do you use a pair of cheap speakers, in case you've made some fatal error, or do you hold your breath, close your eyes and hook it up to your good ones?
I will take a liberty here. I reckon I am the biggest dumbass on this forum but I can tell you this without reservation. If you hold any affinity for your "good" speakers go find yourself some that you care nothing about.
I always use a cheap speaker for the first few hours of listening. I once had a DC blocking output capacitor installed backwards and that failed as a short and took out a cheap speaker. And I thought I had checked everything out.
I test by measuring the output, and if everything appears satisfactory then I connect to “test speakers” having a 5W automotive lamp in series.
While I’ve never had an issue, I’m a speaker protection circuit kind of person. You can buy the cheap relay types for a couple dollars, but if you really value your speakers (as I do) there are Mosfet types available, too.
While I’ve never had an issue, I’m a speaker protection circuit kind of person. You can buy the cheap relay types for a couple dollars, but if you really value your speakers (as I do) there are Mosfet types available, too.
Yeah I agree completely. I took a 20 year break from building but just recently built an F5. I didn't have a cheap pair of speakers around so I tempted fate but it was all good. Now I'm going to build a couple more amps so just purchased a pair of budget Klipsch bookshelf speakers for the smoke test.
You have been around here since 2006 but hell man, if money's tight I will give you some pretty nice ones if you will come get them.
I did that once with a guitar amplifier I was rebuilding. Put a power supply filter cap in backwards even tho I am usually very careful about that stuff. Really broke my heart to see that new cap bulge, ooze and smoke.
For myself, there is nothing quite so gratifying as watching a set a set of speakers explode then burn down to copper and ash. Your mileage may vary.
I used to hook up a cheap speaker but lately I check for DC, then hook up an 8R test load and my sound card FFT test rig, and check that the output is reasonable.
Once I had the drain and source connections unknowingly reversed in a single ended SIT amp and that was only tested on a cheap speaker. I then put it into my system and after days of listening, I did some FFT measurements and discovered that it was clipping at a low output level. That was not apparent during listening to music as my speakers are quite sensitive.
Once I reversed the drain and source connections, it measured good.
Once I had the drain and source connections unknowingly reversed in a single ended SIT amp and that was only tested on a cheap speaker. I then put it into my system and after days of listening, I did some FFT measurements and discovered that it was clipping at a low output level. That was not apparent during listening to music as my speakers are quite sensitive.
Once I reversed the drain and source connections, it measured good.
If you build/repair/customize/ship an amplifier you need to own a multimeter.
Before you connect the amp to speaker, turn on the amp and see what the DC voltage is.
That covers 95% of possible damage.
Before you connect the amp to speaker, turn on the amp and see what the DC voltage is.
That covers 95% of possible damage.
Not to brag of course, but I've never had to worry about hooking speakers up to any amp that's I've built or serviced.
However, I'm not an amateur either.
However, I'm not an amateur either.
My new builds and re-builds go through at least two bias current setting sessions on the bench to confirm power supply operation and DC offset at the speaker terminals. Each session is at least an hour long, starting from cold state. With new builds, I will run a 1 kHz signal through the amp and observe the harmonic distortion while driving an 8 Ohm load. If everything checks out, I hook them up to my speakers.
I pour a nice glass of Cabernet...