MBOWI 3-Way Phase and Measurement Question

[Alex2507]

. But if you want to handle more power, use a 20 watt resistor or two 10 watt resistor in parallel. The power handling of two 10 watt resistors will be the sum, or 20 watts

I could use two 3 Ohm resistors in series to get 6 Ohms and 20 watts. That's what today's trip to the electronics store reminded me. The guy said he's gonna close up shop in a year or so. That means U-Do-It Electronics up in Mass will be the only store around for this stuff. Bummer.

Need photos

The factory crimp:



My plan to bring + and - to the xo's and back to the terminal cup for the mid's band pass.



You can always count on me for wire pic's. The little terminal strips are a little nicer than Verdinut's but at a premium! I was gonna clean out the store but no. Good thing my PE order glitched last night. I'm going to get a few extra resistors to have a few options for my 6 Ohm concerns and Dennis' suggestions for the high pass tuning tweaks. BTW, the original 3-way linked in post 1 with the schematics, has Dennis saying Black Hole is a recommended product but he gives cheaper alternatives. My foam isn't black hole. It looks like something else PE might sell though and I'm unclear who put it in. I'm pretty sure that pound fore pound, rigid fiber glass trumps any foam. Even expensive foam but I've got mystery foam and I have no way of knowing what it is.

Mas editing:

If Rtotal =6 and N = 2, R must be 12.

So what's better, two 3 Ohm resistors in series or two 12 Ohm in parallel?

More editing:

I've thought of a couple of funny names for this particular pair, the latest being The Educators.

 

[Swerd]

So what's better, two 3 Ohm resistors in series or two 12 Ohm in parallel?

If I remember correctly (I learned this stuff back in 1968 and almost never used it) the power handling of two resistors in parallel is the sum of their wattage ratings. Two 12 ohm 10 watt resistors, in parallel, become the same as one 6 ohm 20 watt resistor.

Two 3 ohm resistors in series will add up to give you 6 ohm resistance. But their power handling remains the same as one resistor alone. If you have two resistors each rated at 10 watts in series, one or the other can fail at the rated 10 watts. That would leave you with one cooked resistor and an open circuit.

Read all about parallel and series circuits and how resistors, inductors, and capacitors behave in each. https://en.wikipedia.org/wiki/Series_and_parallel_circuits . Once you learn all that, Peng will give you a quiz .

Nice looking terminal strips. I like how those lugs hold onto those quick disconnects (QD). In the past, I tried a cheap bag of 50 aluminum QDs from PE, but none of them would hold. I tried pinching them tighter with pliers and crimping tools. I succeeded in mangling them but they still didn't hold. Now when I have to connect wires to speaker driver terminals, I buy some brass QDs in an auto parts store, like the blue ones in the photo. They fit and hold tight. Madisound also sells some good ones.

 

[Verdinut]

There used to be several types of expensive cabinet linings. They're no longer sold and I don't remember their name. Maybe @Dennis Murphy can remember. Don't remove it before he chimes in.
How about a photo, and a link where to buy them?

About the terminal strips, I had bought them through a seller on eBay 4-5 years ago. They are pretty hard to find nowadays unfortunately.

 

[Alex2507]

Two 12 ohm 10 watt resistors, in parallel, become the same as one 6 ohm 20 watt resistor.

As I was going over the Dennis' instructions on resistor options I simply decided to get what you said cause if you thought the threes lined up was the way to go you'd a said it.

About the terminal strips, I had bought them through a seller on eBay 4-5 years ago. They are pretty hard to find nowadays unfortunately.

My guy didn't even know where his came from. They were like mystery parts.

I like how those lugs hold onto those quick disconnects (QD)

There's even like a slight stamp in the metal to engage the hole on the male prong. Slip resistant. I'm a get some grill cloth while I'm at it. Okay ... parts list time.

Once you learn all that, Peng will give you a quiz .

I didn't even click on it yet. I'm scarred. Everything I click on is a rabbit hole. I just read something about the Audyn Cap Plus ... you know, for not much more ...

 

[Swerd]

My guy didn't even know where his came from. They were like mystery parts.

There's even like a slight stamp in the metal to engage the hole on the male prong. Slip resistant.

I'd be willing to bet they were NOT made in China. And that's also why they can't be found anymore.

Also, there's been a push to eliminate those type of solder lug strips. They're too inexpensive, too easy to use, and obviously unsafe. For our protection, they're being replaced by these:

I didn't even click on it yet. I'm scarred. Everything I click on is a rabbit hole. I just read something about the Audyn Cap Plus ... you know, for not much more ...

Audyn Cap Plus… don't bother. They're rated at 800 or 1200 volts, expensive, and not available in the 47 µF size. Besides, they're meant for audiophiles who suffer from overbearing feelings of capacitor inadequacy.

 

[Alex2507]

they're meant for audiophiles who suffer from overbearing feelings of capacitor inadequacy.

I let price be my guide. All but the 47 mfd cap ended up being Dayton 250 volt. The resistor selection came up short for 12 Ohm so I got the 6 Ohm but rated for 12 watts. I gotta keep these xo's outside the cabinets for a while, just to look at 'em. The sh!t part is cleaning off the leads on the stuff I'm reusing. I'm learning that I'm really into this other hobby called 'listening to music'. I got confused and got into something called 'making speakers'. Now my speakers are teaching me that I might rather get into this new thing called 'doing nothing'.

Parts are coming. $100. Not too bad.

Edit: In an effort to desolder components I started a mass removal of electrical tape and began cutting all the wires off the leads. Before I needed at least one board together as a reference. I've got this thing in my head now and could probably get most of this right from memory, given the parts. Somehow the world does not revolve around these speakers and I'm sidetracked again.

