Axiom Home Page Forums General Discussion Technical Questions I just blew my amp (Denon 4308CI) now what?

OK here's the setup.

Denon 4308CI Amp, 4 Axiom M80v2(2 on Front A)(2 on Front B), VP150 Center Channel, 2 QS8 Surround (Have 2 more still in box for Surround Back but not hooked up yet), HSU Research VTF-3 MK3 Subwoofer, 10 awg wire to all speakers. Sub is wired preout from amp.

I've had this amp for a little less than 1 year. Occasionally, I get the chance to JAM when no one is home. Well, Friday was one of those days..... and after a round of trying to crush beer cans with sound waves - my amp shut off. The amp is dead. Still under warranty, so I took it back. They said 3-4 weeks for repair/replacement. They gave me a Denon 2809CI as a loaner.

Anyway, I was concerned with the lack of power from the 2809 I started to wonder if the M80s could be rewired for 8 ohm so that I didn't blow the loaner amp. So I took one of the M80s and remove the speaker wire and jumper clips. I grabbed my Fluke to get am Ohm reading and was surprised to find the the upper posts had a resistance of 9.2 Ohms and the bottom post had a resistance of 3.2 Ohms.

Before I got the resistance reading my thought was to wire the upper and lower posts in series with each other by jumping the lower(-) to the upper(+) and connecting the speaker wire to the lower (+) and upper(-). But after getting a different resistance reading between the upper and lower posts I am assuming that the internal wiring of the M80s is not the way I thought it was. I thought that each pair of binding posts were wired to 1 woofer, 1 mid-range and 1 tweeter.

Any and all comments and suggestion are welcome. I am looking for information on internal wiring of the M80s and possible setup changes that might help the loaner amp survive and improve performance (beer can crushing capability) when the 4308 comes back.

Thanks in advance for any help.
PEENERHEAD

What you are essentially doing is running two M80’s in parallel off of one amp. There’s no way the 4308 will carry that load (2 ohm), which is why it blew. For now, run one set of M80’s with the loaner and don’t get crazy with the volume control. If you really want or need to run twin M80’s in parallel, you should pick up an outboard two channel amp that will support the load. Use the 4308 as a pre/pro for the R/L channels. Be prepared to shell out some serious coin for an amp that will drive a 2 ohm load.

These amps aren't necessarily pretty, but they'll do the job if you need something that will drive a 2 ohm load. (700 watts into 2 channels at 2 ohms)

(Plus, it's remarkably cheaper than continuing to blow out 4308s)

Crown XTi 1000 Amp

Jason

Sorry, I should have explained my setup better. I have the second set of M80s on the Amp Assign. Electrically, I thought that this would control each pair individually (4 ohms) rather than in parallel (2 ohms)please correct me if I am wrong.

On the question of the different Ohm readings for top and bottom binding posts, are the readings I am getting normal? If so how are the speakers wired internally? If the reading is not normal what should the correct readings be? And finally is there a way to rewire the speaker to get a higher resistance?

I have an old Harman Kardon PA2400 in storage I think it was rated @ ~200 wpc if I recall correctly. Would this be sufficient to power the M80s ? I use to run 4 Cerwin Vega VS150s on this amp and never had a problem.

Thanks

The top posts are to the 2 mids and 2 tweets, the bottom posts are to the 2 woofers.

I'm still confused on how you have things wired. (which is likely my fault, not yours)

In the first post, you said they were connected to Front A / Front B. I have the 3808 and don't remember such an option. I took a look at the 4808 manual to see if there was a difference and while there are some different connection options for multi-zone playback, I don't see this specific option there either.

In your second post you said you have the second pair set up on "amp assign." In the 4808 manual, there is an option listed to have one set of front speakers designated for multi-channel listening, and a second set of speakers for direct/stereo modes. This allows you to have 4 front speakers, 2 of which are active depending on what mode you are in (surround versus stereo). The manual lists this option in the section having to do with bi-amping and bi-wiring your mains.

I can't find anywhere in the manual where they give the option of running both sets of main speakers at the same time. The only settings I know of on the 3808/4808 to run 4 speakers through 2 channels is on the Surround A / Surround B option, which I imagine they support since typical impedance of surround speakers is fairly high.

