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JPW AP2s - worth repairing or not?

Rob, once again thanks .

Personally as you are aware I am appreciative of your knowledgeable perspective and the fact you are prepared to share it without obfuscation or bullshit . It wasn't my intention for this thread to drift towards epping and contrasting approaches . Room for all as far as I'm concerned ,clearly it aint a competition as I am the idiot who will decide , but whatever I decide , I am grafeful for your comments and I will make a better decision for me because of them .
 
Robert said:
If the changes are preferred then that's of course absolutely fine, I'm simply pointing out what will happen since it won't be subtle and you'll end up with something very different to a JPW.
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Indeed, and I also wouldn't like to stop anyone from experimenting accordingly. It's just I've seen the results and am familiar with having to sort the mess out when things go wrong.

As an example, I currently have a pair of loudspeakers that have been sitting unused for over two years since I acquired them. The previous owner decided to upgrade the crossover components and, in doing so, managed to reconnect the wires to the tweeters incorrectly, sending low frequencies to them and destroying them. The tweeters in question are ribbons and are rare, hence my continuing wait for a replacement pair to turn up somewhere!
 
AP2's are definitely worth repairing and certainly worth modifying as per DQ's suggestions.

They may no longer be AP2's but who cares when performance is raised to a much higher level. To anyone thinking of this I would only advise them to do it - you will not be disappointed.
 
I suspect that most regular visitors to the Classic room are more interested in the preservation and restoration of beloved favorites from years gone by.

Going all 'Jimmy Hughes' circa 1984 and ripping the stuffing out of infinite baffle loudspeakers is generally not what the collector of classics is on about.

Perhaps there should exist a Modder room down the hall past DIY?
 
"ripping the suffing out" is completely and easily reversible. Try it and if you are not impressed then simply put it all back. The additional mods whilst needing a degree of surgery serve to take things further performance wise and in no way do they alter the aesthetics of these classic JPW's.

It has been a ear opening and very enjoyable journey - one that cost less than £100 in components including SH purchase of a nice pair of AP2's.

That bloke from Epping certainly knows his stuff alright, so much so I've bought a few pairs of NVA interconnects to further the enhancement :cool:


John R.
 
Actually, I have done, if only to listen out for leaky enclosures and/or vibrating crossover components, when testing repair speakers where the drivers weren't faulty.

None sounded the better for it, but one certainly could clearly hear into the box through the bass driver cone.

Perhaps it is the early box reflections amping up the sound that appeals?
 
Thanks Craig, yours is an interesting viewpoint and perhaps not to be dismissed as it's based on your personal experience.

Nevertheless, we all differ in our subjective likes/dislikes and I also accept we all hear a particular system/speaker’s output differently which is great as we have variety and choice.

Perhaps you are alluding that removing the wadding in some way colours the speaker’s reproduction of music? If so and for the benefit of others who may wish to undertake these excellent mods, can you explain then how BAF wadding works to reduce “box reflections from amping up the sound” as I struggle to understand what these early box reflections are and how wadding affects it?

Personally, I am only really interested in the perceived improvements of recorded music replay via my system. Implementing these mods has been a revelation. I now perceive a clearer, seemingly more natural and a more detailed sound, with a wider soundstage as an additional benefit. Musicians appear to play as a band and I can hear their interaction which makes sense, it’s as if I’m on stage with them or at least very near the stage.

I have well known recordings that have really surprised me with all that this perceived clarity brings. That can only be a good thing can it not?

John R.
 
Removing stuffing will do three things:

Firstly it allows the output from the rear of the driver to be reflected from the internal walls back into the room through the cone. This reflected output is uneven and out of phase with the front cone radiation. In short it both colours and smears the output.

Secondly, the empty box allows internal standing waves to develope between the surfaces. The stuffing reduces this effect in most cases.

Thirdly, in a sealed box the internal stuffing has a similar effect to slightly increasing the box volume and this impacts (improves) LF extension.

As has been said above, some may prefer these amplitude and phase distortions.
 
Well I certainly can't be of much help beyond what Robert has succinctly provided.

Also, I've not done any critical listening to speakers with completely undamped enclosures. Quite the opposite really, as I have on occasion changed out or added damping to those loudspeakers that I found to be critically underdamped.

In particular, I'm referring to the plethora of what we used to call dealer 'house brand' speakers; these being rarely fully formed due to intentional budget constraints that made them very attractive to a certain class of dealer on a complete system package profit margin basis.

Regardless, I would be the first to agree that if your modded AP2s sound better to you then that is definitely a good thing.

