First timer bookshelf build

[inchy97]

Hello, so first time attempting DIY speakers. I plan to use these in a medium room mainly for computer use.

I do not own the correct equipment nor do I possess the skill to create my cabinets. So I plan on buying semi-premade cabinets

Cabinets:
Denovo Audio Knock-Down MDF 0.23 cu. ft. Mini Bookshelf Speaker Cabinet


I have been shopping around and looking at the best woofers that match my internal volume using this

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Tweeters:
Dayton Audio DC28F-8 1-1/8" Silk Dome Tweeter

Not really sure what to get here. Does the tweeter need to match the wattage of the woofers? Advice / Suggestions here would be great.

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Woofers:
FaitalPRO 5FE120 5" Professional Midbass Midrange Woofer 8 Ohm

HiVi F5 5" Bass/Midrange

HiVi M5N 5" Aluminum/Magnesium Midbass


So I really like the 5FE120 as it hits my vented Vb of .23 almost right on, and has decent reviews. But I see that the RMS wattage is more than twice that of the HiVi 5"s at around 80W RMS.

I currently have a pioneer vsx-d850s which can supply 110W RMS to each channel @ 8ohms so I can power the 5FE120s but I kinda wanted to move away from the big chunky receiver for my computer speakers.

But in the end I want the best sounding speakers I can make.

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Amplifiers:
VSX-D850S - 6 Channel Audio/Video Receiver | Pioneer Electronics USA

Lepai LP-2020A+ Tripath Class-T Hi-Fi Audio Mini Amplifier with Power Supply

I really like the Lepai 2020A+ as I found a bunch of mods I can do to it to increase performance. With a 5A power supply I can easily get to the 20W RMS per channel of this amp. And I enjoy the small design for connecting it to my computer.

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Crossovers

2500Hz
Dayton Audio XO2W-2.5K 2-Way Speaker Crossover 2,500 Hz


3000Hz
Dayton Audio XO2W-3K 2-Way Speaker Crossover 3,000 Hz


So, I could cut cost and create my own crossovers but these just look so easy to use and install so I may or may not go with these.


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Any Advice would be greatly appreciated as I need help putting it all together


Thanks!

 

[sreten]

Hi,

Oh dear, forget about premade crossovers if you want good speakers.

For computer use you won't go wrong choosing :
Overnight Sensations MT Speaker Kit Pair
https://sites.google.com/site/undefinition/diy-overnightsensations
Note the already routed baffles. Your best choice IMO.
(FWIW routing the baffles is harder than building boxes.)

You need terminals. Plain posts are the easiest, just drill holes in the back.

rgds, sreten.

 

[inchy97]

"Oh dear, forget about premade crossovers if you want good speakers."

Good to know will definitely build my own then

"Overnight Sensations MT Speaker Kit Pair"

Yeah I was going to just buy a kit until I realized knockouts where a thing. I really pride myself on trying to do it myself by trial and error. I really enjoy the amount of research and experience I gain by not using a kit.

I was planning on just face mounting the woofers with a hole saw so I don't have to rout them flush. Is this a okay?


"You need terminals. Plain posts are the easiest, just drill holes in the back."

Yeah forgot to add them they will be these guys

Parts Express Gold Recessed 5-Way Banana Speaker Terminal Cup Rectangle

 

[sreten]

Hi,

So you think you can design a proper x/o's by trial
and error ? Think again, you can't, and it is not the
way to build the "best sounding" speakers you can.

Tweeters need to be flush mounted, bassmids not so much.

The OS kit including cabinets is by far your best bet.

https://sites.google.com/site/undefinition/diy-faqs-provendesigns

You will have enough on your plate as a first time builder
to learn a lot about the mechanics of building and finishing
speakers, don't ruin it by attempting to design crossovers.

rgds, sreten.

You can design x/o's if your an expert with simulation tools.
Completely different ball game to any actual building skills.

 

[inchy97]

"You can design x/o's if your an expert with simulation tools.
Completely different ball game to actual building skills."

I did forget to mention I will be receiving an undergraduate degree in electrical engineering next fall so I have built 1st-4th order butterworth filters / cheb by hand. So I just need the research to find the correct cutoff which seems to be in a two way system roughly twice the resonant freq of the tweeter. I have faith that I can correctly build the crossovers I just need to know where to put the cutoff and then can calculate the values from there.

