My HiFi Boom Box

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   Hi guys, after much deliberation and consideration I have more or less finalised my design for my HiFi Boom Box.  From the beginning of the signal chain is the best place to start I think.  
Firstly I will have a sure bluetooth receiver board, this I will be able to turn on and off independently.  

I will then have the Sure volume control board into which the bluetooth receiver and a  mini jack can connect.  Then it is off to a miniDSP (awesome bits of kit, thanks to amlu and ginger biscuit for advising me on this one).  

The signal will then be split at 500Hz or thereabouts to sub and mid/top, 

Sub will go to a sure 2 x 300W Class-D TAS5630

This will drive 2 x Monacor Number One SPH-275C 10" drivers, they are rated at 8 ohms, but I am not too fussed about that, seems most half decent drivers are rated at 8ohms, or at least those with a low fs that are not huge do anyway.

The mid/top signal will be sent to a sure 2x100W Class-D STA508

The mid/top signal will have to be crossed passively at 5kHz, mids are Monacor MSH-115HQ 4" drivers, they have excellent reviews, and are really well priced, seem to have a really flat response up to around 5.5kHz too, again rated at 8 ohms

The tweeters I am using will be Monacor Number One DT-250 dome tweeters (8 ohms), was considering ribbon tweeters, but they seem like a bit too much hassle to be honest.

Power will be supplied with 3 options available, either 12V from the car, 36V from a 36V/20Ah Li-Ion battery, or a mains operated 36V power supply.  I have a step-up 12V-36V transformer from the car option, and have a 36V-12V step-down transformer for the other options.  All will be run off relay activated switches and all power supplies will be incorporating diodes in-line to prevent any problems.  total size is 87cm long, by 37cm high and 37cm deep.  I might have to make it 40cmx40cm though depending on how much room the electronics take up.  I have simed the box and it should perform rather well, right down to 35Hz where I will high pass the subs.  not thinking of expecting much more than 250W out of it total (but will unlikely drive it that hard very often) and the drivers have been simed with no cone excursion issues encountered thanks to their 6mm Xmax.

I will be building it out of 12mm birch ply, and will be finishing the box in a nitrocellulose lacquer with an amber tint, all-black hardware with a really minimalist feel to it.

I will post build pics but will not be starting the project until early August as I have a load of course work to do and this project is a bit of a treat to myself for doing a good job of the course (I need incentives to work hard).  Will keep you guys posted though, regards, Baron Greenback!

Edited by Baron Greenback - 22 June 2013 at 7:27pm

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Baron Greenback Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 08 March 2011 Location: Shropshire UK Status: Offline Points: 456	Post Options Post Reply Quote Baron Greenback Report Post Thanks(0) Quote Reply Topic: My HiFi Boom Box Posted: 22 June 2013 at 7:23pm
	Hi guys, after much deliberation and consideration I have more or less finalised my design for my HiFi Boom Box. From the beginning of the signal chain is the best place to start I think. Firstly I will have a sure bluetooth receiver board, this I will be able to turn on and off independently. I will then have the Sure volume control board into which the bluetooth receiver and a mini jack can connect. Then it is off to a miniDSP (awesome bits of kit, thanks to amlu and ginger biscuit for advising me on this one). The signal will then be split at 500Hz or thereabouts to sub and mid/top, Sub will go to a sure 2 x 300W Class-D TAS5630 This will drive 2 x Monacor Number One SPH-275C 10" drivers, they are rated at 8 ohms, but I am not too fussed about that, seems most half decent drivers are rated at 8ohms, or at least those with a low fs that are not huge do anyway. The mid/top signal will be sent to a sure 2x100W Class-D STA508 The mid/top signal will have to be crossed passively at 5kHz, mids are Monacor MSH-115HQ 4" drivers, they have excellent reviews, and are really well priced, seem to have a really flat response up to around 5.5kHz too, again rated at 8 ohms The tweeters I am using will be Monacor Number One DT-250 dome tweeters (8 ohms), was considering ribbon tweeters, but they seem like a bit too much hassle to be honest. Power will be supplied with 3 options available, either 12V from the car, 36V from a 36V/20Ah Li-Ion battery, or a mains operated 36V power supply. I have a step-up 12V-36V transformer from the car option, and have a 36V-12V step-down transformer for the other options. All will be run off relay activated switches and all power supplies will be incorporating diodes in-line to prevent any problems. total size is 87cm long, by 37cm high and 37cm deep. I might have to make it 40cmx40cm though depending on how much room the electronics take up. I have simed the box and it should perform rather well, right down to 35Hz where I will high pass the subs. not thinking of expecting much more than 250W out of it total (but will unlikely drive it that hard very often) and the drivers have been simed with no cone excursion issues encountered thanks to their 6mm Xmax. I will be building it out of 12mm birch ply, and will be finishing the box in a nitrocellulose lacquer with an amber tint, all-black hardware with a really minimalist feel to it. I will post build pics but will not be starting the project until early August as I have a load of course work to do and this project is a bit of a treat to myself for doing a good job of the course (I need incentives to work hard). Will keep you guys posted though, regards, Baron Greenback! Edited by Baron Greenback - 22 June 2013 at 7:27pm
	The doctor recons I'm paranoid... well he didn't say it exactly, but I just knew the bastard was thinking it!