Craig
 
Thank you both for your thoughts/explanations, but frankly it does not explain why my AP2's are delivering a performance that to my ears is offering a wonderful sense of clarity, additional detail and consequential musical cohesion. This was not the case prior to mods. They were a nice speaker, but now there's no comparison in my system/room/ears.

I must add that cabinet damping with these mods is handled by adding mass in the form of steel plates fitted inside the cabs which almost doubles the mass of each speaker. The fibre wadding I removed is mostly nothing but trapped air at atmospheric pressure, so how can this achieve anything in a sealed box that is already filled with air at atmospheric pressure?

Personally, given what I'm hearing now with these modified old JPW's I am quite happy to leave them as they are, but I may also damp the crossovers with Blue tac - which is also great stuff for gaskets after I've added some better quality components - would that yield further improvement I wonder?


John R.
 
Beobloke said:
Hmm, I'm going with 'No' on that one! :D
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Thanks Adam.

My tendency is to fully accept your advice on that, as another source of info and inspiration suggests likewise. :cool:

However, did not Celestion use this tweak a while back?


John R.
 
The internal stuffing of speakers can also be an attempted sop to hide the fact that, most speakers are built down to budget when it comes to the cabinet in favour of drivers and then crossovers. There are some beautifully finished speakers that ring like a church bell when you give them a serious tap even though, they are stuffed to the gills with wadding.

There are some quite expensive speakers that suffer from the "fur coat and no knickers syndrome" when it comes to the cabinet build quality. Not so much in how they are put together rather, the materials used, no matter how much you furtle with them post build are inherently weaker, ie MDF. Most of the best smaller speakers I have heard of late, are Corian, Baltic birch and usually 1 inch thick. I don't think it's a coincidence that the first thing people comment on is, "The Bass for the cab size is amazing" and there's usually, no bloat, no overhang just taut, extended bass.

Obviously, there's a law of diminishing returns and smaller drivers have their limits however, with say the JPWs, it would be fascinating to hear them moved to a pair of cabs constructed from 25mm sandwich birch with a lead lining and the crossovers moved out of the cabinets, compared to the standard boxes.
 
John R said:
Thanks Adam.

My tendency is to fully accept your advice on that, as another source of info and inspiration suggests likewise. :cool:

However, did not Celestion use this tweak a while back?


John R.
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Various loudspeaker and indeed audio electronics manufacturers have done similar over the years. Still doesn't necessarily mean it made any difference...:D
 
Beobloke said:
Various loudspeaker and indeed audio electronics manufacturers have done similar over the years. Still doesn't necessarily mean it made any difference...:D
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But isn't it fair to say that view could be applied to anything..?

We all have different opinions on how systems/equipment perform, with some agreeing a mod is good, others of course will have a differing views and that's fine an dandy we me.;)
 
If you have JPW AP2's or 3's I can vouch for the fact well worth doing the following "Doc mods"

This includes junking the BAF wadding. Lining the interior with 4 or even better 5mm steel plate, Remove the series inductor to the 8" bass/mid driver and doping the cone.

I accept these mods may fly in the face of convention and many here on pfm will strongly disagree; but given they are a low cost pair of stand mounters seriously, you will not believe the increase in detail, clarity and overall enjoyment rendered. Just don't to too far with the doping and listen to what the Doc says!

Richard Dunn of NVA is certainly onto something with these simple mods. His cables are great too with my Avondale pre- power set up.


John R.
 
I thought my AP2's and AP3's already had heavy bitumen pads glued onto the inside of the cabinet panels. Not looked inside for years though.
 
They do. No need to remove it: if they are in good nick (no reason to assume they won't be) use rubberised contact adhesive to affix steel plates of the same size over them.

But experiment first - don't do all the "Doc mods" at once! Carefully remove the wadding first and listen for a while. If you like what you hear then proceed to the next stage.

It's a fun and very rewarding journey. Will help you though it it you take the plunge!

Regards.

John R.
 
Hope it's not passe to resurrect an old thread, but to add my 2 bits, I also had the rotting surrounds and fortunately for me there is a speaker repair shop in our small town. I spent about $100usd to have them do it for me, but they did offer to sell the parts for around $15 or so. I was happy to pay the difference for labor. After reading all the recent spin about the Elac speakers, I tried a pair of the $800/pr floorstanding uni-fi uf5's to see how modern production would compare. If the Elac's garner that much praise (universally?), it makes me wonder what kind of outlay I'd need to put the hurt on the ap2's? The gap in sq wasn't subtle at all.
 
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