Replacement Woofer for Infinity Kappa 8.1i

[swechsler]

This was an interesting project, especially with all the measurements you took, so thanks for that. However, since the modified speakers don't appear to show much (if any) of an improvement in low bass response, I have to wonder if this was cost effective, relative to finding a single Kappa woofer on the used market...yes, they appear to be better made, but does that translate into better sound?

 

[Sam1879]

This was an interesting project, especially with all the measurements you took, so thanks for that. However, since the modified speakers don't appear to show much (if any) of an improvement in low bass response, I have to wonder if this was cost effective, relative to finding a single Kappa woofer on the used market...yes, they appear to be better made, but does that translate into better sound?

Your welcome.
I dont think it was cost effective. Though i can definitly say from my point of view the low bass has improoved in a surprisingly impressive, positiv and in a interesting way. The difference was quiet intense, especially when listening at higher volume / „near concert levels“.
And i did not expect this to be so good.
Its sounds now much more like what you would expect in a high end system with a great engineered and powerful (and most important!) almost perfect integrated subwoofer. My Subwoofer is not that great.
The deepest bass region is in my opinion the point what makes live concerts often so much better than at home.
And well produced recordings sound now much more like if you were really at the concert. Especially at some well produced live recordings.

Might be because better distortion handling at higher volumes. (Anyone knows for sure?)
There seems to be a dip in ca. 70 Hz though. I‘m a bit concerned about this one. It‘s not bad, but i‘m missing some of the former „magic“ of the speaker in this area.
Here i think i’m going to try fixinging it with some dsp-equalizing.
—-update soon.

 

[Sam1879]

... but i think the speaker needs more power now. Maybe even broght the amp into clipping a little.
Could also be that the power grid is not perfect here... Living a bit rural here out of the city in the hills.

btw: There were some power problems in texas as far as i know because of the cold weather. Only the best wishes for them, hope you are alright.

 

[swechsler]

Your welcome.
I dont think it was cost effective. Though i can definitly say from my point of view the low bass has improoved in a surprisingly impressive, positiv and in a interesting way. The difference was quiet intense, especially when listening at higher volume / „near concert levels“.

Yeah, that was a little unclear from your previous posts. You had written "subjectively the bass room modes are definitely more pleasing." which I missed, but the graphs didn't appear to show much of an improvement in low bass extension. Or did I miss something? Did it improve the quality of the bass without adding any lower frequencies?

What kind of amp are you driving them with?

 

[goodolpg]

ah, ok. didnt think about that. thanks

You could change out one of the new woofers for the good original if you did want to listen for changes/differences.
But for long term and/or serious listening I think matched drivers would be recommended.

 

[Sam1879]

Yeah, that was a little unclear from your previous posts. You had written "subjectively the bass room modes are definitely more pleasing." which I missed, but the graphs didn't appear to show much of an improvement in low bass extension. Or did I miss something? Did it improve the quality of the bass without adding any lower frequencies?

What kind of amp are you driving them with?

You‘re right. My posts are a little unsorted, too. Sorry for that..
Subjectivly low bass quality got better.
I think there is some improvement in the curve i pictured in the second measurement after optimizing the fixation of the driver.

Guess this kind of curve is only one picture in the story of distortion, frequency and loudness.

I have them on a NordOne NC500 DM with Hypex modules.
2 x ~ 500W RMS
2 x 1200W SMPS

https://www.nordacoustics.co.uk/product-page/nord-one-nc500dmst

Posted my System here: https://audiokarma.org/forums/index.php?threads/sams-hifi-setup-8-different-brands-combined.949581/

 

[Sam1879]

NAD released their new Flagship with kind of successors of these hypex modules.

 

[Sam1879]

mostly i really like the amp and it‘s performance. though in my opinion this amp didnt harmonize well with my earlier speakers. (Dali Opticon 6) but great with the kappas.

 

[Sam1879]

might be interesting:
https://www.audioholics.com/loudspeaker-design/audibility-of-distortion-at-bass

 

[Sam1879]

... but i think the speaker needs more power now. Maybe even broght the amp into clipping a little.
Could also be that the power grid is not perfect here... Living a bit rural here out of the city in the hills.

