RFI: Building your own desktop speakers for general use.

[chyc]

I'll cut to the chase, I want something like the Genelec 8010a, but passive and not so eye-wateringly expensive. If you've seen my other threads, you'll know I have caught the bug about building my own cabinets. It's a lot of fun, so I'd like to make one here. Trouble is I am nowhere near the stage of designing my own enclosure or crossover.

 

Use case:

• Bragging rights for building my own desktop speakers
• Gaming
• YouTube watching
• Very light bass practising. It has to be better than the Vox amplug2 cabinet, but not by much: I accept the compromise.

 

It doesn't have to be as good sonically as the 8010a. It doesn't have to be quite as small as the 8010a, but it should be small enough to look reasonable either side of a 14" laptop. Is there a source of designs for this type of speaker? If not I'm currently eyeing up https://celestion.com/product/an3510/ as a single driver (no tweeter) in an easy sealed enclosure. Is that madness? Sensitivity seems rather low, but it's for me sat at my desk and I don't want to wake the neighbours. The Celestion is a little larger than the 3" speaker in the Vox, and I presume its xmax is orders of magnitude higher.

 

 

[stevie]

It's a nice idea but, unfortunately, there's more too it than sticking a driver in a cab. The problem is that the nice flat response of your full-range driver will stop being flat as soon as you put it in a cabinet. The baffle step will rear its ugly head and the overall sound will be very middy - and not at all hi-fi.

 

I've designed this kind of speaker in the past and sometimes you can get away with just a passive notch filter to flatten the response. Sometime you''ll need more than that. But you won't be able to design the filter unless you can measure the results.

 

 

 

 

Edited November 28, 2022 by stevie

[itu]

External crossover may be pretty cheap. Older ones cost tenners. Even a cab built by Mediocrates can be tamed with a powerful eq (X-over, that is). Probably the end result isn't like Genelec but decent. Any ideas to use a tweeter?

[chyc]

I wouldn't say no to a tweeter. Principal aims, in order of descending priority

1. Bragging rights to say I've made it myself
2. Dinky
3. Not sucky performance. A frequency chart looking like the Himalayas is fine so long as there's not too much distortion at reasonable volumes (looking at you Vox Amplug Cab) and a smidgen of bass.

I've looked on eBay and I reckon the second two criteria could be had within £20 or so. In fact if I ignored the first criterion and spent the same amount as I would have on a pair of AN3510s and some wood I probably could get something both compact and fairly decent and active. The Creative Pebble Pro has RGB lighting to boot

 

Doesn't scratch the woodworking itch though.

 

[LukeFRC]

Are there not diy plans for hifi stuff you could follow in the same way there are some diy plans for bass cabs?

[nekomatic]

There are some free-to-download plans on the Blue Aran website - they have a 2 way design with 6in woofer that looks like the sort of thing, and the cabinet construction looks interesting.

 

I did a quick web search for 'loudspeaker kits uk' and found lots of places doing just-add-woodwork kits, although many of them are very expensive. Impact Audio had some cheaper ones, but still £300 plus per pair. Have a look around though, you may hit on something better suited.

[chyc]

Thanks @nekomatic. I did see those but 6" is too big for my desk. My current cheap-as-chips bookshelf speakers at 4.5" and they're already too big.

 

I would love to get (even pay) for plans for something like this, although I suspect I'm not going to strike gold here. People doing this stuff will be looking for performance that I don't need, and will be prepared to spend levels of money that I don't have.

[bertbass]

Many, many, years ago, probably very early 1970s, I acquired a pair of 4 inch ITT hifi speaker chassis.  I made a couple of boxes, probably about 6 x 6 inches, out of old 1 inch shelf and mounted the speakers in them.  The cabs had no backs but I did put something like carpet felt over the backs of the speakers.  They sounded truly amazing.  Wish I still had them!

[Chienmortbb]

Look at the Faitlal Pro 3/4" drivers on the Blue Aran site. You will need to model them though.

[RhythmJunky]

Wouldn't you be better off buying a s/h pair of hifi speakers ? Something like Wharfedale Diamonds.

 

I use an old pair of Acoustic Energy AE100s as my monitors above my piano. They're pretty small. 

[chyc]

9 hours ago, RhythmJunky said:

Wouldn't you be better off buying a s/h pair of hifi speakers ? Something like Wharfedale Diamonds.

Doesn't fulfill my first use case 😁

[LukeFRC]

23 hours ago, chyc said:

People doing this stuff will be looking for performance that I don't need, and will be prepared to spend levels of money that I don't have.

Just bodge some drivers in a box and use something to tune it the best you can? 🤷

I dont really get it tbh - the cheapest way in terms of time and money is to buy something - if you are investing time in making nice boxes (nice hardwood outers?) why not spend enough to get something better technically than anything you could afford to buy? 
plus then you get to level up your bragging rights! 

