Apogee Centaur Woofer upgrade

[Rozz]

First of all i`d like to say hello cause i`m a new member.

Second is to ask a question about the woofer`s i`d like to upgrade.
I know the questions about the Apogee`s should be in ESLs, planars, alternative technologies, BUT since i only want to ask about the woofers, i think it would be better to post here.

OK, here`s the deal.

I have gotten a set of Centaurs which where very badly abused by the former owner...so i need new ribbons and have already orderd them, thats not the issue.

What is the issue, the Vifa`s installed (P21W0-20-08) need replacing. but i dont really know with what!

I could buy the original vifa`s again, but i think there are much better woofers nowadays.

my eye has fallen on the Scan Speaks 21W8555 (dont know if the 01 is better than the 00??)

My question is: are the scan speaks a good/better replacement? i use the speakers for home cinema and am not an audiophile...so small changes will not be heard.

If i do decide to use the 21W8555, do i need to replace the X-overs? or upgrade some parts?

Info on the objects can be found here:
Apogee Centaur Website
Vifa`s P21W0-20-08 (PDF file)
Scan Speaks 21W8555-00 (PDF file)
Scan Speaks 21W8555-01 (PDF file)

[LineSource]

The original Vifa is 91db sensitivity, while the two ScanSpeak are about 87db...about 2x less efficient...you will notice this if you do not chance the crossover. The scanspeak 8555-00 has a closer Qts and would be a better match to the Vifa's box design.


You may just want to consider yourself lucky that the original speaker is both a pretty good design and still available, and puchase a direct replacement that will save you work on the crossover and box.

[Daveis]

Originally posted by Rozz

...so i need new ribbons and have already orderd them, thats not the issue.

Are Apogee ribbon drivers available to DIY community?

My BG RD40 planar experiment never did get me to approximate the sound of Apogee Centaur Major's... one of the all-time favorite speakers.

[DAMIC]

Of course, there is the guy from Australia, Gratz, and he is selling all Apogees replacement parts – ribbons, except bass ribbons for Stage (Mini Grand) and Studio Grand, as I recall. His products are even better than the original ones, with a much tighther tollerances. So, there is a great opportunity for DIY-ers, specialy if they make hybrid speakers like Centaur/Slant Apogee series. Here is the link:

http://www.apogeeacoustics.com/repai...eeribbons.html

[Rozz]

hmm....making it a difficult decision.

Stay with the vifa`s or "upgrade" to the scan speaks.

In the meantime, thinking of getting a set of DIY mono amps to feed the Centaurs.
Take a look at this and tell me what you guys think:
Velleman DIY kit K8040

[DataDay]

Originally posted by Rozz
[B]hmm....making it a difficult decision.

Stay with the vifa`s or "upgrade" to the scan speaks.

No, I do not think this is a difficult decision. Go for the original woofers and avoid some big disappointments.

Regards,
DataDay

[DAMIC]

I would like to say that Rozz and me are also the members of other, Apogee acoustics user group – forum where members mostly are Apogee owners. Consequently, majority of this members are true audiophiles and less kind of DIY-ers. Few weeks ago Rozz posted on the a/m forum similar thread like this one but with not a lot of response. Then, I suggested him to address to this forum, knowing that there are a lot of people who are more DIY directed and possibly he will got some better advice here.

For those people who are not familiar with Apogee hybrid Centaurus series, which appeared on the market in the begining of the 90's, here is a brief explanation.

Centaur Minor, floorstander, dim 100 x 35 x 22 cm , 26 inch long aluminium/kapton ribbon working as dipole, and 6,5 inch cone driver mounted in sealed 16 liter enclosure. Midwoofer is mounted on the front baffle near the middle of the ribbon.X-over freq. 800 Hz, with 6 dB slope at the begining and later continuing with 12 dB. It seems that in this kind of x-over is the secret of good blending ribbon and cone driver different radiation patern.

Centaur (middle model like Rozz have), enclosure similar but bigger, same 26 inch ribbon and 8 inch dinamic woofer, lower x-over point.

