60 Degree DIY Mid Hi - AKA PM60

[Mark Wilkinson]

Re: 60 Degree DIY Mid Hi

This is more or less what I have done with the Lake – make the amplitude and phase flat (within reason) within each band. When you add everything together with linear phase crossovers they add perfectly and there will be no issues in the time domain.

To minimize the system's latency I have used an IIR filter between the subs and low.

In my latest settings I have EQ-ed the natural roll-off of the DIY to perfectly match a 12dB - 100Hz Butterworth function (to about -10dBor more). Then I add 12dB Butterworth high-pass filter to create an almost perfect 24dB LR curve (Two 12dB Butterworth filters added together = 24dB LR)

I then used a 24 dB LR crossover on the subs and an all-passfilter so that the phase response of the sub matched the DIY from between (about) 50Hz to 200Hz.

Yes, the more i look into the issues with trying to FIR the sub, the more it points to what you and maybe everybody seems to be doing...ie IIR the sub.
So I think I'll get the unit for playing with the DIY, and if all goes well and I still think trying to move down into sub freqs is worth a try, I can just bootstrap in a 2-channel version of the same box for sub (with same processor and much greater per channel tap count)

 

[Mark Wilkinson]

Re: 60 Degree DIY Mid Hi

Any cheap forklifts in your area? Most forklifts usually do over 4 meters, even if it was a lower lift one you could build it up with pallets etc. Forklifts are an item when brought at the right price, you should easily get your money back on a few years down the track. Not sure what your physical surroundings and space freedoms are though..... Here in NZ I would usually be able to get a rough one for 2 grand(after keeping an eye on the market for a few months), not too much when considering you can pretty much get that money back when your done and when you’ve already spent so much on the project. Obviously most people don't have the space for this luxury. A little outside the box thinking........

Thx Jim, great idea..I agree, you can't really lose. I had a farm till about 2 years ago...I would have done that...

Now, living at a lake....I'm left with this kind of jury rigging haha

 

[Don J Davis]

Re: 60 Degree DIY Mid Hi

Thx Jim, great idea..I agree, you can't really lose. I had a farm till about 2 years ago...I would have done that...

Now, living at a lake....I'm left with this kind of jury rigging haha

Looks like a nice place to live! I also use a speaker stand and painters pole to hold the test mic. I remove the 1-3/8" adapter and the pole slides neatly into the stand with no need for zip ties. Might work on yours if the handle isn't too big.

 

[Uwe Riemer]

Re: 60 Degree DIY Mid Hi

Yes, the more i look into the issues with trying to FIR the sub, the more it points to what you and maybe everybody seems to be doing...ie IIR the sub.
So I think I'll get the unit for playing with the DIY, and if all goes well and I still think trying to move down into sub freqs is worth a try, I can just bootstrap in a 2-channel version of the same box for sub (with same processor and much greater per channel tap count)

Have you looked at the Ashly NE4800 ( 384 tabs at 48kHz ) or the Linea Research ASC 48 ( Linear phase filters modelled after LR24 ).
Booth units are about the doubled price of the Mini DSP, but have a more complete feature set for PA application IMO including limiters and balanced I/O.
For me especially the ASC 48 looks like a bargain.

If you are not familiar with Linea Research, you could buy the Danley branded version :razz:

 

[Brandon Wright]

Re: 60 Degree DIY Mid Hi

Yes, the more i look into the issues with trying to FIR the sub, the more it points to what you and maybe everybody seems to be doing...ie IIR the sub.
So I think I'll get the unit for playing with the DIY, and if all goes well and I still think trying to move down into sub freqs is worth a try, I can just bootstrap in a 2-channel version of the same box for sub (with same processor and much greater per channel tap count)

Mark, as another option if you are set on the Mini DSP, why not get the 2x2 balanced version? You could use the crossover, EQ, and Limiters that you already own in the PLD and just use the mini dsp upstream for phase correction?

 

[Mark Wilkinson]

Re: 60 Degree DIY Mid Hi

Don, damn, why didn't I see that?! Simple and brilliant, handle fits fine....thx 8)~~

Ewe, check out this thread https://www.minidsp.com/support/for...opendrc-has-some-new-competition?limitstart=0
Lot of good posts comparing consumer FIR to pro audio processors ... post #21877 lists the ASC 48

Brandon, I should consider that. I think the real reason I'm leaning to the 8 channnel, is I'm so new to all this I was thinking being able to tune section by section (MID, HF, VHF) completely individually first, might make it easier to put it all together and have smooth phase and summing.
OH, and BTW, great progress on the DIY60 !

I'm kinda thinking that right now I need education more than hardware.... so I guess first priority is how to get educated as cheaply as possible..even if it means letting go of integrated balanced I/O, etc.

But definitely still researching...not set on anything yet. Thanks guys

 

[Uwe Riemer]

Re: 60 Degree DIY Mid Hi

... check out this thread https://www.minidsp.com/support/for...opendrc-has-some-new-competition?limitstart=0
Lot of good posts comparing consumer FIR to pro audio processors ... post #21877 lists the ASC 48

...I'm kinda thinking that right now I need education more than hardware.... so I guess first priority is how to get educated as cheaply as possible..even if it means letting go of integrated balanced I/O, etc.

But definitely still researching...not set on anything yet. Thanks guys

Yes the ASC48 is mentioned, but the price ???
My distributor quoted much less, need to inquire that.
And features??? No import of custom FIR in the latest software version, only Linear phase filters, quite similar to the LM Peter is using.

Generally there seems to be an obsession with tab numbers in the thread you linked.
I would never consider creating more than 10ms of latency for live sound or even DJ application.

