N804 phase plug upgrade?

[watchthewaves]

Wondering whether any N804 users have upgraded their plastic phase plugs for the mid-range unit to the aluminium ones of the Signature series? Any discernable improvement in audio quality?

Is this a simple DIY upgrade of unscrewing the existing phase plug and screwing the new one on?

Finally, I have someone visiting me from the US next month, so I was thinking of asking that person to hand carry it back for me. Would any of you all in the US be able to let me know whether I can order (via Internet or phone) for delivery in the US (Fremont, CA) and approximately how much it would cost? (Recall sikiniko saying it might be around $80, is this correct?)

Thanks.

[Fife]

You can always get the Copperhead upgrade from Japan.
AC2 in Japan..translated in English
Costly though.

[junior77blue]

That's just gotta be cosmetic...

[sikoniko]

Nope. it stiffens the driver. Ive read somewhere that it does make a difference. I don't know anyone who has done it though.

[zaza4]

Stiffens the driver?

How? The phase plug doesn't even touch the driver.

That copperhead plug looks cool but does it really change anything? I'm sure there are different resonance properties between plastic, aluminim and copper. Anyone know?

[junior77blue]

I'm with you on this one Zaza.

Purely cosmetic...

[hillen]

B&W found that aluminium is the best material, better than copper or other metals.
It influences the inductance of the voicecoil. I replaced the bullets ( of the 802 midrange ) by the original Alu ones of the Sig 800, removed the paint ( very important, because then the Alu is making direct contact with the pole ), and was stunned while listening. Its a giant LEAP forwared. Much smoother, more impulsive, less distorted sound!!!!!!!!!!!!!!!!!

[junior77blue]

How does aluminium an non-magnetic material influence inductance?

[DanR]

Give me a break! Have any of you even thought what a phase plug does? It simply keeps the sound waves from colliding at a point in front of you. Any surface, be it plastic, metal, wood, glass etc. will defract sound waves. It does no more or less. And yes, aluminum is non-ferrous, so how in God's green earht can it influence inductance?? The signature series uses metal because of the perceived "cheapness" of plastic and people paying that kind of money don't want plastic parts. If it was a true upgrade, don't you think more companies- or B&W itself would sell them for non-Signature lines?

[junior77blue]

Thank-you Dan!!!

My Thoughts Exactly!!!

[RobP]

You do have to take in account the resonance factor of the different types of phase plugs, each different type if tested, would all show different characteristics, which could change or color the sound slightly. I am sure that B&W has already taken this in to account in their design.

[ti33er]

...this is an interesting thread, if anyone does go ahead and do this I would like to know what the outcome is!? - regardless of sound that copper head does seem quite attractive, nice tweak - personally I would prefer a silver alloy over the copper look, but that is just me!

[caleb]

Cheapest way

How about this for another argument.

Try taking the plastic plug out completely and have a listen - i can find sod all difference to at 80$ for the aluminium ones you must have more money than sense.
Caleb

[sikoniko]

taken from the SCMS notes...

The system comes complete with a custom wall bracket that allows angular adjustment in both horizontal and vertical planes.

go figure...

[sikoniko]

wrong thread... doh!

[ti33er]

I dont know if this applies, but I found out today (by pressing things) that the phase plug actually MOVES with the entire cone on the new S805 / HTM4 ....I don't know if this will be very good seeing as alloy is heavier than plastic?

[junior77blue]

I believe the phase plug only applies for the FST mid-range.

[watchthewaves]

So does the material really matter?

More info that I've uncovered:

FWIW, I checked with the HK distributor and their view is that the material of the phase plug does not affect the sound quality. It is the shape of the phase plug that matters.

I also took a look at the Signature 800 manual and this is what it says:

"Fitting the midrange grille:
A grille is supplied in the accessory pack to
cover the midrange drive unit if desired.
Fitting the grille also requires the centre
bullet of the drive unit to be replaced by the
alternative version with a hole in the tip
from the accessory pack.To fit the
alternative centre bullet, simply unscrew the
fitted part and screw in the replacement,
taking care not to damage the voice coil
former. Hand tighten only."

