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KG4 Modification Project


M.Att

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Hi Everyone,

 

  I'm a new member but long-time viewer of the Garage Sale and Alerts! threads.  I've had a few Klipsch speakers over the years starting with a KLF-C7 which I was too young to really appreciate and gave to a brother of mine ten years ago.  Over the weekend that brother dropped off a pair of nice KG4 cabinets completely devoid of everything save the wood and stuffing and asked if I could help him refurbish them.  Last year I rebuilt a pair of Polk RT55s and he really liked the results and would like these to complement the C7 as the L/R channel speakers for his TV and also use for stereo music.  (I pity his neighbors)

 

I figured it'd be a fun project to rebuild these and already purchased some K-80-K horns and original crossovers from Ebay which should be delivered next week.  But here is where I am left to reach out to the community.  First woofers, I think the K-80s are a few DB more efficient than the original K-74s.  Would this preclude the original/NOS K-8-Ks?  Are there FRD/ZMA files around for the K-8s?

 

If those files aren't readily available, or even accurate pictures that I could use to create them, what do you all think would be a good enough replacement?  I'm not trying to break the bank with Seas drivers. 🙂  I have some competing goals, it seems, cost, efficiency, bass.  Would the passive radiator make up the difference with higher efficiency PA type speakers?  e.g. Dayton PA-200?  

 

I also want to wire up a new XOver to add a Zobel network, L-Pad and whatnot.  I read this entire thread and really like the idea of a 2.5 setup.

KG5.5 Update 2.5 Way Conversion - Klipsch Community

 

Has anyone added internal bracing to the enclosure and measured the results?

 

Thanks in advance and if there's an important question I haven't asked please ask for me, I don't know what I don't know and would like to learn.

 

 

 

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Edited by M.Att
Change Topic name to more correctly reflect the intent.
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  • M.Att changed the title to KG4 Modification Project

probably easier to buy original KG4 woofers for them or some of the repro copies so the specs stay as original design for the cabinet.  experimenting with other woofers will be hit or miss & a waste of money if they dont work as good as the originals.  im sure youve seen whats available on ebay since you bought other parts but if not, heres some current kg woofer options. 

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=klipsch+kg4+woofer&_sacat=0    

 

as for bracing the cabinets, you will get mixed opinions on that, being they are so small they are more rigid than a larger cabinet so probably dont really need bracing... but some recent comments on here suggest the cabinets are part of the speaker design & they will lose some of the bass if braced or braced too much.  one guy on the AK forum did some heavy bracing & added insulation to some forte3 & said they lost a lot of the bass impact & depth compared to stock.  i would focus on getting some good/correct drivers, new gaskets for them & spend your time & money on the crossovers & maybe consider the titanium diaphragms?

 

KG4 are great speakers for the price/size, i wouldnt try to deviate from their original design too much, but thats just my opinion, im sure others will have more input for you if you decide to go further down the modification rabbit hole.  

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Hi All,

 

  Thanks for the replies.  The more I've thought about it since posting the more I tend to agree with going for a stable/known baseline first.

 

  I emailed with the techs at parts-express and while I really like the Dayton woofers (I have made a few of their DIY kits and greatly enjoy the Classix II) I don't think any of their 8" woofers will match the sound of the originals for the price of the originals either on EBay or two sets from Midwest Speaker Repair.  (https://www.midwestspeakerrepair.com/shop/home-audio/woofers/klipsch-1/mw-audio-mw-5082-8-woofer/)

 

  Now that I'm going that route, I need to consider the crossovers.  I have some originals which I'll use as a baseline, but I suspect since they are original I'll need to rebuild them.  Going back to my original post, what are your thoughts on a 2.5 setup? 

 

And now for a new question,  the K-80 tweeters arrived yesterday.  They seem clean, I've not checked the impedances yet, but one of them has some black gunk, which seemed a lot like grease, between the magnet and diaphragm.  Am I correct to assume that this is a normal thing for their age?  I'll get a picture later if the description doesn't make sense.

 

Thanks,

M

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2 hours ago, M.Att said:

 the K-80 tweeters arrived yesterday.  one of them has some black gunk, which seemed a lot like grease, between the magnet and diaphragm

 the K-80  carry  the 2nd Generation klipsch  tweeter diaphragms Mylar/polymer that added  Ferro-Fluid in the voice coil  for better sound reproduction  , cooling  , and durability , these are very high tech ,very good sounding ,  Ferro-Fluid dries and hardens with age , it is VIP to top up  these tweeters with  Ferro-fluid for proper operation

 

Welcome to the Klipsch Forum

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Thanks, I'll pick up some replacement fluids for both then.

