For PM and Pat: a noob question about DSP

Kpatch

Junior Member
I haven’t played with DSP yet but I will soon. How often do you tweak the sound of your speakers using DSP? Is DSP basically a ‘set it and forget it’ one time affair, i.e., once your speakers have been properly positioned and DSP has been used to adjust the sound for the room, is that it? Or do you fiddle with it occasionally to adjust the bass and treble for different recordings as you could with the bass and treble knobs on an ss amp?
 

Olson_jr

Active Member
I used a DSPeaker Anti-Mode 2.0 for a while and found that one can do both.

After setting it up I would still use one of its features called room tilt (?) to boost the bass at low levels and with some older CDs that seem to have been recorded with reduced bass impact.
 

Prime Minister

Site Owner
Staff member
I haven’t played with DSP yet but I will soon. How often do you tweak the sound of your speakers using DSP? Is DSP basically a ‘set it and forget it’ one time affair, i.e., once your speakers have been properly positioned and DSP has been used to adjust the sound for the room, is that it? Or do you fiddle with it occasionally to adjust the bass and treble for different recordings as you could with the bass and treble knobs on an ss amp?
I haven't seriously messed with mine since I got them. I went into the software a few times just to learn it, but there has been no need otherwise. Everything sounds brilliant the way it is.
 

Pat McGinty

Senior Member
It depends. Pretty much, you can get the room EQ right then forget it. But if you have more than one way of listening you can make different setups on the Presets. The processors I'm using have three or four.

Let's say your phono wants a different EQ than your digi source - carts are nonlinear - you'd make one Preset that selects the analog input, sets an appropriate level and adds whatever phone specific EQ to your room EQ. Then you just toggle Presets to switch sources and all of the settings follow along. I can get my whimpy Grado to sound much better.

Maybe you want to prevent your teenagers from destroying your rig (back in the day I lost MANY woofers to a dear sweet daughter) you'd make a Preset that limits the level and never tell 'em how to access the control. Damn, that kid had a lead foot but her taste in music was excellent; at least most of the woofers went to Hendrix Heaven :-)

Or you may want a different EQ for low level listening, TV, etc. One guy wanted a setting for 'loud dance party' in his rec room, so we raised the bass rolloff frequency. You don't need low bass for that sort of music, and the system could play much louder without trouble.

BTW - High passing your woofer correctly brings nothing buy good. I'd be happy to explain.

Just me, pita, I find that a setup may sound great at first, then reveal tiny shortcomings with time. Upper mids being most touchy. So you can adjust. The nice thing is that you can save as many files as you care to, and always go back.

If you're using DSP to execute the filters the situation becomes much more complex. But delightful.
 

Kpatch

Junior Member
Thanks all, appreciate it.

Pat, would you be open to a doing a brief DSP tutorial? I’b bring my speakers and, of course, I’d pay you for your time.
I’ve read the miniDSP User Manual but I’m missing something. Actually I’m missing a lot. My speakers have PWR-ICE 250
amps.
 

Pat McGinty

Senior Member
Thanks all, appreciate it.

Pat, would you be open to a doing a brief DSP tutorial? I’b bring my speakers and, of course, I’d pay you for your time.
I’ve read the miniDSP User Manual but I’m missing something. Actually I’m missing a lot. My speakers have PWR-ICE 250
amps.
Sure. Let's see if this gets you past the bumps. A video as part of my mentoring duties.


It stops short of filter design, I just haven't gotten to that yet.
 

Kpatch

Junior Member
Sure. Let's see if this gets you past the bumps. A video as part of my mentoring duties.


It stops short of filter design, I just haven't gotten to that yet.
Thanks Pat. I’ll play with things a bit and then get back with you. Appreciate it. The filter design part has me stumped but perhaps I won’t have to concern myself with that. Basically all what I want to do is soften the highs and boost the mids and bass.
 

Fran604g

Just Call Me Junior
Man, would I love to experiment with a pair of these amps and my 604-8Gs. (Sorry for my thread crapping - I don't want to kick-off the pirating of the OP's post).

Nice info!
 

Pat McGinty

Senior Member
Thanks Pat. I’ll play with things a bit and then get back with you. Appreciate it. The filter design part has me stumped but perhaps I won’t have to concern myself with that. Basically all what I want to do is soften the highs and boost the mids and bass.
I think you'll grow more comfortable with it once you've had some success with the PEQ. You'll notice that there are PEQs on both the Inputs and Outputs. They sum. The idea is that the Output PEQs - which are specific to just one channel, woofer or tweeter, are to be used to EQ the individual drivers, while the Input PEQ is global - so you'd use it for room and overall EQ. It gets messy if you mix the two.

If your top is hot, yep, a 1st order high shelf starting somewhere in the trebles, then fiddle around. Often you'll need 1dB or less to relax the edgies.

Here is the killer strategy for improving bass while cleaning up midrange:

Try snuggling a high pass filter (in the Output PEQ) up against your speaker's natural low freq roll off. Most speakers acoustic roll off is roughly second order. So try, say, a 2nd order Butterworth at maybe 30Hz then raise the F a few hertz at a time until you hear some bass go away, then back off to where it wasn't hurting. This will reduce a bunch of excursion that wasn't really getting any work done, plus reduce current thru the coils. That will noticeably reduce congestion in the midrange on difficult music. Plus cooler coils doing less excursion makes for better dynamics across the driver's entire band. Free lunch!

