[gixxerific]

Alright got my Focal's in today they sound great, or should I say, sounded great. Only had them on for maybe a hour went to do some cranking normal LOUD levels with the previous 20 yr old pieces of **** no problems with them.

Than the receiver goes into protect mode. I let it cool down with a fan in fact for a bit. Turned it back on and it sparked heavily twice very fast. I couldn't turn it off quick enough not that it matters. I even think I saw a small flame burst. Well it's fried for sure!!!!!!

The Focal's say they are 8 ohm but putting a Multimeter on them they read a constant 4.6 ohm. Is that normal when brand new or are they just labeled wrong or am I just an idiot who needs to shoot himself in the mother****ing face?

Oh and the reciver in question is a Denon 2106, 6 ohm

[planet10]

DCR of 4.6 ohms would mean a nominal 6 ohm speaker.

dave

[mitch stl]

A multimeter is only going to give you the DC resistance of the speaker. That is not the same as impedance, which varies with the frequency of the signal. Speakers have peaks and dips in the impedance, so the "nominal" 4 or 8 ohm figure that you normally see is kind of a "safe bet" territory. The impedance may drop below 8 ohms (or whatever other figure given) but not by much and only for a limited range.

Focals are a well regarded speaker so I doubt the impedance figure given is wrong.

I'd hazard a guess, based on limited info, that the focals are not as efficient as your old speakers. You may be driving the amp much harder to reach the same room volume as the old speakers.

Another possibility is that your Denon had developed a problem and the new speakers put just enough of a demand on the amp to turn a problem into a failure. How old was the Denon?

[gixxerific]

A multimeter is only going to give you the DC resistance of the speaker. That is not the same as impedance, which varies with the frequency of the signal. Speakers have peaks and dips in the impedance, so the "nominal" 4 or 8 ohm figure that you normally see is kind of a "safe bet" territory. The impedance may drop below 8 ohms (or whatever other figure given) but not by much and only for a limited range.

Focals are a well regarded speaker so I doubt the impedance figure given is wrong.

I'd hazard a guess, based on limited info, that the focals are not as efficient as your old speakers. You may be driving the amp much harder to reach the same room volume as the old speakers.

Another possibility is that your Denon had developed a problem and the new speakers put just enough of a demand on the amp to turn a problem into a failure. How old was the Denon?

Yes I know that imp will fluctuate with given freq output. I guess I'm just confused by the DCR and the rated impednace values. I know enough to be dangerous but not everything. "Did he just say dangerous, hell that guy will burn you house down".

And yes the reciever is about 5-6 yrs old. Thing is I just had it fixed beause I blew it up about 6 month's ago trying to repair some free speaks I got, think I shorted out a speaker wire. Whoops the first time. Should have just bought a new rec'r with HDMI. But I didin't want to cut into my speaker budget too much. Next time I get something good to, hmmmm, let's say 0.5 ohms. The Focal's are sensitve to 92 db have no idea what the old ones were.

Oh yeah I figured out the problem with the amp. It shoots sparks and fire out it. I don't think that is right is it?

[KnowTalent]

Alright got my Focal's in today they sound great, or should I say, sounded great. Only had them on for maybe a hour went to do some cranking normal LOUD levels with the previous 20 yr old pieces of **** no problems with them.

Than the receiver goes into protect mode. I let it cool down with a fan in fact for a bit. Turned it back on and it sparked heavily twice very fast. I couldn't turn it off quick enough not that it matters. I even think I saw a small flame burst. Well it's fried for sure!!!!!!

The Focal's say they are 8 ohm but putting a Multimeter on them they read a constant 4.6 ohm. Is that normal when brand new or are they just labeled wrong or am I just an idiot who needs to shoot himself in the mother****ing face?

Oh and the reciver in question is a Denon 2106, 6 ohm

aside from a straight impedance rating you want to look at phase curves as reactive components will change impedance...often for the worse.

A NAD C372 integrated should be plenty of amp to drive those and AudioAdvisor had a demo model for ~$600 last I checked.  Call and ask for Tim Hahn and tell him Eric sent you if you're interested.

[KenSeger]

If your Focals are the Chorus 836 V they are rated at 180 W RMS, nominal 8 ohm impedance, and sensitivity @ 2.83 volts @ 1 meter.  Translated into english, since E=IR therefore I = E/R, and since P = IE, therefore  P =Esquared/R so E= 2.83 and R = 8, so Esquared = 8.0089 (call it 8 for govt work) so 8/8 = 1, in conclusion, one watt will crank out 92 db one meter in front of the speaker. Not the worst in efficiency, but certianly not high efficiency.  So on the Focal Chorus 836 V, if 1W = 92 db, then 2W=95db, 4W=98db, 8W=101db, 10W=102db, 16W=104db, 20W=105db, 32W=107db, 64W=110db, 128W=113db, 160W=114db, and 200W=115db.

Solid state amps just aren't very friendly when they run into clipping.  Depending on the type and style of music, the peak power to average (RMS) power can be anywhere from 3 : 1 to as much as 10 : 1 also depending on what the recording engineer considers a "reasonable" amount of compression, gain-riding, or limiting.  It's not uncommon for a solid state amp to blow if repeatedly clipped.