amlu Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 30 November 2009 Location: london Status: Offline Points: 740	Post Options Post Reply Quote amlu Report Post Thanks(1) Quote Reply Posted: 22 June 2013 at 8:21pm
	i would use a proper preamplifier or mixer instead of sure volume control board. it will help to bring a weak signal (phone, laptop, mp3 player etc) to nice line level output. sure board can only turn the volume down. will be good to place a double volume pots on minidsp outputs. to adjust how much midtop/bass you have. no need for relays, they consume power and make things more complicated. 20 amps toggle switches do the job well http://www.ebay.co.uk/itm/Heavy-Duty-Double-Pole-Double-Throw-DPDT-Toggle-Switch-On-Off-On-20A-125V-/261075756117?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3cc953e455 and go proper and no minijacks input. they suck and are a work of the devil. double rca is better :-)

Baron Greenback Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 08 March 2011 Location: Shropshire UK Status: Offline Points: 456	Post Options Post Reply Quote Baron Greenback Report Post Thanks(0) Quote Reply Posted: 23 June 2013 at 9:55am
	Hi Amlu, I have been looking at reasonable pre-amplifier options, (thinking a tube pre-amp) and it looks like it will mean having to convert 12V-DC up to 230V-AC and then down to 12V-AC, all this will generate quite a bit of heat/wasted power, any ideas as to how to overcome this? or were you thinking of an inline turntable style 9V pre-amp?
	The doctor recons I'm paranoid... well he didn't say it exactly, but I just knew the bastard was thinking it!

amlu Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 30 November 2009 Location: london Status: Offline Points: 740	Post Options Post Reply Quote amlu Report Post Thanks(1) Quote Reply Posted: 23 June 2013 at 7:32pm
	those things come and go, ebay is the place for searching, you can search for "mini mixer" and have a look what comes up. there is a lovely one seems to working on native 12v: http://www.ebay.co.uk/itm/MIX02-1A-4-Channel-Mini-Mixer-by-Gear4music-/271221407264?pt=UK_Mixers&hash=item3f260e3e20 never seen that before but looks like you can connect 2x signal and some mikes or instruments too. nice vu meter there too :-)

Baron Greenback Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 08 March 2011 Location: Shropshire UK Status: Offline Points: 456	Post Options Post Reply Quote Baron Greenback Report Post Thanks(0) Quote Reply Posted: 24 June 2013 at 9:46am
	Hi amlu, I have opted for a 24VDC Bravo V2 headphone amp, I did look at your mixer option, but felt that it looked a bit on the cheap side, and suspect that it would have introduced noise like the behringer EQ did which I do not want. I have read good things about the above mentioned amp. I do however want to enquire as to what rating the pots should ideally be post miniDSP? Thanks. Edited by Baron Greenback - 24 June 2013 at 9:48am
	The doctor recons I'm paranoid... well he didn't say it exactly, but I just knew the bastard was thinking it!

