I have not tried the newer Sure amps like the 6x100,as I am wary of their fears about overheating.
I have used heaps of the 2050 2x100 amps with no problems till connecting them to the MiniDSP.
The 2024 amps are bulletproof.
This is not hum from bad earths.The board is making the noise.
Using a Pro amp with balanced inputs made it disappear.
It's up to a cleverer person than me to explain why.
I have used heaps of the 2050 2x100 amps with no problems till connecting them to the MiniDSP.
The 2024 amps are bulletproof.
This is not hum from bad earths.The board is making the noise.
Using a Pro amp with balanced inputs made it disappear.
It's up to a cleverer person than me to explain why.
My one (and only) neuron tells me that answer has to come from somebody else...
To be fair, I still need to eliminate the possibility of the faint noise be associated with the power supply and cabling arrangement I am currently using. Other than that, the board sounds better than I expected.
Once I get my miniDSP I will experiment and report back.
Cheers!
Maybe the new amp is just a better design than the boards.
FWIW, I don't get noise running my miniDSP's to a well-designed amp with unbalanced inputs, on speakers with mid-90's 2.83V/1m sensitivity. However, I'm always interested in reducing the footprint of my audio system, and increasing its energy efficiency. So if there was an inexpensive 6-channel class D board could provide adequate power and equally low noise...I'd be all over that.
I've had hiss with both the unbalanced and balanced versions of the minidsp..
After reading more about gain structure I finally got around to fixing my issue...
I had my high end attenuated digitally ( -3db ) in the minidsp plugin...
So.. I made a t-pad for about 6db (closer to 6.3db with the resistors I had on hand) to go between the minidsp and upper end amplifier... I did attenuate the sub portion to account for the additional 3ish db on the upper end, but I'm having to boost everything on the low end by at least 3db so there should be little loss...
IT'S SILENT!
I removed the digital attenuation, so I'm also back to my original volume on the high side speakers.... it's wonderful... I should've done this a long time ago....
in case anyone is wondering, I'm using tang band w1808's and dayton reference HF 15" subs in an open baffle... (I know, I didn't think the dayton's would work in OB - but talked to a PE tech and he thought it should be fine).. they sound awesome.. just have always had this annoying "feature"
After reading more about gain structure I finally got around to fixing my issue
...I had my high end attenuated digitally ( -3db ) in the minidsp plugin...
So.. I made a t-pad for about 6db (closer to 6.3db with the resistors I had on hand) to go between the minidsp and upper end amplifier... I did attenuate the sub portion to account for the additional 3ish db on the upper end, but I'm having to boost everything on the low end by at least 3db so there should be little loss...
IT'S SILENT!
I removed the digital attenuation, so I'm also back to my original volume on the high side speakers.... it's wonderful... I should've done this a long time ago....
in case anyone is wondering, I'm using tang band w1808's and dayton reference HF 15" subs in an open baffle... (I know, I didn't think the dayton's would work in OB - but talked to a PE tech and he thought it should be fine).. they sound awesome
.. just have always had this annoying "feature"
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Ok, after more tweaking I've removed the digital attenuation and modified the levels for the low side...
Another note... as far as balanced vs unbalanced, the balanced version is far easier to tweak since you have to power it externally anyway, you don't have to shut it down to connect it to a pc...
Another note... as far as balanced vs unbalanced, the balanced version is far easier to tweak since you have to power it externally anyway, you don't have to shut it down to connect it to a pc...
Hi,
I agree with MiniDSP that this is a gain structure problem.
In my opinion digital filtering and DAC volume control has a limit, when you get too closer to the noise floor.
I am using 118db BMS drivers with a 71A (0,5 Watt) tube amplifier.
I just bought a pair of xlr balanced -20db attenuators.
I expect to solve the issue with this.
Best,
I agree with MiniDSP that this is a gain structure problem.
In my opinion digital filtering and DAC volume control has a limit, when you get too closer to the noise floor.
I am using 118db BMS drivers with a 71A (0,5 Watt) tube amplifier.
I just bought a pair of xlr balanced -20db attenuators.
