System DIY rebuild! starting with the SUB

[NdG1977]

Hello everybody!
I decided to rebuild my system, I'm starting from the sub, but I'd need some suggestions as I'd like to have an idea about a general configuration.

Here some data to start with (a lot of...):

current composition:
Cambridge Azur351R 5.1 (50x4 75x2) I love it, keeping it!
JBL SCS 175 (4 small satellites + small active ported sub)
Volume wise is ok don't need much more, but I want a nice and clear step up in quality! shouldn't be that difficult...

Room:
rectangular 4.17m x 3.55m (pic attached created with the most used engineering tool: PowerPoint)

Listening habits:
50% Music (70% Frozen Soundtrack 30% Hard Rock, but I hope it will change in the future), 50% Movies (Again 70% Frozen, 30% proper movies)

Requirements:
High SAI (Spouse Acceptability Index) that means speakers have to stay where they are (Upper corners...) I'm working on it, might be able to move them toward the centre out of the corners (The front ones at least) but surelly not floor standing or on pedestrals, not enough space and the little girl running around.

Front Speakers:
They will need to be small (otherwise I cannot hang them over the door! ), max height about 250/270mm (can get to 300mm if I sucseed in the negotiation), width and depth are less critical but they still have to look decent (ref. SAI)
I was thinking about 2 way 5in driver + tweeter (Dayton Audio RS125 evetually? if they fit).

How low should I expect them to go? 70/80hz? being "small speakers" they will be cut at 100hz by the AVR anyway from my understanding.
Ported or sealed? I haven't seen many bookshelf sealed speakers around maybe because they don't work well?
Not having the need to go very low couldn't a sealed configuration work? Might be spouting blasphemies...not srue...

Where should I aim to crossover with the sub? (ball figure will need proper calculation)

Subwoofer:
Max External dimensions:
H 610mm
W 400mm
D 400mm (could stretch up to 450)
About 2.5 cuft internal volume give or take
Current objective is to disguise it for a cabinet and that's the size of the door with variable depth.

External or internal amplification TBD, wattage any needed, DSP if needed as the Azure is quite basic from EQ point of view (LPF and boost at 100hz only).

Sealed or ported? I quite like the sealed ones, but the investment on DSP and Ampli can be quite high...still have to understand if necessary...

Budget:
Let's say 60quid/month? Odd right? but that's how it works for all of us when diying...a piece at a time and when it's finished you sart over...if more expensive it takes longer...but please dont make me wait until I'm 60 to listen to it...

What do you think? How would you squeeze the most from this configuration?

I think I'm not the only one looking for those info as the documentation online is quite scarse.
You can easily find a lot of very skilled designers creating very high end systems, and a lot of improvised audiodiyers creating compromised solutions made worse by incompetence.

There is a lot of need for very good designers willing to create the best possible compromised solutions!

 

[kipman725]

So you have about 100L external volume to work with on the sub. Are you more keen on output or the overall quality of the bass? if you split this into two 50L subs it would help combat modal effects in the room. If you want to hide it in furniture be aware that the SPL in close proximity to the sub is much higher than in the room so any possible rattles will be excited.

For such small subs I would use sealed with high excursion drivers and a lot of power/EQ to correct for their natural roll off.

The Azure has a sub out at line level so I would recommend using this to drive a separate sub amp which can have a DSP to do the EQ for the subs and room correction. Something like an inuke/nx that has been fan modded with a giant fan in the top to make it silent could be a good low cost option for this.

 

[tvrgeek]

For music, I prefer low Q sealed subs. Critical Q. For HT where special effects are more important, then ported seems to work better.

The Dayton DSP plate amps seem popular.

Sub and small is unfortunately an oxymoron. Just physics. You can force it with lots of power and EQ, but distortion skyrockets. How audible it is to you, you have to figure out. My living room sub ( 12 inch Peerless, critical Q,) is disguised as a Chinese chest.

 

[NdG1977]

thanks guys for the answers!

So you have about 100L external volume to work with on the sub. Are you more keen on output or the overall quality of the bass? if you split this into two 50L subs it would help combat modal effects in the room. If you want to hide it in furniture be aware that the SPL in close proximity to the sub is much higher than in the room so any possible rattles will be excited.

I'm just building it so that it looks like one, will be close-ish but just a modem and a nas in the cabinet.

For such small subs I would use sealed with high excursion drivers and a lot of power/EQ to correct for their natural roll off.

The Azure has a sub out at line level so I would recommend using this to drive a separate sub amp which can have a DSP to do the EQ for the subs and room correction. Something like an inuke/nx that has been fan modded with a giant fan in the top to make it silent could be a good low cost option for this.

I was thinking more of a double TPA3116 and mini DSP or something like that, to build piece by piece, but from a convenience point of view the inuke wins for sure, I'll consider it for sure if I find a good occasion!

Alternative is to go ported or TL, in that case amp requirements are smaller and then re-update to a bigger better powerful sub in a few years if I don't find the ported one amazing of course!

Sub and small is unfortunately an oxymoron. Just physics. You can force it with lots of power and EQ, but distortion skyrockets. How audible it is to you, you have to figure out. My living room sub ( 12 inch Peerless, critical Q,) is disguised as a Chinese chest.

Yes I know, nasty physics, screws my life every day ...but I'm not looking for single digits. I tend to be far more critic on music than movies...

By the way the front speakers will be small form factors with low sensitivity...around 80db (Looking at speedster, stand, overnight sensation and similar)...so I'm not expecting to need impressive power to drive the sub. (room correction excluded, if I have to damp 10db I'd need it...)