JPW AP2

All general audio posts go here.
Alfi
Posts: 1137
Joined: Sat Jun 08, 2013 11:01 am
Location: Kidwelly, West Wales
Has thanked: 14 times
Been thanked: 11 times
Contact:
Wales

Re: JPW AP2

Unread post by Alfi »

Sorry about that jammy but needs must, I had work to do :grin:

So coming back to my tweaking of the AP2's. Such has been the positive nature of the Doc mods I felt I should shell out for some better components...

New inductor, resistor and MKP cap - only that I changed the value of these from 4.7 uF to 3.3uF as Doc had alluded on another tread. I must add, the size of the new inductors surprised me as the ones I had from Wilmslow were 0.6mH but these appeared the same physical size as the original 1mH JPW bass driver. Obviously much thicker wire has been used for the Wilmslow ones - hopefully better quality too?

Anyhow all wired up and back in place. Oh dear- I was greeted with what appeared to be a very ponderous sound and where the timing/interaction of the drivers seemed miles out - utterly awful TBH.

I felt I'd remove the resistor and listen again. What a difference! Now we're cooking with gas, so dare I say it...?

Doc is right yet again...! 3.3uF cap, one less component in the XO and these speakers are performing even better to my ears :clap: :clap: :clap: :dance:

One question remains.... How much more can be squeezed from these humble JPW's?

I feel another NVA upgrade coming on!


Alfi.
Last edited by Alfi on Mon Mar 09, 2015 9:39 pm, edited 1 time in total.
I am in the hi-fi trade.
Status: Manufacturer.
Company Name: Analogue innovation.

User avatar
Dr Bunsen Honeydew
Posts: 30758
Joined: Wed Jul 11, 2012 7:26 pm
Location: Muppet Labs
Has thanked: 0
Been thanked: 48 times

Re: JPW AP2

Unread post by Dr Bunsen Honeydew »

If you have doped the cone properly you don't need the inductor. The bass driver should be left full range.

Alfi
Posts: 1137
Joined: Sat Jun 08, 2013 11:01 am
Location: Kidwelly, West Wales
Has thanked: 14 times
Been thanked: 11 times
Contact:
Wales

Re: JPW AP2

Unread post by Alfi »

That's the case Doc, the bass driver is sans inductor.

What I've done is to fit a new Wilmslow air core 0.6mH inductor to the tweeter after a 3.3 uF cap - no resistor at all - so only two components in the entire XO.

With the performance I'm getting now, I surely must have tuned the bass cone with dope just about right. It's magical to my ears. :shock:

Alfi.
Last edited by Alfi on Mon Mar 09, 2015 6:52 pm, edited 1 time in total.
I am in the hi-fi trade.
Status: Manufacturer.
Company Name: Analogue innovation.

User avatar
Dr Bunsen Honeydew
Posts: 30758
Joined: Wed Jul 11, 2012 7:26 pm
Location: Muppet Labs
Has thanked: 0
Been thanked: 48 times

Re: JPW AP2

Unread post by Dr Bunsen Honeydew »

Okay Dokay, just checking :guiness;

Alfi
Posts: 1137
Joined: Sat Jun 08, 2013 11:01 am
Location: Kidwelly, West Wales
Has thanked: 14 times
Been thanked: 11 times
Contact:
Wales

Re: JPW AP2

Unread post by Alfi »

Thanks Doc!


Alfi
I am in the hi-fi trade.
Status: Manufacturer.
Company Name: Analogue innovation.

Daniel Quinn
Posts: 8586
Joined: Thu Jul 12, 2012 7:16 am
Has thanked: 24 times
Been thanked: 399 times

Re: JPW AP2

Unread post by Daniel Quinn »

I'm confused by this what is an inductor going to do better than a resistor. Is this personal preference or something I should investigate ?

User avatar
Dr Bunsen Honeydew
Posts: 30758
Joined: Wed Jul 11, 2012 7:26 pm
Location: Muppet Labs
Has thanked: 0
Been thanked: 48 times

Re: JPW AP2

Unread post by Dr Bunsen Honeydew »

A resistor resists, and an inductor inducts :lol:

Capacitors and inductors are filter elements as they resist according to frequency. But they behave opposite to each other. To protect a tweeter from low frequency which would damage it all it needs is a series capacitor. If you want the curve a bit sharper in the attenuation then add a coil (inductor) in parallel after the capacitor. BUT each time you make the crossover point sharper by making the filter have more elements it start to mess with the phase (timing) of the signal, obviously in this case music, which is not a good thing.

Alfi
Posts: 1137
Joined: Sat Jun 08, 2013 11:01 am
Location: Kidwelly, West Wales
Has thanked: 14 times
Been thanked: 11 times
Contact:
Wales

Re: JPW AP2

Unread post by Alfi »

The bog standard AP2 crossover (on the tweeter) consists of a 2.4 Ohm resistor and 4.7uf capacitor feeding the tweeter via a 0.6mH inductor..

Docs philosophy majors on less components the better - yes? So I did some research and found that he also advocates a tweeter capacitor value of 3.3 uF.

No resistor in the tweeter circuit on my AP crossover anymore! Try it you may like it - I certainly do but understand it may not be for everyone in their systems/rooms but it suits mine for the time being :dance: :dance:


Alfi.
Last edited by Alfi on Mon Mar 09, 2015 7:25 pm, edited 1 time in total.
I am in the hi-fi trade.
Status: Manufacturer.
Company Name: Analogue innovation.

Alfi
Posts: 1137
Joined: Sat Jun 08, 2013 11:01 am
Location: Kidwelly, West Wales
Has thanked: 14 times
Been thanked: 11 times
Contact:
Wales

Re: JPW AP2

Unread post by Alfi »

All I know is this..

If the Volts don't Volt and the Amps don't Amp then you're buggered :lol:

I'll leave the clever stuff to the Doc and "Hoover" up his advice. :guiness;

Alfi.
I am in the hi-fi trade.
Status: Manufacturer.
Company Name: Analogue innovation.

User avatar
Dr Bunsen Honeydew
Posts: 30758
Joined: Wed Jul 11, 2012 7:26 pm
Location: Muppet Labs
Has thanked: 0
Been thanked: 48 times

Re: JPW AP2

Unread post by Dr Bunsen Honeydew »

Mr Volt, Mr Faraday, Mr Ampere, Mr Henry, No Mr Resistor I am afraid. It is electrical immortality :mrgreen: Will Doc Mods ever achieve it, will it be measured in Dunnys (ask an Oz :lol: )

Post Reply