I recall reading on other forums that horn compensation should not be EQed out actively and that horn compensation should be done with passive components.
Currently I have a MiniDSP 2x4 and will probably purchase another. I was going to use the DSP to compensate the horns with EQ. I have had mild success with the JBL 2446 on a 2380a horn.
Recently I found some Electro Voice ST350b and since the compensation and crossover looks like it would be relatively cheap (cheaper than cloning a JBL network) I was considering using the passive option on them if there was any benefit versus active.
I'm not worried about amplification costs for the active set up.
This is my first build and should have started with an simple 2 way design, but so far I have broke even from parting out cabs and not spent any money of drivers yet. So I have JBL 2241, 2226, 2446 and EV ST350b to play with. I know there are better components out there, but nothing beats the price of $0. Plus it makes it challenging.
Any advice given is greatly appreciated and let me say thank you in advance!
Currently I have a MiniDSP 2x4 and will probably purchase another. I was going to use the DSP to compensate the horns with EQ. I have had mild success with the JBL 2446 on a 2380a horn.
Recently I found some Electro Voice ST350b and since the compensation and crossover looks like it would be relatively cheap (cheaper than cloning a JBL network) I was considering using the passive option on them if there was any benefit versus active.
I'm not worried about amplification costs for the active set up.
This is my first build and should have started with an simple 2 way design, but so far I have broke even from parting out cabs and not spent any money of drivers yet. So I have JBL 2241, 2226, 2446 and EV ST350b to play with. I know there are better components out there, but nothing beats the price of $0. Plus it makes it challenging.
Any advice given is greatly appreciated and let me say thank you in advance!
The only real advantage in passive horn compensation would be to present a specific impedance load to certain types of amplifiers that are "picky".
There are also some "purists" that desire to have the least amount of active electronics in the signal path.
Your MiniDSP can save hundreds of dollars in passive component costs, and days of design and experimentation time in achieving the desired acoustic response from whatever drivers you choose to use.
For adding VHF tweeters such as the ST350b passive can avoid additional amp channels, but as that is not a concern for you, DSP for each band offers the best control options.
Art
What specific reasons do they say?
The impedance peaks can be tricky, as mentioned, but the response can be changed either way and this is the primary desired effect.
The impedance peaks can be tricky, as mentioned, but the response can be changed either way and this is the primary desired effect.
If it's an active PA system you're considering building, a single capacitor between the amp and the compression driver may be used to provide a last line of defence in case of amp clipping.
Opponents of active components generally believe that the distortions caused
by them are greater or more audible than those caused by passive components. Distortion in an active crossover/eq may be caused by AD-DA conversion if the component is digital, as well as by analogue electronic components (e.g. opamps, etc.) in the circuit.
Opponents of active components generally believe that the distortions caused
by them are greater or more audible than those caused by passive components. Distortion in an active crossover/eq may be caused by AD-DA conversion if the component is digital, as well as by analogue electronic components (e.g. opamps, etc.) in the circuit.
I honestly think that multiband EQs of yore were probably what the post was thinking about, expressing that the solution is worse than the original state of the unmodified driver. It was on a EV Sentry post, but there was plenty of switching between T-35/T-350/ST-350 in the post, so who knows. Honestly I think most of it was balancing impedance was the primary concern in the post.
I will be adding a single cap on each channel below the the crossover point an octave (or is it 2?) below to prevent anything nasty from blowing out the diaphragms.
Ultimately I will probably plan to have the set up fully passive in the future and invest in a better amp, or eventually use my kenwood ka-9100 to power the speakers down the line.
But next up is getting rid of the 2380a and time to build some yuichi A-290s!
Thank you all for your replies, it is much appreciated!
I will be adding a single cap on each channel below the the crossover point an octave (or is it 2?) below to prevent anything nasty from blowing out the diaphragms.
Ultimately I will probably plan to have the set up fully passive in the future and invest in a better amp, or eventually use my kenwood ka-9100 to power the speakers down the line.
