Rebuild of Boombox - Looking for tips

[Buzzyll]

Hey!

I have this project I have made like 2 years ago. It is a big outdoor boombox.
HeavyMan!! - Boombox - Galleri

Anyway the thing is as you may notice, it is quite big... To make it possible to use more often I would like to rebuild it to a smaller version.

The stuff that I have available are as follows:

2x Eminence-Delta-15C-15-Speaker-400Watt-4Ohm-48Hz-4kHz

2x 8" Celestion TF-0818MR

6x Monacor MPT-016

1x BX55 - Boss Audio Systems

1x 4 x 100Watt Class D Audio Amplifier Board TK2050

1x 2 x 100 Watt 6 Ohm Class D Audio Amplifier Board TDA7498

2x Car batteries

1x Voltage Converter


Any ideas around a good design for a more compact base cabinet? I was looking at a "Iso-Barik (Compound)", but I have no idea if it is a good option for what I am building.


I am also ready to buy some new stuff, but it would be nice to be able to use atleast the speakers that I have.


Would be awesome with some help and tips 😀

 

[ewollowe]

Metal system sir.

Something to look at is aperiodic speakers. Basically putting the woofers in a "leaky" box. You get less big boomy bass than a reflex put a much smaller box, smaller than even a modeled sealed enclosure.

 

[picowallspeaker]

Eh ! 55 $$ for an electronic crossover ! 🙄
But it doesn't perform well for our job, as we need just the classic 0.8/5 kHz X-O points. I don't see any subwoofer, so the sub-out is useless.
Also the 4-channels ...😕

 

[Buzzyll]

Eh ! 55 $$ for an electronic crossover ! 🙄
But it doesn't perform well for our job, as we need just the classic 0.8/5 kHz X-O points. I don't see any subwoofer, so the sub-out is useless.
Also the 4-channels ...😕

Thanks for the reply but it doesn't really help me... And like I wrote I am ready to buy some new stuff as long as I can keep the speakers. What would you recommend instead of the electronic crossover, and do you know any good place to buy it? And not really sure what you mean with "the 4-channel" sorry.

 

[Jerms]

Not quite sure if that's a boom-box or a boom-building.... 🙂
It certainly doesn't look portable. Can imagine trying to daily commute with it! - LOL.

Only thing I can think is to maybe break it down into components....
1) A more portable boombox running the tops and 8s.
2) The subs in maybe a double THAMxx tapped horn.

 

[horst303]

or keep the 15"s and run them two way with a compression driver crossing around 1.5KHz, oh and put them in separate boxes, easier to transport, and will sound better, because stereo just does.

 

[picowallspeaker]

Thanks for the reply but it doesn't really help me... And like I wrote I am ready to buy some new stuff as long as I can keep the speakers. What would you recommend instead of the electronic crossover, and do you know any good place to buy it? And not really sure what you mean with "the 4-channel" sorry.

Just make an electronic crossover for your needs.
So you can put in use your 4-ch amps.
You just need 3*(dual)op-amps
So the structure is: source>buffer>lowpass><highpass>amplifiers>bass speaker>mid speaker( treble driver is to be highpassed passively ).

OR / And

Use a real subwoofer, so all the box volume will be dedicated to it.
The 15"s will be on separate panels, as the 8"s which can be mounted separately ( as the HF driver).

In this case you need something like the "boss X-O", which performs L+R summing then steep lowpass for the sub; highpass for the complementary satellites; mid-band LP and HP ( still the tweeter will be crossed passively )

 

[Buzzyll]

Just make an electronic crossover for your needs.
So you can put in use your 4-ch amps.
You just need 3*(dual)op-amps
So the structure is: source>buffer>lowpass><highpass>amplifiers>bass speaker>mid speaker( treble driver is to be highpassed passively ).

OR / And

Use a real subwoofer, so all the box volume will be dedicated to it.
The 15"s will be on separate panels, as the 8"s which can be mounted separately ( as the HF driver).

In this case you need something like the "boss X-O", which performs L+R summing then steep lowpass for the sub; highpass for the complementary satellites; mid-band LP and HP ( still the tweeter will be crossed passively )

I am to inexperienced to build my own electronic crossover (unless I have like a full DIY kit).

My 4-channel amp has two seperated RCA inputs, so I can controll each "side" of the amplifier from my now existing crossover. So it is more like 2x 2channel amplifier in one. So atleast my intention was to have 3x dual channel amps and controll each one of them from my crossover, and I am quite sure that is how it is wired now.

Is it like this you mean I should use the Op-amps or what is the point of them?

