Definitive Technology Mythos STS Issue

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NDyse10

Junior Audioholic
I have a pair of Mythos STS super tower speakers. Been having an issue where the right speaker's powered sub won't work unless I plug it in and out. For reference, the red light is off and sub won't work. Then I'll undo the plug into the speaker and replug it back in and the red light comes back and the subwoofer works. I was listening to music today and after doing the plug fix it stopped working after roughly a hour. Just randomly cut mid song.

I've also noticed occasionally the right channel won't work at all but that is sporadic. When this happens I usually just have to power cycle inputs/receiver and it works.

Where should I start with troubleshooting? Is it something wrong with the speaker/power cord or receiver? If receiver could it be a setting I have or more likely to be a hardware issue?

Receiver is a Marantz SR5005. Running a 5.1.
 
Kvn_Walker

Kvn_Walker

Audioholic Field Marshall
Is it under warranty? That sounds like a problem in the electronics.
 
N

NDyse10

Junior Audioholic
Is it under warranty? That sounds like a problem in the electronics.
I am not sure. I bought them from a friend who got them from Best Buy. Not sure when exactly but guessing between 2010-2013.
 
TLS Guy

TLS Guy

Seriously, I have no life.
I am not sure. I bought them from a friend who got them from Best Buy. Not sure when exactly but guessing between 2010-2013.
Def Tech electronics is renowned for failure. You will have to contact them for repair/replacement advice.
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
May want to download the manual and read the section about the sub.

here is a part that may be of interest:
The Mythos STS has a special circuit which automatically turns the powered subwoofer section on when a signal is fed to the loudspeaker and does not require an on-off switch. Please note that if you hear a pop from the speaker when the amp powers up, this is normal. The LED on the back panel will light up when a signal is sensed and the amplifier turns on. After the cessation of a signal, it may take up to an hour for the amplifier to actually turn off. In some instances, because of stray radio signals (RF) in your area, the LEDs may not turn off. However, this is nothing to be concerned about as the amplifiers draw almost no power when they are idling
 
N

NDyse10

Junior Audioholic
Messaged Def Tech and they confirmed they believe it's an issue with the amp. I can repair for $300 but requires me taking apart the amps.

Being that I have a subwoofer already is there a performance issue associated with continuing on with the right speaker's sub being intermittent? Can I risk damage to the speaker or other units?

Do the speakers work without being plugged in? Is that even advisable? Again being that I have a subwoofer trying to gauge how important it is to do the repair.
 
everettT

everettT

Audioholic Spartan
Messaged Def Tech and they confirmed they believe it's an issue with the amp. I can repair for $300 but requires me taking apart the amps.

Being that I have a subwoofer already is there a performance issue associated with continuing on with the right speaker's sub being intermittent? Can I risk damage to the speaker or other units?

Do the speakers work without being plugged in? Is that even advisable? Again being that I have a subwoofer trying to gauge how important it is to do the repair.
I wouldn't put $300 into that speaker. I'd run both towers without their internal powered woofers.
 
TLS Guy

TLS Guy

Seriously, I have no life.
I wouldn't put $300 into that speaker. I'd run both towers without their internal powered woofers.
Messaged Def Tech and they confirmed they believe it's an issue with the amp. I can repair for $300 but requires me taking apart the amps.

Being that I have a subwoofer already is there a performance issue associated with continuing on with the right speaker's sub being intermittent? Can I risk damage to the speaker or other units?

Do the speakers work without being plugged in? Is that even advisable? Again being that I have a subwoofer trying to gauge how important it is to do the repair.
I would suspect that they do. However, the crossover to those 4.5" mids is 150 Hz. So if you do use a couple of subs then you need to set the crossover to the speakers at 150 Hz. At that frequency you will need to place the subs right next to the speakers, or you will have a localization issue. The other issue will be cascading crossovers. There is a crossover to those 4.5 mids which is passive. So to make this work correctly you need to set your receiver speakers set up to subwoofer yes and large, so that the Mythos get a full range signal from your receiver at their speaker terminals. Now set the crossover to 150 Hz. This will work as long as your sub can reach to 150 Hz and you will need two subs. If you do this you will have to run the speakers the same way, and you have to use two subs.

