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Discussion Starter #681
Is there not something else going on there then? The DNA-360 should be exactly 10 dB quieter than the 4594. If you go from an un-noticeable hiss at the seats to being able to hear it outside the room it must be way more than a 10 dB difference.
Close mic SPL measurements confirmed it was 10db as well.

Even now the "hiss" can still be heard at the seats if you listen for it, but if you add 10db to the noise floor it's almost comical.

10db in the range our ears are most sensitive goes a long way.

I really wanted to use my CC4000 to power the BMS CDs. With the amp gains at max and the BMS plugged directly into it you had to get your ear within a few inches to hear the noise floor. Plug the MiniDSP into the CC4000 and whoa! HIIIISSSSSSSSS

I love the 10x10 for my subs, center, and the lower portion of the mains though. I'm using all 8 analog outputs on it.
 

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The miniDSP 4x10HD is operating in 24/96 and I am using the balanced inputs and the balanced outputs. I hope this helps.
 

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Rothwell attenuators

^ I have 2 of the XLR attenuators (10 dB) and can of course buy a 3rd one (LCR build). If I put one on each HF amp input only, would that be good practice? The mid doesn't need it, correct?

I have the miniDSP now hooked up to the amp and speakers. Tomorrow I am going to hook up my Mac to the miniDSP and try to measure the separate drivers at 1 m and 3 m.
 

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In 1992 I built my first 4-way active system.
To minimize the hiss introduced by a NADY 4-way 24db per octave crossover I did the following steps based on the concept of minimizing gain applied to noise inputs.

(1) Use a CD player with variable outputs.
(2) burn a cd with max volume (0db) sign sweeps and put that in the CD
(3) use an oscilloscope on the cd player output to find the highest gain setting without clipping at any point on the 0dB sweep
(4) connected the crossover and checked each output for clipping. Increase the input gain to max without clipping. (seems it was ok even with gain maxed)
(5) checked each output of the crossover and found the max no-clipping output gains
(6) connect the amplifiers, move the scope to the amp outputs and reduce amp input gains until clipping is absent.
(7) connect speakers except for tweeter and balance the outputs for SPL by reducing amplifier input gain.
(8) reduce the output of the cd player by 20dB or so. Set tweeter amp to minimum gain.
(9) Attach the tweeter. Increase the tweeter amp gain until it's output is balanced with the rest of the drivers.

Steps 8 and 9 are used to avoid burning the tweeter out.
Steps 1 through 7 create a high initial signal level that allows your amplifier gain to be set at the lowest point possible and still be able to reach max power.
With the amp gains at this lowest practical setting, you minimize the amplification of noise from the crossover.

It seems this approach might help reduce noise of your DSP units.

Also there is some possible performance improvement if you replace the single amp and high level passive crossover of the horn driver with a dual amp and passive low level crossover made up of capacitors and resistors. maybe like this:
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html

EDIT:
Currently I use a source with XLR outputs. These "pro" units are usually able to output 14dB higher than "consumer" signal sources. That means a big improvement in signal to noise from the very beginning of the signal chain. There is a jumper in the miniDSP that needs moving to use this option.
 

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:)
A buddy of mine loves his tube amps and has been drooling over the SEOS-24. One of our ideas is to use the BMS 4594ND in a fully active arrangement. To avoid hiss, we might use a combination of passive line-level and speaker-level high pass crossovers on the HF section of the 4594. From the preamp output a passive circuit will provide some high pass and eq ahead of the tube amp. The tube amp output would then go into a speaker level high pass to form the remaining part of a 24dB/octave LR high pass. This puts only capacitors in the signal chain for the HF section to hopefully minimize hiss.

The LF section of the horn would be fed through a normal active 3-way crossover mid frequency section. (high pass channel unused because it was replaced by the passive implementation and tube amp)
The 18" cone drivers would be fed from the lowpass of the active crossover. (there is also the possibility of using a DSP stereo amp for the LF horn and 18" which would eliminate the need for the active crossover)

Do you feel that the hiss problems would be adequately reduced by this arrangement?
 

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I thought i'd chime in here with my findings. I've recently finished a project using some used gear and i wanted to try the Hypex Ncore Fusion Amps as a basis for the build. Using the Hypex Fusion FA123 amp/XO/dsp my noise floor was non existant on the BMS 4590's i utilized for Mid/High's. I put a JBL 2226 as the lows, been sitting in my closet for 3 years so happy i found a home for them. Saved a bunch of $$$ too by not having to buy seperate amps, pre, crossovers, etc. Pretty fun project and i'm glad i purchased the Hypex Fusion plate amps. Their software for designing the filters is meh, but i got the hang of it after a day.
 

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^^ What flare are you using for the 4590's please?
 
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I thought i'd chime in here with my findings. I've recently finished a project using some used gear and i wanted to try the Hypex Ncore Fusion Amps as a basis for the build. Using the Hypex Fusion FA123 amp/XO/dsp my noise floor was non existant on the BMS 4590's i utilized for Mid/High's. I put a JBL 2226 as the lows, been sitting in my closet for 3 years so happy i found a home for them. Saved a bunch of $$$ too by not having to buy seperate amps, pre, crossovers, etc. Pretty fun project and i'm glad i purchased the Hypex Fusion plate amps. Their software for designing the filters is meh, but i got the hang of it after a day.
Interested to know what you are using there... I've never seen that before.
 

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Interested to know what you are using there... I've never seen that before.
I used a Klipsch K-510 horn. Crossovers are all 24db 515hz & 6300hz.
 
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I used a Klipsch K-510 horn.
I've read about those before, maybe at diyaudio, and the measurements if I recall are excellent. They're available as spare parts too aren't they? I have a pair of 4590 gathering dust (mine were the first pair south of the equator, and were used in my last 5 way FLH system with Arai 290s) and plenty of other suitable drivers to complete a system with them. Cheers.
 

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I've read about those before, maybe at diyaudio, and the measurements if I recall are excellent. They're available as spare parts too aren't they? I have a pair of 4590 gathering dust (mine were the first pair south of the equator, and were used in my last 5 way FLH system with Arai 290s) and plenty of other suitable drivers to complete a system with them. Cheers.
The horn is fairly rare to come by in the second hand market. You can buy the horn and compression driver through a dealer outlet but it isn't the cheapest. I was able to get them used for a trade. The horn measures great down to 500hz on up.
 

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The horn is fairly rare to come by in the second hand market. You can buy the horn and compression driver through a dealer outlet but it isn't the cheapest. I was able to get them used for a trade. The horn measures great down to 500hz on up.
I didn't notice that they had a new version of the 510, I remember that horn being a more traditional horn with sharp corners but it appears they filled that in.


I also agree, it appears to be hard to find on the second hand market.
 

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I didn't notice that they had a new version of the 510, I remember that horn being a more traditional horn with sharp corners but it appears they filled that in.


I also agree, it appears to be hard to find on the second hand market.
Yeah, the new horn has what they call mumps.
 
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