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2x10 Eminence BP102 cab build

#41
Woodstockz said:
Sigh.
You are missing the point. Have you read the whole thread? The topic is the crossover point, not the impedance.
Click to expand...
You missed my point. You recommended that he use a PXB2:500. He can't, and it has nothing to do with the crossover frequency. With a 2x10 (did you read the whole thread?) using 8 ohm BP102s he can wire the woofers in parallel for 4 ohms or in series for 16 ohms. The PXB2:500 cannot be used with a 4 ohm or 16 ohm load. It can only be used with an 8 ohm load.
I don't know why some are saying that making the baffle wider will get rid of the 250-700 hz dip, because that dip was measured with the speaker mounted on a 2x2 foot baffle that's mounted in a wall. Besides, the dip is only 4 dB deep.
I looked at my copy of the Simplexx 10 plans. Where Bill says that the BP102 and 3010LF aren't strong in the midrange he's not talking about 500 hz, he's talking about 1800-2500 hz. That's where the 2510 works a lot better, especially if you don't have tweeters.
 
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#42
Rick James said:
dip was measured with the speaker mounted on a 2x2 foot baffle that's mounted in a wall.
Click to expand...
That's an infinite baffle measurement, so no baffle-step

Rick James said:
Besides, the dip is only 4 dB deep.
Click to expand...

yes, around 3-4dB
It's very likely caused by a cone edge / surround resonance, there's a hick-up in the impedance plot around 350hz that's probably related to this issue.
Most 10's have this issue around 700hz, but the higher Mms (cone mass) of the BP102 may shift the problem to a lower frequency.
 
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#43
I think it is very good to to really try to get an understanding of different "voicings" of transducers as well as complete systems. Speaker design is so much more than just playing around with numbers in simulation software, to look at the effect of the frequency range where the spekaer acts in "pistonic" fashion. A lot of the character and "sound" lies in the mids, which is also the range our ears are most sensitive. That area is alos much less sffected by room acoustics and boundry effects than the tru lows, making it easier to compare and analyse how different transducers, crossovers etc work together.

I always find it interesting to read how all you other "DIY" guys develop and complete your projects! :)
 
#44
Woodstockz said:
It doesn't have to be 800Hz. 500 Hz is OK.

8 Ohm system with Parts Express prices:

Eminence BP102 $74.99 (Readily available used for cheaper)
Eminence PXB2:500 $49.99
Faital 6FE200 $44.00
---------------------------------
$168.98
Not a bad system for someone on a budget.

Substitute in your favorite mid.

A wide baffle is OK, but there is the portability issue with a bigger cab. Also, if I were making an 18' wide cabinet, then I would be putting 12" neos in there to push more air.
Wide baffle is OK if you already have the speakers, or are getting them cheap.
Click to expand...
As I said, I have practical experience from crossing the Alpha 6 at 400 Hz with 12 dB/octave, which is very close to 500 Hz. The woofer I used had slightly less capacity than two BP102s. I doubt an Alpha 6 will keep up with a pair of BP102s, if crossed over at 500 Hz.
 
#45
Yes, mids are very important. I want my mids to be tight 'n accurate and the loudspeaker must be able to project all the micro-details. That's one of the reasons I use a coaxial mid/high unit. No regular two or three way system I've build has matched that.
 
#46
Rick James said:
You missed my point. You recommended that he use a PXB2:500. He can't, and it has nothing to do with the crossover frequency. With a 2x10 (did you read the whole thread?) using 8 ohm BP102s he can wire the woofers in parallel for 4 ohms or in series for 16 ohms. The PXB2:500 cannot be used with a 4 ohm or 16 ohm load. It can only be used with an 8 ohm load.
I don't know why some are saying that making the baffle wider will get rid of the 250-700 hz dip, because that dip was measured with the speaker mounted on a 2x2 foot baffle that's mounted in a wall. Besides, the dip is only 4 dB deep.
I looked at my copy of the Simplexx 10 plans. Where Bill says that the BP102 and 3010LF aren't strong in the midrange he's not talking about 500 hz, he's talking about 1800-2500 hz. That's where the 2510 works a lot better, especially if you don't have tweeters.
Click to expand...

I dunno, I'd say 4db is pretty deep, but I've only actually completed two speaker projects, I'd love to keep it up on returning home though, I'm already on the planning stage. I have noted though, that a lot of midrange drivers, at least in oldschool hi-fi speakers (like marantz and such) seem to have mids for a much higher range. Very small cones at that. Of course, home hi-fi (and oldschool old hifi at that) is a whole different beast from PA gear, or gear made for bass. For ideal sensitivity, perhaps crossing over hard at 1000hz could be best, at least second order (12db/octave) and going with one of the closed-back alphas could be better, and perhaps padding the mid for sensitivity could work best. Although it's probably peakier than an "original" alpha, the extra sensitivity could be a good compromise to better keep up with the pair of woofers and maintaining a certain pricepoint if need be.
 
#47
Rick James said:
You missed my point. You recommended that he use a PXB2:500. He can't, and it has nothing to do with the crossover frequency. With a 2x10 (did you read the whole thread?) using 8 ohm BP102s he can wire the woofers in parallel for 4 ohms or in series for 16 ohms. The PXB2:500 cannot be used with a 4 ohm or 16 ohm load. It can only be used with an 8 ohm load.
I don't know why some are saying that making the baffle wider will get rid of the 250-700 hz dip, because that dip was measured with the speaker mounted on a 2x2 foot baffle that's mounted in a wall. Besides, the dip is only 4 dB deep.
I looked at my copy of the Simplexx 10 plans. Where Bill says that the BP102 and 3010LF aren't strong in the midrange he's not talking about 500 hz, he's talking about 1800-2500 hz. That's where the 2510 works a lot better, especially if you don't have tweeters.
Click to expand...