Is that still totally wrong and stupid? If so please try to explain it more in details 🙂

Buying a new Subwoofer is not really any option sorry. I believe I have more than enough speakers already.

 

[picowallspeaker]

If you open that "boss" el.cross. you'll find lots of op-amps; the point is that you don't need any "front" nor "rear" systems, just the two channels (...front !! ) . Also that Boss has one sub out, though you don't have any subwoofer.
Those big 15" are just...woofers.
AND I see that the correct cutting frequencies aren't present !
( or maybe it's variable continously, as in a "state variable filter")

 

[picowallspeaker]

So, you'd better with an "old style" el.cross. type with just two settings ( high pass and low pass and gain for each one)
That said, it's not so difficult to "replicate" the sound of those crossovers: just three Opamps and a breadboard plus some resistors and capacitors ( trimmers or potentiometers for volume; for "gain" you need extra Opamps or make it Q dependable altering Opamp's gain )

The passive crossover between midrange and tweeter might be performed passively

 

[Buzzyll]

If you open that "boss" el.cross. you'll find lots of op-amps; the point is that you don't need any "front" nor "rear" systems, just the two channels (...front !! ) . Also that Boss has one sub out, though you don't have any subwoofer.
Those big 15" are just...woofers.
AND I see that the correct cutting frequencies aren't present !
( or maybe it's variable continously, as in a "state variable filter")

Picture - https://s32.postimg.org/gvvlehqd1/Kopplingsbild_stereo.jpg
I made a picture showing how everything is wired right now. And the settnings on the crossover.

Lets say I do a passive crossover on the tweeters with a MKP-kondensator 4.7 uF - Monacor MKPA-47
and Effektmotstnd 8.2 ohm 10W - Monacor LSR-82/10
which is what the store recommends.

Then I only need to highpass and lowpass the mid and the bass. Wouldnt the mid woffers get harmed if they do not have a bandpass filtering? They should play between 600hz - 4500
I understand that I do not have any real subwoofers and the "boss" crossover has a subwoofer output. BUT what does it really matter? Is it not just a lowpass filter, which I need anyway? The lowpass on the "sub channel" goes up to a 4,2k hz, and that is enough since the speakers only handle up to 4000hz.
Well there might be difficult to find exactly the right frequency when the slider is so close to the various frequencies , but you should get it close enough I guess.

That I only need 2 channels you mean I have the mid and tweeters (passive crossovered) on the same channel and the 15" on the other one right?

I understand that I do not NEED the el.crossover I have now, but does it really do any harm, or make it sound worse?

Thanks for helping me 🙂

 

[picowallspeaker]

Hi, no, the midwoofers won't get harmed without a lowpass...probably you'll get harmed- your ears. Some 0.1/0.3 mH coil might do for LP.
A 15 " can get to 4 kHz but how ? Bad, very badly.
Since the midrange is said to "work" from 600 Hz frequency, you can choose the cutting point in the nearby ( 6-7-800 Hz ).

...the sound ( the quality of the perceived sound) of the X-O unit and all the system, it's up to you to verify.
The channels: they are L and R, and each channel is divided into 2-3 bands

Read the datasheet of TDA 2040 ( chip amplifier )and the application notes of the TDA 2320 a Opamp, as they have a brief summary of multi-amplification.
The design is with dual supply and it can be converted to single supply.

 

[Buzzyll]

Hi, no, the midwoofers won't get harmed without a lowpass...probably you'll get harmed- your ears. Some 0.1/0.3 mH coil might do for LP.
A 15 " can get to 4 kHz but how ? Bad, very badly.
Since the midrange is said to "work" from 600 Hz frequency, you can choose the cutting point in the nearby ( 6-7-800 Hz ).

...the sound ( the quality of the perceived sound) of the X-O unit and all the system, it's up to you to verify.
The channels: they are L and R, and each channel is divided into 2-3 bands

Read the datasheet of TDA 2040 ( chip amplifier )and the application notes of the TDA 2320 a Opamp, as they have a brief summary of multi-amplification.
The design is with dual supply and it can be converted to single supply.

I read the datasheet but I do not feel like I have the ability to create that by myself...

Is there somewhere where I can actually buy the stuff you mean I should use instead, more like ready to go? I have no problem soldering a little bit, like putting a passive onto a speaker, but I do not feel comfortable creating them from scratch.

 

[picowallspeaker]

Sorry, no, I don't. My literature in this field ends with those application notes
and I have absolutely no experience in car audio, where all those el. crossovers belong to.
Actually, I'm more versed to classic stereo amps with speaker systems having passive crossovers, as it implies less processing to the signal.
But you'd have to discard from your extra channels ...
( which might be good in terms of power compsuntion...)
🙂