dan_thebassman Posted October 21, 2015 Share Posted October 21, 2015 I guess this doesn't come up that often, at least not usual on quality units. I recently got a great little Eden ex 112 4ohm and been running my Aguilar TH 500 as the top. Did about 4 gigs, loud but only halfway on the amp. I started smelling a mild burning smell as the air was forced through the port on the last gig, no crackle or loss of sound. Did a rehearsal about an hour in it just stopped. As you do, checked my board and all the cables, all ok. As it was used I have no warranty, it's a whizzer cone and Eden said its about £90 to replace. Anyone know how to test the speaker before I have to get a new one?? Know why it would fail like that? The TH runs down to 4 ohms. Eden said a replacement driver will have a 6 month warranty but if it's likely to fail again due to the head I might replace it and move it on. Quote Link to comment Share on other sites More sharing options...
3below Posted October 21, 2015 Share Posted October 21, 2015 (edited) ex 112 claims 300W (no idea if this is thermal or excursion power). TH 500 claims 500W at 4 Ohms. Halfway on amp is anyone's guess. Does 5 on markers mean 250W power, 1/2 max loudness or what. How accurate are the markers? The 'mild burning smell' was probably the insulation melting / degrading on the speaker coil, bad news To test, get a multimeter and measure dc resistance of speaker. 2.7 to 3.3 Ohms is in the ball park. Zero or infinite (open circuit) Ohms is bad news. I suspect damaged voice coil due to excessive power that the speaker could not dissipate. Edited October 21, 2015 by 3below Quote Link to comment Share on other sites More sharing options...
dan_thebassman Posted October 22, 2015 Author Share Posted October 22, 2015 Thanks for the response. It's a good point, is halfway on the dial 250w?? I know with a 1x12 I'm not shifting large amounts of air but I have a little... ish Marshall 150w combo that seems louder, it's just heavier! The idea was a tiny box for small gigs and drag out the 4x10 for bigger shows. I'll test it later and let you know! Quote Link to comment Share on other sites More sharing options...
dan_thebassman Posted October 23, 2015 Author Share Posted October 23, 2015 So yeah did a multi meter test and got zip, de nada, nothing! Tried the 9v battery test too! Luckily I live near enough to the mother company Marshall HQ so I took the speaker there, it was out of warranty, they identify from the number printed on the back. I was quoted £89 but only got charged £61 in the end and so the story ends! I'll get the new one in and test it hoping I get no more burning smells! Quote Link to comment Share on other sites More sharing options...
JTUK Posted October 23, 2015 Share Posted October 23, 2015 And then get another of the same cab to run with it. I know from when I started power ratings on chassis' were a very iffy process so I never take as gospel power ratings, tbh. I agree that that is a historical 'fear' but still think it applies... And you'll like the sound bonus of a pair, I'm sure. Quote Link to comment Share on other sites More sharing options...
Passinwind Posted October 24, 2015 Share Posted October 24, 2015 [quote name='dan_thebassman' timestamp='1445515703' post='2892045'] Thanks for the response. It's a good point, is halfway on the dial 250w?? [/quote] It might be under some complex set of variables coming together just so, but you can only know by actually measuring it in real time as you play. And then as soon as you play harder or softer, or just a different note, or touch an EQ or gain control, things will change. Halfway on the master volume can very easily be full power, or beyond full rated power (clipping), or even essentially no power at all if you aren't sounding a note. Quote Link to comment Share on other sites More sharing options...
3below Posted October 24, 2015 Share Posted October 24, 2015 (edited) [quote name='JTUK' timestamp='1445636284' post='2893107'] And then get another of the same cab to run with it. I know from when I started power ratings on chassis' were a very iffy process so I never take as gospel power ratings, tbh. I agree that that is a historical 'fear' but still think it applies... And you'll like the sound bonus of a pair, I'm sure. [/quote] Likewise, when I started (in the dim and distant pass) the rule of thumb was speaker power should be 2x amplifier power. When Celestion or Fane 12" speakers were rated at 25 or 30W each the result was using two 4x12 cabinets for the Marshall or Hiwatt 100W head. Edited October 24, 2015 by 3below Quote Link to comment Share on other sites More sharing options...
dan_thebassman Posted October 24, 2015 Author Share Posted October 24, 2015 If I get another identical cab I didn't think I could run two 4 ohm cabs together?? two 8 ohms yes as that runs it full power down to 4 ohms..... Am I right thinking that?? Don't think my Aguilar goes down to run at 2 ohms?? I did have an SWR that did way back. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted October 24, 2015 Share Posted October 24, 2015 If you wanted to use two then you'd have to get a series lead made up so you presented an 8ohm load to the amp. I'm sure you could ask OBBM to make one up for you. Where the volume settings are can bear little relationship to the actual power and Alex Claber has a sticky in the amps and cabs forum that explains this. You can't trust speaker ratings as anything other than a rule of thumb. The speaker designer can't control how you set up your eq or how you play. Your speaker will probably handle 300W at higher frequencies but below 100Hz there may be times when 50W would take it out of it's safe zone. That's normal and true of many commercial bass speakers Whether that would cause a problem is down to exactly how you use your speaker and how you play. If you use a lot of bass boost or an octaver it might well be troublesome. You might get a thumpinator which would make a huge difference to the safe operation of a small speaker like this. Quote Link to comment Share on other sites More sharing options...
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