JPW P1 & AP3 advice please

[rossman]

I wasn't sure whether to put this here or in Past Masters so apologies if this is the wrong place.

Over the last few weeks I have managed to pick up 2 pairs of JPW speakers. The P1s were from a local ebay auction and on initial listening the tweeters sounded a bit "hot", a few hours of use seemed to get rid of the problem and they have had the original woofer surrounds replaced with a rubber kit. Overall I am impressed with these speakers but couldn't help wondering if they would be better with foam surrounds. As I didn't want to mess with these I had a bit of a search about for some other JPWs.

I found a pair of AP3s with knackered foams that didn't sell on ebay and after a few emails a price was agreed providing I was willing to collect. As it was a mornings round trip and fuel cost less than postage I was happy to do this.

I've had a look in the AP3s this morning and they have been wired internally for biwiring, I will probably revert to single wiring as I only use single wire cables. It will be easier to use links between the two pairs of binding posts but I am wondering if there are any advantages to hard wiring internally. The bass sections of the crossovers are on the lower terminal panel and the treble sections are on the upper panel so it could be awkward to do. Any tips or advice here?

The wires to the drive units are soldered in place, is this how they would have been done originally or would they have had female spade connectors like I have seen in several other budget speakers? I would consider replacing the wire with some Talk 3, which is my speaker cable, if it is not too thick to use easily. However I am concerned about de/soldering causing damage to the tweeter because the wires are soldered very close to the body rather than on the spade terminals. My soldering abilities are ok but not great.

I am a bit torn about how to go about replacing the mid/bass. I have thought about buying a foam kit and having a go myself but I'm not sure if I would be able to make a good job of it (I've read a few threads about refoaming and I am still unsure). I have also considered buying new drive units from Falcon Acoustics and getting some Clarity Cap caps at the same time. The advantage of doing it this way is that I am much more likely to do the job, if I go the DIY route there is the possibility that the speakers will just stay in the garage and not get repaired. But then new units would cost about £100 more per pair. Can anybody comment on any other pros/cons of getting new drive units or suggest anywhere that the job can be done in the NE.

Once (if) I get the AP3s repaired I will put them on the same stands that I am using the P1s on at the moment (Atacama SE20) until I decide if they deserve a better stand.

Thanks in anticipation

[istari_knight]

Having owned quite a few pairs & messed around with the innards of most of them I would suggest:

Bi-wire using external jumpers.

Dont bother re-wiring, the stock cable is perfectly fine.

The drive unit connectors are soldered, that is normal.

Either buy new foams from Good-Hifi/Audiofriends in NL & fit them yourself/ask for help on here... I'm sure someone will offer to help you do them [quite a few members here have re-foaming experience.] If you decide not to refoam, replacement drivers can be purchased from Puresound.

While you're in there, replacing the series tweeter capacitor is very worthwhile, they are 4.7uF and pretty much any film cap will be an improvement.

Foams: http://www.ebay.co.uk/itm/2x-Foam-Surround-JPW-AP1-AP2-AP3-THE-RIGHT-ONE-/360377181186

Puresound: http://www.puresound.info/id2.html

[Macca]

Memory is hazy but didn't the AP series use rubber surrounds on the mid/bass? Was there earlier and later versions that used different mid/bass units? In any case worth getting them up to scratch I always rated them pretty highly for a 2-way.

[rossman]

Having owned quite a few pairs & messed around with the innards of most of them I would suggest:

Bi-wire using external jumpers.

Dont bother re-wiring, the stock cable is perfectly fine.

The drive unit connectors are soldered, that is normal.

Either buy new foams from Good-Hifi/Audiofriends in NL & fit them yourself/ask for help on here... I'm sure someone will offer to help you do them [quite a few members here have re-foaming experience.] If you decide not to refoam, replacement drivers can be purchased from Puresound.

While you're in there, replacing the series tweeter capacitor is very worthwhile, they are 4.7uF and pretty much any film cap will be an improvement.

Foams: http://www.ebay.co.uk/itm/2x-Foam-Surround-JPW-AP1-AP2-AP3-THE-RIGHT-ONE-/360377181186

Puresound: http://www.puresound.info/id2.html

Thank you James.