Can you elaborate on which channels you are using to run your 4 M80s and what mode you are listening in (or were listening in) that runs all 4 at the same time?

Jason

I actually have the 4308 not the 4808 (don't know if there are differences). The Amp Assign outputs allow me to send a 2 channel signal to a second set of speakers (what I referred to as Front B since that's where they were). This could be done by wiring to the Surround B/Amp Assign or Amp Assign 2. I believe I had my Front B speakers wired to Amp Assign-2 but can't be sure. Since I don't have the amp at the moment, I don't recall exactly what the setting was in the menu to activate both pairs. I will have to dig out the manual to check, but i believe it was the bi-amp setting that allowed me to do this.

I was able to get sound from all 4 front speakers in any mode as I recall. Any surround sound mode or 5/7 channel stereo played fine.

Sounds to me like a faulty amp to begin with or speakers incorrcetly hooked up, as Jason has eluded to a bit of confusion with the posts.

I have run ~2 ohm loads as a center on both my 1804 and now my 3808, with no problems, albeit not cranked right up but around 80db.

Peenerhead - (love that name)

4808 was a typo by me... I meant 4308 (and that was the manual I looked at).

If Jakewash is right that they can handle 2-ohm loads then I guess it doesn't matter how they were hooked up, though if the speakers were hooked up to different amp channels, it definitely shouldn't have mattered as I'd think it would be quite capable of running 4-ohm loads on separate channels.

Let us know if you're able to crank it back up when you get the new one.

We all know no one uses that kind of power, one watt is more than enough

Those watts from my mono's sound better.

Calvin,

Thanks for answering my question. Is there a specific advantage to wiring the speaker this way? Is there a crossover internally that separates the signals and sends them to the correct location?

I think your referring to Ken. Ken is just pointing out that the top terminals are for the mid's and tweeters, and the bottom are for the woofers. You normally do not want to remove the gold strap between them unless your going to bi-amp which is useless unless your going to bypass the internal crossover ad use an external crossover device.

Just leave them as they are and enjoy.

Yes, but could it support "Beer Crushing" levels at 2 ohm ??
I defer to your expertise verses my guesswork but from his wording, he sounds like he's pushing the limit pedal pretty hard.

You're right I meant Ken.

Coffee hasn't kicked in yet.

I would have certainly hoped it would have just gone into protect mode and shutdown till it cooled off, but that doesn't sound to be the case.

I think there is still a question out there as to how the 4 M80's are hooked up, are they on the A and B for the mains, a ~2 ohm load for the main amp when A and B are both on, or are they hooked up through the Amp assign feature, zone 2 etc., on the surround amps.

No, I don't think they're a 2 ohm load; if they're on different amps, they're on different amps, and they're a 4 ohm load each.

I think the real question here is, "Why do you need 2 M80s per channel?!"

Yeah, wouldn't it be better to hook them up to the "rear" channel for multi audio sound.

The 2nd set of M80s are on the Amp Assign. I incorrectly referred to the as A/B in my 1st post. I hope that clears things up on the wiring.

hmm.. I thought the amp assign feature was for connecting two sets of speaker cables to the same speakers....

WHY NOT! lolololololololololololololol

Actually, the layout of my house is open. So much so that the opposing wall from the M80s is 60ft away. There is furniture, a partial wall and a pool table between but that is it. Sounds great under the pool table but I can't really get into the groove from there!

So the second set is there to help fill the room with sound. I was also considering adding another system on the opposing wall and wiring them together to work in unison. That way BEER CAN CRUSHING POWER can be had from anywhere in the room!

My only worry was being able to sync the sound from 2 different amps (even if the same make and model) when they are 60ft apart.

Apparently, Denon's idea of "protect mode" is to let the $2500 amp blow to save the $5 fuse?

So it blew with a 4 ohm load. You must have really had it cranked up for awhile.

Did you check the fuse yourself or just take it back in due to warranty concerns?

Actually, I have a question, peenerhead. In your initial post, you mention "jamming". Are you connecting electric musical instruments to a domestic amp?

You are correct but there are other options. I assume it's not too different from my 3806 where the extra amp can be assigned to duty for
-- "Surround Back" for use as rears in 71.
-- "Front" used for bi-amping.
-- "Front B" used for a constant second stereo channel (duplicates fronts)
-- "Zone 2/3" used for fronts in another room that can be turned on/off independently.