 

Another question that comes to mind, in addition the XOver ones, what was the mass of the original passive radiator?

 

The rabbit's hole comment is quite accurate, it seems that I like taking on fractal problems.

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Thanks for sharing that crossover, $50 for the whole set of speakers is a great deal!   The cabinets we found were that much alone. 

Are you doing anything to pull the tweeter down?  (I don't see any resistors in it)  Your picture reminded me to ask, why and when would a designer use a ferrite core inductor as opposed to an air core?  I see both here and I assume the ferrite is used parallel to the speaker and air is series.

 

Going back up a number of posts, the comments on resonances has been resonating with me, it seems that cabinet resonances are wasted energy that could otherwise be applied to the passive radiator were that energy not being used to move the wood.   Is there anything available to read on why and how they tuned the KGs to work with the resonances to enhance bass? 

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On 3/2/2022 at 9:21 AM, M.Att said:

Thanks for sharing that crossover, $50 for the whole set of speakers is a great deal!   The cabinets we found were that much alone. 

Are you doing anything to pull the tweeter down?  (I don't see any resistors in it)  Your picture reminded me to ask, why and when would a designer use a ferrite core inductor as opposed to an air core?  I see both here and I assume the ferrite is used parallel to the speaker and air is series.

 

Going back up a number of posts, the comments on resonances has been resonating with me, it seems that cabinet resonances are wasted energy that could otherwise be applied to the passive radiator were that energy not being used to move the wood.   Is there anything available to read on why and how they tuned the KGs to work with the resonances to enhance bass? 

 

To protect the tweeter, and not in view here, is a Raychem Poly Switch (79 cents each?). If things get too loud for too long this thing will act like a house breaker for the tweeter till the music gets turned down and the switch cools down. No need to open the cabinet up and reset anything, it'll do it by itself. As far as attenuating the tweeter; this design doesn't have a transformer much less one with multiple taps to choose from. So, you'll have to just turn down the tone control at the pre-amp/receiver.

 

As far as using an iron core inductor vs. an air core; Air-core inductors are much more expensive and designed for higher power applications. For instance, nobody would expect their KG4's to get as loud as their K-Horns (even though the K-Horns are more efficient). But, in this case as well as most, it's more important to have the correct electronic value. As far as replacing the inductor? Don't bother, they either work or they don't. There is no changing value over time that (can) happens with capacitors.

 

If you're going to do this yourself, here is a very important thing to do. You'll notice I put some hot glue at the contact points of the capacitors. This is because the inside of a speaker is a VERY hostile place when it comes to vibrations. Vibrations, over time, will cause connections to fatigue and break. Much like bending a paperclip the same way till it breaks in two. Since I took this picture, I loaded up even more hot glue just to be sure.

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2 hours ago, M.Att said:

Going back up a number of posts, the comments on resonances has been resonating with me, it seems that cabinet resonances are wasted energy that could otherwise be applied to the passive radiator were that energy not being used to move the wood.   Is there anything available to read on why and how they tuned the KGs to work with the resonances to enhance bass? 

 

probably not much to read on the klipsch cabinet resonance thing, it was some comments on a recent thread that said the cabinets are part of the design.  maybe post a new thread asking why they do this.  lots of people brace the cabinets & swear to the improvements so im sure theres some valid benefits to it & some benefits to not doing it. 

 

its not just the Kg series, its pretty much all models of klipsch, they dont do any real bracing in the cabinets & internal sound damping is minimal... that would suggest its done for a reason... yet most other mid to upper level speakers have a lot of internal bracing & absorbing material & other features to avoid the speaker sounding "boxy".  

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Thanks for pointing out that poly switch, I was looking at the schematic for the XOver and didn't know what that was.

 

Two deliveries today, for this project, the original crossovers and a Dayton DATS device came in!  The crossovers appear to be in good condition and I've been able to get some T/S parameters for the K-80s.  One of their impedance charts looks a little off though, the same one that I noticed the ferrofluid in.   Do you all have any thoughts on this driver?   For debugging, I moved the diaphragms between the two and the impedance oddity followed the magnet and not the diaphragm.

