First build - Common mistakes

[Hugo82]

I'm hoping to begin my first DIY build my first DIY build sometime next week and i was wondering what are the mistakes that alot of beginners make with thier first project
I'd like to know that so i can avoid making them myself

So what do we first timers do wrong?

[5th element]

Any mistakes I have made/make are usually due to impatience or complacency.

1) Take your time.
2) Check everything at least twice before making changes you can't go back on.
3) Ask if you are unsure.

[valleyman]

"I'm only going to do the one, so I'll just get some cheap tools."

Maybe you already have what you need, but that's what I did and have ended up replacing most things - very false economy. It's very addictive once you start

"I'll just load it up and have a listen before I finish and paint them"

Is another good one which has led me to have several working but ugly looking speakers around the place. My advice is to get the boxes looking how you want before you put anything else in

Honestly, aside from that there's little that can go wrong with a FR build. If you're looking for woodworking advice, theres loads on the web, even tutorial videos that will help.

Having a quick look at your other thread though I would give consideration to the CSS FR125. Given that you say you are going to be running these from a PC I think its a real rival to the FE127. It does lack (only slightly) in detail, but one key thing to look at is the Xmax. The FR125 has 6mm, about 10x the xmax of the FE127 and you can very simply make use of the EQ in whatever media player you use to afford much more bass than you would otherwise have. The Fostex really isnt suited to this as it runs out of excursion (which the EQ eats) very quickly.

Edit: Oh, I'm not sure of sources of the FR125 in the Netherlands, but in the UK they are carried by www.madaboutsound.com for £83/pair. The owner is a member here and will probably be happy to send them to you and it could work out well since the pound is so weak against the Euro now

[jupiterjune]

cracking veneer-

I used yellow glue and contact adhesive. Both peeled and cracked. Use Gorilla glue, but don't get it on top of your veneer, or it won't finish.

Set up your crossovers on a prototype board so you can easily tweak them. Don't solder them all together and then mount them inside the speaker, 'cause it is a lot of work to make changes that way. Finish tweaking the Xovers, and then solder them up.

JJ

[planet10]

Originally posted by valleyman
Having a quick look at your other thread though I would give consideration to the CSS FR125. Given that you say you are going to be running these from a PC I think its a real rival to the FE127. It does lack (only slightly) in detail, but one key thing to look at is the Xmax. The FR125 has 6mm, about 10x the xmax of the FE127 and you can very simply make use of the EQ in whatever media player you use to afford much more bass than you would otherwise have. The Fostex really isnt suited to this as it runs out of excursion (which the EQ eats) very quickly.

The FR125 is a good driver (especially once i'm done with it) but the xmax argument may be a little deceptive. When the FR125 runs out of excursion it hits its stops and makes a real annoying farting sound.. the FE127 may have less linear xmax, but as it runs out it does so much more gracefully.

The other thing to consider are amplifiers & sensitivity. For the same levels the FR125 requires 4x the power. It is thou much more tolerant of less than stellar amplifiers. The FR125 also does not like SE amplifiers -- tube or SS.

dave

[valleyman]

OK, so maybe the situation isnt quite as bad as the numbers suggest, but the css definitely has the ability to produce more bass than the fostex. Even if we take the Fostex as being OK up to 1mm (1.5 x Xmax) and the css coming to a dead halt at 6mm it still has a lot more headroom. Also running a driver beyond Xmax is clearly not an ideal scenario and necessarily introduces distortion.

I'm not saying the css is a better driver - actually I don't think it is. I own both and will almost always use the fostex so long as a sub is available, but if it's not I prefer the css simply for the extra bass I can get from it. Then again, I listen to a range of music that includes a lot of electronic music where bass is important
Hugo mentioned he has 35-40W available which is enough for either driver

[Smirker]

As always, measure twice (or three times) cut once.

Double double check your wiring.

Make a dry run assembly before you even LOOK at that bottle of glue.

Don't paint when the forecast calls for rain.

Screwdriver tips and woofer surrounds are cosmically drawn to each other. Be Carefull!!!

Some things always take longer than you thought they would.

Most importantly, have fun. If you get frustrated take a break, drink a beer (unless you're a mean drunk) come back to it later.

Hope this helps.

[s7horton]

If you are going to veneer, learn how to do it properly instead of ignoring yellow glue and contact cement and going straight for gorilla glue. That, in my opinion, is bad advice.

[madisonears]

If you are using a proven existing design, you can be more comfortable with what to expect when completed.

If you are modifying a proven design or using an original design, be prepared to do a lot of experimenting. Don't put any effort into finishing the cabinet or "tying" things down perfectly until you have done a LOT of listening. Very few designs, no matter how carefully derived and crafted, will work perfectly in their first iteration.

Which brings me to the next bit of advice: select your test music carefully, as you will be listening to it a lot. You must use the same music (and the rest of the system) for the major part of every listening test, and listen very attentively. If you don't care for the music, no matter how good it sounds, you will not put enough concentrated effort into achieving the best arrangement of your drivers, xover, and enclosure.

Once you're satisfied with the sound, then you can put a lot of time and effort into finishing the enclosure and invest in other final touches such as better Xover components, better wire and connectors, etc. Don't waste any money on fancy caps and coils or wonderful wire until the speaker sounds good. No amount of fancy stuff will make a bad design sound good, but it will make a good design sound better.

Peace,
Tom E

[chrisb]

Originally posted by planet10


The FR125 is a good driver (especially once i'm done with it) but the xmax argument may be a little deceptive. When the FE125 runs out of excursion it hits its stops and makes a real annoting farting sound.. the FE126 may have less linear xmax, but as it runs out it does so much more gracefully.

The other thing to consider are amplifiers & sensitivity. For the same levels the FR15 requires 4x the power. It is thou much more tolerant of less than stellar amplifiers. The FR126 also does not like SE amplifiers -- tube or SS.

dave

note confusing typos on model numbers above:

FE125, FR15 & FR126 all refer to CSS FR125.


My own 2 cents - for a desk-top computer monitor, the sensitivity and X-Max issues are probably far less significant than the sonic flavour of the amp/speaker combo.

There's no argument that we all have our own preferences, and FWIW, I find the CSS FR & WR 125 siblings a bit too recessed and dark in the midrange - something that could not be said for the Fostex drivers, particularly the FE126E.

Loudspeakers' rated specs, for all they're ever worth are generally taken at 1 metre (39") - you'll likely be closer than that to your computer most of the time, and 92dB at 1 watt at 1 metre is pretty loud.


Re veneering, a vacuum bag or cold press would be nice to have, but they have their own limitations. I take the cheap & lazy way out, and use paper back veneers and the DIY iron-on method*. It allows adjustment of cut veneer pieces for precise grain matching that contact adhesives simply can't.

If you're hasty, and don't sand the substrate smooth overall and flush at joints, don't get good even glue coverage on both surfaces, or rush with the iron - you'll have problems with telegraphing or air bubbles - but I've yet to have the veneer crack.


edit: *Titebond II yellow carpenter's glue, fine nap velour paint roller, and cheap clothes iron set on Linen. When folks mention "Gorilla" glue, I tend to think of the moisture cured polyurethane glues, which are certainly wonderful for enclosure assembly, but they have long curing time, swell substantially, and can not be repaired with an iron afterwards - not something I'd want to ruin a project with.