The stock cable does look to be of reasonable gauge and quality. I think that any benefits gained by changing the wire might be outweighed by possibility that my soldering might not be of the same standard as those already in place. The P1s don't leave me thinking that the wiring is a problem. It looks like the original wiring is staying then :thumbsup:

It would be great if there is someone fairly local that could help me out. I also forgot to ask if there is preference to the type of adhesive to use. I would consider contact adhesive for a better bond over PVA type but that would reduce working time and be less forgiving if a mistake is made, at least with PVA there is more chance to make adjustments.

As far as cap replacement goes, I wouldn't go any more expensive than Clarity Caps from Falcon (approx. £12) but I've also been thinking about Monacor and Solen or possibly something from ebay. I assume that they are best hot melt glued in place. In the past I have been able to tie wrap caps in place and not used hot melt but I can't see where I could attach a tie wrap in this case.

[rossman]

Memory is hazy but didn't the AP series use rubber surrounds on the mid/bass? Was there earlier and later versions that used different mid/bass units? In any case worth getting them up to scratch I always rated them pretty highly for a 2-way.

Hi Martin,

Sorry, I must have been typing at the same times as you were replying. If I remember correctly, the guy that I bought the P1s from said that they were foam originally, but my research has shown a few people that have thought that later drivers had rubber surrounds. My P1s look like a later pair though, I think that they are vinyl wrap rather than real wood

[Macca]

Hi Martin,

Sorry, I must have been typing at the same times as you were replying. If I remember correctly, the guy that I bought the P1s from said that they were foam originally, but my research has shown a few people that have thought that later drivers had rubber surrounds. My P1s look like a later pair though, I think that they are vinyl wrap rather than real wood

That would explain it then. I acquired some AP2 for the wife of a friend and was quite upset that they were massively better than the B&W I was using at the time. She was smart enough to decline my offer of a straight swap too.

[istari_knight]

I always use PVA - This stuff to be exact: http://www.ebay.co.uk/itm/Anitas-Tacky-Glue-60ml-/291134077354?pt=UK_Crafts_Cardmaking_Scrapbooking_ Glue_Tape_EH&hash=item43c8f179aa

I tried contact adhesive once & its a complete PITA... If PVA is good enough for wood then its good enough for some paper & foam IMO ;)

Capacitor wise I'm fond of Jantzen "cross caps" they tend to have a smooth sound that really goes nicely with the vifa polyamide domes which can be a little spitty... They're also really cheap which is a bonus !

[Reffc]

Bear in mind Paul (this IS important) that if the original crossover uses electrolytic caps, you'd be best replacing those like for like as if using polys in place of electrolytics, the ESR (equivalent series resistance) is much less and this WILL shift the crossover point and could ruin them. You can add a small series resistor in line with polys but you have to be pretty sure of the ESR difference between them. 1 Ohm difference in series for the HF will result in a significant shifting of crossover frequency. Some speaker designers used electrolytics to employ a small degree of electrical damping for resonant circuits too. If the originals are polyprops, then you're safe to do a like for like value swap. ESAa are great in the signal path. Out of the signal path (ie shunted between rails) ordinary Solens or other inexpensive polys work just fine and will save you money. Just my advice but ultimately it's your project so enjoy!

[rossman]

I always use PVA - This stuff to be exact: http://www.ebay.co.uk/itm/Anitas-Tacky-Glue-60ml-/291134077354?pt=UK_Crafts_Cardmaking_Scrapbooking_ Glue_Tape_EH&hash=item43c8f179aa

I tried contact adhesive once & its a complete PITA... If PVA is good enough for wood then its good enough for some paper & foam IMO ;)

Capacitor wise I'm fond of Jantzen "cross caps" they tend to have a smooth sound that really goes nicely with the vifa polyamide domes which can be a little spitty... They're also really cheap which is a bonus !

James, it looks as thought that adhesive would give neat and accurate gluing to the cone. If I go with DIY I will get some.

I have had Jantzen cross caps in the past but I wasn't impressed with their build because the lead out legs weren't centred which didn't inspire confidence. I've used Clarity Caps in some modified Wharfedales

Paul, I believe that the caps in the AP3s are electrolytics. I'd be willing to give some PP caps a go, I can always go back to an electrolytic if I needed to. If I replace with electrolytics first I will have a reference to compare with. Is there a minimum rating required for crossover capacitors? Would an upgraded JPW crossover using poly caps be something that you could make?

