Wharfedale Boombox project

[jimmyjimmy19702010]

You are making life a little difficult for yourself trying to cram in so many speakers and a huge amp, equalizer and battery all the while trying not to disturb the cabinet tuning!!

Ok, if you’re already reducing the internal volume, then the tuning will have changed. This will result in the tuned frequency of the ports to be either raised or lowered. So no, the speakers will no longer sound the same. (Bass performance).

Ideally, you want to have the tweeters sitting directly above the drivers. The tweeters are responsible for much of the stereo imaging so having them close to each other will reduce your stereo effect.

 

[Reli]

Is one of those speakers really a mid driver, or are they both the same?

 

[jimmyjimmy19702010]

Is one of those speakers really a mid driver, or are they both the same?

The 8 inch driver in the centre of the stack is a mid range driver.

 

[Superduper]

I'm not really familiar with those drivers. But I have a few questions and observations:

Many tweeters and midrange drivers have sealed backs. If they did not, and all the drivers share the same airspace in the cabinets which are sealed, the pressure waves emanating from the woofers will "drive" the midrange and tweeters into the same or similar low frequencies, which will not be a good thing. Think about how a passive radiator works, yeah, same thing here. So with high x-max drivers, woofers typically have a different airspace than the higher frequency drivers. This may be accomplished through either sealed back drivers, or baskets, or separate chambers. Because high frequency drivers don't require much chamber space, this space can be small or just use sealed baskets. The rest of the cabinet can be separated, or not. If the frequencies reproduced by the low drivers are very low, then sharing the same space probably won't be critical since low frequencies aren't directional anyhow so whether a low emanates from the left or right driver isn't all that important. I actually don't think the internal components are going to make much difference. If any, would probably tighten up the bass. Many speakers are crammed full of polyfill anyhow, and deliberately so. I recall once testing a 10" woofer and having it work in free air -- bass was poor. Then I slowly brought it over a cardboard box with a hole in it (like a speaker). As the driver got closer to the box, the bass improved, even though I was just holding the driver over the hole of the box. The further into the box, the better the bass (and sound quality). This leads me to think that the actual size of the box is important and the actual air volume maybe less so. Anyhow, this just from experience.

 

[Owenf]

Good questions everyone.

The 4 large speakers are all the same. Each original Wharefedale speaker cabinet has no internal baffling and houses 2 large speakers and a tweeter. They do however run through the crossover I've pictured below.

The rearrangement of speakers below may give me the best sound but I'm not sold on the look, too much free space. I'll keep juggling.

Specs on the speakers are below

 

[metalhandbag]

Can't wait to see the finished item.

 

[Reli]

I just looked at the advertising literature, and it says there are 2 different crossover points. So even if the 2 woofers are the same physically, one of them is being used as a midrange driver.

 

[Owenf]

Correct, I’m going to use the crossovers that came with the speakers. I’ve rearranged the speakers again with the tweeters on the top outside of the front panel to aid in the stereo separation as suggested. Front panel is marked up and gets cut tonight and then build the box from there.

 

[Owenf]

Front and rear panels are cut, finish the rest tomorrow, then hand fit the speakers, iPad and eq in the front panel.

 

[Superduper]

If the system is basically going to be an iPad boombox with no AUX-IN source, then you can ignore what follows. However, if you are going to have additional line-in sources, then.........

Are you going to install a preamp? If not, how are you going to throttle (meter) the input signal level? Because if you plug in a true line-in source (external tuner, CD player, tape deck) and the external source does not have it's own level control, you are probably going to blow up the amp, the speakers, or your ears. Unless.... your equalizer has a volume control. Even if you personally know to cut down the signal level of your iPod or whatever, it's still a good idea to install a volume control in case someone else not familiar with it plugs in a different source.

 

[Owenf]

If the system is basically going to be an iPad boombox with no AUX-IN source, then you can ignore what follows. However, if you are going to have additional line-in sources, then.........

