The opposite, to maximise S/N and dynamic range, the digital source should be run as close to 0DBFS as possible, the amps turned down as low as possible for the SPL desired.
Very good tip to read than MiniDSP is not quiet enough for high effcienty active design 
What do you use guys ? PA brands ? Convolver or DSP in digital domain before more quiet front end before the drivers?
Sorry for this off topic, but as it is also about wallet management here... * ... Btw, I tried too Google for a Community M200A... I didn't find any sellers ! It seems very more PA than current PA !
(* "if your wallet is not deep enough for an Onken compression, let it flat with a planar" - old chineese citation)
What do you use guys ? PA brands ? Convolver or DSP in digital domain before more quiet front end before the drivers?
Sorry for this off topic, but as it is also about wallet management here...
* ... Btw, I tried too Google for a Community M200A... I didn't find any sellers ! It seems very more PA than current PA !(* "if your wallet is not deep enough for an Onken compression, let it flat with a planar" - old chineese citation)
Last edited:
That would only be true if using amplifiers with too much gain, with no attenuation between the MiniDSP and the amplifiers, so the DSP is not using the available dynamic range.Very good tip to read than MiniDSP is not quiet enough for high effcienty active design
With proper gain structure, the MiniDSP dynamic range of 103 dB should be more than sufficient.
If you want minor improvements in signal to noise or dynamic range, expect to pay many times the cost- look at the prices of Xillica, Lake, BSS, and high end DBX DSP.
This is interesting. Every implementation of miniDSP using horn-loaded loudspeakers (high efficiency) that I've been made aware of have all experienced noise problems that have not been resolved.
All the implementations of the other active digital crossovers that you mention above have been successful in the same regard.
I find it interesting that these statistics aren't acknowledged or considered important.
miniDSP has steadfastly refused to address and fix those issues with all those that I know that have contacted them, and have refused to accept returns based on those noise-based problems. That doesn't inspire confidence.
Chris
Chris,
Although I have not actually used the miniDSP, there are many on this forum that do use them with high efficiency horn-loaded loudspeakers with no complaints about the noise. This makes me think that noise issues are most likely a result of running the DSP at too low a level due to excessive amp gain.
That said, I have no idea of the unit to unit consistency of the miniDSP, there could be "lemons" that have too much self-noise to be usable. If a miniDSP does not meet spec, and they won't take it back, that is not good.
Do you have any S/N measurements of the miniDSP from individuals that experienced unresolved noise issues?
What was the amplifier gain for those that experienced unresolved noise issues?
Statistically speaking, there are a large percentage of users that do not understand gain structure, and that percentage is higher for those purchasing entry level equipment, so I would expect more noise complaints from them than those buying far more expensive pro-level gear, who generally have a better understanding having worked their way up.
I have also addressed noise issues with plenty of people using pro-level DSP, most all of it resolved with proper gain staging, elimination of ground loops and attention to the influence of noise producing power supplies located nearby.
Art
Although I have not actually used the miniDSP, there are many on this forum that do use them with high efficiency horn-loaded loudspeakers with no complaints about the noise. This makes me think that noise issues are most likely a result of running the DSP at too low a level due to excessive amp gain.
That said, I have no idea of the unit to unit consistency of the miniDSP, there could be "lemons" that have too much self-noise to be usable. If a miniDSP does not meet spec, and they won't take it back, that is not good.
Do you have any S/N measurements of the miniDSP from individuals that experienced unresolved noise issues?
What was the amplifier gain for those that experienced unresolved noise issues?
Statistically speaking, there are a large percentage of users that do not understand gain structure, and that percentage is higher for those purchasing entry level equipment, so I would expect more noise complaints from them than those buying far more expensive pro-level gear, who generally have a better understanding having worked their way up.
I have also addressed noise issues with plenty of people using pro-level DSP, most all of it resolved with proper gain staging, elimination of ground loops and attention to the influence of noise producing power supplies located nearby.
Art
As Weltersys says, the opposite. You want a strong signal from the source and only as much gain as needed in the amp. If the amp is quiet enough on the horns with its volume turned to zero, or the input shorted, then any extra noise is coming from your source. That's not uncommon. Sometimes the amp can be too noisy all on its own without nay input at all. Horn speakers don't need much signal to make noise.
If you look in the articles section of diyAudio, you'll find an article I wrote about gain a few years ago.
Generally, the source impedance should be a much lower impedance than the amp input impedance, a 1/10 ratio or higher is common.
Impedance bridging/matching of the two really has nothing to do with the type of speakers used, other than the obvious - if a horn raises the sensitivity by 10 dB, any noise in the system will also rise by 10 dB, sounding twice as loud.
Reduce amp gain by 10 dB, problem solved, unless as Pano mentioned, the amp itself has too much self noise.
In the "good old days" of passive crossovers, the midband response of a horn was usually attenuated by 10dB or more to match the woofers, when going active removal of that attenuation can reveal component noise that previously was below the ambient noise threshold.
Art
"The miniDSP itself is roughly three inches square and maybe an inch tall. A USB input is also present and serves as the unit's power supply, though the required USB to power adaptor is not provided. This leads me to believe that it is the intent of the miniDSP's creators that it remain plugged into a PC or Mac 24/7, though I did not use it in that capacity."
