discussion Some home audio upgrades

[lowfat]

So I replaced the electrolytic caps on the 100's crossovers. Still no tweeters. So had to the film caps, which I can't but from Digikey, etc. Hopefully Solen or some other audio shop stocks them. Won't be cheap tho.


Not sure how I didn't notice originally, but midrange on one of the 60's wasn't working. Pulled all drivers out as I assumed it was a cap on crossover. But there is so much foam in cabinet I can't find the crossover lol. So I measured continuity on mid. Nothing . But I highly doubt they could burn voice coil on a mid so lol at driver. O thank heavens. No idea how this could happen but I'm thankful.


Also took off tweeter diaphragm in order to push out the cone. Not perfect but pretty close.


And now on to the NAD 2200. It would cut out at low volumes. For last couple months I've been using the the Aiyima A07 Max, which tbh is pretty damn awesome for size/price. But I'd like to get back to using the NAD. I suspect the issue is either the protection relays or a broken solder joint. Not seeing a broken solder joint anywhere do ill try the relays. They are known to fail, just generally not in this manner. White things at top.





Finding 40 year old replacements not always easy. There are a couple replacements that are similar tho. About $50 for a pair from Newark. They don't fit tho without some modding. Pins aren't the same size.


Had to drill out holes a bit.

Haven't done an actual test yet. But I've done a continuity test and they all seem to work.


Will test in a few days. Need to watch some vids to remind me how to set DC offset and bias to make sure the amp is calibrated correctly.

 

[lowfat]

Hmm. So I hook up amp tonight. It works and I haven't been able to duplicate the issue I had before with a channel dropping. So next step is to bring the mosfet bias and DC offset on line. Test bias for both channels. Tad low. Adjust left and it goes well. Adjust right, nope, adjusting potentiometer has almost no impact. It only ranges from 4.2mV to 4.6mV. And it is supposed to be at 7.5mV. Guess I'm going to have to remove the pot in order to see if its working right. And if it is, then no idea.

EDIT: Yup she is humped. Should read about 1K.


EDIT2: By some crazy luck I had the exact pots I needed. Had 2 so replaced both left and right channels. Will hook amp up again tomorrow to test.

 

[lowfat]

Well the above amp repair was a success. I was able to adjust bias (point where amplifier switches from A to B mode. good vid on differences

) to +/- 0.2mV (spec is 0.5). And DC offset (amount of DC voltage on speaker outs) is also within 0.2mV (below spec again). Been over a week of use and issue is 100% fixed.

Speaker diagrams showed up a couple days ago. So time to attempt this again. I have 3 of the new speakers to do. Pic of a non-working diaphragm. Voice coil is burned out.


Remove the diaphragm from the plastic piece, and it just crumbles . There are more cracks that haven't broke yet. This piece isn't usable. Vifa, the brand of tweeters Paradigm used for many years, was bought by Peerless at some point. They don't make these tweeters no more. But they had similar ones but cheaper diaphragms. I asked an audio repair FB group if this plastic piece from newer parts would fit. But one guy told me Paradigm should still may sell them. So I did fire off an email to them.


But I moved on to another. This one was not brittle at all. Glued replacement in place. It isn't a bare aluminum like the original. These look better TBH.


High powered tweeters often need ferrofluid as a lubricant / coolant. Thankfully a guy in BC sells it for $25/vial. So grabbed a couple vials, which should be good for the 5 speakers I need to do.


Was browsing FB marketplace the other day. And someone posted a JL 12" W3V3 subwoofer for a great price. So I picked it up. Now I have a pair of these. Did some cabinet design and modeling. 2 of these subwoofers @ 200W in this specific enclosure would seriously outperform the other high-end JL @ 800W.

So spent a couple hours modeling up enclosures. Plan was to have the subwoofers facing the floor. But my brain wasn't working and never realized I couldn't mount the feet due to the port. So they'll have to face foward. Started cleaning out the basement workshop. So making these is my next on my to-do after fixing the above speakers.

 

[Jokester]

Hope your neighbours don't live too close

I just run a single B&W 200w and it's a lot of thump!

 

[lowfat]

Hope your neighbours don't live too close

I just run a single B&W 200w and it's a lot of thump!

For music 200w can be ok. But I want that low bass you feel in your chest for movies / tv. I'll actually be using 3 subs. 2 for music, then 3 for movies / tv.

Woke up this morning. Started playing some music. And the sub was just squealing. Like 2-3kHz. Was still happening after a few hours of it being off. So I pull the sub and amp in order to test. And it just works fine.



My capacitor tester showed up today. Ended up ordering the cheaper one but it will still work for most things. Testing my crossovers for the Studio 100v3s. All caps are holding capacitance. But maybe the resistance is too high? The ones for the tweeter are about 1ohm. So I'll probably night the bullet and spend the $50ish to replace.

On to the tweeters again. Cleaned out the old ferrofluid. And go to add the new stuff. The magnetic on thr tweeter was pulling it right out of the syringe without me touching plunger. And unfortunately I never realized how much. Ended up wasting close to 0.5ml or about $20 worth due to ovefilling. I had to clean the first 2 out again.




Reapplying thermal paste.

Success. Testing them in the Studio 60s and they work perfectly.