I believe what he is describing is that he has his second set of M80s hooked to this extra amp and has the Amp Assign set to "Front B" or the equivalent. If this is correct, it is indeed only a 4 ohm load being presented to each amp.

No, I made a touchscreen jukebox that is hooked up to the amp via an spdif output from the soundcard on the computer.

The problem is that it is still only one power supply feeding all the amps and 2 amps with a 4 ohm load, while being played at high volume may have fried the P/S.

Exactly! Well said. Thanks for helping explain in way way that I was apparently incapable of.

I think Jason may have the right of it there.

Anyway, in answer to your original question, the binding posts are split like that (1->woofers, 1->midranges and tweeters) for biamping and biwiring, two dubious audio practices.

Edit: In response to the single power supply being a weakness in this configuration... (a few posts popped in while I typed.)

Agreed. I was just trying to help sort out the wiring questions.
Good call on checking the fuse too. I know I would go through a short period of mental anguish before settling my brain down enough to pop the cover to check the fuse and look for toasted components.

Amp was on max (+ 3db) when she blew. I think I was actually boosting the signal from the spdif on the computer also. I had it there for about 30 min. And before the amp blew it was vibrating the lights in the ceiling fan sooo much that one the the light bulbs popped. I had to turn the fan on so that the centrifugal force overcame the vibration, otherwise it woulda been lights out!

It did not blow the fuse strangely enough. It actually fried the amp. I was on the phone with technical support for 30 minutes until the told me to bring it in.

Regarding the resistance measurements. You can't just measure it with a multimeter and get an accurate picture. Impedance changes with frequency response. Take a look at an impedance curve. like this one.

http://www.churchsoundcheck.com/imp1.html

You'll see that the impedance is highest at the resonance frequency. This is because of electro-magnetic properties of the transducer. As the voice coil moves within the magnet assembly, it produces a voltage in the voice coil, this can be thought of as some "backpressure" on the system, that's why the impedance is higher.

Selecting the "nominal impedance" that a company puts on it's spec sheet is a bit of an artform. Some will select the lowest value, others kind of an average, after throwing out the extremes.

re-wiring your M80's is a bad idea.

All I can say is

Dude?!?!?!?!?!?!

Respectfully, you have some nice gear to enjoy for the rest of your life. Try and make sure your ears last just as long.

In a previous post you said the binding posts are 2 mid and 2 tweeters on 1 set of posts and the 2 woofers on the other. This made sense to me based on the Ohm reading I got. If it really is 1,1,1 shouldn't the reading be the same or at least very similar?

Hope I didn't misread something between the 2 posts.

No, no, I meant the same thing with this post--as in one set of posts is to the woofers, one set of posts is to the mids and tweets.

Seriously, dude? You need outboard amps. You can't expect a receiver to survive on max volume pushing 2 sets of 4 ohm loads. I suggest you look into some seriously high power units, maybe the Axiom 1400-8, maybe something at around 300WPC... It would probably be best with the Axiom amp if you used it only for the M80s. That would give you ~350WPC. Or maybe I'm just talking overkill and you could use the 1400 with all the speakers.

Ken meant "one set of binding posts for woofers (2 of them), one set of binding posts for midranges and tweeters (4 drivers total)"

Sorry, I actually did misread something.

Anyway, how does wiring the woofers separately from the mids and tweeters help when bi-amping or bi-wiring? Wouldn't it balance the load on the amp more evenly if they were wired 1,1,1.

Ken,
Do you have or ever tried this amp? I would be interested in your opinion.

I have to agree with Ken, it is time for some serious power. I have yet to run my 3808 for any length of time, a song or two, above -10 and this is really loud(~95-100db depending on the cd, IIRC) in my room. Your room size and what you are trying to achieve I feel are beyond the Denon's capabilities.

You could also get some monoblocks from Outlaw Audio, Odyssey Audio, Emotive, etc. which would be more cost effective. I love my mono's.

. The A1400 is a unique amp in that it can direct as much power as needed into a single channel and Axiom's testing would show it can handle any speaker and room size, well almost any room size. Those that have the A1400 appear to love this amp and the few reviews that have been done say it is a very good amp.