I wonder if they sell white peg board.

Edit: ... or black plastic.

 

[Alex2507]

So here we are, xo work complete.

High Pass:







Band Pass:







Low Pass (plus a 90 mf cap from the band pass):





All Together Now:





Random:

 

[Swerd]

I gotta keep these xo's outside the cabinets for a while, just to look at 'em.

They're really nice to look at. Thanks for the naked XO photos. In comparison, mine are sloppy. TLS Guy might say mine look like a "dog's lunch".

I like how you rounded off the pegboard corners, and cable tied longer wires so they can't move – all cool . Some of those caps are as big as the nearby inductor coils.

I'm going to have to study the schematic you used so I can better follow the system you used with those terminal strips. The photos are good, but I'd like to also see the schematics. Would you email them to me?

 

[Alex2507]

I'd like to also see the schematics.

My version of these speakers has the Peerless 10" woofer used in this design:

http://murphyblaster.com/content.php?f=MBOW1_3-WAY_previous.html

The 90 mf from net 2 (band pass) got placed onto the net 1(low pass) board. It's a black Solen 80 and a white Sonicap 10 in parallel.

A few large caps had real short leads which forced oddly close terminal strip proximity. My soldering skills made a come back of sorts as I neared completion.

I actually painted the peg boards 'espresso'. That was the color I had laying around. I really just wanted to seal the boards to prevent the dust from flaking off the rough unfinished sides.

I couldn't decide on what color electrical tape to use everyfuckingwhere so I went with bare solder.

Edit: I was looking at net 3, mistakenly thinking I moved that first cap to a different board but I knew I had 6 components on the board instead of 5 so I dragged my @ss out of bed to sort it out before 3 AM.

The more I think about it the more I think I should have lit my head on fire instead of driving to Maryland that day way back when.

More editing: About half way through any project I start hating the work. I've been half way through with this for a long time now but the good news is that hate keeps me warm.

 

[Alex2507]

Wondering what to do while I sit here doing nothing ...

That black felt ...



... turned the back of presumably Del's very well constructed cab ...




into a nice cushion for the xo ...



The bass cab's got the treatment too but that was before the felt came ...



... so I made some stands ...



... and now they look like this:













Not quite 'live' yet but I can only sit around doing nothing for so long ...



EDIT: Went live. Earned a "turn that down" from the next room. Small miracle that the speakers just 'worked'. More loud music got the speakers a personal visit from SWMBO. After a cursory once over in bad light, she asked if I built them. She thinks I come up with the design and it would be cool if I did but it's more like unused pieces of wood laying around come together like they were never apart.

... and they sound f^%&ing wonderful.

 

[Alex2507]

Grills on magnets



Still gotta vacuum up the saw dust from predrilling the holes for the screws on the speakers that the magnets stick to. Pic's or it didn't happen though, right?

 

[Matthew J Poes]

Did you ever get your measurements sorted? I apologize I didn’t have the patience to sort through everything. Just wanted to chime in and note that measurement was corrupted (the first you posted that started this all). Nothing to interpret from it. Hopefully you have it figured out now.

 

[Verdinut]

BTW, Verinut, if you ever get back around, Madisound is selling 7 mfd Solen caps.

Those 7 µF caps were most likely specifically made by Solen for Madisound. On their own website, Solen don't sell that value but sell the 6.8 and 7.5 µF values.

Cheers,

 

[Alex2507]

Hopefully you have it figured out now.

Probably not ... well ... certainly not but we're past the phase question due to a new-ish xo that is wired correctly. My REW-Fu is weak. It's been awhile since I used it (probably with a Vista computer) and even then I was just past the set up stage. Now I need to set this Windows 10 machine up with ... everything.

 

[Matthew J Poes]

Probably not ... well ... certainly not but we're past the phase question due to a new-ish xo that is wired correctly. My REW-Fu is weak. It's been awhile since I used it (probably with a Vista computer) and even then I was just past the set up stage. Now I need to set this Windows 10 machine up with ... everything.

Why have I got something for you!

Just posted last night!

May help you out.

Personally, I think it's always a good idea to measure your DIY speaker projects. You want to be sure everything is work as expected.

 

[Alex2507]

Got the TV down to paint. Pic's are gonna be done by phone for now.

So I got that going for me.

The armoir got yanked and cannibalized. A smaller form factor rack will emerge from the ashes.

It's the weirdest thing, I hate doing this stuff. Yet I'm not really happy unless I'm making something I want to look at. Maybe the motivation is to make stuff stop looking like it's a work in progress. What-ev ... game on but make no mistake, I'm not diggin' it. It just needs doing is all.

Okay, fine: I'm a little excited about having it all back together and working.

... soon.

EDIT: Then it'll be time to finally give the woofer tester and rew the level of attention needed for me to once and for all ... get it. I'll be giving design lessons in 3 more posts.

 

[Alex2507]

 

[Alex2507]

Thanks, Kurt for selling it to me and thanks everybody else for not buying it from me.

 

[Alex2507]

‘Bout a thousand feet of 14 ga because Craigslist

 

[Alex2507]

I think I used about 25' of the 1000' I had on hand.

Better to have it and not need it ...

Got it calibrated and finally got around to letting it rip with some Robert Cray. That was nice. Listened to a DVD-A of Harvest last night running the disc from the living room to this system. Something caught my attention and the comparison was easy enough as SWMBO was out.

I never should have let this take so long. I'm having real trouble leaving the house.

This thing ... it's not letting me go.