alphabetikal Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 20 May 2010 Location: UK Status: Offline Points: 217	Post Options Post Reply Quote alphabetikal Report Post Thanks(0) Quote Reply Posted: 24 June 2013 at 4:03pm
	those gear4music mixers are interesting. nice find. this one runs on 9v batt too http://www.gear4music.com/Recording-and-Computers/USB-Micro-Mixer-MX-4U-by-Gear4music/PVJ

alphabetikal Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 20 May 2010 Location: UK Status: Offline Points: 217	Post Options Post Reply Quote alphabetikal Report Post Thanks(0) Quote Reply Posted: 24 June 2013 at 4:16pm
	also, seen this, 'no batteries required' ? how?!?! http://www.amazon.co.uk/Pokket-PM11BLA001-Mixer-Black/dp/B005VXT7JG/ref=sr_1_sc_1?ie=UTF8&qid=1372086955&sr=8-1-spell&keywords=pocketmixer

lost eden Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 04 April 2011 Location: Dundee Status: Offline Points: 942	Post Options Post Reply Quote lost eden Report Post Thanks(0) Quote Reply Posted: 24 June 2013 at 5:13pm
	If you don't put batteries in, it works in exactly the same way that an in-line volume control on a pair of headphones works - just has a potentiometer. It'll probably reduce the power of the signal quite considerably though, even at 'max' volume.

amlu Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 30 November 2009 Location: london Status: Offline Points: 740	Post Options Post Reply Quote amlu Report Post Thanks(0) Quote Reply Posted: 24 June 2013 at 5:38pm
	how it does bass/mid/treble control?

Baron Greenback Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 08 March 2011 Location: Shropshire UK Status: Offline Points: 456	Post Options Post Reply Quote Baron Greenback Report Post Thanks(0) Quote Reply Posted: 24 June 2013 at 7:53pm
	That Pokket mixer is awesome, also being passive it will not introduce any extra noise, very nice find, very nice indeed as it is the perfect way to switch between various different ipods etc without having to turn the volume down first, this would be ideal in a party situation me thinks! Also it is made in Germany! that in it's self adds major reassurances, it is one thing being designed in a place and then made elsewhere such as behringer gear, but stuff that is actually made in Germany is usually very good build quality. Edited by Baron Greenback - 24 June 2013 at 7:56pm
	The doctor recons I'm paranoid... well he didn't say it exactly, but I just knew the bastard was thinking it!

bitSmasher Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 23 June 2012 Location: Melbourne Status: Offline Points: 2295	Post Options Post Reply Quote bitSmasher Report Post Thanks(0) Quote Reply Posted: 26 June 2013 at 6:35am
	You'd still want a preamp in the system with that passive mixer

Baron Greenback Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 08 March 2011 Location: Shropshire UK Status: Offline Points: 456	Post Options Post Reply Quote Baron Greenback Report Post Thanks(0) Quote Reply Posted: 26 June 2013 at 9:37pm
	Hmm funny you should say that... I have decided to use a bravo V2 Tube Pre-amp, I have the parts for the mods on order and for the great total cost of around £60, I should have myself a pretty decent tube pre-amp, for relatively very little cash, also runs off DC so great news all round on that front! I was a bit dubious about going tube with the mini dsp due to the hot signal, although the mini dsp does have settings for such an occurrence and I have read that others who use this configuration have had good results. I will be sorting my gain structure with an oscilloscope and placing Bar-Graph meters before the bass input on the power amp to monitor clipping, the volume will be controlled by the potentiometer integrated in the MiniDSP. I have read that it is really a case of swings and roundabouts regards whether to attenuate in the digital realm or analogue. Just waiting on the parts arriving the cost however is certainly adding up... best not tell the wife .
	The doctor recons I'm paranoid... well he didn't say it exactly, but I just knew the bastard was thinking it!