 

 

 

 

20220302_103659.jpg

K80-Clean.png

K80-Funky.png

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Keeping this thread going for documentation sake.  I replaced the ferrofluid today in both tweeters.  The one above with the strange looking impedance graph was fairly dry when I went to soak up all the old fluid.  Upon replacing it and re-running the tests the impedance is smooth.  So, in case anyone comes along in the future, treat it like your car's 100,000 mile checkup.

 

 

 

 

K80-NoLongerFunky.png

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  • 2 weeks later...

Hi Everyone,

  Update on this slow moving project.  I ended up purchasing the MidWest Audio 8" woofers for these speakers since they were the closest to OEM and dropped them in yesterday!  Up next is the re-capping the crossovers.  Does anyone on the forum know the original added mass of the passive radiator?  I'm running the Dayton's without anything yet.

 

 

20220313_122121.jpg

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Looking fantastic Matt!

 

Seeing as you've changed the woofers perhaps if you have trouble finding original passive radiators you might simply purchase a Dayton PR to fit and a calibrated mic so you can tune the PR to your taste but with a little data to help you dial in what you're hearing?

 

The mic will take out the guess work and if you haul a cabinet outside you can easily take ground plane measurements to accurately verify your results.

 

You could even use an Audyssey mic plugged into your PC with REW and get an accurate result - I've tried this and it works great.

 

Good luck! 🍻

 

...

Groundplane.jpg

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Thanks, Maz, I do have anAudyssey mic from my old Onkyo AVR receiver.   If you know off hand, how many grams of weight should be added to the PR to get back to the original ~35hz tuning?

 

Also, keeping with my DATS measurements, here's the KG4 with original Xover impedance in the box using a Dayton DS-315 PR.  I hope to rebuild the XOvers this weekend with the new capacitors, impedance correction, and LPad. 

 

 

 

 

KG4-StockXO-Impedance.png

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I forgot you said you have the DATS - that's great! No idea how much mass to add but it'll be easy for you to determine.

 

To do this measure a woofer with DATS and use the T&S specs you get with Hornresp or WinISD etc to model up the Dayton PR to get you how much mass to add to it. You could then use your mic to measure the speaker to compare modelled with the actual result to fine tune. 

 

Would be great for you to post the T&S data you take from your MidWest Audio 8" woofers into the Klipsch Impedance Curves thread for others to find too.

 

Good luck! 🍻

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On 3/4/2022 at 5:05 PM, M.Att said:

Keeping this thread going for documentation sake.  I replaced the ferrofluid today in both tweeters.  The one above with the strange looking impedance graph was fairly dry when I went to soak up all the old fluid.  Upon replacing it and re-running the tests the impedance is smooth.  So, in case anyone comes along in the future, treat it like your car's 100,000 mile checkup.

 

 

 

 

K80-NoLongerFunky.png

Thanks for the post! I have two pairs of KG4, and I found one pair had fluid while the other did not. I'll have to put some in. I never critically compared the two to notice the difference. 

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Hi All,  I have a working XO in the box now, testing at lower volumes, and not glued down, but so far it seems to be working well.  I don't think it's a 2.5 way any longer, more like a 2.166 way system.  I didn't have a bigger inductor on hand and went with the salvaged one off of the original KG4 crossover.  When I ran an impedance sweep of the finished unit with everything buttoned up the Re was about 5.1ohms and it didn't bottom out much below 4.  There was only a slight rising impedance at the Fs and the high frequencies were relatively flat.

 

My next steps are to finish XO #1 and then wire up and test #2.

Final_XO.jpg

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On 3/17/2022 at 1:56 AM, Maz4bz said:

I forgot you said you have the DATS - that's great! No idea how much mass to add but it'll be easy for you to determine.

 

To do this measure a woofer with DATS and use the T&S specs you get with Hornresp or WinISD etc to model up the Dayton PR to get you how much mass to add to it. You could then use your mic to measure the speaker to compare modelled with the actual result to fine tune. 

 

Would be great for you to post the T&S data you take from your MidWest Audio 8" woofers into the Klipsch Impedance Curves thread for others to find too.

 

Good luck! 🍻

 

 

XOs are done and mounted!  Impedance for the new setup coming shortly.

 

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