miniDSP kits, our answers to your technical questions

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fatbattery

Member
Joined 2010
shielding will get you closer to god.

DQ828 said:
I'm working on a Power Board with filtering.

There are plenty of people who don't have my problem, I'm not sure if its the configuration I am using. I'll build the filter & then see how I go.
Click to expand...

Try some ferrite's on you twisted pair power supply cables and line in cables and if it helps you have got a hint of your problem. The large ones that samwhich over ac leads. If you want trick filtered ac leads get thick ac home twin and earth. Strip it and weave it macramé style. Works great. Straight out of Allen wrights cable cook book . God rest his soul.

Want to try somthing trick on ac input sheilding. I cant stress how important sheilding and rf filtering is with digital.

http://www.dhtrob.com/schemas/afbeeldingen/Cinch.gif This is somthing I am about to try.
 
DQ828

DQ828

Member
Joined 2010
fatbattery said:
Try some ferrite's on you twisted pair power supply cables and line in cables and if it helps you have got a hint of your problem. The large ones that samwhich over ac leads. If you want trick filtered ac leads get thick ac home twin and earth. Strip it and weave it macramé style. Works great. Straight out of Allen wrights cable cook book . God rest his soul.

Want to try somthing trick on ac input sheilding. I cant stress how important sheilding and rf filtering is with digital.

http://www.dhtrob.com/schemas/afbeeldingen/Cinch.gif This is somthing I am about to try.
Click to expand...

I'm making one of these http://lampizator.eu/AC FILTER/SILK/FILTER.HTMLhttp://lampizator.eu/AC
 
M

mrwireless

Member
Joined 2009
It might be worth running minidsp off a 12 V battery just to see if mains born interference is a problem (before going to the trouble of building a filter - no doubt that design is very effective).

I thought i had nose issues with miniDSP balanced. Ran it off a 12V car battery yesterday (in the house). No change to noise. However connecting up a rather expensive pre-amp for comparison i'd have to say miniDSP sounded essentially the same in terms of noise, so not that bad. The noise needs about 15 dB of attenuation before it is acceptable via a power amp with 38x voltage gain into 101dB ribbon tweeter.

I have managed to get rid of a high pitched squeal (very very quiet), not sure how.
 
DQ828

DQ828

Member
Joined 2010
mrwireless said:
It might be worth running minidsp off a 12 V battery just to see if mains born interference is a problem (before going to the trouble of building a filter - no doubt that design is very effective).

I thought i had nose issues with miniDSP balanced. Ran it off a 12V car battery yesterday (in the house). No change to noise. However connecting up a rather expensive pre-amp for comparison i'd have to say miniDSP sounded essentially the same in terms of noise, so not that bad. The noise needs about 15 dB of attenuation before it is acceptable via a power amp with 38x voltage gain into 101dB ribbon tweeter.

I have managed to get rid of a high pitched squeal (very very quiet), not sure how.
Click to expand...

I like the 12V battery idea, will give that a go. I already have all the parts for the filter so will build it anyway :)

That 15db attenuation is on the DSP outputs I assume
 
K

katarakt

Member
Joined 2011
Can someone tell me if EXACTLY the miniDSP Balanced Kit US$125 is in the miniDSP Balanced 2x4 US$145 ? Because the docs are different (e.a. no volume pot, no I2S on the second one) . I think this is only because of the enclosure, but if the pins are in there i can drill a hole for the volume pot.

For the project i want to build (digital amplifier with miniDSP in the same enclosure) it is maybe better to use the second miniDSP with a closed aluminium enclosure to avoid EMC troubles ?
 
D

doug20

Member
Joined 2009
mrwireless said:
It might be worth running minidsp off a 12 V battery just to see if mains born interference is a problem (before going to the trouble of building a filter - no doubt that design is very effective).

I thought i had nose issues with miniDSP balanced. Ran it off a 12V car battery yesterday (in the house). No change to noise. However connecting up a rather expensive pre-amp for comparison i'd have to say miniDSP sounded essentially the same in terms of noise, so not that bad. The noise needs about 15 dB of attenuation before it is acceptable via a power amp with 38x voltage gain into 101dB ribbon tweeter.

I have managed to get rid of a high pitched squeal (very very quiet), not sure how.
Click to expand...

FWIW, I ran a little measurement test with my TAD TD-4001s. I use a ATI 602 amp, its the best comercial amp I have found wrt to SNR and it has gain control on the back.