I expect to solve the issue with this.
Best,
Just thought I'd mention my setup here, which is adequate but not perfect with my older miniDSP 2X4 and high sensitivity speakers:
I'm using a FaitalPro HF144 (110dB) for HF and a Lorantz 15" woofer (98dB) for LF.
I've tried a rotating fleet of amps before settling on a small group that are adequately quiet (a collection of some of the "usual suspects" from DIYaudio, but right now its a JLH1969 class A on HF and a Tripath TA3020 module from ConnexElectronics on LF).
Input is entirely via optical SPDIF (minidigi) - to keep the PC side isolated from the audio side as much as possible.
I had to LPAD my compression driver 7dB down to 103dB to get any amp handy not to have audible hiss at the listening position, connected to the miniDSP or not.
Even even with the 7dB attenuation even lower power amps (5W-15W) seem fine for driving the HF portion crossing over at 600hz or above.
I have found the MiniDSP 2x4 doesnt have enough output to drive a lot of my amps at anywhere near full power at their default gain, I've made some very simple opamp buffers with stepped attenuators I use to control the levels coming out of the miniDSP so I get a broad "enough" range of volume for the amplifier fleet using the software volume control. At highest gain these increase the noise levels, but for most sensible settings it is quiet.
With this and "OK" amps I can keep the noise level down audible hiss with ear close to the drivers, but quiet at the listening position.
I'm using a 12VDC linear power supply to power the miniDSP (and the opamp buffers) - when I plug in the laptop via USB to reconfigure the system the noise level increases a lot, but I dont leave the laptop connected when not making changes so thats OK.
One smallish gripe with the software volume control is it doesnt go to 0 when at minimum? why make a volume control that when you turn all the way down... goes almost all the way down, but not silent?
I'm using a FaitalPro HF144 (110dB) for HF and a Lorantz 15" woofer (98dB) for LF.
I've tried a rotating fleet of amps before settling on a small group that are adequately quiet (a collection of some of the "usual suspects" from DIYaudio, but right now its a JLH1969 class A on HF and a Tripath TA3020 module from ConnexElectronics on LF).
Input is entirely via optical SPDIF (minidigi) - to keep the PC side isolated from the audio side as much as possible.
I had to LPAD my compression driver 7dB down to 103dB to get any amp handy not to have audible hiss at the listening position, connected to the miniDSP or not.
Even even with the 7dB attenuation even lower power amps (5W-15W) seem fine for driving the HF portion crossing over at 600hz or above.
I have found the MiniDSP 2x4 doesnt have enough output to drive a lot of my amps at anywhere near full power at their default gain, I've made some very simple opamp buffers with stepped attenuators I use to control the levels coming out of the miniDSP so I get a broad "enough" range of volume for the amplifier fleet using the software volume control. At highest gain these increase the noise levels, but for most sensible settings it is quiet.
With this and "OK" amps I can keep the noise level down audible hiss with ear close to the drivers, but quiet at the listening position.
I'm using a 12VDC linear power supply to power the miniDSP (and the opamp buffers) - when I plug in the laptop via USB to reconfigure the system the noise level increases a lot, but I dont leave the laptop connected when not making changes so thats OK.
One smallish gripe with the software volume control is it doesnt go to 0 when at minimum? why make a volume control that when you turn all the way down... goes almost all the way down, but not silent?
Trans Coupling
I think you nailed it there. Trans isolation is so important with these sort of devices. It will help with the dc thump problems too.
I think Most users would be surprised at the improvement that trans make.
I think you nailed it there. Trans isolation is so important with these sort of devices. It will help with the dc thump problems too.
I think Most users would be surprised at the improvement that trans make.
Thank you for acknowledging my genius.
