OB help!

Thanks for the replies. I have seen all the above mentioned programs. I know the MJK software is well respected and Martin spoke of the edge when he did his OB design, but seemed to stop short of recommending it. ABC dipole seems to include everything like MJK so i guess it will be between those two. Gainphile, I have read a lot of your blog with a great deal of interest. I may try to do something similar to your s12 OB. I hadoriginally been looking at the JAMO r909 which is also similar. THinking about using Emimence 12LFA, with either Wild burro Betsy or new Alpair 10.2 for midrange, and either Vifa d26nc55, Seas 27tdf, or Neo 3pdr for highs. I guess we will see
 
I may try to do something similar to your s12 OB. I hadoriginally been looking at the JAMO r909 which is also similar. THinking about using Emimence 12LFA, with either Wild burro Betsy or new Alpair 10.2 for midrange, and either Vifa d26nc55, Seas 27tdf, or Neo 3pdr for highs. I guess we will see

The relation between midrange diameter and baffle width is critical. There is a reason why Orion, Nao looks that way.

Jamo's 909's 5" midrange is acoustically to small for that wide baffle which caused major frequency dip and irregularities on the above spectrum. This behavior is well known and you can see it in various independent measurements of the speakers. Try to simulate that with ABCDipole and then try to change the baffle width.

The Tweeter section is always an achilles heel. Have a read on "Nao Note" to see why John had to go to all that trouble with such weird looking baffle. I simply choose to live with it :p
 
I have read about the changes made to the NAO Note you spoke of. This is why I was interested in the naked driver threads. Why not make individual baffles for the high, mid, and bass supported by a spine like the one on the Jamo. Only problem I see is possible vertical rolloff issues , but I am a newbie. On your newer designs are you just using the same.drivers and interchanging them?
 
Gainphile,
Did you chose the EA 15 for its high Qts. I have read a great deal about reasons for selecting different drivers but no definitive answers. I am considering trying to drive the setup with (Pass F2) current amps using passive XO like MJK. I know it doesn't offer as much control but seems like a interesting experiment. I figure if it does not workout, just try going active XO.
 
I've used ABCDipole, along with the Edge, Linkwitz's spreadsheets, and many others. Your best resources for modeling are MJK's mathcad worksheets, and a good measurement setup. Active crossovers and DSP make crossovers very much easier... Good luck!

If you want to go passive on the bass end, you want high QTS. Most assumptions include voltage amps, not current amps thought. I think the results might not be the same...
 
I've used ABCDipole, along with the Edge, Linkwitz's spreadsheets, and many others. Your best resources for modeling are MJK's mathcad worksheets, and a good measurement setup. Active crossovers and DSP make crossovers very much easier... Good luck!

If you want to go passive on the bass end, you want high QTS. Most assumptions include voltage amps, not current amps thought. I think the results might not be the same...

How have you been using the Mathcad worksheets, I have tried getting mathcad explorer with no luck, I cannot find a way to make them work no matter what I do.
 
Thanks for the help cuibono.

If you want to go passive on the bass end, you want high QTS. Most assumptions include voltage amps, not current amps thought. I think the results might not be the same...

My limited understanding about using a current drive says that although QTS is low, it can be brought higher with passive XO just like Linkwitz did with active XO. Transconductance amps affect speakers differently ans supposedly offer more control over driver response. I belive this is done by raising the Qes which effectivly raises the Qts. It is spoken of in this article:

The First Watt Model F1 Current Drive Power Amplifier Review By Dick Olsher

The 12HO rated nominal impedance is 8 ohms and its sensitivity specification of 95dB is obtained the old fashioned way – by using a 109 ounce magnet. It is not surprising then that it is overdamped with a total Q of 0.29. The 12HO's Efficiency Bandwidth Product (EBP =Fs/Qes) is 138.8, suggesting that a vented bass box would be optimal.

The bass boost derived from current drive operation was used to extend the bass response. The overall Q of the alignment is controlled by the use of a shunt resistor across the woofer terminals...
 
Gainphile,
Did you chose the EA 15 for its high Qts. I have read a great deal about reasons for selecting different drivers but no definitive answers. I am considering trying to drive the setup with (Pass F2) current amps using passive XO like MJK. I know it doesn't offer as much control but seems like a interesting experiment. I figure if it does not workout, just try going active XO.

I had them because they were popular and my understanding was very little at that time. Today I would care only the *target* Q and ideally it's 0.5. I had sold them since.

Any woofer can be made to adjust to target Q using Linkwitz Transform, so the argument which woofer no longer matters. I'd get the Beta because it's already inherent with 0.5 Q. But these woofers have very high Fs which is not ideal.

I'd go with SL's route which is selecting woofer with very low FS and great XMAX (The peerless are 18hz) and EQ them accordingly to the target Fs and Q. In the Orions it's 20hz and 0.5.
 

skorpion

Member
2004-10-26 7:12 pm
Beeing in the USA and wanting the best OB bass, I would look at Acoustic Elegance Dipol15 or if on a budget their IB15. EA15 are good enough but can definitively be bettered. Most important would be to separat bass baffles from mid- and tweeter units to gain clarity and definition.

/Erling
 
Any of the AE woofers would be wonderful and functional, but considering the cost, they are out of the running. Is there any way to get away with two 10" Peerless woofers vs the 12". I know the Fs is 30, but I think that would be very acceptable since this is experimental to some degree. Doing so would save me about 80$ which would pay for the Neo 3's I plan on getting.
 
How have you been using the Mathcad worksheets, I have tried getting mathcad explorer with no luck, I cannot find a way to make them work no matter what I do.

Hi DQ828,

Did you try right-clicking on the Mathcad Explorer icon, and then choosing "Run as administrator"? Plus there are some other options via right-click. I got it working on XP, Vista and Win7. If you provide more info, I would be happy to give you what little knowledge I have :)