Guess its not a good thing when brightness of the light bulbs changes when bass kicks in haha.

 

[Sam1879]

in my subjectve opinion the systems bass sounds really great so far with the following dsp configuration.

Intense and engaging - but lacking something in the bass area from 60 - 250 Hz- without dsp.

thin lines: measured, thick lines: calculated correction



edit:


maybe even better with this one, as it pushes the speaker less into correction.

though depends on the track played.

 

[Sam1879]

NAD released their new Flagship with kind of successors of these hypex modules.

more precise: Flagship Integrated, M33

 

[Sam1879]

Conclusion for RSS315HF-4 12" Reference HF Subwoofer 4 Ohm

So far... (and of cours subjective and in my system).
Without changing the crossover and without DSP:


Pros:
Less distorted/boomy bass, especially at higher volumes.
More deep bass, makes a huge difference, especially at higher voulmes.
Replacement drivers are widely available.

Cons:
Less bass in area between +/- 60 - 80 Hz, especially noticeable at tracks with fast beats in baseline.
Maybe needs a more powerful amp than with original drivers for higher volumes.
Replacement needs a little bit of work at the cabinet.
Drivers are not cheap.


Would I do it again?
Yes, but the important point is i could fix the the +/- 60 - 80 Hz area with DSP-correction.
Was a little tricky but worked great in the end after some tries.
Without DSP-correction (or maybe crossover modification) i can not completely recommend this driver as a Kappa 8.1i woofer replacement, though the enhancements in sub-bass is impressive.
The differences to the original are just too big and some parts of the bass around 70 Hz are reduced too much.

Final in-room measurement:

(green line is the right speaker thats not placed in corner, with added subwoofer).



Calculated correction.






Wish you all a great week.

 

[Bkphoto]

Have to remember while your speakers are “really nice” they will differ from the sealed compartment Infinity’s...ported speakers was not a usual thing for infinity...it’s a compromise, easier to run...

 

[Sam1879]

Took the defective driver appart. The voice coil was ok. The problem was caused by a loose glued connection between the voice coil-element and the cone. Could probably have been fixed by a skilled repair service with a new surround. Allthough in my opinion the spider has deteriorated not to little, too. Could also have been renewed, i guess.

 

[Bahamayellow]

Hello just wondering if you have considered using a different amp. Or maybe bi amping. I’m using 2 carver a500x in a bi amp mode and bass is off the charts on the 8.1s. I actually need to tune it down a bit. I know they won’t go sub Sonic but adding a sub would do it. Not for me though. I have plenty. If your craving more bass in an infinity speaker maybe consider the Kappa 9 or 9.1s.

 

[Sam1879]

Hello just wondering if you have considered using a different amp. Or maybe bi amping. I’m using 2 carver a500x in a bi amp mode and bass is off the charts on the 8.1s. I actually need to tune it down a bit. I know they won’t go sub Sonic but adding a sub would do it. Not for me though. I have plenty. If your craving more bass in an infinity speaker maybe consider the Kappa 9 or 9.1s.

Hi.
Bass is awesome now! With biamping and without.
Was also great before changing the drivers but still made quite a positive difference with driver change (and described DSP correction). Especially intensive is the much better linearity under 30 Hz.
But what happened was: my subwoofer (Klipsch R-12SWi) was not working properly together in its position next to the speaker after the woofer change. Have tried different phase/freq configurations.
Now i placed it on the opposite side of the room, integrated with a minidsp 2x4 (ca. 100$) for filling some room reflections (recommended!) and it's much better this way.
But of course is individually different, especially the bass is so depending on the room and used materials and absorbtion and and and...

Have investigated the described "clipping" in the last days a bit more.
This "clipping" only happend in tracks with quite extreme transients at at really high volume. (for expample: soldier by erykah badu, patience by nas and damian marley, listen before i go by billie eilish (at ca 1:40),
What i found when playing with PA amps and biamping was that clipping occured in the "high pass" section of the speaker. Not really in the woofer section.
So this "clipping" has nothing to do with the woofer change. Quite sure with that.

