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DIY FB1i anyone?

They use LEAP. Read all about their service here. Of course, it'd better to have your own CAD system and DIY properly - but the Madisound service is a cost-effective alternative.

James
 
I found out PMC do a 'i' version upgrade kit, comprising new crossover and tweeter. Im going to find out how much they cost. If its a good price then all I need is a pair of woofers and 2 kits and Im all set!
 
Mike, do pmc let you buy the kit now? When I asked about upgrading my db1s to + they said it had to be factory or dealer done, and cost roughly £300
 
James Evans said:
Mike, do pmc let you buy the kit now? When I asked about upgrading my db1s to + they said it had to be factory or dealer done, and cost roughly £300
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I spoke to PMC today and they quoted me £250ish for a pair of '+' kits. They dont do a 'I' upgrade kit and wouldnt tell me why, when I asked the guy said "ERRRRRR", bullshit, he knows why! (they probably want you to buy new speakers!). When I asked about purchasing a pair they told me I'd have to go though a dealer, so I asked for a local dealer and got a number. I called the dealer and they tried to tell me I had to have them installed for me, I explained that its not difficult to change a tweeter and wire in a new crossover and that I was only interested in buying the kits. I was then told that I would have to wait while the guy called PMC to "check". He didnt get back to me yet. I asked if I'd need serial numbers of my standard PMC speakers (LOL!) and he said he thinks theres no need. I guess PMC are aware of the cloning that goes on and are trying to ensure people dont do exactly what Im attempting! Maybe theyre reading this as I type!!!! (I shouldnt have given my name, doh!!) Now im paranoid:(

He might call back on Monday, fingers crossed.:);)
 
hi fi fo fum said:
How are they coming along ?????

Steve
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Nothing yet, funds are tight and I have a couple of other projects in the pipeline. Im still waiting for a quote from Wilmslow for the cut panels. Good news is that FB1+ upgrade kits are available (ca. £250) so all you need is Vifa midbass, some egg crate foam and a couple of sheets of MDF.

I hope to get started soon, I realize its probably cheaper to have the front baffle made for me and do the rest myself. I'll probably be getting a circ saw and a decent guiderail at the end of the month.

Zener,

Any chance of a shema of your crossover? Its know its not the + or i version but its a starting point, and cheaper than buying a + upgrade kit.
 
Hi everyone!

I just got back from Latvia and found a nice package had arrived....

PMC FB1+ crossovers!!! Ok, theyre a bit kanckered, I was lucky enough to find - while googling - a thread on AVforums where a guy had suffered hi-fi sabotsage at the hands of his daughter. She'd thrown a party while Dad was away and managed to fry his crossovers. I asked if he wouldnt mind sending me the busted networks and here they are.

At first glance it I can see 3 resistors that are fried and it looks like the HF caps are cooked too. Fortunately the markings are still readable on the caps and resistors. I'll de-solder the components soon and have a look at the PCB, seems ok though, just a little scorched. Big respect to PMC for using Solen MKP's on the HF section. Will post some pics soon.
 
Right here are the pics of the crossovers. As we can see it appears that just 3 resistors and 2 caps need replacing.

l_76bad8436bbd1777e92384111530fa43.jpg


The PCB is dual sided and looks to be ok. The underside of the crossover with the worst damage is a little cracked, but I cant actually get to it it without de-soldering first. The problem is that there's alot of hot glue in the way. A freind once suggested freezing it with freeze spray or something, this makes it brittle so it can then be chipped off, apparently. Anyone tried this or is there a better way to remove it?

Anyway, at the very least I have a circuit to copy and all the neccesarry values are shown clearly in the photo below.

l_9bc0b6a9dd87508d930ddf79590ab6d9.jpg


One other thing I've noticed is that the coils look a bit messy. I'd expect perfect and neat windings in a speaker costing over a 1K. Is this a problem? Should I remove them and tidy them up?

Many thanks to Glenn of AVforums for kindly donating these crossovers. Top bloke.
 
looks like warranty repair to me :):):):)
I love seeing stuff like this you know it must of been a ROCKING party for a while !!!!!!!
 
OK, lets list the component values that are clear.

Electrolytic cap 20uF, 100V - should be OK, but replace to be safe.
Poly cap 3.3uF, 400V - I'm sure this will be fine.

All resistors 7W.
2.7 Ohm - both look OK, but probably replace to be safe.
6.8 Ohm - both sad
56 Ohm - one sad, one visually OK. Replace both to be on the safe side.

Two ferrite cored inductors. These are not marked in value, and probably the easiest thing is just to recycle them. I don't think minor unbundling of the last turn of wire is either here or there.

To damage a 56Ohm 7W resistor they must have had some real stick - the main drivers must have been absorbing well over 50W average for some time!
 
Thanks PD.

Yeah, apparetly one of the woofers suffered a blown voicecoil!

Im not sure the Solen caps are ok, they look like they've suffered heat damage but it could be that just the outer plastic has melted and internally theyre fine?

How about removing hot glue then? Any suggestions?
 
When I took the same parts off my DB1 xovers I used a sharp modelling knife to slowly cut under the hot glue, and once I had leverage prised the parts off - no pcb damage.

There's no doubt better ways of going about it!
 
mikesnowdon said:
Im not sure the Solen caps are ok, they look like they've suffered heat damage but it could be that just the outer plastic has melted and internally theyre fine?
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I think the Solens have got some smoke on them from the burning resistors, but have no idea if they are effected inside. At a minimum, check with a DVM that they are not short circuited; if not there is a good chance that they are OK.
 
Depends if you're keeping the pcb, or going to do a separate external hardwired XO, which is probably what I'd do in this case. Then you're not tied by cap size and can experiment. My DB1s had a 10uf electrolytic where you have a 20uf and a bennic PP cap on the tweeter. The pcb looks identical. The pcb had just enough space to fit a 10uf bennic PP, but they are pretty small compared to other PP caps. I bought my mills resistors and PP caps from partsconnexion - take a look at their site/prices and make a judgement call on the caps. Solen are pretty cheap so may be a good starting point, with a view to trying out other caps in the future.
 
Another source for crossover caps and parts is Wilmslow (despite the appalling site).

I would second JE's suggestion of rebuilding hardwired, rather than trying to salvage the PCB.
 
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