Centaur Major, the biggest model, dim 163 x 46 x 30 cm, 40 inch ribbon, 10 inch woofer, x-over at 450 Hz.

All models have additional three-position switch marked low, normal and high which attenuates the woofer's output level in 1,5 dB increments.

At my expirience, as well as the other member of Apogee acoustics user group, the quality of Vifa woofers employed in Centaurus series is very low. So it is pitty, I think, to stay with old designed, and bad sounding driver and mixed it with first class ribbon. Just to mention that the very same 26 inch ribbon is employed in famous Apogee stage (Mini Grand) and for the longer 40 inch ribbon version, some Apogee acoustics user group members said that it is the best mid-tweeter ribbon ever made.

That is why I suggested to Rozz, he should choose some another cone driver instead of original Vifa, but with much better sonic performance.

I am not any expert or great speaker specialist but suggesting two options as nobody from this forum suggest anything.

First, simplier version, if the enclosure of the midwoofer remain stock-sealed, I should go to new 8 inch driver with T/S parameters as much as possible closer to Vifa's original specs, specialy concerning senitivity (91dB).
In this case, Scan –speak that Rozz suggested could not be used due to 3,5 to 4 dB lower sensitivity.

Second, more comlicated version like I did last year with my Centaur Minor's. Actualy, I changed the 6,5 inch Vifa midwoofer with much better Audax driver and increased the volume adding on the bottom 10 liter MDF box as a stand connecting it firmly with main speakers. Than I add a port and made bass reflex speaker box. Later, I found on this forum that I accidentaly made double bass reflex design. The sonic change in low freq.comparing to stock C/M is dramatic. On this forum somewere is my mentioned topic from the last year.

If Rozz shoul go to modify his woofer enclosure increasing the volume on the similar way, the a/m Scan-speak's could be employed as reflex design will gain about 3dB and he will still be in position to correct woofer output with additional 1,5 dB if needed. The calculation of duct porth diameter and length as well as additional volume needed is another story.

Just to mention that Apogees later hybrid series, Slant 6 and Slant 8 are with bass reflex design.

Concerning the x-over, I should go maybe only to refresh the old caps, or buypassing the present ones with a small quality ones.

As I previously said I am not some speaker specialist, and if I said something wrong, please feel free to correct me. Thank's in advance.

[sreten]

Hi,

I'd guess with any ribbon hybrid you are going to think the cone
drivers are rubbish and "why didn't they use a better driver".

The crossover schematic shown does not make a great deal of sense.

The Vifa is not a poor driver.

http://www.partsexpress.com/pe/showd...number=297-310

It is designed to be reflexed, but this depends on the
Centaur internal volume whether this would work well.

As it stands you are looking at a light cone (for an 8") bass / mid,
around 91 dB sensistivity, with no midband peaking, equivalent
parameters suitable for said box.

Not many of the above around now, most would have been paper drivers.

The Scanspeaks are not suitable. Audax aerogels ?

or possibly - chucking money at it : (very low distortion driver)

http://seas.no/PDF%20data%20excel%20...NY001E0045.pdf

Need to add a port for the above.

/sreten.

(Shown are alignments for the Vifa)

[sreten]

Hi,

Seems the Centaur Major only has around 30L internal volume,
the Minor has 16L so presumably we are looking at in between,
I'm guessing 22L, q=0.8 which is a fairly workable alignment.

For an 8" you are looking at a sealed box, basically too low for venting.

Really it seems on paper the original woofers are the best choice.
But it seems they are not liked by owners .....
So you could try similar Audax Aerogel or Seas paper drivers.

But given around 91dB 8 ohm driver and 20L good low bass is not going to be possible.

If anything Id go for a lower Q alignment and add stereo subwoofers for the low bass.
(This could be one amplifier but two boxes)

However ......

If you are prepared to bi-amplify with say double the power in the bass and
adjust amplifier gains to suit then a lower sensitivity driver could be used,
with better bass, but then single amplifier working would not work well.

/sreten.

[Daveis]

What's the cost of replacement ribbons for Centaur Major?