This does look to be a good resource for component values
2-Way Crossover Designer / Calculator

Then I will use MultiSim or Pspice to model the frequency response from 20Hz to 20KHz

"Tweeters need to be flush mounted, bassmids not so much."

Dayton Audio ND16FA-6 5/8" Soft Dome Neodymium Tweeter

Then for this tweeter all I would need is a hole saw at 1" then I can dremel from there.

This tweeter looks a bit better as the cutoff is around 4k and it matches the sensitivity of the woofer.

 

[sreten]

I did forget to mention I will be receiving an undergraduate degree in electrical engineering next fall

Hi,

FWIW as an EE myself all I can say EE's can be / are pretty
much the worst for thinking they already know enough about
speakers when they simply don't understand the big picture.

You don't. As they say a little knowledge is very dangerous.

FWIW online x/o calculators are the spawn of the devil.

SPICE based modelling is also pretty useless for speakers.
(Though speakers simulators are based on SPICE simulators.)

https://sites.google.com/site/undefinition/simulated-measurements
Then search for the free Xsim speaker simulator.
http://www.rjbaudio.com/Audiofiles/FRDtools.html

Look at the designs here : Zaph|Audio
And get your head round understanding the x/o's.

rgds, sreten.

I like the free TinaTi circuit simulator for my SPICE.
(FWIW it started out as a student training package,
and consequently has some excellent tutorials.)

 

[inchy97]

Hi,

FWIW as an EE myself all I can say EE's can be / are pretty
much the worst for thinking they already know enough about
speakers when they simply don't understand the big picture.

You can say that right! After some consulting from you and reddit, I just dont have the experience to just go off and make a scratch for my first build.
Going to research the Overnight Sensations!


Question: Thoughts on the Lepai 2020A+

I really like the ability to modify the amplifier by replacing a few caps, inductors, or the amps. But looks like just adding a 12V 5Amp power supply improves performance greatly.

 

[sreten]

Question: Thoughts on the Lepai 2020A+

I really like the ability to modify the amplifier by replacing a few caps, inductors, or the amps.
But looks like just adding a 12V 5Amp power supply improves performance greatly.

Hi,

I'd suggest its pretty pointless changing the 5532 op-amps.
I don't recommend messing around with the inductors.

There are lots of posts about this amplifier and its various versions.

Be judicious in your upgrades, i.e. apply some common sense.
(i.e. avoid anything that has no sensible pragmatic basis.)
Its a cheap amplifier, and can only have its faults fixed.

I'd suggest a capacitor bank in the lead from the PS to the amplifier.
An option that might be better than brute force upgrading of the supply.

rgds, sreten.

 

[inchy97]

Be judicious in your upgrades, i.e. apply some common sense.

I'd suggest a capacitor bank in the lead from the PS to the amplifier.
An option that might be better than brute force upgrading of the supply.

rgds, sreten.

Will do,

I found this in another forum listing the priorities of the upgrades.

would set the following priorities in modding this amp:

1) Power supply. The provided 2A supply isn't sufficient, but a decent 3A supply should do the job. Also, if you can find a low-cost 13.5V supply you could get about 25% more power. If you add the extra diodes shown in the TA2020 data sheet, you can use a 14.5V supply, or a 15V supply with a series diode.

2) The output inductors. The inductor should have a high enough current rating to make sure the inductance vs current is linear and to ensure that the core doesn't saturate. The originals look a bit on the small side. If you unsolder one and accurately measure the resistance, you could determine whether they are adequate.

3) The op amp. 4558's are not low distortion or low noise. There are many good options, but even the low cost TL082 would be a major upgrade.

4) C30 & C31. They look like they could be low quality XR5's and they are ceramic caps that appear to be in the signal path (hard to tell for sure from the picture).

5) Coupling electrolytics

6) Filter caps (the large electrolytics). With a decent power supply, changing the filter caps is probably not necessary, although it might help with high current output.

Thoughts on these?

I wont be swapping the op amps as I dont want to deal with surface mount soldering, such a pain.

 

[sreten]

Hi,

I'm not going to trawl through again the posts I've read about this amplifier.

The basic supply is adequate and a bigger supply only marginally improves
maximum volume, there is no "great" improvement. If you want improvement
generally, like I suggested use a capacitor bank between the PS and the amplifier.

From what I can recall you can change coupling values to improve bass,
that is bass is limited as I recall due to some coupling capacitors values.

From what I recall about reading about these amplifiers the above
two are the first things you should do and probably leave at that.

rgds, sreten.