USB power supplies can be terribly noisy, or quite clean. Although they should be providing DC power only, poor designs have all sorts of "hash" riding along- not a problem when used to recharge a battery, but not good for an audio PSU.
There are perhaps dozens of people that I know about that can use this information to address their common issue. I wonder why miniDSP themselves didn't identify and publish this fix?
Since I saw the noise complaints beforehand, I never invested in one of these units, and never had the opportunity to investigate. This is very good news if it removes all noise problems and reveals an internal fidelity that is indicated by the unit's specifications.
Mr. Bateman: does the unit perform well relative to other digital crossovers mentioned above after the PS fix? Is the unit's analog circuitry up to par?
(Back to your regularly scheduled programming.)
Chris
This sums it up nicely.
Think about going from a typical bookshelf speaker with a sensitivity of 86 dB to a horn with a sensitivity of 106 dB. Any noise coming from the amp, preamp or source is going to be a lot more noticeable. With some amps in active systems, I've had to put an L-Pad on the horn, just to keep the noise floor within reason.
I couldn't find the perfect horn either (for <$1000) - that's why I got the biggest horns I could (for <$200 delivered) and am now modifying them - extending throat and mouth, 'fixing' throat angle - somewhat delayed by messing about with diaphragm changes and trying to get things 'perfect'
The horn Pooh & I have linked to (the VFM horn for 2" driver) would keep pattern control lower if you simply extended the mouth.
I think a frame of stiff ply + curved sections (using bendy ply or 3mm MFD) to do that should be a reasonably quick build.
If you don't have many tools, you can order ply precut, so all you have to do is drill, glue and screw. You can cut bendy panels with a carpet knife or similar - 3mm material is only a small step up from foamcore.
If you're nearby - in Victoria - I could put it together for you, basically for the fun of building / hearing a new project, without having to pay for it
Caveats:
1) 'quick' for me might be ~a month
2) I'd leave it to you to use filler / sanding / paint / grill cloth to bring them up to whatever visual standard you wanted
Thanks mate I appreciate the offer however I'm in Sydney! I am going to give the VFM horn a try. It might be enough for now anyway. Will also experiment with cardioid woofers to extend directivity even lower. Cheers
Last edited:
I built a horn based off bwaslo's synergy horn calculator spreadsheet - 60x60 degrees down to 400 hz - using a TG9FD
Amazing sound!
So dynamic!
It's only made from 3mm mdf and painted with left over wall paint so at lower frequencies the horn walls vibrate a little - maybe some CLD will fix that in the future
https://youtu.be/ARZWYU9RsW4
Lessons learnt
- 3mm MDF and acrylic gap filler (caulk) are awesome for horn prototyping
- Make sure you have a rear chamber for the driver - at high frequencies the sound coming out of either end are about the same level and reverberates around the room
Amazing sound!
So dynamic!
It's only made from 3mm mdf and painted with left over wall paint so at lower frequencies the horn walls vibrate a little - maybe some CLD will fix that in the future
https://youtu.be/ARZWYU9RsW4
Lessons learnt
- 3mm MDF and acrylic gap filler (caulk) are awesome for horn prototyping
- Make sure you have a rear chamber for the driver - at high frequencies the sound coming out of either end are about the same level and reverberates around the room
Last edited:
some pics:
Very cool oohms. Not sure how i missed this post
Are you still enjoying these horns?
What is the throat size?
PRV 2" compression drivers
For selfish intentions 'm posting here, but I think it is right in with what the OP is raising.
For example there is a 'new product' with a phenolic diaphragm that seems to be right on point, including the price:
PRV Audio D4400Ph Phenolic Compression Driver 8 Ohm 4-Bolt
...and there is another not designd to go quite so lo, but at less than $100 US.
PRV Audio D3220Ph 2" Phenolic Horn Compression Driver 8 Ohm 4-Bolt
I picked out the phenolic models, as I have always read that that would respond better to running a compression driver towards the bottom of it's bandwidth. There is some Ti stuff too.
Just tossing it up and seeing if it sticks...
For selfish intentions 'm posting here, but I think it is right in with what the OP is raising.
For example there is a 'new product' with a phenolic diaphragm that seems to be right on point, including the price:
PRV Audio D4400Ph Phenolic Compression Driver 8 Ohm 4-Bolt
...and there is another not designd to go quite so lo, but at less than $100 US.
PRV Audio D3220Ph 2" Phenolic Horn Compression Driver 8 Ohm 4-Bolt
I picked out the phenolic models, as I have always read that that would respond better to running a compression driver towards the bottom of it's bandwidth. There is some Ti stuff too.
Just tossing it up and seeing if it sticks...
Last week I got a couple of the Tymphany compression drivers that Bill Waslo is using in his latest synergy horn project.
It's an odd compression driver. Though it's not as efficient as the competition, it's bandwidth is nearly as wide as a TAD. Which is pretty awesome considering it's $30.
It look like it will legitimately cover 700Hz-16000Hz. You might even get it to go down to 500Hz.
Hard to beat at the price.
It's an odd compression driver. Though it's not as efficient as the competition, it's bandwidth is nearly as wide as a TAD. Which is pretty awesome considering it's $30.
It look like it will legitimately cover 700Hz-16000Hz. You might even get it to go down to 500Hz.
Hard to beat at the price.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.