JPW P1 Doc Mods

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Quarknosis
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JPW P1 Doc Mods

Unread post by Quarknosis »

After a few weeks of working on the cabinets of a pair of JPW P1 speakers and lining them with 5mm steel plate I have finally managed to get the drivers and crossover back in and have a listen. The mid/bass drivers and crossover were transferred over from the another pair of P1s to keep things reasonably consistent. I wanted to put the original crossover back in so that I have a comparison with the previous speakers rather than going straight to the 3.3uF cap and 12ohm resistor.

The cabinets also had the tatty vinyl veneer peeled off, the grille lugs removed and the holes filled. They were then painted with satin black. This has given me a pair of speakers that I think look better and more purposeful than the original boxes. The appearance seems to match the weight of the speakers in my opinion. All of which would be of little importance if they didn't sound any good.

Image

I have been listening to Gregory Porter's Be Good CD a lot lately and listened to it before and after the changes. Initial impressions are very good but surprisingly the first thing that I noticed was an improvement in the sound of a high hat which sounded more realistic than with the previous pair of P1s that I had been using. I was expecting the first thing that I would notice would be a less bass but I'm not sure how to describe it. It is as if the bass is less prominent and possibly slightly less extended. As I said difficult to describe and I feel that I will miss it. However there have good been improvements in clarity and soundstage width and depth and positioning of images, tonality seems to be better as well.

Next stages will be to listen to these for a while and get the new caps and resistors fitted to the spare speaker binding plates that I have, ready for listening without inductors.

In between the 2 versions of the P1s I did put my JPW AP3s in for a short while. I found the AP3 very nice, a bit warmer than the either of the P1 pairs and with more detail. The AP3s have recently had the crossover caps replaced with original spec electrolytics , the P1 crossover still has the original electrolytics in place. Also the P1 drivers aren't to original spec, they were fitted with rubber surrounds in place of the original foam. Could these differences account for the increased detail of the AP3s?
Main System. Amp - Luxman LV-120, CD - Pioneer PDX505 & Hitachi DA 401. Turntable - Trio KD-2055/Denon DL-110 & Ortofon VMS20E. Cassette Deck - JVC KD A55. Speakers - Arcam Alpha connected with NVA LS3.

Headphone System - Little Dot Mkiii headphone amp, various vintage CD players into NVA P50 with Sennheiser HD600 and Beyer DT 880

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Dr Bunsen Honeydew
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Re: JPW P1 Doc Mods

Unread post by Dr Bunsen Honeydew »

What you are used to is false bass, technically frequency or bass doubling due to energy being held, almost like low frequency reverb. You don't have it anymore. If you want more bass move the speaker closer to the wall.

Don't ever use electrolytic capacitors in speaker crossovers.

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Re: JPW P1 Doc Mods

Unread post by Dr Bunsen Honeydew »

IMO old fashioned paper in oil are best, but huge and hard to find now.

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Quarknosis
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Re: JPW P1 Doc Mods

Unread post by Quarknosis »

I've got some Clarity caps already. I have always found them to be very clear :mrgreen: they are also quite large in diameter. I'll try these first anyway and I can always give the Ansars a try later.

I've stuck with electrolytic caps in the JPWs so far because of a lack of space to fit polypropylene caps on the binding post box, although I have used them in other speakers. Without inductors it's going to be a lot easier to get the larger caps in.

I was getting used to the bass as listening went on but I haven't tried moving the speakers closer to the wall yet, there's not a lot of space anyway, probably about 8 inches between the speakers and the wall at the moment.
Main System. Amp - Luxman LV-120, CD - Pioneer PDX505 & Hitachi DA 401. Turntable - Trio KD-2055/Denon DL-110 & Ortofon VMS20E. Cassette Deck - JVC KD A55. Speakers - Arcam Alpha connected with NVA LS3.

Headphone System - Little Dot Mkiii headphone amp, various vintage CD players into NVA P50 with Sennheiser HD600 and Beyer DT 880

Daniel Quinn
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Re: JPW P1 Doc Mods

Unread post by Daniel Quinn »

What you describe was my experience , but if you listen , it is because the music is cleaner , it is easier to follow the drums and bass guitar , there is less box induced musical artefact .

if you do play something with drums on it they sound better, more musical and real.

edit - you do not need a crossover board ,if you are going to go the whole hog and directly couple the bass driver and just have an inductor and resistor on the tweeter. Just hot glue them to the floor of the speaker when all is wired up.

of course you can always get rid of the terminals and hard wire the lot . :grin:

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Quarknosis
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Re: JPW P1 Doc Mods

Unread post by Quarknosis »

Thank you for the suggestions. I'll probably keep the binding posts but everything will be hard wired internally.

DQ, can you tell me how much difference there is in size between the original JPW driver and the Doc Mod version and how you fixed it in place please.

I think the P1 is the same size as the AP2 but doesn't have the bitumen damping inside. The AP3 is larger and has the damping and is much heavier than the P1, more than you would expect from the difference in size so those bitumen panels must be quite heavy. I would estimate that my steel lined speakers are about 12-15kg so the steel lined AP2 would be even heavier.
Main System. Amp - Luxman LV-120, CD - Pioneer PDX505 & Hitachi DA 401. Turntable - Trio KD-2055/Denon DL-110 & Ortofon VMS20E. Cassette Deck - JVC KD A55. Speakers - Arcam Alpha connected with NVA LS3.

Headphone System - Little Dot Mkiii headphone amp, various vintage CD players into NVA P50 with Sennheiser HD600 and Beyer DT 880

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Re: JPW P1 Doc Mods

Unread post by The Permed One »

'P1'/'AP1'/'AP2' are all the same bass units..

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Quarknosis
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Re: JPW P1 Doc Mods

Unread post by Quarknosis »

The Permed One wrote:'P1'/'AP1'/'AP2' are all the same bass units..
So has the AP3, I believe all the tweeters and crossovers are the same too, just differences in cabinet dimensions and damping in that range. It was buying my first pair of P1s which eventually led me to NVA, wish I'd done it years ago.
Main System. Amp - Luxman LV-120, CD - Pioneer PDX505 & Hitachi DA 401. Turntable - Trio KD-2055/Denon DL-110 & Ortofon VMS20E. Cassette Deck - JVC KD A55. Speakers - Arcam Alpha connected with NVA LS3.

Headphone System - Little Dot Mkiii headphone amp, various vintage CD players into NVA P50 with Sennheiser HD600 and Beyer DT 880

Daniel Quinn
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Re: JPW P1 Doc Mods

Unread post by Daniel Quinn »

"DQ, can you tell me how much difference there is in size between the original JPW driver and the Doc Mod version and how you fixed it in place please. "

They fit fine. The only problem is the frame for the drivers as a smaller diameter, It is about 5mm smaller and so they do not fit the original screws holes and leave these exposed . This was a slight problem for me ,because mine are light oak veneer and so I filled them in with appropriately shaded wood filler. With your being black painted it will be somewhat easier to fill in and hide .

I fixed then in place with a combination of wood screws and sealant to make them air tight .

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Re: JPW P1 Doc Mods

Unread post by Dr Bunsen Honeydew »

Not needed just use Bison Kit to fit the drivers.

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