Then maybe add a peak five to ten, or so, hertz above that F and jiggle the F, the Q and amplitude around until your bottom end fills out. The combination of those two filters 'buys' you nicer bass. Obviously one can go too far....

Once you feel like you've mastered that, you can buy a little more performance by judiciously using the compressor which allows you to press your luck even further on both extension and boost. Cleverly balancing those three ideas will bring happy times! One caveat: be sure to leave the compressors bypassed until you're ready to learn how to use them because an incorrect setting can be strangely noisy in a way that you'll never figure out what's going wrong.

When you're ready to jump over your passive filters, let me know, that's where the fun is. Happy to help.
 

Pat McGinty

Senior Member
Thanks Pat. I’ll play with things a bit and then get back with you. Appreciate it. The filter design part has me stumped but perhaps I won’t have to concern myself with that. Basically all what I want to do is soften the highs and boost the mids and bass.
Running one 250 on each side, so just one channel into a conventional speaker? Might as well bridge it. 250+250=500. In the upper right change Amplifier Mode to BTL then use the Red and Yellow outputs, tie off the Black and Blue. Then you'll have just one Output Channel - so simpler. Anyway, hey, who can't use another 3dB?
 

Kpatch

Junior Member
I think you'll grow more comfortable with it once you've had some success with the PEQ. You'll notice that there are PEQs on both the Inputs and Outputs. They sum. The idea is that the Output PEQs - which are specific to just one channel, woofer or tweeter, are to be used to EQ the individual drivers, while the Input PEQ is global - so you'd use it for room and overall EQ. It gets messy if you mix the two.

If your top is hot, yep, a 1st order high shelf starting somewhere in the trebles, then fiddle around. Often you'll need 1dB or less to relax the edgies.

Here is the killer strategy for improving bass while cleaning up midrange:

Try snuggling a high pass filter (in the Output PEQ) up against your speaker's natural low freq roll off. Most speakers acoustic roll off is roughly second order. So try, say, a 2nd order Butterworth at maybe 30Hz then raise the F a few hertz at a time until you hear some bass go away, then back off to where it wasn't hurting. This will reduce a bunch of excursion that wasn't really getting any work done, plus reduce current thru the coils. That will noticeably reduce congestion in the midrange on difficult music. Plus cooler coils doing less excursion makes for better dynamics across the driver's entire band. Free lunch!

Then maybe add a peak five to ten, or so, hertz above that F and jiggle the F, the Q and amplitude around until your bottom end fills out. The combination of those two filters 'buys' you nicer bass. Obviously one can go too far....

Once you feel like you've mastered that, you can buy a little more performance by judiciously using the compressor which allows you to press your luck even further on both extension and boost. Cleverly balancing those three ideas will bring happy times! One caveat: be sure to leave the compressors bypassed until you're ready to learn how to use them because an incorrect setting can be strangely noisy in a way that you'll never figure out what's going wrong.

When you're ready to jump over your passive filters, let me know, that's where the fun is. Happy to help.
Oh, (the penny drops).
Thanks very much. Very helpful. I’ll play with this a bit. Appreciate the assist. I see where I want to go first so at least that a start.

But you give me too much credit if you think that I’m at the point where I’d be comfortable bridging the amps and tieing off outputs. I should titled this thread “Complete Noob who’s slightly dense has questions about DSP”.

Thanks again.
 

Pat McGinty

Senior Member
Oh, (the penny drops).
Thanks very much. Very helpful. I’ll play with this a bit. Appreciate the assist. I see where I want to go first so at least that a start.

But you give me too much credit if you think that I’m at the point where I’d be comfortable bridging the amps and tieing off outputs. I should titled this thread “Complete Noob who’s slightly dense has questions about DSP”.

Thanks again.
Yeah, the 250 is so darn versatile, but the controls to get at all of the features can be a bit intimidating. After you learn it, it all makes perfect sense.

It can be used in three "Amplifier Modes", buttons at the top and upper right.

1) In 2-ch mode it will run your choice of source channel, either L or R or Mono (L+R) into both of the 250W amps - so the same source going thru the processors for filtering then into both amps - usually you'd use one for tweeter and one for woofer. The amps output on the Yellow/Blue for tweeter and Red/Black for woofer.

2) Here's an Extra Tricky Part: if, in Channel Mode, you select Stereo it will send L to Output Red/Black and R to Output Yellow/Blue. So you can use a single 250 in the same way you'd use a regular 2x250W stereo amp, but with onboard DAC and a bunch of other nifty features including PEQ.

The L/R/L+R/Stereo selection is possible because the SPDIF signal contains both channels, you're just telling the two DACs which one(s) to play. The analog rules are just a bit different but you can accomplish the same things.

3) If you switch Amplifier Mode to BTL(bridged) it will take the input of your choice, add the two 250Watters to a single 500W and output on Yellow/Red (-/+). You'd just tape up the Black and Blue wires so they don't cause trouble by whipping around and shorting something.

You'd essentially have a 500W monoblock with all of the lovely additional features.

You really can't hurt anything except for overpowering your speakers, so have a happy time fooling around with it.
 
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