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#173847 - 08/05/07 01:20 PM M80 tweeter damage - may need a separate amplifier
haylo75 Offline
veteran

Registered: 03/20/07
Posts: 132
Loc: Kansas City, MO USA
Hi all, I recently took delivery of the Epic 80 5.1 home theater w/ EP600 subwoofer. If you want, feel free to read the long version of my story here. If not, skip to the words "SHORT VERSION" below.

Like many, the majority of my cartons arrived having taken significant damage due to mishandling with gashes and punctures abound. Luckily I could not find any cosmetic damage due to Axiom's well thought out packing strategy. DHL!%#!&*

Anyway, before ordering my speakers I talked to Brent at Axiom and told him I recently purchased an Onkyo 805. I also told him about the space I need to fill, which is 3,000 cubic feet directly in my listening area that has three walls with the entire right side wall opening to another 3,500 cubic feet, then secondarily opening to another 3,000 cubic feet.... in short, a lot of area. Basically, I live in side-to-side (or California) split home with the listening room on the lower level. The 805's setup screen has a speaker impedance setting of either 4 or 6 ohms. I'd done some reading here and at AVS, and Brent said I should be okay running the 805 provided I set Speaker Impedance to 4 ohms. I received my speakers the other day and have been playing around with placement ever since. During this time, I've been playing the system over 100db at length to get a feel for how things sounded in the secondary and tertiary rooms. I was listening to a Natalie Merchant CD this morning and began hearing some crackling/static distortion from my left M80. While isolating the tweeter causing the static, the same thing began happening with one (or both) tweeters in the other M80, then also a hint of it from my VP150 center.

I shut the whole system down and called Axiom. I spoke with J.C.(sp?) and told him the issues at hand. He said straight away that the 805 isn't going to be a good fit for the M80's and my cubic footage due to lack of power. He stated that switching the Speaker Impedance setting to 4 ohms cuts amp power to keep it from overheating, thereby compounding the power issue. He recommended that I look at a good quality 2 channel amp to run the M80's. I also noted that my speaker runs are in-wall 16 gauge runs, and he recommended I switch to the shortest run possible @ 12 gauge. J.C. was very kind and said to let Axiom know how many tweeters are damaged so they can send replacements. I am a bit confused about the conflicting recommendations from different Axiom folks about all the variables in my setup, but regardless I am very thankful for the top notch service in that they are offering to replace damaged drivers without batting an eye.

{are you still with me?}

My highest priority is to not damage my equipment as I intend to keep it for at least 8 years like I did my last home theatre. I can replace my 16 gauge in-wall runs with direct runs @ 12 gauge at virtually no cost. This, however still leaves me with the power issue, which is undoubtedly the biggest factor here. If that means using the 805 solely as a preamp, then so be it. J.C. said that, with the VP150 and my two QS8's being 6ohm, the 805 should be okay running those provided I set the Speaker Impedance setting back to 6 ohms. I do like to run my system at high volume for house parties and whatnot, so I don't want to ultimately underpower any other channels, and as I said I believe I may have already damaged my VP150.

SHORT VERSION

I have damaged the tweeters in my M80's, and possibly my VP150, while driving them at high volume using an Onkyo 805 receiver. Axiom is kind enough to replace any damaged tweeters, though at a minimum I will most likely need to run the M80's with a separate amplifier. I am debating whether to do so for the VP150 and two QS8's as well. I ultimately have ~8,000 cu/ft of area that I want to fill with sound, and the last thing I want to do is risk underpowering the speakers as I intend to stay with this home theatre gear for years to come. I've read other threads here and know various users run the gamut with amplifiers and the price range they've paid i.e. Outlaw, Rotel, Odyssey, Emotiva, etc.

What are your thoughts people? Stereo amp only? 5 channel integrated? Monoblocks all the way round? Another combo? Any advice is greatly appreciated.
_________________________
A: Epic 80 * 600 / Integra DTC-9.8 / A1400-8
V: Samsung HL-S6187W / Tosh HD-XA2 / PS3 / Oppo 970HD

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#173848 - 08/05/07 01:55 PM Re: M80 tweeter damage - may need a separate amplifier [Re: haylo75]
alan Offline

connoisseur

Registered: 01/29/02
Posts: 3256
Loc: Toronto/New York/parry Sound
Hello haylo 75,

JC is absolutely correct about not using the Onkyo 805 (or any Onkyo AV receiver) to drive the 4-ohm M80s and I regret that Brent suggested you could do so. As JC has advised you, the 805 will be fine driving the other channels (a 6-ohm load presents no problems for any AV receiver; it's as benign as an 8-ohm load) but you will need a separate 2-channel power amp for the M80s if you continue to use the Onkyo.

In Brent's defense, it's extremely misleading for Onkyo and some other manufacturers to suggest that their receivers will drive 4-ohm loads, THX "certified" or not. Moreover, the manufacturers (almost all of them) use the totally bogus "dynamic power output" spec to mislead consumers into thinking that an AV receiver will not only drive 4 ohms but even produce hundreds of watts into as low as 2-ohm impedances. The receivers will do so for a tiny fraction of a second, then shut down!

The only "dynamic" power output spec that has any meaning is "dynamic headroom" into 4 ohms, which is expressed in dB. That spec is seldom stated because the receiver's amplifier is rigorously stressed in that test.