And the Signature 800 white paper says:

"In addition to the reducing source effect described in
Appendix I, the dispersion of the drive unit is improved
by the use of a bullet-shaped plug protruding from
the centre pole of the magnet. To complement the
aesthetics of the system, an aluminium plug is fitted
on delivery, but the original plastic version of the
Nautilus™801 is supplied should it be required to
secure the optional midrange grille."

And the 700 series white paper says:

"Because of the lower excursion in a midrange
driver, distortion created in the motor system is
inherently lower than in bass or bass/midrange
drivers. Nevertheless, the centre pole has a layer
of copper and the aluminium centre bullet also
helps control variations in voice coil inductance.
The result is a driver with unparalleled levels of
detail retrieval."

and,

"The second stage came out of work to
investigate how and why the sound of drivers
was affected by the material used for fixed centre
phase plugs. It consists of adding a disc of
aluminium to the pole tip and the induced eddy
currents further affect changes in coil inductance.
The graph (figure 10) shows the line gradient
reduced virtually to flat and it is one of the rare
cases that one can actually claim that a type
of distortion has been truly eliminated, rather
than simply reduced.
It is the combination of copper cap and
aluminium disc that constitutes Balanced Drive
and it is new to the 700 Series. The reduction
in intermodulation distortion is a major factor
in the improvement in detail retrieval and realism
shown by the drive units compared to equivalent
older designs."

What does this all mean? That B&W initially thot that using aluminium for the phase plug was just aesthetic, but by the time they did R&D for the 700 series, they found that the material does matter? For those more technologically knowledgeable, could you comment on the last excerpt above from the 700 series paper?

[caleb]

B&W advice

I spoke to the techincian at B&W yesterday about the phase plug.

He said that it was not available from them as an accessory, but could be supplied to dealers if owners have lost them or damaged them (does this make sense?)

He talked about the aluminium plugs giving Subtle differences, smoothing frequencies and all the other marketing bullsh#t that these people use.

As I said before - try taking the plastic ones out and listenng without them - then save your money.
Caleb

[georgev]

? More Psychoacoustics

I had a chat with the B&W importers/distributors(who incidentally have a pair of 802Ds) about this plug.
I quote "You would be wiser investing your money in some good Cd's".
This coming from the importers............ Makes one wonder and marvel at the power of the mind.
They do not have any in stock to let me try out before I make such an investment. They obviously do not think it makes a difference.

[Jason R]

Hi george nice to see a post from you. And must agree dropped my proceed off for repair and enquired about a new levinson amp, its coming soon is all i got, some things never change, Frustrating.

must get together sometime and have a listen your gear, sure its sounding superp.

[caleb]

AC2 in Japan

Hi all you Forumers in Japan.

I tried the AC2 site and sent a mail asking about the price of the copperhead conversion for my 802's but got a reply that they don't ship out of Japan.

Anyone there like to make an enquiry and let me know the price?

Thanks
Caleb

[DrBoom]

If anyone is still interested in aluminium phase plugs, there's a german site that sells them too (not the copper version) and I do believe they ship worldwide.
You can find them here, they cost €49 ($40 or so) per pair, and €159 for the gold plated version.

[KEF]

What does engineering tell us?

And yes, aluminum is non-ferrous, so how in God's green earht can it influence inductance??

Case in point, not to pick on anyone - I am not going to argue that these phase plugs do or do not make a difference, but I can accept the fact that they may based upon what engineering tells us.

and I quote:

"The type of material the wire is coiled around greatly impacts the strength of the magnetic field flux (and therefore how much stored energy) generated for any given amount of current through the coil. Coil cores made of ferromagnetic materials (such as soft iron) will encourage stronger field fluxes to develop with a given field force than nonmagnetic substances such as aluminum or air.

The measure of an inductor's ability to store energy for a given amount of current flow is called inductance. Not surprisingly, inductance is also a measure of the intensity of opposition to changes in current (exactly how much self-induced voltage will be produced for a given rate of change of current). Inductance is symbolically denoted with a capital "L," and is measured in the unit of the Henry, abbreviated as "H." "

My point is simply this: a material does not need to be ferrous or magnetic to affect inductance. As an example, many aluminum rolling mill use eddy current flaw detectors to scan for surface defects.

