Wich of this 2 woofer would be better? Speaker project

[elnaldo]

Hi,
I'm planning to build a 3 way speaker with this drivers (3 first pictures), (actually I already have the tweeters, just want to use them in a 3 way or 2 way speaker), but there are 2 woofers at the same price, that have very similar specs, the bigger difference is "Vas" (16.4L vs 21.9L the other).

Here are the woofers specs:
m6a.pdf
f6.pdf
I think the aluminium one will visually match better with the midrange driver.
I really don't know if 3 ways will be better than 2 ways in this kind of low priced speakers. I don't have any experience doing or building speakers.

Here are the possible drives. Of course, any advice is welcome !
Audax TW025A0 1" Textile Dome Tweeter
Hi-Vi B3N 3" Round Full Range, Copper Color Cone
Hi-Vi M6a, 7" Alloy Cone Woofer
Hi-Vi F6 Kevlar/Paper Cone 7" Woofer

 

[turboyam]

I would go with the F-6 in a 2 way. Audax domes are pretty good too!.
Do you have access to a design software? to see if they blend well/ if
sensitivities are equal or close?.
Tried the D6G from HI-VI, very good results but needs a midrange.

 

[elnaldo]

Actually my first idea was that, F6 in 2 way. But then I thought to add a midrange...I always thought that 3 ways speakers sounded better than 2, but I don want to add 1 driver if i don't need it...
Looking for a midrange, found that copper color one, so I started to think that the F6 is too different (looking) to the other, so the M6 seemed a good looking idea...

Sensitivity is 90dB the audax tweeter, 88 dB both woofers, 81dB the 3" midrange.

I don't have any design softare (yet) since I don't have any idea (yet) about designing speakers !!! But I can build a house, so I think a speaker is much smaller and much simpler than a house !!

 

[4343]

...
Sensitivity is 90dB the audax tweeter, 88 dB both woofers, 81dB the 3" midrange.../QUOTE]

That's sort of a problem there with the midrange being so, uhh, insensitive...

That is, IF you want to be able to hear it.

With 88 db woofers you should look for a mid that is at least as sensitive (88 db or more) or you will be trying to pad down the woofers to match, never a good idea.

The 90 db tweet will only need 2 db padding to match your 88 db woofs, so no problem there.

 

[elnaldo]

Thanks, I didn't know how different was 81dB against 88dB.

So, it seems the way is go for 2 ways, the Kevlar 88dB woofer and the Audax Tweeter.

What is that "2dB padding"? I just thought to crossover them at approx 2500Hz, using a 8uF cap in the tweeter and a 0.5 mH inductor in the woofer, and give it a try...
(values calculated in this web-site)
http://www.bcae1.com/passxovr.htm
(I'm sure there are better crossovers to get the best of the drivers, but they are out of my knowledge...)

 

[JimPA]

Some people like metal cones I think they sound tinty. The kevlar can be difficult to tame above 3500hz because of the peaks. I like ,5mh to .33mh inductors. 6.8 .mfd for tweeter if using Re on + tweeter circuit instead of L-pad and Re of 15 ohms in parallel of tweeter with zoebel on woofer. Try 10ohm Re for woofer zoebel Why not try series circuit.

 

[elnaldo]

What is that "2dB padding"?

I've found it:
"An l-pad is a passive device which lets you control the output level of speakers without changing the impedance seen by the amplifier. "
Extracted from here: http://www.bcae1.com/lpad.htm

Some people like metal cones I think they sound tinty. The kevlar can be difficult to tame above 3500hz because of the peaks. I like ,5mh to .33mh inductors. 6.8 .mfd for tweeter if using Re on + tweeter circuit instead of L-pad and Re of 15 ohms in parallel of tweeter with zoebel on woofer. Try 10ohm Re for woofer zoebel Why not try series circuit.

I've seen also that Zoebel consist in a resistance + capacitor in series, both parallel with the driver. Are there any rule to build this? In the example I've seen, there is a 6.5 uF cap in series with a 6.5 ohm resistance.
You are telling me to use a 10 ohm resistor. Should I add a 10 uF cap to this zoebel?

Wow, this bcae1.com web site is really helpful ! (no affiliation..)