Many of us are waiting for Axiom to come out with a 2 channel version of the A1400-8

OK OK My classified ad will read as follows:

Denon 4308CI - surround sound amp, recently factory inspected and approved, still under warranty! Never abused, only used for playing Christmas Carols at our annual church get together.

Oh, no, I've got a little piddly Harman/Kardon AVR-525--85wpc into 4 ohms! Woo! And I've never had it above, oh, -10 or so.

Oh, but you'll still need to use something as a pre-amp. You probably don't need the denon for that, unless you're going to go with a set of 4 monos or you're planning on driving the surrounds and center from the receiver instead of the amp. In which case you still need to dump a lot of power from the receiver into those.

The thing that is nice about the Denon is that it has 4 hdmi inputs, 2 hdmi outputs, 3 spdif inputs and 2 spdif outputs. I am using every single one of these. Oh yeah, it has XM radio also. Outside of the fact that it has a paltry 140W x7 channels its actually a pretty descent amp.

So keep using it as your pre-amp. That's not a big deal.

My 2805 works great as a preamp for my 80's.

That's 140 x7 into 8ohms but the 4 ohm load increases the output by about 45%, you are running about 240Watts into the M80s and the 4308 was never designed to run that much power out. This is why we are suggesting the seperate amps, at least for the M80s.

An Emotiva XPA-5 would probably be just fine. Solve your problem for about $800.

After everything that has been posted (thanks to all) I think we can all agree...

WE NEED MORE POWER!

Is it ok to continue the new amp discussion here or should I start a new thread?

Not like we don't sidetrack threads all the time. Here's as good as anywhere else, and at least we remember why we're talking about it.

Talking about what?

Not sure. I think JP lost me here...

Wasn't that Negative Orange's first single?

I'm not sure, but I bet Charles has the perpetually confused look to prove it!

This to me is pretty wild ... can y'all imagine how loud that had to have been regardless of the room size? Ouch.

I must really be getting old.

You are, getting old that is.

Yea, with really good hearing to boot.

PH, permanent hearing damage level is a bit lower than beer can crushing level.

. . .says JohnK drawing from extensive testing in college. . .

OK, last night I hooked up the loaner amp (Denon 2809). The setup is the same as in my 1st post except that I took out the extra set of M80s. I powered everything up and now the subwoofer (HSU Research VTF-3 MK3) does not respond. The cable is from the Pre-Out SW. The HSU has power to it but just doesn't do anything. My first inclination is that something blew inside the sub (of coarse). Is there a way for me to verify that the Denon is actually sending a signal to the sub? I have a Fluke 79 III multimeter for signal testing.

Thanks

Are your sure you have it on the Sub "Preout", and not one of the other sub jacks like Ext In?

Yup, I'm sure.

If you clip your fluke to the center pin and the side of the RCA cable attached to the SW pro-out, then you'll detect voltage swings if there's signal on the cable.

I assume I set the meter to DC volts?

No. Audio uses AC to push and pull drivers past their neutral resting position.

Even though this is not the signal that is doing the pushing and pulling? If it is AC, what range should I expect mV or V?

Thanks

Hi peenerhead,

The "Subwoofer Out" level is typically in the 200-mV to 2-volt range. It's supposed to be standardized, but there are wide variations from one brand of gear to another.

Regards,

Alan

Thanks Alan,

In addition I would also like to post the response from Hsu Research because I thought it might be helpful to someone else in the future.

"Hook up a DVD player's analog outputs directly to the sub using a different cable. If it still does not have any sound, take out the woofer and connect that to your receiver. If that plays fine (muffled, but clean), then its the subwoofer amp. "

I distinctly disagree.
although it should have been obvious that running any electronic component at 100% could cause a malfunction [that combined load and power use would have seriously if not critically taxed the PSU of any receiver] why not look at the other factors affecting the 'problem' such as distance rather than trying to compensate with power?
you have to remember that in adding more power, speakers will come to their physical excursion limits which still may not produce the sound pressure levels that you would like to have 60 ft. away from your stereo system.

possibly what you need are either much larger speakers like those designed for rock concerts, or move closer to your stereo!

along that same line of thinking, move part of the system closer to you.
I don't understand why you have to be 60 ft. away to listen to sound pressure levels from four speakers when you can move half of them closer. Take your second set of speakers, move them closer, and only run one pair at a time off of the receiver depending on where you are in the room.