[Phil Starr]

On 27/11/2022 at 22:54, chyc said:

It has to be better than the Vox amplug2 cabinet, but not by much: I accept the compromise.

I think you may have thrown people by mentioning the Genelecs 😂

 

There's a reason this sort of thing doesn't really exist. Getting any sort of bass out of a tiny driver means huge excursion even at modest levels and that makes the driver unsuitable for the high notes. That little Celestion speaker is designed to work with a subwoofer and even the low mids are rolled off. 

 

If you want a project it might be worth looking around for something used that can be repurposed. An old cassete player (am I allowed to say Ghetto blaster) or mini hi-fi with plastic speaker cabs where you can  rehouse the speakers in a better wooden cab. Alternatively when I worked in a recording studio we had a couple of car radio speakers in home made boxes. This is what people used to listen to music through and so we'd check the sound was good through  those as well as on our monitors. It's a very long time ago but I think they had a single 7x4" speaker salvaged from a TV.

[chyc]

Genelecs in terms of form factor! I don't own a pair but I know someone who does and quite frankly I was astounded the amount of noise that came out of it. He played dance music in a hall.

 

The Vox Amplug2 comment is just a nod that I accept that these speakers don't need to sound like the Genelecs. IIRC when the speaker was released Vox made noises that it was appropriate for bass practice, but they seem to have rowed that back now looking online. I can practise just fine on it: I just need to hear myself. However it distorts too easily, which is probably not helped that it's battery powered, and cheap, and nasty.

 

A bass-specific combo with a single 4" driver exists   in the form of the PJB X-4 combo. By my maths, a pair of 3" is bigger than a single 4" (4.5π > 4π), so it's not like it's impossible. Whether its 15kHz upper bound means anything is another matter.

 

Thanks for the advice everyone. I will trawl GumTree for spare Altec Lansings at bargain basement prices, and rebuild the cabinet. Good idea Phil.

[Dan Dare]

There are so many cheap decent active desktop speakers around these days it's really not worth building your own. The PreSonus Eris is well reviewed and can be had for 80 quid. Spend a bit more - on the baby Adams, for example - and I reckon you'd be hard pressed to better them with any self-built speaker unless you spend a lot more.

[Balcro]

Have a look at the Faital-Pro 4FE 35; also on the blue Aran site. It's ferrite and therefore heavier than the neo Celestion. However, even allowing for Celestion's usual very conservative ratings for xMax, the Faital has more low-mid bass extension, both in terms of frequency response and power handling. Only £16.45 a piece.

Probably just pipping the Faital, is the ferrite Beyma FR40 8 Ohm. £21.23 @ Blue Aran.

The trade off is that the Celestion is clearly louder (more efficient) (according to my SPL chart) over nearly the whole frequency range, despite Faital claiming otherwise.

None of these speakers are really intended for playing bass, so even inputting 8w will just put  them onto the xmax line in medium/low bass @ around 135Hz. In the lower mids (300Hz) the Beyma will output 95.7dBA, the Faital 94.5 and the Celestion 97.7dBa. Just a few comparisons out of many possible comparisons.

All comparisons made with an internal volume of 3.5L and an input of 8w. In my opinion they wil all work well for gaming and youtube, but for bass practice the Beyma & Faital have a bass boost (120 - 250Hz for a warm and punchy sound) and more low/mid frequency reserve.

[Jack]

You can get the Bill Fitzmaurice SLA with two 4" drivers I think. 

 

But, I mean, Presonus Eris.

Edited December 7, 2022 by Jack

[BassmanPaul]

What does RFI refer to apart from Radio Frequency Interference?

[chyc]

53 minutes ago, BassmanPaul said:

What does RFI refer to apart from Radio Frequency Interference?

Lol. Request For Information

[Dan Dare]

Interestingly, monitors are often designed to be RFI (as in Radio Frequency Interference) shielded to prevent issues in studios that are stuffed full of equipment sitting cheek by jowl.

[agedhorse]

I think you will find that the smaller the box and the greater the expectations, the more difficult and expensive the project will be.

 

The advantage of buying already well designed speakers is that the while you are paying for the designer's experience and knowledge, you are also indirectly paying for a number of prototype builds that may have been much poorer and "scrap worthy" than the finished product. 

 

Respectfully, I understand the desire to build your own, but you are comparing to a very high quality and expensive speaker. As a professional designer, I know how hard it is to get results like that without churning through 6 or 8 prototypes, and the cost of custom drivers also. Stock drivers are not intended for this type of product, which is why custom drivers are used. My coworker is the engineer who designed the entire KRK monitor line, I know how much work that was to extract that much performance in such a small, reasonably cost effective package.