 

[lowfat]

Man getting these Studio 100V3s working has just been a chore. I do a full recap on the crossover. Same issue. All resistors test good. I post on the big audio repair group on FB asking if an inductor could cause this. Almost everyone said the inductor isn't the issue. Pretty much everyone said it was my tweeter repair, which obviously doesn't work.

In proving to the group my tweeters worked by measuring impedence with the Dayton Audio DATS V3. I noticed I can measure inductors and capacitors. Which I noticed this early and I could have saved $65 on a meter to measure the caps. And the DATS is WAY more accurate.

Anyways I measured the inductors and sure enough they they are cooked. But I still don't know the value of the originals. I emailed Paradigm and they wouldn't tell me, but they did offer to repair them for $125USD / each. Which is more than I'd like to spend.

I then remembered I had some unused car audio crossovers. I stole an inductor out of it and installed on the 100V3 crossover. And sure enough tweeter is working. So 100% inductor fault.

So I unwound the inductor and counted turns. 194 turns and about 40ft long. And the wire has an impedance of 0.8ohm. But I can't find any calculators that give me values that should correspond with my results.

The only option I think I have left reassemble the speaker w/ the JL inductor installed. Then do some acoustic measurements. Then see if there are any peaks / valleys in the 1000-3000Hz range. If not I'll use them. If so, then who knows....

 

[anabioz]

wow, this stuff is beyond my knowledge, but this is awesome.

 

[lowfat]

The above pic is the impedance graph of the stock tweeter diaphragms. The below is the aftermarket. Not near as smooth. This had me scared.



Hooked up the measurement mic and took a whole lot of sweeps last night. Remembered I actually kind of enjoyed this. Red is a 60V3 with a stock tweeterPurple is the aftermarket tweeters I repaired. The aftermarket tweeter diaphragms are hot garbage. So I'll definitely be ordering some genuine ones.


And now in green, the 100V3 w/ the repaired crossover including the inductor I stole from a car audio part. Red is stock 60V3. Both w/ the original tweeters. There is a few dB dip from about 1.5K to 3K. Increasing inductor size may help. I do have a slightly larger inductor to try to see if this moves. Not sure why the 100V3 tweeter response is so much more flat after 5K, its the same tweeter. hmm.


On the above the midrange seemed to have a ton of valleys for some reason. Wanted to see if it was environment or something about the speakers themselves. So I hooked up both stock 60V3s. And they both have similar issues. Hmm. These use the same drivers as the 100V3s but the 100V3s have a fancy enclosure. I'll have to try swapping the enclosure over to see if it helps.

 

[lowfat]

I tried a bunch of different inductor sizes for the 100V3 crossovers. From the inductor calculators online, I thought 50mH would be what was used by default. But I found that 60 seemed to work best. So I had ordered a couple from Aliexpress. Installed them tonight.


Also the replacement genuine diaphragms from Paradigm showed up a couple weeks ago. So also installed them on the 100V3s and the center channel tonight.





Had to remove the midrange on center channel to access tweeter. This is what an exploded capacitor looks like. The mid sits directly above crossover.


Now on to the older Paradigm Studio Monitors that I started this thread with. Earlier I had tried to replace the tweeter diaphragms with some from eBay. They didn't fit. But I didn't notice until after I damaged the originals removing them. Paradigm used tweeters manufactured by Vifa. They haven't been made in probably about 10 years. Was googling and found 6 ohm variants on Aliexpress, which is what older Paradigms used. So I ordered them. To my surprise they are genuine new old stock. No idea how. Original Paradigm on left, replacement on right.



Did have to do a tiny bit of trimming to the diaphragm plastic to get it to fit the Paradigm mounts. I did impedence sweeps and they are perfect. Actually smoother than the tweeters I repaired above.


I've been putting it off for weeks, but tomorrow I'm going to work on replacing the vinyl for the 100V3 cabinets.

 

[lowfat]

Got a essentially free Soundstage LF500 8" sub off FB with a purchase of an AVR. Specs claim 500W, but power draw is 420W. Hmm, must break physics. Anyways it seemed kinda decent although didn't hit very low. Specs claimed 44Hz.

So I hooked up my DATS to measure impedence. This way I could find the tuning frequency of the passive radiators it uses. Ended up being 42Hz.



Adding mass to the cone of a passive radiator lowers its resonant frequency. Good passive radiators have an area on the back where you can add weights. These are basic af and literally have no tuning at all. Grabbed some 10mm threaded rod from shed, cut it down. 3d printed some mounts. Then glued it to center of radiator. Mounted radiators upsidedown so I could play w/ weight amounts. I did try twice as many washer but it just had negative impacts. Ran wire through the screw holes in order to connect the DATS to the subwoofer terminals.


Here is the impedance graphs of both version imported in to REW for comparison. Hmm. Not sure why its a hump instead of 2 distinct peaks. But it is tuned about 5Hz lower now.


I reinstalled the radiators the correct way. Added some foam and polyfill insulation as the box was empty. Hooked it up in living room and I am impressed! Now it isn't anywhere near in the same league as my 15" Paradigm, as the Paradigm has nearly 3" the cone area. But for $20 in supplies I am very happy. Absolutely will pair nicely for the Klipsch bookshelves I plan to use for my PC.