[istari_knight]

Re crosscaps: fair enough, I'm yet to get a bad one bad as you've found YMMV.

Re 'lytic vs film: Cant disagree with Paul there but the AP range isn't an unknown quantity, a Google search will reveal dozens that have upgraded to a film in that position & liked the improvement.

[rossman]

Having had a think about refoaming, I was wondering if there would be any problem leaving the drivers unsupported at the edges for a couple of weeks if I remove the existing foam from the surrounds and edges of the cone. At the moment the foams seem to be giving a little bit support to the cones but they do seem as though they should be able to support themselves.

If I can safely go ahead and make a start without concerns about the cones sagging it might give me the confidence to go ahead and do the rest myself.

[istari_knight]

The last one's I did were without surrounds for 2 weeks until the foams arrived & I got around to doing it... So yeah, they'll be fine.

I find isopropyl alcohol works very well on the metal basket for removing the gunk but don't put any liquids on the cone surround, usually a bit of careful scraping with a Stanley blade is enough for that.

[rossman]

The last one's I did were without surrounds for 2 weeks until the foams arrived & I got around to doing it... So yeah, they'll be fine.

I find isopropyl alcohol works very well on the metal basket for removing the gunk but don't put any liquids on the cone surround, usually a bit of careful scraping with a Stanley blade is enough for that.

Good news regarding the cones. I work 12 hour shifts so won't be able to get started for at least another week, I won't be rushing anything.

I'm all out of Isopropyl at the moment and don't really have plans to get any more, I'll see if there are any suitable alternatives in the cupboards.

[rossman]

I managed to get away from work earlier than expected today and have removed the remainder of the existing foams this afternoon. I've gone ahead and ordered some new foams from audiofriends. Hopefully they will arrive before next Monday as I should have the whole day available to do the rest of the refoaming. I'll make sure that the cones are operating well before doing anything about the caps.

[istari_knight]

Nice one. FWIW you don't need to remove the dust caps & shim the voice coil... You can if you want but it makes a mess of things. Far easier is to connect a bit of wire to the spade terminals & using a 1.5v battery repeatedly touch the wires against the battery contacts "pulsing" the cone... This helps centre the cone & prevents the voice coil from rubbing. I've refoamed eight pairs of speakers using this method & it never fails ;)

[rossman]

My Audiofriends kit arrived today.

Fitting to the cones went better than I expected. I did use a battery to centre them and after allowing the glue to dry for a few hours the drivers don't seem to be rubbing anywhere when pressed. Overall the appearance is better than I thought would be possible from a kit.

I should be able to get the drivers refitted to the AP3s on Friday and try them out.

If I think that they are better than the P1s after I have listened for a few weeks, I'll have to look at getting some suitable stands.

[The Grand Wazoo]

Well done Paul.

[istari_knight]

Nice one, but... :worthless:

:D

[rossman]

Nice one, but... :worthless:

:D

I know, unfortunately I didn't take pictures during the repair as most of the things would be just rehashing what is available elsewhere. Also I don't tend to spend much time behind a viewfinder at all. However I will put up some pics of the AP3s in situ when I have some spare time.

In the meantime though the speakers are in place on top of the same Atacama SE20s that the P1s were on. I have just listened to Jimmy Smith - Main Title Theme From The Carpetbaggers and it sounded the best that I have ever heard it. Listening to a few tracks previously the AP3s have better dynamics and much deeper bass when it's there on the recording, as would be expected, but this doesn't overwhelm anything higher up the frequency range. Bass also has more texture so it's not just depth that is improved. To me these are better than the P1s as they do everything that they do but with bass improvements that I was looking for when playing electronic music.

It's early days yet as I have only been listening for less than an hour but I don't think that there is any doubt that these will be staying unless there are huge objections from my wife. They are a bit larger than the P1s (but not by much when viewed from the front) which she already thought were too big. I'm just waiting to see if she makes any comment. They obviously stand a bit taller than the P1s on the same stands but I might be looking for a shorter pair anyway which will help them fit in a bit better visually. However as I look at them more in the position that they are now the more "right" they appear to be, plus the tweeter height is pretty much spot on. Anyway that will be for later once I have listened for a week or two.