Ignore the dB Scale, I never calibarted the exact voltage levels in ARTA (think of 120dB on it as really 90dB). The MiniDSP does not really effect the signal chain that much. The DCX definitely increases the output by around +6dB and also increases distortion levels.





TAD + ATI 602
TAD_NO_DSP.gif

TAD + MINIdsp (unbalanced) + AT 602
TAD_minidsp.gif

and for reference of with the popular DCX
TAD + DCX + AT 602
TAD_DCX.gif
 
Last edited:
minidsp

minidsp

Member
Joined 2009
@ katarakt

The miniDSP balanced 2x4 in a box is indeed the exact same board as the miniDSP balanced kit. It's just in a box. :)

So providing you drill the front panel, I guess that you could indeed upgrade it to a version with a volume pot with ease.

Hope this helps.

DevTeam
 
D

doug20

Member
Joined 2009
np, I have always been curious about the differences between the DCX and MiniDSP. I have always had gain issues and an excessive amount of hiss when using the DCX and 110dB CDs. The miniDSP made definitely more manageable.

Now can you please "somehow" add linear phase filters !!! :D Im about to spend $2K on the DEQX but before I do that I want to give you a chance to have more of my $$$ ;)
 
D

Davey

Account Closed
Joined 2001
You can do linear-phase filters with the miniDSP. Use it to create a first-order acoustic, or maybe a filler-driver second-order, or etc. :)

Seriously though, linear-phase filters might be handy, but they shouldn't be near the top of miniDSP's development to-do list.

Cheers,

Dave.
 
D

doug20

Member
Joined 2009
I didn't know MiniDSP can do LP filters, I still can not see how it can actually.

either way, I think everyone should like MiniDSP decide what is important on the to-do list.

Besides that, I say lets put up $$$ in front of our wishlist items. I have $2K to send to MiniDSP to help them decide what is more important :D I wouldnt be the first time someone buys a spot at the front of the line. Its the way the real world works :D

NOTE J/K......Im using the $2K to buy the DEQX.
 
D

Davey

Account Closed
Joined 2001
Fellas,

There are different types of linear-phase crossovers. :) First-order acoustic, second-order filler driver, and a few others are linear-phase results that can be created in the analog world. Since the miniDSP generates filter responses that are identical to analog equivalents, it can achieve those objectives.

Now, if you desire an eighth-order Linkwitz-Riley result, then you can't there with the miniDSP......as currently offered. :) However, if this (lack of) capability is a show-stopper for you then by all means spend the big bucks on a DEQX (or similar) solution.

The are lots of opinions on whether linear-phase crossovers bring enough/any advantages to the final product to warrant the cost/complexity. Unfortunately, most folks have never evaluated linear-phase and non-linear-phase solutions in a true apples-to-apples comparison.

Cheers,

Dave.
 
K

katarakt

Member
Joined 2011
minidsp said:
@ katarakt

The miniDSP balanced 2x4 in a box is indeed the exact same board as the miniDSP balanced kit. It's just in a box. :)

So providing you drill the front panel, I guess that you could indeed upgrade it to a version with a volume pot with ease.

Hope this helps.

DevTeam
Click to expand...

I've just overflown your answer, what a shame :eek: !
I'm going to order one soon, excellent and fast service here, thanks a lot :cheers:
 
Saturnus

Saturnus

Member
Joined 2005
Davey said:
Fellas,

There are different types of linear-phase crossovers. :) First-order acoustic, second-order filler driver, and a few others are linear-phase results that can be created in the analog world. Since the miniDSP generates filter responses that are identical to analog equivalents, it can achieve those objectives.

Now, if you desire an eighth-order Linkwitz-Riley result, then you can't there with the miniDSP......as currently offered. :) However, if this (lack of) capability is a show-stopper for you then by all means spend the big bucks on a DEQX (or similar) solution.

The are lots of opinions on whether linear-phase crossovers bring enough/any advantages to the final product to warrant the cost/complexity. Unfortunately, most folks have never evaluated linear-phase and non-linear-phase solutions in a true apples-to-apples comparison.

Cheers,

Dave.
Click to expand...

Many people also tend to forget that loudspeaker drivers themselves are very rarely linear phase themselves, so to get a true linear phase output you will have to use a non-phase linear crossover.
 
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