Can you follow the discussion of Michael, Frank and Mark in the FIR filter thread? I cant.
But I know, what the goal is: Creating a valid target response to attack with FIR.

There are some nice lectures on Youtube about Digital Signal Processing.
Lets talk again in a year or so ~~:smile:

 

[Mark Wilkinson]

Re: 60 Degree DIY Mid Hi

Yes the ASC48 is mentioned, but the price ???
My distributor quoted much less, need to inquire that.
And features??? No import of custom FIR in the latest software version, only Linear phase filters, quite similar to the LM Peter is using.

Generally there seems to be an obsession with tab numbers in the thread you linked.
I would never consider creating more than 10ms of latency for live sound or even DJ application.

Can you follow the discussion of Michael, Frank and Mark in the FIR filter thread? I cant.
But I know, what the goal is: Creating a valid target response to attack with FIR.

There are some nice lectures on Youtube about Digital Signal Processing.
Lets talk again in a year or so ~~:smile:

Heck no, I can't start to understand the mathematical machinations the guys are talking about.....although my gut says, like everything, it's often more a matter of learning vocabulary and nomenclature, than anything really mind bending...

There does seem to be obsession with tap numbers in the "purist" discussions. I guess I'm willing to play with maybe higher latency because in some ways it seems like maybe we are used to more of it than not. I mean, alot of guys use horn load subs for live, and my guess is that with bandpass filters in place that means needing a delay to the tops usually in the 12 to 20ms range....

 

[Jason Allen]

Re: 60 Degree DIY Mid Hi

Can someone explain better the back of this cabinet . Since there is a void opening, do you cover this from inside with a piece of wood to recess speakon jacks? Or leave it open to the point you can see the middle boards of the baffles? Thanks Jay

 

[Peter Morris]

Re: 60 Degree DIY Mid Hi

Can someone explain better the back of this cabinet . Since there is a void opening, do you cover this from inside with a piece of wood to recess speakon jacks? Or leave it open to the point you can see the middle boards of the baffles? Thanks Jay

Here are a couple of pictures that may help.

The "void" serves as a suitable recess for the connectors. By removing that piece of wood it reduce the weight a little and provide an additional handle point.

 

[Jason Allen]

Re: 60 Degree DIY Mid Hi

Thanks Peter. That's what I was thinking . Always help to see it in use .

 

[Jason Allen]

Re: 60 Degree DIY Mid Hi

Sorry for more questions. When adding the speaker pole mount to the bottom, are you adjusting the brace in shape, size, or location? Can someone show me how they mounted the pole mount? Thanks

 

[Peter Morris]

Re: 60 Degree DIY Mid Hi

Sorry for more questions. When adding the speaker pole mount to the bottom, are you adjusting the brace in shape, size, or location? Can someone show me how they mounted the pole mount? Thanks

The pole mount MUST be located at the centre of gravity. The box will weigh about 35 Kgs and it must be perfectly balanced on the pole. The brace should be adjusted to suit, and you need a strong quality pole mount.

Peter

 

[Jason Allen]

Re: 60 Degree DIY Mid Hi

The pole mount MUST be located at the centre of gravity. The box will weigh about 35 Kgs and it must be perfectly balanced on the pole. The brace should be adjusted to suit, and you need a strong quality pole mount.

Peter

Thanks Peter, does anyone have the mount location measured out for the top hat so I can locate it precisely?

 

[Peter Morris]

Re: 60 Degree DIY Mid Hi

Thanks Peter, does anyone have the mount location measured out for the top hat so I can locate it precisely?

The problem is that it will change slightly depending on what drivers and timber you use. What I did was build the box, load the drivers and find the point of balance using a small piece of dowel under the base. It should be about 200mm from the back of the box.

 

[Jason Allen]

Re: 60 Degree DIY Mid Hi

Makes sense....Once completed I will have to do the balancing trick and locate the center of gravity. Does it matter if I use 8 ohm or 16 ohm 4594?

 

[Peter Morris]

Re: 60 Degree DIY Mid Hi

Makes sense....Once completed I will have to do the balancing trick and locate the center of gravity. Does it matter if I use 8 ohm or 16 ohm 4594?

No it does not matter - I used 16 ohms to make the noise floor a little less. All of my amplifiers are large (Powersoft K6's and K10's) and the 4594HE is just soooo efficient that amplifier hiss is more noticeable than usually.

The peak power capacity of the 4594 is 1000W ... not sure I would like to test that but I think it would be appropriate to be able to deliver close 6 dB on top of the rated power of 150 watts i.e. 600 watts.

 

[ShemSeto]

Re: 60 Degree DIY Mid Hi

There are very few boxes commercially available that can do this. As far as I am aware for its size and weight there are none that offer the performance this DIY does in terms of SPL or sound quality.
To squeeze 2 x 12” horn loaded drivers and a high frequency horn into a box and have it pole mount means that weight and size become critical. At the moment I’m pushing the size and weight as far as I would like, accordingly I was prepared to accept it being a little more complex to build to save as much weight and size as possible.

 

[Jason Allen]

Re: 60 Degree DIY Mid Hi

Hello, can someone please tell me the best way to wire the box for amplification? If I have two 8 ohm 12" and a 4594 8 ohm, is it best to wire the 8 ohm 12" in parallel and the 4594 the same, or series parallel for each? And then bi-amp the box signals to the HF and LF? This is probably common sense for most on here, but just don't wanna mess this up. thanks

 

[Ossian Ott]

Re: 60 Degree DIY Mid Hi

The 12" is best in paralell, but the hf and vhf has to be on different amp channels and processed differently as they aim at different passbands. Or get a passive crossover between hf/vhf if you want to save a amp channel(personally what I probably would do)