Ever since I joined Axiom five years ago, I've been warning against using Onkyo AV models for the 4-ohm M80s (based on Axiom customer experience and lab tests by some magazines) as the Onkyos either go into severe current limiting when set to 4 ohms (producing perhaps 30 watts per channel or less), or they shut down.

As I've explained in previous posts, the AV receiver brands that Axiom has found able to drive the 4-ohm M80s without severe current limiting or shut-down are: Sherwood Newcastle (which we have bench-tested and which Axiom sells on-line); Denon, Harman/Kardon, B&K, Rotel, NAD, and McIntosh.

The AV receiver brands to avoid if you want to get the 4-ohm M80s are: Sony, Kenwood, Onkyo, JVC, and Yamaha (except for one or two models).

We do not have enough customer feedback on Marantz and Pioneer to make a recommendation. The one previous Pioneer with Mosfet output devices that would drive the M80s is no longer available.

Regards,
_________________________
Alan Lofft,
Axiom Resident Expert (Retired)

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#173849 - 08/05/07 01:58 PM Re: M80 tweeter damage - may need a separate amplifier [Re: haylo75]
alan Offline

connoisseur

Registered: 01/29/02
Posts: 3256
Loc: Toronto/New York/parry Sound
p.s. to my previous post: In my list of recommended AV receiver brands that will drive the M80s, I forgot to include Outlaw Audio.

Regards,
_________________________
Alan Lofft,
Axiom Resident Expert (Retired)

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#173850 - 08/05/07 02:07 PM Re: M80 tweeter damage - may need a separate ampli [Re: alan]
haylo75 Offline
veteran

Registered: 03/20/07
Posts: 132
Loc: Kansas City, MO USA
Alan,

Thank you for the fast reply and advice. The numbers game driven by the industry is lamentable at best. I am frankly astonished to see the ~30W number.

When it comes down to it, I'm not married to the Onkyo as I've two weeks left to return it. I have a number of HDMI devices so have been looking for something to do HDMI switching for me. Looks like I may be back to the drawing board from a source standpoint!
_________________________
A: Epic 80 * 600 / Integra DTC-9.8 / A1400-8
V: Samsung HL-S6187W / Tosh HD-XA2 / PS3 / Oppo 970HD

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#173851 - 08/05/07 02:08 PM Re: M80 tweeter damage - may need a separate amplifier [Re: alan]
Wid Offline
axiomite

Registered: 06/22/03
Posts: 6789
Loc: The Peoples Republic of Il.

I'll be damned, I thought we only needed as little as a half a watt for the M80s at decent dbs
_________________________
Rick


"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud


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#173852 - 08/05/07 02:22 PM Re: M80 tweeter damage - may need a separate ampli [Re: Wid]
haylo75 Offline
veteran

Registered: 03/20/07
Posts: 132
Loc: Kansas City, MO USA
Well then my 30 should be more than sufficient!

I noticed you are running a Rotel amp - which model if you don't mind my asking?

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#173853 - 08/05/07 02:26 PM Re: M80 tweeter damage - may need a separate ampli [Re: haylo75]
Wid Offline
axiomite

Registered: 06/22/03
Posts: 6789
Loc: The Peoples Republic of Il.

I have the RB 1080, it is rated @ 330 into 4 ohm.
_________________________
Rick


"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud


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#173854 - 08/05/07 03:09 PM Re: M80 tweeter damage - may need a separate amplifier [Re: Wid]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 4613
Quote:

...I thought we only needed as little as a half a watt for the M80s at decent dbs




That's right. In my 4,000 cubic foot space, half-a-watt per M80 gives me an average SPL of 75dB. With the 600 on, the average goes up to 85dB. This is my typical listening level for music. For movies, I got up to a few watts on the M80s.

Last night, while everyone was sleeping, I was down to less than a tenth of a watt per M80.

What would happen if the Onkyo is set to 6 or 8 Ohms? Do you have the M80s set to small and are you crossing them over at 80Hz?

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#173855 - 08/05/07 03:29 PM Re: M80 tweeter damage - may need a separate ampli [Re: Mojo]
haylo75 Offline
veteran

Registered: 03/20/07
Posts: 132
Loc: Kansas City, MO USA
Quote:

What would happen if the Onkyo is set to 6 or 8 Ohms? Do you have the M80s set to small and are you crossing them over at 80Hz?




The Onkyo has one other setting, which is for 6 ohms. I haven't tried this setting with the M80's connected. I suspect it would run very hot and may shut down as it was running very hot to the touch at the 4 ohm setting. I've experimented with various crossover settings and spent most of the time with them crossed over between 40hz and 80hz. I did run them for a bit at full range on their own while listening to two channel audio.
_________________________
A: Epic 80 * 600 / Integra DTC-9.8 / A1400-8
V: Samsung HL-S6187W / Tosh HD-XA2 / PS3 / Oppo 970HD

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#173856 - 08/05/07 04:27 PM Re: M80 tweeter damage - may need a separate ampli [Re: haylo75]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 4613
If you want to listen to music in other spaces, you really ought to install speakers in those spaces as opposed to blasting your amp in the main listening area. Look at some M3s as they've been getting rave reviews on these boards.

If you want to experiment with the Onkyo 6 and 8 Ohm settings, just turn your gain up slowly. If you see/hear any misbehaviour, turn it down.

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