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I'm very impressed by FIR filtering to say the least. The things you can do with it far outshines any traditional IIR-type filters. I would never go back to a traditional DSP-setup nowadays.
Brother,

Symmetric FIR filters are nice (and sort of causal in the mathematic sense), but the concept of asymmetric filters and group delay decolouring means that one can pretty much correct everything except for perhaps the impulse response of the speaker. One can get the output of the speaker to be much closer to the input signal.

So I figured why start with an IIR DSP(?)... when I can enter in with a FIR based DSP(?). It seemed to be more towards being on the best (leading) edge of technology. One can do this on a computer, but Raimonds is doing it on an imbedded ASIC chip or something like that. I support that R&D and hence I got his product. Hopefully it has enough of a following to stay supported and in-production. It seems from the specs to be pretty special. Over time the approach should be common place, as it is technologically optimal.
 

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Totally reasonable, I'm sorry for reading too much into your last post and accusing you of being defensive.



I think you made the right choice. If I was strictly looking to use a DSP, I'd avoid running multiple smaller DSP units. I'm just looking for a project. Since I was able to get the MiniDSPs for a little bit over $100 each, it actually enabled me to feel okay with modding them (and potentially blowing up a board if things go horribly wrong).

Also in my case I'm going to be using a stock-headunit-to-toslink adapter which will retain volume control in the headunit and output a digital signal. That digital signal goes to a splitter which splits it into 3 connections which goes to the MiniDSPs. If I was using RCA's out from my headunit or from a high/low level converter then that whole setup wouldn't make much sense as I'd be passing the signal through too many different devices and hurting signal integrity. Digital won't have that same problem.

The last component is the selecting of which preset for the DSP. I'll use an arduino and 3d print a set of 4 switches to help facilitate the communication of which preset is being used and send it to the 3 DSPs.

Between the MiniDSPs, the cost of the upgrade opamps and parts, and the arduino, I'm still below $500. And that gets me 3x the processing power of the 8x12 C-DSP, plus I expect higher sound quality after the mods. This comes with the price of a heck of a lot more hassle and engineering. Plus if I wasn't doing volume over toslink, I'd need to also make a volume controller. But that stuff is for fun, for me at least. But I probably wouldn't have gone this route if MiniDSP had equipped their 8x12 with FIR out of the box. There's also another DSP coming to market later this year, if they can release it on time, which should be really really promising.



I'll do a build thread for it. I'll definitely be A/B testing them since I have 3, but I'm trying to figure out a way to non-subjectively measure the results.

That shouldn't be a big deal, but I know it's been a major point of contention with this forum, relating to amplifiers. Some believe that amplifiers all sound the same. Yet it's pretty well established that opamps sound different. For those who disagree, go on hifi forums and try saying that to them. They do and I've heard the differences. It's kind of what timbre is to speakers, except for solid state chips. Timbre isn't able to be expressed with waterfall charts and frequency graphs. Since different amps use different opamps and circuit architectures shouldn't it be that it's possible that different amps sound different? Anyways, I shouldn't even start that discussion here seeing how prior threads have gone. :laugh:

As a quick rundown of what I'm doing, I'm planning on:

Replacing the JRC2068 opamps with AD8599 opamps
Replacing the output DC filtering caps with Silmic II audio 100uf 6.3v caps (expecting it to improve bass attack and depth)
Upgrading the two clock oscillators with higher quality crystals (might skip this since I should have nice power)
Upgrading the linear voltage regulator to it's bigger brother with 2x output capabilities
Adding Panasonic ECWFE 1uf film capacitors to the new opamps as bypass caps.
I may also upgrade the SMT 1000uf power supply cap with something bigger since it seems to get warm, but I'll need to find a replacement that fits.
I'm going to make a DC/DC isolated power supply for the 3 MiniDSPs using a Cincon EC4SBW-24S12 20 integrated DC/DC converter module to provide clean isolated power.
All in all, I'm expecting these mods to make a pretty big improvement in sound quality, not that it's bad now.

I have all class G/H amps too, and I'm considering recapping and upgrading the opamps on them too, even though 2 of them are NIB. They are using JRC 5532's which really aren't that bad though.

Anyways, sorry for getting off track OP. I'd love to hear some more subjective impressions of the APL DSP. It's a beauty. Same goes for you Holmz, when you get yours I'd love to see you do a thread on it and get some in-depth feedback on it.
Very cool, I don’t know much about all this but I’m curious, as my 2x8 with better components definitely sounds better than previous ones.
There’s also the new mini shd for soon I hope, not much infos yet. But I don’t want to derail too much
 

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I like how these can be ordered a la carte with some different options.


Is there any way the manual can be posted here so that I can take a look at it? I'm an APL1 owner now and of course very interested in this unit. I could potentially ditch my current DSP and use this as my single solution.