You must follow these instructions exactly or it will not sound right at all. So it might be cheaper to have your amp repaired if you don't have two subs. What is you sub by the way?
 
Eppie

Eppie

Audioholic Ninja
Messaged Def Tech and they confirmed they believe it's an issue with the amp. I can repair for $300 but requires me taking apart the amps.

Being that I have a subwoofer already is there a performance issue associated with continuing on with the right speaker's sub being intermittent? Can I risk damage to the speaker or other units?

Do the speakers work without being plugged in? Is that even advisable? Again being that I have a subwoofer trying to gauge how important it is to do the repair.
I see TLS Guy just beat me to it. Yes, the speakers will work with the power cords not connected. The subwoofers will simply not function. The problem is knowing where the midranges drop off and how to properly integrate a separate subwoofer with those speakers. Without the built in subwoofers you don't have a proper 2-way speaker though. You can try crossing the sub at 150Hz as suggested, but with those speakers I think you may be better off to bite the bullet and get the amp repaired.
 
TLS Guy

TLS Guy

Seriously, I have no life.
I see TLS Guy just beat me to it. Yes, the speakers will work with the power cords not connected. The subwoofers will simply not function. The problem is knowing where the midranges drop off and how to properly integrate a separate subwoofer with those speakers. Without the built in subwoofers you don't have a proper 2-way speaker though. You can try crossing the sub at 150Hz as suggested, but with those speakers I think you may be better off to bite the bullet and get the amp repaired.
Well I did research this and look at John Atkinson's data. The cross from that ABR bass unit to the mid units is at exactly 150 Hz and fourth order 24db. per octave high and low pass. The instruction manual says to set the receiver to large for the connection to the speaker terminals which are from the left and right outputs. So this needs a full range signal to those terminals. So in that case there is a passive fourth order high pass filter to mid units most likely, alternatively there could be a second order high pass passive and an acoustic second order roll off of the sealed drivers. Either way there is a 24db. per octave high pass.

So that is why the receiver must output a full range signal to the speaker terminals on the back. So the speaker set up has to be LFE + main. The crossover to the sub output should be set to 150 Hz, and the crossover on the subs as high as possible. This should hopefully give a balanced fourth order 24db per octave high and low pass filters at 150 Hz. That will be as closely as a separate sub unit could be contrived if he does not want to repair the amp. How well this will work is open to conjecture. Those speakers in fact measure quite well. There is however some crossover gain at 150 Hz and some degree of peaking.

The unknown is how well his subs function to 225 Hz. Since the cross is at 150 Hz, and the order fourth, he needs good performance from the sub at least half an octave above 150 Hz which would be 225 Hz, ideally an octave above which would be 300 Hz.

His best solution is to get the amp repaired. He has to test the sub driver in that defective speaker and report the DC resistance to DefTech, otherwise he gets no warranty.

The number may be out of the ordinary, as DefTech are known for highly unusual impedances in their active woofers and subs, often in the 75 ohm range. So it is anyone's guess what the DC resistance should measure.

I think the OPs best options are either to repair the amp, or ditch the speakers and replace. Those amps are miserable class C units.
 
N

NDyse10

Junior Audioholic
Really good information here guys - thank you.

I only have 1 SVS PB12-NSD sub. Not sure if that helps provide clarity on how things would go if I were to use as is and setting the crossover at 150hz.

Unfortunate timing as I was going to upgrade my receiver from a Marantz SR5005 to a newer unit and was also going to geta 55 LG OLED C2. New speakers weren't part of the budget. I concede it may be the best option.

The instructions to take apart the amps from Def Tech was more involved than I expected.
 
AcuDefTechGuy

AcuDefTechGuy

Audioholic Jedi
Really good information here guys - thank you.

I only have 1 SVS PB12-NSD sub. Not sure if that helps provide clarity on how things would go if I were to use as is and setting the crossover at 150hz.

Unfortunate timing as I was going to upgrade my receiver from a Marantz SR5005 to a newer unit and was also going to geta 55 LG OLED C2. New speakers weren't part of the budget. I concede it may be the best option.

The instructions to take apart the amps from Def Tech was more involved than I expected.
It may not be ideal, but first thing is just see how it sounds with what you have now.

