What value resistor is this?

zingo

I want to confirm this is 47ohm, not 4.7ohm before I order:

soundfreak1

Bad boys rape our young girls but violet gives willingly.

FTGV

:arrow:.47:arrowl:

mhardy6647

soundfreak1 wrote: »

Bad boys rape our young girls but violet gives willingly.

Good mnemonic but in this case it doesn't help much - it's a sand cast power resistor :-P

gimpod

Wouldn't a 0.47 Ohm be 0R47?

Measure it to be sure.

disneyjoe7

Looks as it is a .47 Ohm 7 watt.

zingo

I think you guys are right that R47 is .47 as it measured under 1 ohm in the circuit.

zingo

Thanks everybody! Order two Mundorf .47 MOX resistors to replace the sand blocks as part of my XO refresh. It's on the mid/high board of the XO, so if I got the value wrong, the tweeter will just be hotter, as the resistor was a late addition to the run of the speakers anyway. I'm excited to hear the diference with replacing sand block resistors and 15 year old electrolytic caps!

soundfreak1

Yea i had to burn some braib cells to pull that back up. But only good on std. Resistors.just wanted to see if anyone would know what it was. HeHe u showed your age .they tought us yhat back in 1972 in electronics school.

mhardy6647

soundfreak1 wrote: »

Yea i had to burn some braib cells to pull that back up...

braib cells?! I think it's even worse than you thought!
;-)

Tbone289

zingo wrote: »

I'm excited to hear the diference with replacing sand block resistors and 15 year old electrolytic caps!

The caps in your picture aren't electrolytics. They're metallized polypropylene (MPT).

zingo

Correct, but the caps on the woofer board are electrolytics. I will also be replacing those MPT caps with newer and closer tolerance ones, with the ultimate goal to upgrade them to Mundorf to match what the factory releases currently. :cool:

Tbone289

Right-o. Just wanted to be sure... Good luck with the upgrades!

zingo

zingo

Received all the parts for my crossover update: MOX resistors and 1% poly caps. Should be able to get them installed this week, and interested to hear any changes. I'm not expecting a lot as I didn't go crazy on parts, but improvements may come if current poly/electro caps have drifted out of spec. Plus, switching from sand-block to MOX resistors should open things up a little.

zingo

Is this a 7uF capacitor? The schematic for the speakers say this should be 5.3uF in the woofer XO, so I picked up a 5.7uF without actually checking the board. My pair of speakers are late in the production, so maybe B&W tweaked a few things by that point.

Tbone289

Yes, that is 7uf.

zingo

Thanks. I know it was a stupid question as a big 7 is printed on the side, but I just wanted to confirm with others as it does not match the schematic.

disneyjoe7

7uf 70 working volts and non Polarized

zingo

Thanks for the confirmation. I'll be replacing those caps with these, in my task to bring the crossovers up to current B&W production specs. Time to place another order...

ViperZ

disneyjoe7 wrote: »

7uf 70 working volts and non Polarized

Why would you say that there is no "----" stripe on the other side? Looks like an electrolytic cap to me.

FTGV

It is an NPE( non polarized electrolytic).The indentations at both ends (not just one) is also an indicator of such.

mrbigbluelight

soundfreak1 wrote: »

Yea i had to burn some braib cells to pull that back up. But only good on std. Resistors.just wanted to see if anyone would know what it was. HeHe u showed your age .they tought us yhat back in 1972 in electronics school.

1972 ? BEEP in SD, CA ? Then ETA (R, SPS10) on TI in SF, CA ? NPS at MI, CA ? NPTU at IF, ID ?

Mnemonics, or numb-onics, I'm not sure. Sorry, I got sidetracked again. :redface:

zingo

FYI; just order the Mundorf caps from Parts Connexion and got 20% off! Forgot they were having a sale, but it does end this month, so order-up some Thanksgiving for yourself; or a loved one...

zingo

One speaker finished

disneyjoe7

Nice and Clean, how do you like the sound?

zingo

Since only one speakers is done right now, I put on a song that has a similar pace and tone all the way though (Texas Rangers by Rebecca Pidgeon), set my preamp to mono, then used the balanced to switch between my left and right speaker. With only a little time on the components, I already could hear a difference between the two speakers. The upgraded speaker has less sibilance which is the most notable change. Along with that, the decay of sounds is much quicker and cleaner, and sounds are more defined; more sharp. The unmodified speaker sounds in comparison a little warmer and softer, but also more fuzzy around the edges; a little less defined. I'll be interested to hear both with stereo music once I finish the left speaker, but those B&W speakers are built like tanks and every step takes longer to upgrade them.

I don't know specifically what to attribute the change to, but I'm sure it's many things at once. The MOX resistors will make a difference, as will having caps that are within 1% of eachother left to right; and no more electrolytics. I also like that when I'm finished, the new components will be Mundorf, which updates the speakers to match what the factory is producing now.

More to come...

zingo

Second crossover upgraded. Now let the burn-in begin...