tweeter that broke down with the above posters but the midrange

Muttondraw · « **Reply #11 on:** 4 Mar 2006, 12:49 am »

Quote from: KUB3

this must be a bit of an issue with pmc mid range drivers.

The mids on your IB2s are PMCs own driver but the IB1 uses Vifa I believe

KUB3 · « **Reply #12 on:** 4 Mar 2006, 10:29 am »

Yes, they're both different, but equally prone to problems it seems. I've never heard of problems with normal cone design midranges. Just glad my new speaker's won't have them, for peace of mind.

Muttondraw · « **Reply #13 on:** 4 Mar 2006, 06:08 pm »

I am not convinced it is a related problem, xsparky had a buzz with one of the mid drivers. HPower had an issue with a crossover component, Doctor Doug had a dead driver. The symptom is different in each case. You had a problem with your mids too so I can see why you might think it is a generic issue with dome midranges but there are quite a few dome midranges out there including the very well respected ATC SM75-150. I know it is tempting to see a link but it is probably more likely to be circumstantial, certainly that is what I would assume without more consistent evidence.

Incidentally Xsparky, did you decide whether to go down the IB1 centre or CB6 route? I am still undecided which is the best option.

HPower · « **Reply #14 on:** 4 Mar 2006, 09:16 pm »

Hey Mutton,

No, no, no, I think KUB is right, and he is doing the right thing in getting different speakers.

And since he will have such a hard time unloading those defective IB2's, I
could do him a big favour and take them off his hands for a nominal
fee.

Muttondraw · « **Reply #15 on:** 4 Mar 2006, 09:38 pm »

Hey I'm closer... though I've got a suspicion he may have already found another "mug"

KUB3 · « **Reply #16 on:** 5 Mar 2006, 02:14 pm »

My IB2 were fixed under warranty with a brand new matched pair of mids.

However they are already going as a trade in deal very shortly. I'm sure they will be fine for a while yet. The main thing with having them repaired was the down time of no music for 3 weeks.

Muttondraw · « **Reply #17 on:** 5 Mar 2006, 03:41 pm »

Quote from: KUB3

The main thing with having them repaired was the down time of no music for 3 weeks.

Not ideal!

Did you get a good trade in value on them? Second hand IB2s seem to be very variably priced.

It will be interesting to hear how you get on with the AML1s

KUB3 · « **Reply #18 on:** 7 Mar 2006, 08:35 am »

I am looking forward to the extra detail the upgraded treble and fully active nature will bring. Plus that 6" carbon sub and transmission line will be perfectly suited to my new smaller listening room. It's quite nice to halve the size of my equipment rack too, due to the iccle hidden brystons.

xsparky · « **Reply #19 on:** 15 Mar 2006, 07:16 am »

Hi Guys,
It's been awhile since I've been here.I finally go tmy two mid ranges replaced in the IB1's with a matched pair.The new one's seem to sound more open and airy,plus more presence.I would say about 25% better.I don't know if it is newer drivers or what,but the do sound better in a good way.
James explained to me that PMC has modified the mid drivers about 2 years ago by lengthening the tincil leads from the coil to the diaphram.Aparently the driver can handle alot more power than what it is rated at,but was pulling off the leads during the excurtion,and would stop working.Burnt voice coils were not the Issues.My spaeker drivers were manufactured at about the change over time.Also he thought that I had a warped coil which would rub and cause the buzzing.
Anyways,they are fixed and sound better than ever!!My center channel is on hold for awhile as I now have them mated to a McIntosh MC402 power amp which ate up the savings for the center channel.I must say if you are looking for tube sound in a solid state amp,these Mac's are superb!
X.