rob4diy

mini dsp 2x4 balanced vs dayton 408

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wonder whether anyone has knowledge / experience of mini dsp vs dayton 408 with particlular regard to quality

i am getting one of these essentailly to be a sub pre amp/processor; stereo in to mono sum driving a ucd400(already in place) in a ''audiophile''  2.1 system

dsp 2x4 balanced has the advantage of the balanced bit

dayton; setting up via app is certainly useful, and i think the software looks clearer to use

i will be setting up by ear btw - have keyboard to help (can play various bass tones and attenuate boomy ones, and i think i have identified one problem freq) though i guess the potential of the mic thing is useful  for the future

i would need the dayton to provide a good 2v max line out level (not in specs - i am asking them...?)

thanks in advance for any insight 

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Posted (edited)

I hadn't heard of the Dayton 408 so just had a quick Google...

From what I can see both the Dayton and the particular miniDSP you mentioned are limited to about an 8 ms maximum delay, which for you could easily find shorter than you want/need for your setup.

What is your main system? You describe it as 'audiophile' which makes me think you should probably be looking at some of the better performing miniDSP products. If you have the budget of course. 

Edit: I have a miniDSP 2x4 HD myself.

Edited by MartinC
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Posted (edited)

thanks for your reply martin; (rega CD - nc400x2 passive (ucd400 sub) - diy ellam flex btw.)

sub is positioned just behind mains at the mo - would i be thinking i would only really need delay if it was closer to listening position? the extra resolution on the HD seems a bit OTT if only used with sub...?

maybe this leads to thinking about re-position, and note 8ms gives me about 2 1/2 metres - you bring up a valid point for future flexibility, though think the 2 1/2 mtrs will always be in my ball park. 

(the sub is set quite low and are really there for low orchestral stuff)

Edited by rob4diy
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Out of curiosity could you post a link to some info on your sub? I'm drawing a blank from a quick Google.

Regarding timing, if your subs are behind the main speakers then ideally what you would want to do would be to delay the signal to the main speakers to match what arrives from the sub. To do this you'd need something like a miniDSP to process the signal to the main speakers rather than just to the sub.

Sub integration is a complicated subject though. Arguably what is most important is phase matching in the crossover region. This relative phase is different for early arrival vs the steady-state field that builds up due to room reflections. The latter dominates what we hear at bass frequencies and so this is what I match to. Crucially this phase matching will lead to a different decision about time delays than just looking at first arrivals would. What I think makes sense is to use delays that match phase is the crossover region, whilst being as close as possible to matching first arrival times as well.

What sort of crossover frequency do you have in mind between your main speakers and sub? This will impact the sort of delays you will need, since for phase matching the maximum delay you'll need will be one acoustic period at the crossover frequency (e.g. 10 ms at 100 Hz, 20 ms at 50 Hz etc.)

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thanks for further thoughts - i will study your post later - looks v interesting

the mains sound very good and i will not mess with those and keep direct. bringing the sub in front would be the solution for any timing issue - not that i can hear any, possibly as i am crossing at 40hz - the mains go down quite low (8' TL). the subs are for low orchestral sounds mainly, and given the wide placement of an orchestra i think there is a certain amount i can get away with with this music  (particlularly if its 2 ms or something - e.g. a double bass section would line upover 7 mtrs or so anyway...) 

however the dsp would give me the option to tweek this, and you have certainly highlighted  this element. so are you saying at a low xover freq a longer delay might be required?

the sub is a 'home brew' sub scanspeak 30'' discovery in a big cab 90ltr (thats another story...) down facing. this might be modified with the matching passive in addition to the madisound reccomendation. its been in use for a year in a cobbled together temporary fashion with a passive xover which is time to sort out, along with some room resonances. i have advice and plans for this element and am focussing on line level eq and LP/HP as a first stage.

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44 minutes ago, rob4diy said:

e.g. a double bass section would line upover 7 mtrs or so anyway...) 

We quick reply. That lower frequency instruments tend to be further away doesn't affect the potential problem, which is the crossover region between sub and mains. The issue is that when sound at a particular frequency is coming from both mains and the sub you want these signals to add up rather than cancel each other out.

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49 minutes ago, rob4diy said:

i have advice and plans for this element and am focussing on line level eq and LP/HP as a first stage.

Are you planning to keep using this passive crossover, or will the Dayton/miniDSP be used as a high pass filter on the main speakers? Or possibly no filter at all on the main speakers?

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5 hours ago, rob4diy said:

the sub is a 'home brew' sub scanspeak 30'' discovery in a big cab 90ltr 

:notworthy:

Assuming that is not a typo, you are my new hero!

  • Haha 1

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3 hours ago, rob4diy said:

dsp for xover, no filter for mains

I'm slightly confused...

'DSP for xover' to me means a high-pass filter applied to the mains, and low-pass filter applied to the sub?

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hi (yes 30cm, the '' was the end of the quote mark though put 2!)

OK the plan is to run the dsp to the sub alone and use as the low pass xover (with high pass protection).  my current passive crossover for the sub will be disguarded

sub will need  tuning using the eq. in addition; I am now considering moving the sub in front of the mains with delay

(mains will remain unconnected to dsp)

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8 minutes ago, rob4diy said:

hi (yes 30cm, the '' was the end of the quote mark though put 2!)

OK the plan is to run the dsp to the sub alone and use as the low pass xover (with high pass protection).  my current passive crossover for the sub will be disguarded

sub will need  tuning using the eq. in addition; I am now considering moving the sub in front of the mains with delay

(mains will remain unconnected to dsp)

Right I'm with you now. So as the main speakers will be run without a crossover you'll be relying on their natural fall-off at the low end and trying to match the sub to this. Previously have you only been using your passive crossover on the sub like this as well?

Having a sub further away than the mains and just delaying the sub to get phase matching in the crossover region is what most would do, and be very happy with. I have to do this for blu-ray playback actually and it doesn't sound 'wrong'. What is more important is getting the signals in phase in the crossover region which if you're looking to crossover as low as 40 Hz you may well find the 7.5/8 ms maximum delays of the products you mentioned prevents you from doing. I'm using about an 8 ms delay crossing over at 120 Hz and as I wrote above you could need significantly longer delays for lower crossover frequencies. MiniDSP make a huge range of products and I'm never looked through to see how the maximum delay varies, but for info. I do know the 2x4 HD can use up to an 80 ms delay.

You could start trying to move your sub around to try to help get the phase matching right but you'd very likely compromise the performance of your sub if you did. To get the maximum benefit from your sub you want to be choosing its position to optimise its performance instead. Corner placement is often suggested as best if using EQ, since this maximises output and the additional room mode excitation can be counteracted. Placement is something to experiment with in your own room though.

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2 hours ago, MartinC said:

Sadly I'm pretty sure that should read 30 cm :D.

:D  I kind of knew it was too good to be true!

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