(How to address this without getting banned? State the facts. Suppress sarcasm. Inject a little humor maybe?)

No, I didn't miss your point. I just don't agree with it. You are putting words into my mouth by saying that I RECOMMENDED the Eminence PXB2.

I never said that I RECOMMEND the Eminence PXB2:500. Rogypop said that crossing below 800 Hz was a waste of money.

I provided an EXAMPLE of a working 8 Ohm system, one that was not prohibitively expensive and not a waste of money.
I fully DISCLOSED that my system was 8 Ohms.
I also provided a link for the OP to calculate a 4 Ohm crossover. It was an EXAMPLE, not a RECOMMENDATION.

If I had made a RECOMMENDATION for the OP to use an 8 Ohm crossover on a 4 Ohm load, I'm sure that Arjank would have slapped me upside the head.

Now Arjank has provided a feasible crossover solution. I RECOMMEND the the OP try the crossover calculator anyway - even if he gets the same answer that Arjank provided - because there is a lot to be learned in the exercise.
 
#48
Woodstockz said:
(How to address this without getting banned? State the facts. Suppress sarcasm. Inject a little humor maybe?)

No, I didn't miss your point. I just don't agree with it. You are putting words into my mouth by saying that I RECOMMENDED the Eminence PXB2.

I never said that I RECOMMEND the Eminence PXB2:500. Rogypop said that crossing below 800 Hz was a waste of money.

I provided an EXAMPLE of a working 8 Ohm system, one that was not prohibitively expensive and not a waste of money.
I fully DISCLOSED that my system was 8 Ohms.
I also provided a link for the OP to calculate a 4 Ohm crossover. It was an EXAMPLE, not a RECOMMENDATION.

If I had made a RECOMMENDATION for the OP to use an 8 Ohm crossover on a 4 Ohm load, I'm sure that Arjank would have slapped me upside the head.

Now Arjank has provided a feasible crossover solution. I RECOMMEND the the OP try the crossover calculator anyway - even if he gets the same answer that Arjank provided - because there is a lot to be learned in the exercise.
Click to expand...
The lower you go with the crossover point not just the price of filter components goes up but design itself gets much more involved. Without measuring equipment, a bunch of caps and coils to experiment with and proper knowledge how to use it results are crapshoot.
 
#49
Woodstockz said:
Now Arjank has provided a feasible crossover solution. I RECOMMEND the the OP try the crossover calculator anyway - even if he gets the same answer that Arjank provided - because there is a lot to be learned in the exercise.
Click to expand...

The crossover I posted is based on simulation, (online) calculators won't give you the same results since they are based on textbook methods (IMO those are worthless). From experience I know the crossover component values will give the OP very nice results for a basscab, better then with an off-the-shelf crossover.
 
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#50
Rick James said:
You missed my point. You recommended that he use a PXB2:500. He can't, and it has nothing to do with the crossover frequency. With a 2x10 (did you read the whole thread?) using 8 ohm BP102s he can wire the woofers in parallel for 4 ohms or in series for 16 ohms. The PXB2:500 cannot be used with a 4 ohm or 16 ohm load. It can only be used with an 8 ohm load.
Click to expand...

I think that I explained things correctly in post # 11:

"...since you are doing a 2x10, your speaker impedance is 4 Ohms. Most off the shelf crossovers are 8 Ohms. The Eminence PXB2:500 would work OK if you had an 8 Ohm load, but since your load is 4 Ohms, you have to make a custom crossover, or have one made. For calculating the values, you can use an online crossover calculator like this one...

2-Way Crossover Designer / Calculator

With this calculator, you can select your desired crossover frequency, and you can select a mid with a different impedance than your woofer. "
 
#51
Arjank said:
The crossover I posted is based on simulation, (online) calculators won't give you the same results since they are based on textbook methods (IMO those are worthless). From experience I know the crossover component values will give the OP very nice results for a basscab, better then with an off-the-shelf crossover.
Click to expand...

I'm sure that your values are really good. I think that the OP should go through the instructional exercise of making some calcs. I first did them with a slide rule.
 
#57
Regis Rocha said:
Digging up the topic ...
What if I use one Legend B102 (10") as Mid, Crossed in 250Hz? I will use one driver above 2000Hz (3 way) (Selenium D202ti)
Click to expand...
Completly doable with the b102 (not that much with bp102 of which the thread is about.) You could even remove the dust cap and install a phase plug to further extend and smooth out the hi mids and even skip the tweeter. It was used in such fashion with the help of super tweeter in a few quite succesful hi fi speakers.
 
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#60
Thank you Very Much rogypop!

Eu already have 2 x BP102 and driver D202Ti. I'm look for a "mid speaker" to match !

I already mounted a 3 way with 15" and an alpha 6 cbmra, crossed in 800Hz. I found that "missing mids "in small stage. The 15" was much more evident than the 6.

I'm about to buy a B102 (it's available here in Brazil).
Even though I already have an Alphalite 6A (which I'm saving for a fearless 12/6/1)

My plans :
 

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