I have to agree with the limited comments here made about listening levels. the sound pressure level from four speakers playing that loudly can severely damage one's hearing

Holy Crap! My dad is a member of the Axiom Forums too! lol jk

I hate to be preached to as well. My wife has quickly learned that asking me to do something more than once is more likely to extend my procrastination than shorten it. That being said, there are certain scientific facts that can't be ignored.

The time periods vary slightly depending on where you get your data, but the ballpark remains the same. Hearing loss is guaranteed to occur from prolonged exposure and it doesn't take long to add up at high levels.

For anyone who is interested, here are some numbers from a couple of sources. As you can see, some sources are more stringent than others but "beer crushing levels" (luv that term) would rate dangerously high on any scale.

Occupational Safety and Health Administration (OSHA)
85 dB and higher - prolonged exposure will result in hearing loss
90 dBA - no more than 8 hours per day (examples - lawn mower, truck traffic, hair dryer)
95 dBA - no more than 4 hours per day
100 dBA - no more than 2 hours per day (example - chain saw)
105 dBA - no more than 1 hour per day
110 dBA - no more than ½ hour per day
115 dBA - no more than ¼ hour per day (preferably less)
140 dBA - NO EXPOSURE TO IMPACT OR IMPULSE NOISE ABOVE THIS LEVEL (examples - gunshot blast, jet plane at takeoff)

The National Campaign for Hearing Health
85 dB 8-hour period
85 - 90 dB 2-hour period
90 - 100 dB 1 to 2-hour period
100 - 110 between 2 and 15 minutes
110 - 120 less than 30 seconds
130 dB ANY EXPOSURE WILL RESULT IN PERMANENT HEARING LOSS

I forgot to say that, in the end, I respect your choice to do what ever you wish. I mention it more in hopes that you might consider the effects on your guests, especially small children who might not be aware of the risks.
.

Hey, I'm not trying to blow the Vacuum Tube in anyone's amp here. I appreciate the help that everyone have offered.


Maybe the hearing loss issue should be another thread or even a sticky.

No worries, no tubes blown here.
I hate being preachy but I have a good friend who has a very enjoyable and rewarding career counseling the deaf. He has even met his fiance this way. The only unfortunate part is that his career choice was 100% due from his music listening habits as a teen.

I didn't share this in my other posts because then it sounds even more preachy than I intended.

I'd love to have a deaf chick! Then I could make all those funny faces without being laughed at.

Well maybe not,

But I least I could fart and she wouldn't know about it until after I left the room.

Peenerhead has proven he can find the upside in any situation.

I may be seeking his advice on November 5th, then, should things not work out how I want.

I had found this interesting when it came out 2-3 years ago (http://www.shape.bc.ca/resources/pdf/noisehearinglossmusicians.pdf).
It is a nice summary plus, for those interested, it points to a large number of other researches (I can't remember which one had a very comprehensive discussion of how dynamics helps and the increased problems caused by the "db war" in popular music).

There are various standards as to allowable exposure to avoid(or more frequently just minimize)noise induced hearing loss. It should be kept in mind that some of the more frequently referenced tables apply to occupational noise hazards which may actually allow for some hearing loss, but is considered acceptable(at least by some)in a workplace setting. The EPA and WHO set stricter limits for "community noise" (non-occupational)where any appreciable danger of hearing loss is viewed as unacceptable. This table summarizes two occupational standards as well as the community standard which would apply, among other situations, to audio. Another source(Cohen, et al., Sound&Vibration, 1970)extends the range to 16 hours at 70dBA, indicating that at 70dB or below there's essentially no risk of hearing damage, regardless of length of exposure.

Axiom must offer some REALLY GOOD Senior Citizen discounts?

There are people here with 1400 watt Axiom amps that are saying TURN THE MUSIC DOWN????????

LOLOLOLOLOLOLOLOLOL

Not senior citizens, just people that are smart and value their hearing.

Jeebus, Randy, crack a smile or something.