Replacement LF Woofer for PMC TB1 Speaker - Help

[hally]

Hi,
I have blow one of the LF drivers in my PMC TB1 monitors and PMC want to charge me a whole lotta cash to replace it... Does anybody know what driver i need to get to do the job myself or is it possible to upgrade the drivers in both speakers, any help or info would be much appreciated, I really like my TB1's and would love to continue to use them
thanks
hally

[Soundman2020]

To be honest, I wouldn't replace it with anything by the original. The entire speaker unit is designed to work together: it's not just individual parts screwed and glued into the same box. If you change any one item for something different, it won't work as well. You'd need to change other parts too: crossover, baffle location, port dimensions, internal damping materials, size, location, etc. It is all tuned to work together: the whole is greater than the sum of its parts.

And if you go that far, to re-tune the entire internals for your new driver, you are well into the field of "DIY speaker building"... which is a whole different ball game.

I've seen this happen in person, when I was interested in buying a pair of speakers from second-hand sound gear store: one of the tweeters was cooked, but the other speaker sounded great, and tested very nicely with my spectrum analyzer. The dealer said he would replace both tweeters with "something better": I warned him it probably wouldn't work, but he went ahead anyway. When I went back to test them again, they both sounded terrible, and that was born out by the spectrum analyzer. He trashed them both, basically. The driver he used was decent, but it was not designed to go in that box, and the box was not designed for that tweeter. That tweeter in a properly designed box with a matching crossover would have been great... but not as a replacement for the one I was looking at.

So I'd either look for the exact same driver that you already have on e.Bay or some place similar, or just swap out both of the speakers for something better.


- Stuart -

[hally]

Thanks Stuart for your prompt reply.
You are absolutely right in your comments and I'm not suggesting for a second to put any old driver in the cabinet and hope it will sound good, the issue with a lot of PMC designs is that they use modified or specifically designed versions of driver brands and unless u have the inside track its hard to tell if u are dealing with the off the shelf driver or a version modified for PMC. Also the replacement driver PMC offer for the TB1 LF driver is different, it is infact the same LF driver that is used in the later TB2 models. The original LF driver used in the TB1 is no longer being manufactured. My research so far has revealed that the original driver was a
VIFA M17WG-09505, I am hoping somebody might know what LF driver is suitable as its replacement?

thanks

[InsTreet]

It's great for advice It is very good for me as I am a spammer, so you all know to ignore everything I say.

[philippap28]

Thanks Stuart for your prompt reply.
You are absolutely right in your comments and I'm not suggesting for a second to put any old driver in the cabinet and hope it will sound good, the issue with a lot of PMC designs is that they use modified or specifically designed versions of driver brands and unless u have the inside track its hard to tell if u are dealing with the off the shelf driver or a version modified for PMC. Also the replacement driver PMC offer for the TB1 LF driver is different, it is infact the same LF driver that is used in the later TB2 models freelance SEO paris. The original LF driver used in the TB1 is no longer being manufactured. My research so far has revealed that the original driver was a
VIFA M17WG-09505, I am hoping somebody might know what LF driver is suitable as its replacement?

thanks

So do not under any circumstances try to update or how?

[DanDan]

Given the geography, I would get on the phone to PMC. Ask whether you should replace just one, or the two. Ask if they have by any chance even an old V1 driver. Try to get through to a tech in the workshop. Sales and front desk tend to be a bit 'geezer' in my experience.

[Frans Wessels]

Hi,
I have blow one of the LF drivers in my PMC TB1 monitors and PMC want to charge me a whole lotta cash to replace it... Does anybody know what driver i need to get to do the job myself or is it possible to upgrade the drivers in both speakers, any help or info would be much appreciated, I really like my TB1's and would love to continue to use them
thanks
hally

Hi Hally,

Like being stated by the other forum members, don't go that path.

(sidekick) I wonder how you ended up blowing the LF driver, normally you would listen at a level around 85 to 90 dB. The amount of amplifier power to produce that level can't blow up a driver, since its sensitivity os 90dB, it is 1 watt of power.

PMC uses their version of a Transmission Line. The "line" being the internals of the enclosure, is specific for the driver. I know they sometimes have other manufacturers make drivers for them. For the TB1, I understand they us a 170 mm driver, with "VIFA" as the manufacturer, don't have type numbers for that driver. EvenIF you would know which driver from VIFA, you wouldn't know the voice-coil specifics of the PMC (your) version.

Also, PMC states that they try to match 2 drivers for each pair of boxes as much as possible. I don't know the specific driver here, but I would NEVER buy an off the shelve driver not being a PMC version, no matter how good it is by itself. You just don't know if it matches the transmission line. It is possible, with a fair amount of man-hours to do reverse engineering and figure out IF the / a specific driver matches the line, but than we need to figure out the dimensions of the parts of the line AND (most difficult / almost impossible) figure out the TYPE and damping characteristics of the damping foam they used in that model produced at that time.
This (choose a different driver) may MOST LIKELY end up in the low end of the spectrum produced being bad (at least NOT like the other cabinet). Even being BETTER than the PMC one you now have still working is NOT GOOD. They are still not matched to a good enough level, this will influence your mixing / producing / mastering you do.

So, you spend time and money and end up in a bad sounding monitor set from a good manufacturer.

HOWEVER, you have options:

1 - I do see now and than a set of PMC's for sale for a fair amount of money (saw one for 250 pounds as stated perfect condition). Go for a second hand pair and keep your's as spare parts (or sell it with the broken driver, some one els might like to do the repairs) to have less financial impact.
My complete studio is at least second hand and works fine.

2 - Have the driver repaired by a loudspeaker repair shop. Be critical on who to give the job, you only have 1 chance to blow it. That shop would REALLY to know what and how to do this, but (since I guess the coil is gone) repairing is a serious option. ASK COST first, you may end up spending kind of the same as getting a driver from PMC.

3 - Google on PMC drivers being offered, some dealers may have a version somewhere in a closet and want to get rid of them. If it would be an original TB1 version, I'd go for it. It is exactly the same as what PMC can offer you.

4 - As a last one (you might need some time to adapt this one) sell them (stated one LF driver broken) and look on the market for a other brand. There are MANY alternatives, if you life does not depend on a set of PMC's. They are really good speakers, but they are not "the only heaven on earth", other brands can really be an option for the same price.

Good luck.

kind regards, Frans

[Frans Wessels]

Well, after some digging (I knew I had some info somewhere).

It is a Vifa M17WG-09-08 (99 % shure).

Rumors go that they used as good as stock drivers for the smaller cabinets (price wise).

Finding such a driver is the next challenge. I did find what is referred to as a so called replacement, ScanSpeak (VIFA) P17WJ-00-08. Looking at the Freq response I REALLY doubt that.

I attached the specs to the original which is not the same as 100 % proof... a replacement of a kind of the same as the original, hhmmmm, w're drifting......

cheers,

Frans