[Viajero5000]

I love my pair of FB1+, everything sounds tonally accurate and clean, with the exception that the mid range is demonstrating an unnatural, piercing metallic/ sand papery edge, and is tense and lacking definition; this characteristic is most noticeable on high pitched female vocals and words beginning with the letter 's'. Since other users report relaxed, smooth and natural mids on this speaker, I wonder if I'm doing something wrong in my system set up. The system currently consists:

PMC FB1+ loud speaker
Bryston 4B ST amp
Myryad MP100 preamp
Teac and Sony cd players
Radio shack gold interconnects
Monster speaker cable (4ft on one speaker, 10 ft on the other, as the amp is on one side of the room)

The weakest part of the link seems to be the interconnects/ speaker cable; unfortunately that's all that's available here, but I could import from the US if this is indeed the source of the issue.

Have any other users experienced such a problem? I'd be grateful for any suggestions.

Also, (a minor quibble), the serial number tags at the back of the speaker have just fallen off by themselves; did that happen to anyone?

[brucek]

The weakest part of the link seems to be the interconnects/ speaker cable

Both the interconnects and speaker cable are quite good. They are not a source of any distortion.

Consider your room as the likely culprit.

brucek

[Barry.B]

Hi Viajero,

I have a pair of PMC lb1's which I had repaired earlier this year, one of the tweeters failed but PMC replaced both under guarantee.  When I got them back and reconnected them into my system I was surprised at how metallic/piercing/unnatural they sounded.  I almost thought that there was something wrong with the repair.  However, slowly but surely during the burn in process they moved towards the pure, relaxed, smooth and natural that you describe is reported by other PMC users (I had forgotten what they sounded like when they were new).  You don't say how many hours your speakers have have clocked up, but I believe it can take a couple of hundred hours running time before new speakers sound their best.  Some would say longer.  Mine now sound pretty damn good, but I now wish I'd had them upgraded to Signature's while they were at the factory.

I would suggest that you use equal length for your speaker cables as it would put the same load on each of your amps channels for balance.  I am using Chord Co. Chorus interconnects and Odyssey speaker cable which gives a smooth, natural and detailed sound with bags of bottom end. You might like to check that the cable plugs are in the correct orientation, my first set of Odyssey speaker cables were wrongly assembled and put the speakers out of phase (not very helpful).

Maybe a local dealer will loan you a set of different cables etc and see if this calms the treble down.

My system is: -
Meridian G08 CDP
Bryston BP25DA pre
Two vertically bi-amped Lexicon NT212's (Bryston 3BST's)
and the PMC lb1 speakers

I suppose it's always worth reverting to basics and making sure everything is hooked up and working correctly first before changing anything, it's so easy to have a poor connection somewhere in the system (I know as I've done it).

I hope this helps,

Regards,

Barry.B
 

[Viajero5000]

Hi there Barry, thanks for the detailed answer. I normally leave the amp on a lot of the time, but if burn in refers to the number of hours of music played through the speaker, I'm not near the 200 mark yet (maybe they've done 80 hours or so with me, but these were 'demo' units so i'm not sure of the total hours). Maybe I should let them play for a few weeks more and see what happens. I've checked the phasing and everything seems to be in phase, with the exception that if there's an out of phase connection within the speaker itself I wouldn't know. I'll also get equal length cable you mentioned below and see if it helps.
Barry could you kindly let me know what an upgrade to the 'signature' means?
Brucek, the room could be magnifying the problem, but the problem itself is definitely not in the room as I've tried a lot of repositionings and the characteristic doesn't go away, it just becomes more or less noticeable by changing speaker positions. I'll also try playing with the damping of the room (curtains/ rugs) to see if it helps. It's taken a lot of hard work to get them positioned to sound like they do now, and if only I could sort out this issue I'd be very happy.

[brucek]

I'll also get equal length cable you mentioned below and see if it helps

Since  your problem is confined to the mid-range, you can rule out any cable effects. Their influence is predominantly limited to the upper range.

The issue of mismatched lengths and the resultant impedance difference influenced by standard resistance and reactance (frequency dependant resistance caused by inductance) is certainly only a problem in gross length differences. In a speaker cable we don't care about capacitance because it's a low impedance interface, but reactance caused by the wires inductance is important and is additive by the foot.