Here are the impedance curves. Any crossover advice is welcome !!!

 

[JimPA]

Yes a 10ohm and 10mfd is correct for zoebel. The 6.8 mfd could be used for tweeter cutoff. Like I said why not try a series circuit. The key is finding correct Re on tweeter + The value needed runs from 2 to 5ohm with most tweeters. I think a 2ohm would be first choice. You could also use a RC circuit of 2mfd cap paralled with the Re on tweeter+. You can let your ears be the judge. If you have a spl meter and test cd like Stereophile Test CD 3 with treble decade warble tones it is easy. I always assemble crossovers outside the box using alligator clips to get final values. What I am stating most people would argue with. One world reknown designer used this basic configuration of crossover values in his many designs. I have built all of my speakers using series circuits since late 80's after seeing the designs from the kits I have built. You need to have the drivers voice coil centers about 6" apart in this design since it is a 1st order Butterworth configuration . I would build a 2 way and not use the 3". Enclosed is link to series layout.

http://www.humblehomemadehifi.com/Crossover.html

 

[elnaldo]

Thanks for all your answers, very helpful :thmbsp:

Since this is my very first project, I don´t think I can go so "Pro"... I will try a simple crossover, or even copy another design...

My idea is to choose between 1 first order crossover, or go a bit further and try a 2nd order Linkwitz-Riley, just using some web-based calculator...

I would like to know if the impedance to calculate the cap and coil values must be the rated impedance of the speaker, or the real impedance shown in the curves at the desired crossover frecuency.

Thanks again .

 

[michiganpat]

Thanks for all your answers, very helpful :thmbsp:

Since this is my very first project, I don´t think I can go so "Pro"... I will try a simple crossover, or even copy another design...

My idea is to choose between 1 first order crossover, or go a bit further and try a 2nd order Linkwitz-Riley, just using some web-based calculator...

I would like to know if the impedance to calculate the cap and coil values must be the rated impedance of the speaker, or the real impedance shown in the curves at the desired crossover frecuency.

Thanks again .

real impedance at the xover frequency.

 

[JimPA]

Using the parallel Re values I stated will gave an 8ohm impedance once the correct value of Re is used on the tweeter + side. I purchased books by D.Weems and Vance Dickinson which taught me a lot about the crossover design of the speaker kits I have built. Back issues of Speaker Builder mainly 1980 to 1990 are very helpful in understanding the basic theory of crossover and driver loading techniques. Glad to be some help, good listening.

 

[The SGD]

well designing a speaker that is actually going to be a good return on investment really is an art. if it is your first project i strongly recommend that you find a kit from a respected dealer (wilmslow audio for europe, madisound for usa/canadaland, not sure what for argentina!) and follow the kit to the letter, build up your skills and get an appreciation just how complex getting two drivers to work well together is, let alone 3!

best tip i have is get the best value, most wideband mid/woofer with high sensitivity and experiment integrating it with a tweeter. an active crossover is a great place to start.

dont spend mega bucks early, start cheap and have fun!

 

[elnaldo]

Be sure I will not expend mega bucks!!
I already discarded the 3 ways design. Just two drivers to start.

The woofer will be finally a cheap 6.5 poly woofer (Peerless brand) quite sensitive (88.48 dBm) that will match quite good with the tweeter. And is not expensive ($19 each )

I will try a 1st order xover, and later a 2nd order with Zobel network on the woofer.
sm19422, I know you want to make me an expert, but I think I' ll try the series network later, after feeling comfortable with crossovers... The also uses more components, I think more things to match.

About zobel: many web-based calculators ask me the Levc value (Voice Coil Inductance), but the manufacturer data sheet comes with 2 values:
Lecv (Induc at 1kHz) = 0.7016 mH
Levc (Induc at 20kHz) = 0.2098 mH

Should I use one of this, or calculate another value near the crossover freq?

The Revc (DC VC Res) value is 6.25 ohm

 

[JimPA]

I would calculate value around crossover frequency. The Peerless is a good choice. I am sure for the money you will come up with better value for the money spent on building your own design compared to store bought. I look at the tools purchased for construction as a life long investment.