According to:

JerryLove
forums.audioholics.com

An amplifier clips when the power demanded exceeds the power available.
A speaker clips when the excursion (the amount the speaker is requested to piston in or out) demanded exceeds what can mechanically be accomplished.

You fix it by lowering the demand or raising the capability (the latter by replacing the item in question).

... and some tries and playing around It seems clipping happend because of overloading probably the midbase driver (maybe some dB too much DSP boost used in this area) or maybe even bringing the tweeters Zener diodes into activation. Or reaching the limit of the midrange dome. I'm not sure. Limiting factor has definitely not been the amp, but left a dedicated activateable/deactivateable PA amp for "Party Mode" connected on an amp-switcher for bass. Just to be sure having always enough power when needed.

Well it's no longer a problem with some more moderate dsp-boosting in midbase. And i have to accept the speakers limits in midrange
I think what really could be a point is that now it's not anymore the woofer whats the weakest link in the speaker at high volumes and this problem was just not "present" as i used to use the speaker at lower volumes before as the woofer started to distort.


BTW: My ca. 25 years old polydome distorted at high volumes too. Changed it with a replacement driver and it's much better now! Encourage to everyone: Get your old, yellow Polydomes restored by a skilled infinity repair service. Or (maybe) change them to a good replacement. Makes a huge different at high volumes / transients. I really guess most of the almost 30 years old, yellow Polydomes are not capable anymore handling transients as good anymore as one with a new poly cap.


Does anyone have an answer for the questions:
When i did clipping tests at high volume there was distorted sound at transients.
The amp i used for clipping tests was a bridged (700W) Behringer KM750 with a clipping indication LED. (Same in Stereo Mode 350W)
The woofer was not connected.
The clipping LED was glowing red at the the (extreme volume) transients.
Is it possible the amps clipping LED indicates clipping as a result of an overloaded midbass or midrange driver? (according to the quote of JerryLove) or must it have been the zener diodes of the tweeter?
I think not the amps limit is the problem in this configuration, though it's not 2 Ohm stable (when bridged)... Could it be really the amps limitations that caused clipping in this test configuration?

 

[Bkphoto]

You are running 8.1’s

plus a sub...? Holy bass Batman...! Is it a theater set up or just music...?

 

[Sam1879]

haha
it's for music only
the room has a quite a high ceiling and is around 200 m3 (7000 Cubic Feet) and the house is built with wood and isolated with wooden fibres.
guess that has a quite an impact.

in a room built with concrete, probably this would be totally insane. maybe i'm a bit insane too. who knows

 

[Craftsman1]

Hello swechsler

Thank you for your reply and sharing your thoughts.

Do you know if - and how much - the crosover frequency of a crossover/driver-combination is impacted by the specs of the driver itself? And if yes, is the most important factor the impedance curve or anything else?

Could it be possible to get T/S-parameters or impedance curves of an original woofer anywhere? Type: 902-6236

Your right, i'm going to try it with the RSS315HF-4. but i'm really not sure if its the best (new design) replacement.

But i'm already curious about the results. As the chance of damaging anything seems to be not to high, and i could still sell the daytons if it won't work - it's worth a try.

It's maybe (and understandable so) a controversal discussed topic, but in my setup i could tune some frequency-missmatches with the dirac-dsp.
but it would be much better to keep the corrections on a smaler scale or unneccessary for sure.

When i'm going to replace the drivers i'll do some measurements using a UMIK1-microfone and publish it here.

thanks, and if anyone did something similar before on a kappa 8.x it would be great to here the stories.

The kappa 8.1 woofer is 8 ohms. With a resistance of 6.2. I went with an aluminum cone driver as the old img drivers are similar material.
Don't stress on changing out drivers on a 20 plus yr. Old speaker. No doubt the spiders are pretty worn by now, not to mention the foam.
The polydomes are shot. Miller sound can repair those.
Or buy them from Madisound.
I've replaced all my drivers except the emit R.
They sound awesome.
I tried the Infinity kappa 1200 Sub. Too much bass. Did not blend well. Went to Dayton Audio 12 aluminum driver. Awesome now.