This impedance is indeed important, but generally not important enough to care about a few feet. The difference between a foot long cable and a 50 foot cable would have the longer cable acting as a low pass filter. That is to say, the higher frequencies would be somewhat attenuated. They'd still arrive at the same time as the foot long cable, but attenuation at the upper range would be increased. The difference in a ten and four foot cable is considered insignificant, other than equal length cables allow for any future changes in speaker position. And again, you indicate a mid-range problem.

I like Barry.B's thought that the speakers might simply need breaking in. Why not do nothing for a while and see if the problem goes away on its own...

brucek

[MFPMCL]

Hi V

Interesting to read your post. I recognize the part about the S-thing. In the beginning my FB1+ sounded harsh too. now after some months its like this: good bass, a bit laid back mids and most of the times a smooth and detailed treble.

I noticed that the FB1+ really react to every change you make to your system. So experimenting with LS cables could give a more smooth sounding system.

I tried different LS cables and the one with the best result made such a change that i'm now thinking about replacing the internal wiring with them, as you can read in my post. May be that even the sharp S of Lou Reed's cd New York will dissapear?

So experiment with LS cables is what I'm saying.javascript:void(0);

Regards

Johan

[Viajero5000]

Yes Johan, I think it may be a good idea to experiment with cables, these speakers do seem to react detectably to most system changes; I think I'll also just leave them to play music for the next few days to see if they need more breaking in. Brucek, thanks for filling me in on the effects of speaker cable length on sonics; yes, the problem isn't the highs, but the upper mids; vocals sound fine until a female vocalist for example decides to sing some high pitch notes, which just kind of pierce the ears in an uncomfortable manner, not at all like what a real human voice does.

Also, while we're on these speakers, could anyone kindly recommend a sub to go with these? The little woofer, while producing really good, tight bass, just can't scoop up the lowest frequencies. (I don't want to go for the TLE1 due to it's price). I tried a couple of subs, but the result was not good as they couldn't match the cleanliness and speed of the PMC, and I was getting slow incoherent booming instead of tight, fast bass. Any sub $1,000 subwoofers (new or used) that pair well with the FB1+? "

[Barry.B]

Hi Viajero,

Barry could you kindly let me know what an upgrade to the 'signature' means?

If you look at the PMC website, it describes the difference between the lb1 Classic and Signature speakers and at the time my pair were in for repair I asked if it was possible to upgrade them and how much in would cost (£400 GBP).  This involved replacing the transmission line damping material with a better grade, upgrading the crossover and installing a stainless steel back plate.  The results were claimed to be a more detailed and smoother mid range.  As several owners had enquired about this, PMC decided to do a limited run of upgrades, however at the time I couldn't justify the outlay.  I don't know if it's still possible to have this done now as PMC have dropped the lb1 from their range.

Anyway I hope you find a solution soon.

Regards,

Barry.B

[Viajero5000]

Thanks Barry.

[Bob Reynolds]

Also, while we're on these speakers, could anyone kindly recommend a sub to go with these? The little woofer, while producing really good, tight bass, just can't scoop up the lowest frequencies. (I don't want to go for the TLE1 due to it's price). I tried a couple of subs, but the result was not good as they couldn't match the cleanliness and speed of the PMC, and I was getting slow incoherent booming instead of tight, fast bass. Any sub $1,000 subwoofers (new or used) that pair well with the FB1+? "

I, too, found TLE1 sub to be over priced several years ago when I was sub shopping. I'm using M&K speakers in a 2.1 configuration. Best investment I've made in my system to date. They have been making sat/sub systems for professional studios for many years. Their "push-pull" design cancels 2nd harmonic distortion. I think they are a true bargain.

The pro site is here: http://www.mkprofessional.com/
The consumer site is here: http://www.mksound.com/
The direct sales site is here: http://www.mksoundstore.com/store/

You may find something within your budget on the direct site.

My experience has been that using an external crossover (sometimes called a bass management controller) to direct the bass frequencies to the sub only and properly balancing levels are key to integrating a subwoofer.

Good luck,
Bob

[Viajero5000]

Hey Bob, I've been looking seriously into the M&K, they seem to have some good deals on the net, and i think they even have a distributor here. The *desciption* of their sound seems to be in line with the PMC's requirements, but hopefully I might be able to audition here. Thanks for letting me know.