So let's say 5 : 1 on peak to RMS, that Denon is rated at 100 W RMS @ 8 ohms right?  So, if clipping occurs @ 120 watts peak, that would be an RMS of about 24W or 106db on a peak of about 113db.  Now that's loud, but that assumes stability all the way up to 120 W at clipping, AND 8 ohms at all frequencies.

When woofers start moving back and forth they can create some back EMF (voltage) which the whole amplifier damping factor argument is all about.  After all, when you pass a conductor through a magnetic field you ARE going to generate a voltage one way or another.  I've been told that some of the older bigger 4 ohm Infinity speakers had so much back EMF that their effective load on the amp was all of 2 ohms at certain frequencies when played rather loud, which was less than the DCR. Headed in the other direction, since a horn is simply an accoustic analogue of an impedance matching transformer between the mechanical impedance of the air and the mechanical impedance of the woofer cone, you can have a 4 ohm woofer that dynamically measures over 8 ohms or more throughout the range of the loading of the horn.  Of course once you get outside the loading range of the horn the impedance can abruptly change back to the 4 ohms.  Another more approachable example is puting a driver in a bass reflex cabinet and measure the impedance versus frequency which is typically two peaks, and the height and frequencies of those two impedance peaks can be changed by changing the size of port.

So it is possible that at some frequency a speaker's impedance can dip to some impedance that the amp really doesn't like OR the lower impedance is such that the power supply just can't keep up with the amperage flow that the voltage swing tries to create and the amp clips even though throughout the rest of the frequency spectrum the amp is no where near clipping.

Now if the NAD and the Denon are equally stable, the difference between 100W and 150W is all of 1.8 db which on peaky music is inaudible.  But if there is a considerable difference in stability, particulrily if the Focal's have an impedance dip, the audible difference could be substantial.

Ken

[Bob in St. Louis]

............<snip>............. Translated into english.............<HUGE technical snip>............

That's the funniest thing I've read all month Ken. 

Bob

[gixxerific]

Screw it My 15+ yr old Onkyo (4Ohm) is running them quite nicely for now. Time to look for a new recv'r or pre\pro. Not quite sure what I want at this point, this came on too suddenly. Well I know aht I want but I just dropped some serious coin on speakrs. Anyone want a Broken Denon, it comes with a free fireworks show?

Well if anything else the Foca's are pretty frickin' nice. Havn't had a chance to really sit down and listen yet though. Been a kinda hectic couple of day's.

Thanks Dono

[mitch stl]

And yes the reciever is about 5-6 yrs old. Thing is I just had it fixed beause I blew it up about 6 month's ago...

I suspect your answer might be found in this sentence. Sometimes, in a repair job, they replace the obviously bad components but it isn't always easy to find parts that were weakened as a result of the original failure. So your unit comes back from the shop and appears to work fine but it is just a matter of time until the marginal components fail completely.

I'd suggest using another amp with the speakers. If it plays fine and exhibits no problems (clipping, excess heat, etc.) then it probably means nothing more complicated than the Denon has outlived its usefulness.

[Bob in St. Louis]

If it was repaired six months ago, you might try talking to the folks that performed the repair so recently.
Warranty?

Bob

[Scott F.]

Time to look for a new recv'r or pre\pro. Not quite sure what I want at this point, this came on too suddenly.

It sucks that your Denon died. Tell you what, over on AGon there is a Arcam AVR 100 for $350 bucks. It's a darned fine sounding 5.1 receiver. I've had one for about 8 years. Nice clean (but not sterile) sound, good bass and it even has a pretty OK internal DAC (non-oversampling). Granted, its only 85w x 2 but it should drive the Focals just fine.

If you go for it I think you'll find you like its sound much better than the Denon.

[gixxerific]

Time to look for a new recv'r or pre\pro. Not quite sure what I want at this point, this came on too suddenly.

It sucks that your Denon died. Tell you what, over on AGon there is a Arcam AVR 100 for $350 bucks. It's a darned fine sounding 5.1 receiver. I've had one for about 8 years. Nice clean (but not sterile) sound, good bass and it even has a pretty OK internal DAC (non-oversampling). Granted, its only 85w x 2 but it should drive the Focals just fine.

If you go for it I think you'll find you like its sound much better than the Denon.

Thanks but I really would like hdmi interface. I looked on Arcam's site. The AVR600 that is what I would like, a bit out of my price range though at the moment. That is the kind of versataility I'm looking for. Though I will have to make sacrafices.

Dono

[bpape]

Well, if it's just the amp section that's toast, you could potentially just use the pre-outs and get an external amp.

Bryan

[gixxerific]

Well, if it's just the amp section that's toast, you could potentially just use the pre-outs and get an external amp.

Bryan

Not sure if this unit is usable. I havn't opened it up yet but there was one hell of a light show, with flames. By the smell I'd bet to say there is a whole lot wrong in there.

I really don't know how to test that possibility, or I probaly would. I sure don't want to pay somone else to tell me "Yep she's broke".

The old Onkyo will have to do. I don't even remember what wattage it is. I cant' find the specs for it anywhere.