[myles]

Paul, how are you finding the AP3 after these few months? I have a pair of them in the garage and am waiting on a set of foams to do exactly what you have done.

[fatmarley]

After reading the Classicspeakerpages (http://www.classicspeakerpages.net/IP.Board/) I found out that not all replacement foams are made equal, so ordered a pair from Goodhifi (ebay) and a pair from speaker-repairs (http://www.speaker-repairs.co.uk/). The ones from Goodhifi weigh more and were less compliant than the ones from speaker-repairs so I fitted the ones from speaker-repairs. Once dried I measured the Thiele/Small parameters and found that they were a good match for the data sheet.

The other thing to consider is the the gunk that's applied to the edge of the foam on a new driver. Someone on another forum did some distortion tests on a speaker before and after applying some 'gunk' and found distortion was lowered with it. When you replace the foam on an old driver the 'gunk' (looks a bit like silicone) usually peals away when you remove the old foam surround.

The best person to talk to about JPW speakers is Guy from Puresound (http://www.puresound.info/catalog/i25.html). He sells replacement drivers and from what I've seen over at Hifiwigwam, can upgrade the crossover. My guess is he uses something similar to the one used in the Snell k because the K uses the exact same drivers.

[fatmarley]

Oh, and if anyone sends me some old JPW woofers I could fit the foam surround from Goodhifi (I still have them) and compare the frequency response of them to the ones with the speaker-repair surrounds. I could also test the Thiele/Small parameters.

[spendorman]

Thank you, very interesting as I have a pair of of AP3's and a pair of AP2's, that both need new surrounds. In fact, I seem to remember that one bass unit has a damaged voice coil, so may only be able to get one pair working without getting a spare bass unit.

I remember many years ago, comparing the AP3's to Spendor BC1's at home, and I was surprised how good the Ap3's were.

[pure sound]

I am regularly contacted by people who've refurbished these drivers. Sometimes they are happy with the result but as often they aren't. Whether this is because the replacement surrounds have a different formulation or profile or whether it's simply because they haven't centred the voice coil in the magnet gap well enough I don't know. Incorrect alignment will cause an increase in distortion and even buzzing/rubbing in extreme cases. The wrong foam type or poor glueing does also affect the termination at the edge of the diaphragm. Scanspeak, who make the drivers now obviously have the correct foams and assembly jigs and make the driver exactly as it always was albeit at a price. But a carefully refurbished driver with the right surrounds will also give a fine result.

Incidentally, I wouldn't recommend running these drivers for too long without intact surrounds. The cabinet will no longer be airtight but more importantly the voice coil may not be moving in and out in a purely pistonic manner. Once it starts rubbing, you'll lose the insulation on the coil wire & possibly either send the coil open circuit or even possibly present your amp with a short circuit. Once the surround has cracked or has holes either refoam or replace the driver.

[Beobloke]

Incidentally, I wouldn't recommend running these drivers for too long without intact surrounds. The cabinet will no longer be airtight but more importantly the voice coil may not be moving in and out in a purely pistonic manner. Once it starts rubbing, you'll lose the insulation on the coil wire & possibly either send the coil open circuit or even possibly present your amp with a short circuit. Once the surround has cracked or has holes either refoam or replace the driver.

These are wise words for any loudspeakers with foam surrounds that are past their best. I cringe every time I see any pair advertised for sale as "need new surrounds but still sound great"! :doh:

[Reffc]

These are wise words for any loudspeakers with foam surrounds that are past their best. I cringe every time I see any pair advertised for sale as "need new surrounds but still sound great"! :doh:

I'd go as far as to say never buy speakers with perished surrounds as chances are they will have been played with voice coils rubbing away merrily at some stage. If they're your own and the surrounds have perished where the speakers have been standing (but not used) that's a different matter.

[pure sound]

Scanspeak do say that the foam they use now will not deteriorate in the usual 10-15 years but will last a lot longer. I don't know if that's true as none of the units I've sold are that old yet but I expect it is. Polymer technology has moved along a good way since the 70's & 80's.