However, these cheap isolation transformers are usually made for car subs and will take little consideration to treble. Maybe a higher quality Lundahl or Jensen 1:1 transformer would be more suitable. One with specs for the whole register. Whatever those specs are... :S
Seems like Minidsp 4x10HD creates a ground loop that is of no concern when using the compression drivers with a Firstwatt F-5. But when using a Sun Audio 2A3 tube amp clone the minidsp together with the computer produces a lot of hiss and noise. I can hear when I move the mouse. An isolation transformer cures it almost but sounds dull. I tried a separate DAC for the midrange and treble channels and that solved the problem with the hiss. But then the high frequency channel uses another clock for the DAC and even if it sounds clear there is probably some delay between the high and low channels. I use optical SPDIF between the computer and the Minidsp 4x10HD, and between the Minidsp and the second DA, but that only helps when using a second dac for the tube amp. I prefer the tube amp on the high frequency drivers, so that is the last thing to be replaced.
I wish minidsp would have come up with a solution, considering the price of this unit (€720 in Norway).
I wish minidsp would have come up with a solution, considering the price of this unit (€720 in Norway).
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I'm having same sort of issue.
2x minidigi + minidsp
spdif coming from my computer with external soundcard (focusrite).
using different amps (from Rotel till cheap T-amps) makes no difference.
a lot of hiss coming out of my speakers.
I'm using the mindsp for active crossover and room correction.
Any help on this would be great.
2x minidigi + minidsp
spdif coming from my computer with external soundcard (focusrite).
using different amps (from Rotel till cheap T-amps) makes no difference.
a lot of hiss coming out of my speakers.
I'm using the mindsp for active crossover and room correction.
Any help on this would be great.
I have hiss too...
My 100db midrange are fairly silent with a 6db LPAD on the XLR input of the power amplifier and I've optimised the gain structure the most I could for the subs and mid-woofer.
they create noise but it's inaudible from the listening position.
All there is left is the tweeter (channel 7 and 8)
they are 95db efficient and I go thru a 6db attenuator pad (resistive)
When I plug REW and measure the output of the tweeter, I measure 10khz peak in the noise.
I have 2 minidsp 4x10hd and both have the very same ~10khz noise...
Not too sure where it come from!
My 100db midrange are fairly silent with a 6db LPAD on the XLR input of the power amplifier and I've optimised the gain structure the most I could for the subs and mid-woofer.
they create noise but it's inaudible from the listening position.
All there is left is the tweeter (channel 7 and 8)
they are 95db efficient and I go thru a 6db attenuator pad (resistive)
When I plug REW and measure the output of the tweeter, I measure 10khz peak in the noise.
I have 2 minidsp 4x10hd and both have the very same ~10khz noise...
Not too sure where it come from!
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No, they don't. It's some type of measuring anomaly you're experiencing.
To confirm it simply make an REW measurement on the miniDSP unit by itself without acoustic measurement clouding the issue.
Dave.
I have to say I'm using a miniDSP 10x10 HD with very efficient compression drivers and horns and the noise floor is remarkably low, practically non-existent.
I am however, running my USB stream from my computer to a Mutec MC 1.2 which makes all the difference.
I am however, running my USB stream from my computer to a Mutec MC 1.2 which makes all the difference.
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An externally hosted image should be here but it was not working when we last tested it.
hard to say the opposite, I have a 11.6Khz annoying peak.
on 95db tweeter, I hear it from the listening position.
picture show measurement at 1" from the tweeter.
I''ve optimized my gain structure and have only the issue on channel 7 and 8.
Martin,
A properly functioning 4x10Hd unit will not generate such a peak.....unless programmed to do so.
As I said previously, you need to make an electrical measurement of the miniDSP unit BY ITSELF (without acoustic measurement confusion) to satisfy your curiosity regarding this.
It's very easy to measure peaks and valleys in the high frequency response of transducers (especially with a microphone very close.) I'm sure that's what you're seeing in your measurement which, BTW, doesn't link correctly. So, none of us can see it.
Dave.
A properly functioning 4x10Hd unit will not generate such a peak.....unless programmed to do so.
As I said previously, you need to make an electrical measurement of the miniDSP unit BY ITSELF (without acoustic measurement confusion) to satisfy your curiosity regarding this.
It's very easy to measure peaks and valleys in the high frequency response of transducers (especially with a microphone very close.) I'm sure that's what you're seeing in your measurement which, BTW, doesn't link correctly. So, none of us can see it.
Dave.
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