Are you going to install a preamp? If not, how are you going to throttle (meter) the input signal level? Because if you plug in a true line-in source (external tuner, CD player, tape deck) and the external source does not have it's own level control, you are probably going to blow up the amp, the speakers, or your ears. Unless.... your equalizer has a volume control. Even if you personally know to cut down the signal level of your iPod or whatever, it's still a good idea to install a volume control in case someone else not familiar with it plugs in a different source.

Yes, I’m struggling with this. I’ve been looking at ways to place volume pots for each side before the signal gets to the EQ, and is then plumbed to the amp. Also tossing up if I need the amp and just run the 40+40 from the EQ. Another problem I have is line selection. How do I choose between the aux in and the BT receiver? May wire the aux in as bypassed till a signal is present. Any help appreciated.

 

[Owenf]

Wood is cut, trial fit some of the components completed and they are a good fit with some fettling to go.

Chameleon carbon fibre vinyl has been ordered for the front panel. Probably do the other panels in bed liner.

Next steps are to fit up, glue, and screw the box together.

 

[Owenf]

Been a little while - finished one job and working on my own business but this afternoon I had a chance to start buttoning up the cabinet.
I have a bow in both the bottom and top sections to deal with but expect the internal dividers and rear panel to bring it back to true. Lots of reinforcing and cleats to go in yet.......this may need wheels......

 

[Reli]

Wow that's huge!
Bracing will be even more important with such large panels.

 

[Superduper]

If the system is basically going to be an iPad boombox with no AUX-IN source, then you can ignore what follows. However, if you are going to have additional line-in sources, then.........

Are you going to install a preamp? If not, how are you going to throttle (meter) the input signal level? Because if you plug in a true line-in source (external tuner, CD player, tape deck) and the external source does not have it's own level control, you are probably going to blow up the amp, the speakers, or your ears. Unless.... your equalizer has a volume control. Even if you personally know to cut down the signal level of your iPod or whatever, it's still a good idea to install a volume control in case someone else not familiar with it plugs in a different source.

Yes, I’m struggling with this. I’ve been looking at ways to place volume pots for each side before the signal gets to the EQ, and is then plumbed to the amp. Also tossing up if I need the amp and just run the 40+40 from the EQ. Another problem I have is line selection. How do I choose between the aux in and the BT receiver? May wire the aux in as bypassed till a signal is present. Any help appreciated.

So, then it sounds like the equalizer is an equalizer/booster? Equalizers don't generally have built in amplifiers in the sense of an amplifier intended to be the only amplification source. Rather car equalizer boosters are generally intended to "boost" high level signals, or signals that are already speaker level ready such as the speaker outputs of a normal head unit. In either case, you will not likely be able to, or be happy with the sound of your project using only the equalizer booster circuit, although to be honest, I don't know anything about your particular unit, I'm merely going by experience. On the other hand, Kenwood car amplifiers are usually fantastic stuff and with a clean power supply, rivals lower end home audio equipment. I'm talking about the old school class A or AB stuff. No experience at all with the digital amps.

So I just finished a project for Reli and stuffed a input aux source selector into a boombox that included bluetooth. Maybe when I get the chance, I'll post how I did it. However, eBay is full of cheap preamp or volume control diy project boards and source selectors. They are perfect for DIY projects. The only downside is that the quality and performance of them is all over the map with some being virtually useless in terms of quality. They take a long time to come since they are all from China and experimentation if necessary to find one (could take many tries) that plays well. Also interference or hum is a distinct possibility and something that might not be solvable requiring you to try other modules or using DCC isolators, etc.

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Just a thought... many equalizers have a fader function. Setup properly, a fader control can act like a crude but operational volume control.

 

[Owenf]

Progress is slow but.....there is progress. Front and back have been fitted with internal bracing in place.

 

[Owenf]

Well it has been a long while but I got caught up in building another racing sim and have resurrected the boombox project. Still a ton of work to do but at least the face is nice.....from a distance, this will be no beauty queen.

 

[T-STER]

Woah that must be amazing to play on!