New to the forum looking for some guidance

[ethan1701]

Hey everyone my names Ethan,

I just learned its possible to build your own speakers and luckily found this site. I really want to build a home theater setup but realized I should probabaly start off with something cheaper and smaller to practice with so I can learn. So I thought I would try and start off with speakers for my computer. I just recently purchased a Logitech Z506 surround sound speaker set (http://www.logitech.com/en-us/produc...d-speaker-z506). They are loud enough but I am hoping I could build something more accurate without the distortion. So my question is can I build new speakers for it and just plug them into the back of the sub-woofer like the stock speakers?

I am still reading and learning and am grateful for any help

Thanks

[BobEllis]

Hi Ethan, welcome to the wonderful hobby of speaker building. Be forewarned, it can become an obsession very quickly.

The answer to upgrading your Logitech system is, it depends. Probably you can plug new speakers into the jacks, assuming that there isn't any EQ applied to the main speakers. There could be a problem with the speaker with the controls - are you comfortable identifying which leads connect to the volume control and power and which are the speaker connections?

The issue with the distortion is likely as much the low powered amp as the speakers themselves. 75 whole watts? Usually a little more goes to the sub, so I am guessing it's 25W for the sub, and 10 WPC for the rest. Then, those aren't likely to be real watts, but meaningless peak music power watts. There are a lot of good starter projects in the missions accomplished section here, but budget some money for a decent amplifier. You can build them, too. A LM3886 based chip amp is a good starter project. Check out diyaudio for project ideas.

[ethan1701]

Hey Bob,

Thanks for the welcome. Yep your spot on for the watts the little system produces. I was gonna try and use the amp built into the sub box just to keep it simpler but after hearing your advice I might as well do an amp too . I could use a good obsession. Thanks for the help. I am gonna go check out that section and I am sure ill have more questions.

[fbov]

...So my question is can I build new speakers for it and just plug them into the back of the sub-woofer like the stock speakers?...

It all depends where the amp(s) are located.... wait, the documentation tells you all you need. You'll have no problem replacing all but the RF speaker, due to the unique D-connection and requisite controls in that unit. Unless you're comfortable modifying circuits, I'd just add an amp-out to that speaker, bypass the driver and keep the box as-is, otherwise.

Bob's comments regarding EQ still apply.

8w seems like very little power, until you understand what 1W sounds like - far louder than I normally listen. Normal levels are 65dB, I like closer to 75dB, but the wife complains. Speakers can range from 80dB to 100dB output for 1W input. Even a small, inefficient speaker will only need 0.3W to please me, on average. This is important as cheap low distortion speakers are usually small, and low sensitivity, too. Many designs address this by using multiple drivers.

So, what do you want to end up with? No point in aiming low, as the larger, higher end designs frequently have higher sensitivity. Conversely, I just made self-powered, desktop speakers with an 88mm driver, and they play plenty loud at the desk... 1/2m listening distance helps.
- how much can you spend?
- how much can you do yourself (both skills and tools)?
- do you have any preferences, going in?
... and the most important one of all:
- can you attend any of this season's DIY speaker events?

I went to InDIYana in 2008 as a fish out of water - no experience, no idea what to expect, and I've since built one of the designs I heard there, and it's a personal favorite. Nothing tops being able to listen to a bunch of designs, and then talk with the designers. You get snowed until you pick up the jargon, but you learn, none the less, and you can pick designs based on their sound, not just words.

Have fun,
Frnak

[BobEllis]

To my way of thinking, I want to avoid amp clipping at all costs. (It tends to get nasty sounding) That leads me to run a subwoofer with a thermal rating of 400W with a 1KW amp, and feed my 70W rated main woofers from an amp capable of 350 watt peaks. No, I don't listen that loud, but I don't get clipping.

For example, my woofers are ~85 dB/W sensitive, with 5 dB of baffle step correction. That means the system is roughly 80 dB/W. If I listen at a slightly loud 80 dB average I need to feed my speakers 1 watt RMS. ( 2 speakers driven at 1W = +6 db - 6 dB for 2 meter listening distance= 80 dB/W) If the music is well recorded and has significant dynamic range, you can see peaks 30 dB above average. (Dire Straits' Brothers in Arms is one such CD) That means 1W x inv(log(30)) or 1,000W peak power required to make the 110dB the recording is commanding. The tweeters are the limiting factor, keeping me at 105 dB peak, so I end up listening at 75 dB average and not driving my amps into clipping, with ~150W peaks. I could probably get away with smaller amps, but I like the way these sound.

There are plenty of folks that go with flea powered amps, Nelson Pass is a prime example with his First Watt amps. He also tends towards very efficient speakers. Increasing the speaker efficiency by 10 dB reduces your required power by a factor of 10 for the same SPL. Funny, Mr. Pass seems to like Fostex drivers with sensitivities around 90 dB/W in horn loaded enclosures...

[ethan1701]

Hey fbov,

Yeah 8 watts doesnt sound high but to me the z506 speakers are plenty loud enough for me.

what I want to end up with is (not sure how to answer) but a more accurate detailed sound. I use them for playing Black Ops 2 and jamming to music at the same time.

How much can I spend? I would be willing to spend 100 bucks per speaker for drivers and crossovers

skills and tools wise? I know i can build a crossover and speaker boxes. designing the crossover and speakers will be the hardest part. I will need a couple tools but i can probaly borrow from friends or buy if i have to

preferences? not sure what your asking exactly but I would like to keep and use the sub and amp built into it but after listening to Bob and you I took apart two of the logitechs. The RF with D Connection I think Would work it just uses a simple connection to the speaker from the circuit pad for the controls. The other speakers I opened up have no crossover in each unit. So Im assuming each speakers crossover is built into the subwoofer/amp. So I am thinking it prolly is best if I also build amps and make the whole 5.1 system. I was thinking of doing each of the five speakers as 2 ways with tweeter and like 3 inch mid then using the sub to fill in the lower levels. I do not want massive boxes all over my desk.

I would love to go to one of the events. Where can i find the dates for these?

[BobEllis]

No crossover insider the speakers? How many wires enter each one? The "crossover" may be a small capacitor (a tiny cylinder) on the tweeter.

Take a look at the Overnight Sensations or the Swope 5.1.

You might be able to build the amps into one or more of the speakers, if total space is a concern. Something like this might be a decent start. http://www.apexjr.com/Dual25FR.html Steve (who owns ApexJr) is a good guy who has earned a lot of my money over the years. He has many of the parts you'll need to build amps, including LM3886 60W chips. You can buy circuit boards from a lot of sources, like chipamp.com or just wire the few components up on the chip's pins. Put it on Steve's small heat sink and mount in the back of the speaker.

[BeerParty]

skills and tools wise? I know i can build a crossover and speaker boxes. designing the crossover and speakers will be the hardest part. I will need a couple tools but i can probaly borrow from friends or buy if i have to

Your best bet, then, would be to build an existing design from the Mission Accomplished section. Those have already had the 'heavy lifting' of designing the crossovers completed for you. You can be flexible on the build of the cabinet, as long as you don't change some key aspects: the driver spacing and location, the width of the baffle, the volume of the cabinet all need to remain pretty much unchanged.

If you decide to build one of the Mission Accomplished design, you can start a build thread with the design name in the title and ask questions. The designers and/or people that have built the designs are most helpful in answering any questions you might have.