Also, regarding the output delay...I know Hanatsu you had mentioned it does 45ms delay. The software allows you to input up to 100ms. Is the limit actually 45ms or 100ms? That's a nice improvement over most available dsp's.


And also, what is the output voltage on the RCA outs?




Thanks!
 

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I like how these can be ordered a la carte with some different options.


Is there any way the manual can be posted here so that I can take a look at it? I'm an APL1 owner now and of course very interested in this unit. I could potentially ditch my current DSP and use this as my single solution.


Also, regarding the output delay...I know Hanatsu you had mentioned it does 45ms delay. The software allows you to input up to 100ms. Is the limit actually 45ms or 100ms? That's a nice improvement over most available dsp's.


And also, what is the output voltage on the RCA outs?




Thanks!

more importantly whats the input voltage
 

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I too have been in contact with Raimonds. I look forward to getting my processor from here. Possibly...This or a DBX solution.
 

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I too have been in contact with Raimonds. I look forward to getting my processor from here. Possibly...This or a DBX solution.
dBx processors are junk. Very light on features and most of them have 6 outputs or less.
 

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Discussion Starter #49
more importantly whats the input voltage
Specifications (different versions mentioned here, some specs are common with all versions though)

Inputs

2 x RCA balanced, “-10dBV” “+4dBu” levels, 7 kOhm impedance
1 x Coax S/PDIF (up to 96 kHz)
1 x Optical TOSLINK (up to 96 kHz)
1 x USB HD audio (up to 192 kHz)
1 x Remote In
1x USB configuration in

Outputs
10 x RCA, 4V output voltage (half of “+4dBu”), 8V in balanced mode
1 x Remote Out

Operating bandwidth
24 kHz for 48 kHz Sample Rate version unit
48 kHz for 96 kHz Sample Rate version unit

DSP resolution
Unlimited FPGA processing

DSP type
FPGA + Audio signal processor

Signal converters
Cirrus Logic CS4385 CS4272

Signal-to-noise ratio digital input
117 dBA

Signal-to-noise ratio analog input
114 dBA

Total harmonic distortion analog input
0.0003% at 1 kHz at -15dBFS
0.002% at 1 kHz at -0.1dBFS

Crossover / Equalizer
Unlimited options offered by APL Workshop and APL C5 programs

Configuration
APL C5 program

Memory
11 preset memory recalled by 16 position remote switch
Auto restart of DSP
watch dog served restart in case of DSP fault

Time alignment
0 – 85 ms
0 – 28 m
Step 0.02 ms(48 kHz SR) 0.01 ms (96 kHz SR)

Protection
“Musical” output level limiters at all outputs allowing using loudspeakers at they full power with 10 times peak levels untouched


Crosstalk
>90 dB

Operating voltage:
7.1V – 15.7V

Current drawn , power on
500 mA for 48 kHz SR version, 12V power supply
550 mA for 96 kHz SR version, 12V power supply

Current drawn , power off
1.5 mA

Max remote output current 50 mA

Remote IN voltage 7.5 ÷ 15 VDC (1mA)

Fuse
2A PPTC Resettable Fuse


Dimensions (H x W x D)
36 x 270 x 200 mm
1.42 x 10.63 x 7.87 “

Weight
1.618 kg
 

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I will do a separate little video how to measure and how to use the software in the how-to section later!
Curious if you have made a tutorial on this, think Im gonna swap my Mosconi 6to8v8 + APL VST for one of these units. I learn visually, so your vid would be very welcomed! :)
 

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Just seen this and now it has the old curiosity wanting to know more... So I am definitely keeping an eye on this.
 

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The three potentiometers came with the unit and there’s plastic knobs included but I bought other ones instead.
Could you elaborate more regarding these knobs, specifically what you ended up using instead of the plastic knobs that came provided? Did you get them from Raimonds or somewhere else?

Just purchased the 48khz model, hope to have in hand in a few weeks! :cool:
 

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Discussion Starter #58
Curious if you have made a tutorial on this, think Im gonna swap my Mosconi 6to8v8 + APL VST for one of these units. I learn visually, so your vid would be very welcomed! :)


Next week. I’m super busy right now. Finishing a large job this weekend then I’ll start working on this ;)
 

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Discussion Starter #59
Could you elaborate more regarding these knobs, specifically what you ended up using instead of the plastic knobs that came provided? Did you get them from Raimonds or somewhere else?



Just purchased the 48khz model, hope to have in hand in a few weeks! :cool:

I bought mine from tme.eu.

The ones that are supplied with the unit are plastic and quite large (22-23mm in diameter). I got myself aluminum ones with smaller outer diameter.
 

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Would you still use TDA for time alignment, or does C5 incorporate some type of TA measurement built in?

edit: nevermind, I saw Raimonds answer in the APL1 thread. You still use Workshop and TDA as usual, then C5 for management in the unit.
 
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