One can imagine how a phase plug change to Al or Cu could alter the way the mid range driver reacts to the current pumped through the coil. Do I know that it does, absolutely not, I've done no testing - but it might. Since none of us here have the equipment to test these things, IMHO, letting our ears determine wether or not it does is far better than stating things as "fact" that we really don't know or understand -

KEF

[watchthewaves]

Response from B&W

In case anyone of you missed Bram Hillen's post on page 9 of the sticky "New B&W Nautilus Range" regarding B&W's response on this phase plug issue, here is the link:

http://www.htguide.com/forum/showthread.php4?t=10031&page=9

Seems they do hear a difference too but can't measure any difference though.

[caleb]

Now convinced

I had been a sceptic about these phase plugs, and not wanting to go buy at 100 Euro incl postage, I got my engineer to make a set for me using the plastic ones as a template.

They came out of the engineering shop absolutely perfect and polished to a mirror shine.

They look real good in the midrange units instead of the normal black plastic, but now for the good news - they do improve the sound quite noticeably.

The midrange is noticably smoother and more "open"..

The cost? - About 10 US$ ! ! ! !

A question though - is the improvement worth 100EURO? - maybe not ops:

I am getting more made for my 805's now that I am convinced.

Caleb

[weijst]

I am getting more made for my 805's now that I am convinced.

Uh Caleb,
Remember the phase plug 'upgrade' only applies to FST midrange featured speakers (e.g. your 802's and HTM1). I don't think cutting out the phase plug out of your N805's is a wise idea...

[jlee]

weijst,

The old N805, HTM2, SCM1 phase plugs are not attached to the driver. The new 805S, and all non-FST 700 and 800 series have the phase plug attached.

[weijst]

Ok sorry guys, so much for my usefull input .

[sikoniko]

Would you be willing to make a few extras to sell to members of this board? Id give you $100 for 5 of them...

[caleb]

Would you be willing to make a few extras to sell to members of this board? Id give you $100 for 5 of them...

Just let the forum members who want them let me know and we can get some production going.

More I get made and they might get cheaper.

I will wait for a week to see how many are needed.

Caleb.

[RobP]

Caleb, I would be interested in 10 of them. :T

Thanks
Robert P

[gostan]

Caleb:

I would be interested in five.

Stan

[springer49]

Caleb, I would also be interested in 5. Let me know

[Phil Rose]

Caleb,

Depending on the cost and shipping, I'd also be interested in 5. Please advise.

Thanks,

[Jeff]

Depending upon total cost. I would take 2.

Thanks

[Levandier]

I would take 2 as well.

Thanks

[caleb]

32

Hello guys
I count 32 needed so I will make 40 so we have some spare for the "late comers".

Will let you all know when they are ready so we can arrange the deliveries etc..

Thanks for the response.

Caleb

[turbokuo]

2 for me!

[audiofun]

caleb,
can you take a pic on your kelvar with the plug? I want to see if they look good. 2 for me if the plugs improve the look.
thanks
audiofun

[rays]

Really glad to read this post and this really surprise me as I owned 804 for nearly 4 years and I never think of this possibility or making use of phaseplug.

Could you reserve two for me (send to Boston).

Many thanks.

Rgds,
RS

[DanR]

Just spoke with a tech from B&W's US National distributor in Massachusetts and he said that the phase plugs for the Signature Series are graphite, NOT aluminum. The reason for the graphite is heat dissipation, not inductive reactance or any magnetic interaction for that matter. He says it is completley up in the air if there is any sonic difference. They use them on the 800 Sig's because people often hook very high powered amps(specifically monoblock behemoths) to them and the number one cause of mid-range driver failure is overheating. He told me he has the 802's and has left the stock plugs on because he can hear no difference and B&W supports no case saying they sound better.

[DanR]

However caleb, I would purchase two from you and be my own judge.

[sikoniko]

Thats pretty funny DanR... it wont help... however ill take a couple..

[georgev]

Helpless

I would like to take two as well.
Are you going to post the pictures Caleb?