Lowther cones or AER cones (Off Topic)

by GC, Thursday, April 21, 2005, 00:11 (4655 days ago)

I am curious what the experience has been changing Lowther cones to AER cones.

I have Lowther DX4 cones which are nominally 15 ohms. I am planning on moving from Hedlund Horns to open baffle speakers. I may want to accomplish several things at once by making some changes to these drivers.

First, open baffle speakers are better off with higher Qts rating drivers. If I changes the drivers from the 15 ohm voice coils which I now have to one which is 4 ohms (driven by a SET amp on its 16 ohm tap or with a higher output impedance transformer), I will get much closer to a more appropriate Qts for the system. I can use high impedance speaker wire as well (i.e., 31 guage) to further raise the Qts. Does this all make sense?

If I send these out to Lowther, I would make sure that the Hi Ferric material is not used with the new voice coil.

While I switch the windings of the driver, I can change the driver cone to an upgraded Lowther cone or AER drivers. Is there a benefit to using the AER driver cones over the Lowther cones, or are there simply tradeoffs? Does anyone know the cost of adding AER driver cones to my DX4 drivers?

Retsel

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Lowther cones or AER cones

by GC, Friday, April 22, 2005, 00:00 (4654 days ago) @ GC

Hi Retsel,

First, open baffle speakers are better off with higher Qts rating drivers.
If I changes the drivers from the 15 ohm voice coils which I now have to
one which is 4 ohms (driven by a SET amp on its 16 ohm tap or with a
higher output impedance transformer), I will get much closer to a more
appropriate Qts for the system. I can use high impedance speaker wire as
well (i.e., 31 guage) to further raise the Qts. Does this all make
sense?

No sense at all. For more bass you need a higher Q driver, for quality bass you still need a low Q driver (like the Quasar system). A Lowther or AER in an open panel will not give any bass and will only start moving a lot when the Q is made high (no control from the amp and even less when you put resistance in series!!). If you want to kill the music then feel free to increase the Q and add resistance...

If you use a bass driver in the open panel then the mid-high driver (Lowther or AER) should be low Q-ed to keep some "live" unless you want to go back to hi-fi....?

Ciao,

Bert

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Lowther cones or AER cones

by GC, Friday, April 22, 2005, 01:14 (4654 days ago) @ GC

Thanks for your response Bert.

I believe that I saw a frequency response chart of an 8 ohm Lowther on an open baffle and the frequency response was increasing from the lower midrange to about 10 khz. I believe that the response was brought back to a flat response using an inductor. I figured that I would just avoid the inductor by creating a higher equivalent Qts. I can see what you mean by loosing some detail and dynamics with a higher equivalent Qts.

Either way, I would roll off the frequencies to the Lowther driver below 150 hz and have some woofers take over below that.

Well, replacing the voice coil was my primary excuse for doing a couple of things: getting rid of the Hi Ferric and getting better cones. However, if there is no primary reason to remove the cones to begin with, I may not go ahead and do that.

Retsel

Hi Retsel,

First, open baffle speakers are better off with higher Qts rating

drivers.

If I changes the drivers from the 15 ohm voice coils which I now have

to

one which is 4 ohms (driven by a SET amp on its 16 ohm tap or with a
higher output impedance transformer), I will get much closer to a more
appropriate Qts for the system. I can use high impedance speaker wire

as

well (i.e., 31 guage) to further raise the Qts. Does this all make
sense?


No sense at all. For more bass you need a higher Q driver, for quality
bass you still need a low Q driver (like the Quasar system). A Lowther or
AER in an open panel will not give any bass and will only start moving a
lot when the Q is made high (no control from the amp and even less when
you put resistance in series!!). If you want to kill the music then feel
free to increase the Q and add resistance...

If you use a bass driver in the open panel then the mid-high driver
(Lowther or AER) should be low Q-ed to keep some "live" unless you want to
go back to hi-fi....?

Ciao,

Bert

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Lowther cones or AER cones

by GC, Friday, April 22, 2005, 08:42 (4654 days ago) @ GC

Hi Retsel,

Firstly you are on the right Track re Hi-Ferric.

You can remove this from your existing diaphragms by judicious use of lacquer thinners and ear buds.

You need about 4 buds per diaphragm - dip the bud into the thinners and wipe off the excess, then run the bud over the VC - the HF will start to come off.

Work carefully and do not make the VC or paper wet with thinners - just damp on the surface.

Remove ALL traces of HF - even that on the rear of the parchment VC former

HTH

Mark

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Lowther cones or AER cones

by GC, Friday, April 22, 2005, 11:38 (4654 days ago) @ GC

Hi Mark
Interesting to know for future reference.
Can you be a bit more specific about the solvent. There are 'mild' solvents like ethyl and amyl acetates or petrolueum spirits and pretty 'powerful' solvents like acetone. Would not want to use something that may help detach the voice coil.;-) ;-)

Cheers Chris

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Lowther cones or AER cones

by GC, Friday, April 22, 2005, 18:07 (4653 days ago) @ GC

Hi Mark
Interesting to know for future reference.
Can you be a bit more specific about the solvent. There are 'mild'
solvents like ethyl and amyl acetates or petrolueum spirits and pretty
'powerful' solvents like acetone. Would not want to use something that may
help detach the voice coil.;-) ;-)

Cheers Chris

Chris,

I used a lacquer thinners that is used for thinning/spraying automotive paint.
It flashes off exceedingly quickly and leaves no residue at all.
Use it sparingly - it will never remove any enamel insulation from the VC wire and in addition as long as you do not wet the surface too much will not attack the glue under the coil - do not use acetone as it is far too aggressive.

Well I should say that of course users must try this at their own risk etc and of course there is no going back - but then who would want to?

One final observation - I have tried the new Lowther reverse roll whizzer diaphragms and found that they are kind of dead....snap and attack is adversly affected IMO.
Note though that I am using a 130Hz Tractrix Front horn (quite deep at 53 cms odd) - the new diaphragms may work in "rear only" loaded horn enclosures i.e sans any front horn but even then I suspect the reverse roll whizzer is a step in the wrong direction.....mainly because Lowther shortened the whizzer in the process...

HTH

Mark

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Lowther cones or AER cones

by GC, Friday, May 13, 2005, 17:40 (4632 days ago) @ GC

I have noted that the thinners only works on the older Light Grey Hi-Ferric coating and NOT on the later Black Hi-Ferric coating.

Once I have found a suitable solvent for the black type I will post.

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Lowther cones or AER cones

by GC, Monday, April 25, 2005, 09:27 (4651 days ago) @ GC

Hi Retsel,

Well, replacing the voice coil was my primary excuse for doing a couple of
things: getting rid of the Hi Ferric and getting better cones. However,
if there is no primary reason to remove the cones to begin with, I may not
go ahead and do that.

Only if you like to change the tonal character of your Lowthers to a more natural one then its a good reason, for changing Q's and such I would work differently by tuning the bass driver upwards so that there is a good balance. Using a drive unit that is capable to reach the "upper" drive character would be very helpful though...

Ciao,

Bert

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