But next up is getting rid of the 2380a and time to build some yuichi A-290s!
Thank you all for your replies, it is much appreciated!
One advantage of passive compensation is that the gain structure around 2-5 kHz can be about 5-10 dB better, reducing pass through of noise created in the DAC and amplifier. Noise is not always a problem so it depends whether this is a real advantage. Noise > 10 kHz will be a bit worse though.
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Basically what Art said: use the miniDSP.
Also 1) if the miniDSP is 'noisy', try powering it a different way. Mine is noisy when plugged into a desktop PC, but not when battery or laptop powered.
Also 2) I suggest that you get a friend to help perform some blind tests. Set the MiniDSP to do nothing, and see if you can detect, on a large number of tests, if the signal is going through the unit, or if the signal is bypassing the unit.
Make sure volume etc are the same, similar methodology to this:
Richard Clark Amplifier Challenge FAQ
If you can't consistently detect the difference, then the miniDSP is benign (inaudible to your ear), and you can cheerfully ignore anyone who tells you otherwise.
If you can detect the difference, please sell the (obviously junk) miniDSP to me for $5 🙂
That is great stuff for $0!
The devices aren't the best match - that's a slow flare rate driver on a (short) fast flare rate horn, so:
a) the driver is capable of response to ~500Hz, but not on that (short) horn
b) there will be a big change in angle between the driver snout and the horn throat. See link (just look @ the first 2 pix, if the writing is too dense).
http://www.cieri.net/Documenti/JBL/Technical Notes/JBL Technical Note - Vol.1, No.21.pdf
Since the 2380 is a diffraction horn, the slot provides another sharp change in angle.
The 4" titanium diaphragm will have a breakup around 7kHz, and most of the output above 10kHz will be spiky breakup stuff.
Basically, good setup and eq will improve the sound, but the horn+driver pair will put a ceiling on how good it can be, particularly in a 2-way.
A 2-way would be an easy-but-good start.
1) actively cross a 15" to the JBL 2446, with the crossover at ~1.2kHz
2) get that roughly right (fairly flat from 100Hz - 5kHz)
3) add a simple passive crossover to bring in the HF device at 5 or 6kHz
4) re-do the miniDSP eq to aim for flat response to from about 50-15kHz
The step 3) passive crossover doesn't have to be perfect, since you can smooth it out in step 4)
You can steal mid-high crossover ideas from existing builds, e.g. from here:
High Efficiency Speaker Asylum
Note that passive crossover parts get smaller + cheaper the higher in frequency you go.
I'm assuming you have a measurement mic. Get one if you do not.
I agree about the 2380a, that is why I'm hopping that the 2446 paired to a yuichi A290 (hypex) horn will really make the 2446 shine. Plus if I do go passive, there wouldn't be a need for a compensation circuit. Just please don't tell me that a TAD 4001 is what I should get
it's a "tad" out of my price range. (bad pun intended)In the end I think I might have a Frankenstein's monster of a mix of an EV Sentry III and TAD Exclusive with mainly JBL parts...
I have managed a pretty flat response all the way up to 8khz, similar to the two way you described and hoping that with the ST-350b I can push that up closer to 16k.
Also with the extra MiniDSP I can EQ the 2241 in a cab similar to a 4641 and have a 3.1 set up left and right. It is overkill, but once again the price is right.
Thanks for all the help, good info given!
"Shine", as in a searchlight at high frequencies ;^).I agree about the 2380a, that is why I'm hopping that the 2446 paired to a yuichi A290 (hypex) horn will really make the 2446 shine. Plus if I do go passive, there wouldn't be a need for a compensation circuit. Just please don't tell me that a TAD 4001 is what I should get
The on axis beaming does compensate for the falling high frequency response, but results in a very narrow "sweet spot".
A constant directivity horn can be passively or actively equalized flat, but there is no way to correct the off-axis response of a beaming horn.
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