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Old 6th March 2004, 08:53 AM   #1
Nanook is offline Nanook  Canada
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Default help with speaker retro fits.

I need a little help. Have two pairs of loudspeakers needing drivers.

Wharefedal Denton lls, .3984 ft^3, sealed, 8" driver
xover: tweets: .8mH, 16mfd, 50V
woofer: 2.0 mH, 50mfd, 50V np


and Musical Fidelity MC-2:
no xover info
.68 ft^3, heavily stuffed, 2"X6" port

TDL tweeter and woofer


any ideas?
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Old 6th March 2004, 05:45 PM   #2
sreten is offline sreten  United Kingdom
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I have a pair of the rather excellent MC2's.

Have all the drivers gone west ?

TBH trying to reuse crossovers is not the way of
going about it if all the drivers are not working.

The Denton's combination of size and and an 8"
bass driver is going to make life difficult.

If all drivers are gone give up on the crossover.
fit an additional front baffle and build a 6.5"/1"
two way - with offset drivers, suggest using
Dayton drivers - for more info :

http://www.speakerbuilder.net/web_fi.../D2/d2main.htm

Any changes because of the Denton cabinets
can be sorted out here.

The MC2's - more details of what doesn't work please.

The tweeter is a TDL / Monitor Audio unit, the bass/mid
unit is an Audax TPX unit, similar to or the same as:

http://www.blackdahlia.com/the_dahli...ker_system.htm

Incidently the tweeter was designed to be a drop in
replacement (with minor sensitivity padding) for the
near ubiquitous Audax rectangular dome tweeter.

sreten.
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Old 6th March 2004, 06:07 PM   #3
markp is offline markp  United States
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Quote:
Originally posted by sreten
Have all the drivers gone west ?
sreten.
In the US our drivers go south!

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Old 6th March 2004, 09:10 PM   #4
Nanook is offline Nanook  Canada
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Default retrofits.

The tweetes in the Dentons are paper, I'd like to use domes. I have 2 prs of tweeters kickin around, a pair of rectangular tweeters out of a pair of Missions, and a pair of circular ones. One woofer is smoked. I destroyed it postmortem to have a look. I had thought of just starting fresh with a new xover, and creating a stepped baffle for the front and using a smaller driver.The volume is only .4 ft^3

The MC-2s require 1 woofer. They were given to me sans woofer. The previous owner gave up trying to find a decent replacement. They sure look like TDL drivers (actually I know they are as I had called musical fidelity who verified that they were, but alas provided no further info).

thanx for any and all ideas
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Old 6th March 2004, 09:36 PM   #5
sreten is offline sreten  United Kingdom
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Default Re: retrofits.

Quote:
Originally posted by Nanook
The tweetes in the Dentons are paper, I'd like to use domes. I have 2 prs of tweeters kickin around, a pair of rectangular tweeters out of a pair of Missions, and a pair of circular ones. One woofer is smoked. I destroyed it postmortem to have a look. I had thought of just starting fresh with a new xover, and creating a stepped baffle for the front and using a smaller driver.The volume is only .4 ft^3

The MC-2s require 1 woofer. They were given to me sans woofer. The previous owner gave up trying to find a decent replacement. They sure look like TDL drivers (actually I know they are as I had called musical fidelity who verified that they were, but alas provided no further info).

thanx for any and all ideas
paragraph 1 - refer to my reccomendations previously.


paragraph 2 - I know my onions. I own the Loudspeakers.
The reason the MC2 is so heavily damped is the TPX drivers
delivered had different parameters, compared to the original
parameters claimed.
(A phone call, yes well, they are bound to know, not)


Quote:
The Woofer :

Audax claims that they've experienced serious production difficulties with the TPX drivers and have been unable to meet initially advertised parameters. For example, the original TX-2025-RSN was touted as having an overall Q of 0.46 and a free-air resonance of 38Hz, while current production is typically of the order of 0.6 for Q and 49Hz for the free-air resonance. The effect of all this on the bass alignment of the Dahlia is to increase the response peak at 6OHz to 4dB and decrease the half-power frequency to 55Hz. This prompted me to take a closer look at the Audax catalog. The TSN version of this driver, which sports a slightly larger magnet and thus a lower Q of 0.5, appears to be a better choice-it gets much closer to the original bass alignment. The bass peak with the TSN version should be no greater than the 2.5dB originally intended. I asked Audax to send me samples of the TSN cones for evaluation. What I got, however, were more RSNS, so as yet I have no final report on the matter. Since the TSN and RSN versions are identical except for the Q parameter, I recommend trying the TSN for new construction. I would not personally go to the trouble of modifying existing Dahlias, as the sonic differences should be small. In either case, be sure to use the 8-ohm version of these drivers.
from :

http://www.blackdahlia.com/articles/dahlia_debra.htm

Unfortunately it deals with new tweeters not new bass units.


sreten.
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Old 6th March 2004, 09:40 PM   #6
Nanook is offline Nanook  Canada
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Default woofer.

not trying to flog a dead dog here.:-(

the fitted woofers are paper w/rubber surrounds. Production dated are July 1987

thanx for all your help thus far. Do you think that it's worth resurecting these ?
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Old 6th March 2004, 09:47 PM   #7
sreten is offline sreten  United Kingdom
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Default Re: woofer.

Quote:
Originally posted by Nanook
not trying to flog a dead dog here.:-(

the fitted woofers are paper w/rubber surrounds. Production dated are July 1987

thanx for all your help thus far. Do you think that it's worth resurecting these ?
I presume you are referring to the Dentons and the tweeters are OK.

My best guess :

http://www.partsexpress.com/pe/pshow...number=290-063

sreten.
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Old 6th March 2004, 10:55 PM   #8
Nanook is offline Nanook  Canada
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Default Mc-2 woofers..

I took out the one remaining woofer in the Mc-2s. no markings. appears to be poly.
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Old 6th March 2004, 11:18 PM   #9
sreten is offline sreten  United Kingdom
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Default Re: Mc-2 woofers..

Quote:
Originally posted by Nanook
I took out the one remaining woofer in the Mc-2s. no markings. appears to be poly.
mine are marked on the back of the magnet :

22PPGHN8 ohm.

Here is the UK I'd simply buy two Audax 8"s available here
at very reasonable prices from Maplins and play with the c/o.

sreten.
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Old 7th March 2004, 12:50 PM   #10
sreten is offline sreten  United Kingdom
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Hi again,

I've been digging a bit more and the MC2 bass unit is not the
same as the Audax units in the Black Dahlia, though those units
do resemble the clear phase plugged TPX driver used in the MC4's.

I seem to remember at the time that the MC2 was touted as
using a budget version of the MC4's driver and that it used
a TPX cone, its impossible to tell by inspection.

Without ripping all the foam out I remember it being 2nd
order LC for the woofer and RCLC 3rd order with an
attenuating resistor for the tweeter. I seem to remember the
resistor being before the c/o components for the tweeter.

So one possible way forward - remove the woofer components
and the resistor - wire a link across the resistor and inductor
points.

As the speakers are biwirable you can now play with these outside the speaker.

The question is - what pair of bass units to try ?
(0.7 cuft = 18litres)

The P22 here is a possibility :

http://www.apexjr.com/speakerstuff.html

IMO they are worth the saving attempt.
The tweeter is still pretty good and was one
of the earliest to have a damped rear cavity.

The cabinet construction is seriously braced and as
you know stuffed to the gills with high grade foam.

sreten.
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