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Embarking on my first full-blown ground up build


Apr 7, 2024
As the title states I am embarking on a journey to places unknown... Well maybe unknown to me but that's why I'm here, y'all know a whole lot more.

Starting off with the UM 18-22. Pretty sure I'm going the way of DIY amp and I'm going to attach a couple screenshots from this website that I found which seems pretty legit and I'm curious if A anybody's had experience with them and B through my knowledge which pales in comparison to yours the specs look pretty good but I just wanted to see if anybody could confirm that this is a good platform for me to build upon....

Total potential airspace volume is around 17 ft³ and I'm looking at a variation of a full Marty for the box (totally open other suggestions) In short order there will be a second opposing woofer soon as I can afford it so a miniDSP HD 2x4 is going to be in the mix as well. Other amps being considered would be an iNUKE 6000D as well as an XLS 2502 and 3500.

I'm looking for advice on the pros and cons of the three aforementioned and I'm also wide open to other suggestions. Set up will be 70% music 30% HT. Source would be my own DSD library qobuz, Spotify, maybe tidal. Current setup is a pair of focal chora 826s, and that's being fed from a d400 pro. We're not going to discuss the amp that is also feeding them right now because that is changing immediately it's a sore topic don't ask lol.

Anybody curious about the website that I found which I'm entertaining sourcing the board from here it is sure-electronics.com. if anybody has any experience purchasing from them or feedback about the quality of their equipment I'd love to hear it as I'm going in blind right now.

Any guidance would be greatly appreciated on anything above and I look forward to y'alls responses.



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I won't try to recommend an amplifier. The "sound quality" of most amplifiers is "fine". But most pro PA amplifiers have a cooling fan and some people are bothered by the fan noise.

...30% HT.
Note that without a surround decoder you lose the "point one" LFE channel. Of course you get the "regular bass" but the LFE is not included in the down-mix.

Do you have an AVR? That's the most practical/economical way to get a surround decoder.

With an AVR you MIGHT not need the miniDSP.

If you want to use your own amplifiers for the stereo (and maybe surround) speakers, make sure to get an AVR with preamp outputs. (There is always a line-preamp output for an active sub.)

And then you might want to go "full surround". I've "only" got 5.1 and it adds a lot to the movie experience. And personally, with stereo music I like to use one of the "up-mixing" modes to get delayed reverb in the rear channels and the "feel" of a larger room.

...a full Marty for the box (totally open other suggestions) In short order there will be a second opposing woofer
If you are choosing your own woofer make sure to model the design with software to optimize it. (WinISD is FREE or there is other software.) And model it with and without the 2nd woofer. A 2nd woofer will tend to raise the resonance frequency (less volume per-woofer) but of course you can get more output and if it's ported you can change the port tuning.
Doug, thank you so much for your thoughtful and detail reply. Regarding the LFE since the subs will be opposing one another and the amp that I'm going to choose will definitely have a DSP built in I can always just bypass the m mini DSP for my HT use since that will only be 30% of the time and use the built-in.

No AVR currently and definitely intend to use my own power sources however there is a SMSL D 400 pro DAC which I will be utilizing and I'm fairly sure it's atmos compatible.

Regarding full surround that is 1,000% going to happen it's just a matter of time ($). Thank you for the rec on winiSD. I actually have another thread running concurrently to this one over on AVS forum and the guys over there being super helpful in mapping stuff out for me on winiSD as well as CADing out and shooting me over a couple of cut sheets as well as box designs for space I have to work with. It was definitely from here that I learned about it and would totally be lost without it so thank you again.

And regarding the woofer that is exactly what is being worked on and the exact reason why the mini DSP would be in play once the second woofer becomes a reality. None of the higher end power amps with DSP built in have the ability to do infrasonic high-pass filters (it's going to be a necessary safety catch for the tune as well as box design to not blow things up) simultaneously with phase control where the minidsp hd does.
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