DIY studio monitors

S

southpark

New member
ive been looking around the internet and can find plenty of info on crossovers yet i cannot find what impedance to use for the amp and monitor. >>What ??? i know im confused by that tooo__let me spell it out

______________________ Tweeter
Amp->passive crossover <
_______________________Woofer

so if my amp is rated a 4 ohm out, will that work with a 8 ohm woofer and 8ohm tweet run through a crossover
i guess what im asking is how do i find the impedance of my monitor??

im not really sure how to word my question so if anyone could help in some way, i would appreciate it.
Cheers
Dan
 
Not a straightforward question... It's not simply a case of summing all the parts (unless you are savvy) Easiest way to find out (if you have already assembled the speaker is to buy or borrow a multimeter and check the impedence at the input.
The speaker you described should be 4 ohms.
Again as a rough guide the amp should equal or have a value less than the speaker you intend to drive.
 
thanks. i have not built the speaker yet because i want to figure this all out before i buy anything; however, i would like to know how to check the impedance, if you could expand on that.
 
also i am planning to use MDF and isolate the cabinet with some foam i have lying around. is that good for monitors. also if anyone has info on magnetic shielding the monitors so i can put them next to my computer screen.
 
ummm so yeah... i have found nothing about finding the impedance of a two way speaker yet soo if anyone would like to divulge that information.. please feel free to do so....
Cheers
Dan
 
thanks for the replies...
yeah i think fiberglass insulation would be better than foam...
and blue jinn i did check that out and now i am now convinced that an active system is the way to go on this project.... but that opens a whole new can of worms (wow thats a old expressiion?!?!).. now my design is like this

Woofer: Hi-Vi F6 Kevlar/Paper Cone 7" Woofer: Madisound Speaker Store
tweeter: Hi-Vi T20-8, 20 mm Textile Dome Tweeter 8 ohm: Madisound Speaker Store

im gonna use the active crossover design from here: Project 123
and a 20 watt power amp for each speaker.... circuit as show here: 20 Watt Class-A Amplifier

THe qUesTioNS??????
#1. WILL IT WORK??
#2. will it be loud enough for close field monitoring
......... pretty much any input you can give me will be much appreciated
Cheers,
Dan
 
Do you have any idea what you are doing ?? Because if you don"t then you better find a different project because you are just going to be wasting time and a lot of money just to end up with a bunch of stuff that doesn"t work .....

Firstly " Class A " is a bad idea unless you are an experienced electronics guru , it will be complex and expensive and if not done properly will be a disaster but it will at least put off enough heat to keep your house warm ......

Do you know what crossiver point you will need ?? do you know how to properly select your speakers based of the frequency they will be driving ?? Do you also know that you need a seperate amp for the Hi and Low and the Low will need to be 2-4x the power of the high (if you are useing the active crossover you linked too)??

Do you know how to design a speaker box that is tuned to the frequencies of the crossover ??

Not trying to throw a damper on your party but what you are trying to do is a LOT more complex than you think it is .......
 
Interesting thread.
I hope this keeps going cos I've come across some wharfedale drivers and crossovers that I'd love to rehouse, but I'd want to do it right.

wd.jpg

OP. I have some bad boy crossovers left over from breaking some Meridian Argent speakers.
They had three drivers and tweeters. Let me know if they interest you (or anyone).
7.jpg
 
i actually do know all about that stuff your talkin about mr."Blow me!!!" except for the tuning speaker box part. i do know that for the drivers iv selected that the box needs to be 15 liters but im not sure what you mean by tune??
now the real plain question that i have unanswered is what type of amps i should build??... since my last post iv done some research and found the watts needed for my particular drivers so no longer do i need direction on how powerful they need to be....so thank u for questioning my newbness as there are a lot of stupid people on the Internet however i do have a sufficient amount of knowledge to complete this project with a (hopefully) good outcome.
 
I attached a simple and inexpensive to build 2 way power amp .... it includes the active crossover and puts out about 30w for the woofer and 15w for the tweeter .....

You can use pretty much any type of opamp for the crossover section and if you need more power you can use a TDA2050 for the power amp which will give an extra few watts of power ...... If you look in the TDA2040 datasheet there is also a PCB layout and a bit of theory on designing crossovers and a design for a 3 way system .....

You will still need a PSU and transformer ..... and the TDA chips are dirt cheap (I can get them for about 70c each) ......

Cheers
 

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thanks.. i was kinda trying to stay away from using a chip amp because ive heard that they degrade the sound a bit.... would you say they do or do they sound pretty good??
 
If you just google "gainclone" you will find simple "chip" amplifiers that are making many audiophiles drool. They can sound astonishingly good, provided that you don't run them close to clipping. Build one and be happy. Paul
 
Yes , chips are just fine , pretty much everything uses them these days , most studio monitors use a chip like the LM3886 or TDA7293 , most Hi-Fi recievers use Chips most solid state guitar amps use chips .... The IC is usually not the weak part in an audio curcuit , the PCB layout and the passive components have more effect on the sound than the chips ......

A well built chip amp with good quality components and a well filtered PSU can go up against a good discrete amp with the benefit of having a much smaller footprint , less components like capacitors in the signal path and less components that can fail , which is good if you are putting the amps inside the monitors themselves as there isn"t a lot of room , and it is a high vibration environment which puts extra stress on the components ......

Ive personally use Chips to build half a dozzen guitar/Bass amps , a couple stereo power amps for general music listening , have built quite a few Mic preamps using INA217 chips and even the old NE5532 ......
 
sweeet thats good to hear considering that it will cut down on build time and cost!!!! thanks yall now to get started buying and building!!!
Cheers,
Dan
 
Seriously dude if all you want is 20W, pick up a couple of the Tripath raw stuffed PCBs and stick 'em in your cabs. Class D = very little wasted heat = no worries about heatsink design. If you are doing biamp and want 20W for your woofers (kinda light, but OK for nearfields I suppose) then you don't need 20W for the tweeters. Probably 5W will do.
 
you might for a first project (not sure if its your first) look at a simple kit amp - maybe a gainclone lM3886 from chipamp.com - JLM audio are offering an amp kit based on the Lm3886 chip as well probably the best as they are studio preamp specialists and the kit would be targetted to recording.

I don't know your background/skillset but to my way of thinking thats a tall ask. Do you realise how much R & D goes into making studio monitors - I don't exactly know, but I'm geussing its a lot. You may be very experienced, but the fact that your here asking these questions makes me doubt that. I could be wrong -its happened many times before :)

What about trying to build a cheap amplifier kit (approx $35.00 plus transformer, case etc) then getting a cheap pair of passives??? Thats would be pretty realistic and satisfying outcome????

If you are hell-bent on diy active monitors - maybe post Rod Elliot an email and get his thoughts or advice.

Also look at LM1875 (cheaper lower power amp than Lm3886)

Hope this helps
 
Jo-Nathan said:
Just buy some monitors...
Click to expand...

isn't the point of DIY and Homebrew to learn about this stuff and try things out?

Don't learn squat by buying monitors.

For some people the fun is IN trying something and going, "uh-oh ..... that's not right" and trying the next thing until you get it.
 
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