So one of the sub (built-in) is dead. You still have the other built-in sub plus the SVS sub. If it sounds great, then just continue doing that until you have the time and budget to upgrade or do other things.

Still sucks knowing that you have a defective unit.

I used to own all DefTech with built-in Amps. But I looked into my future, since I am psychic and all, and I wondered what happens if these amps would fail. So I made up my mind to never buy any speaker with built-in amps, not even subwoofers with built-in amps.

I sold all my speakers with built-in amps and Subs with built-in amps and started over.

Now you can think about your audio future. :D
 
TLS Guy

TLS Guy

Seriously, I have no life.
Really good information here guys - thank you.

I only have 1 SVS PB12-NSD sub. Not sure if that helps provide clarity on how things would go if I were to use as is and setting the crossover at 150hz.

Unfortunate timing as I was going to upgrade my receiver from a Marantz SR5005 to a newer unit and was also going to geta 55 LG OLED C2. New speakers weren't part of the budget. I concede it may be the best option.

The instructions to take apart the amps from Def Tech was more involved than I expected.
I see that sub you have is specked to 150 Hz. So my plan is an option. However, I am of the view you should devote your upgrade budget to speakers. Usually a speaker upgrade will have a greater impact than any other upgrade. Those speakers are not the worst, except for reliability which you have just found out, but their sound quality is adequate may be, but far from top notch. So my advice is to spend that budget on speakers, and do the receiver and TV upgrade later.
In any event, the amp in the other speaker may well blow up. Who knows how long the replacement will last? Amps in speakers are not a bad idea, in fact a good idea, but the amps must be top notch and reliable. Unfortunately those DefTech amps are misery units, as you have found out.
 
N

NDyse10

Junior Audioholic
I see that sub you have is specked to 150 Hz. So my plan is an option. However, I am of the view you should devote your upgrade budget to speakers. Usually a speaker upgrade will have a greater impact than any other upgrade. Those speakers are not the worst, except for reliability which you have just found out, but their sound quality is adequate may be, but far from top notch. So my advice is to spend that budget on speakers, and do the receiver and TV upgrade later.
In any event, the amp in the other speaker may well blow up. Who knows how long the replacement will last? Amps in speakers are not a bad idea, in fact a good idea, but the amps must be top notch and reliable. Unfortunately those DefTech amps are misery units, as you have found out.
Well while I have your expertise...can we talk speakers?

I have a Marantz SR5005 for a receiver. I'd probably cap my budget off at $2000 for a new pair of speakers, unless extending slightly would be a significant upgrade. I'm also fine spending less if there is truly a Diamond in the rough less than that. As you can see I have extensive amount of replacement to do. Assuming my receiver can power a nice set of speakers I could plug in my Ps5 direct to my Samsung curved 4k and use ARC for the time being. Any speaker recommendations?

Will I need to upgrade my center channel and surrounds to match? Thought I read at one time not to mismatch speaker brands. I have a Mythos 7 center channel and Def Tech Pro Monitor 800s for the rears.
 
TLS Guy

TLS Guy

Seriously, I have no life.
Well while I have your expertise...can we talk speakers?

I have a Marantz SR5005 for a receiver. I'd probably cap my budget off at $2000 for a new pair of speakers, unless extending slightly would be a significant upgrade. I'm also fine spending less if there is truly a Diamond in the rough less than that. As you can see I have extensive amount of replacement to do. Assuming my receiver can power a nice set of speakers I could plug in my Ps5 direct to my Samsung curved 4k and use ARC for the time being. Any speaker recommendations?

Will I need to upgrade my center channel and surrounds to match? Thought I read at one time not to mismatch speaker brands. I have a Mythos 7 center channel and Def Tech Pro Monitor 800s for the rears.
$ 2000.00 is bit lean for decent speakers, but I can get you close. In a way I am not may be the best to advise, as I don't shop for speakers. I design and build my own.
However I can give your a very solid recommendation, the SALK BMR monitors designed by a fellow member here, Denis Murphy. These are thoroughly well designed speakers, that measure superbly. I don't think you will need to replace these, probably ever. Dennis has had the courage to actually market his design. I did it once only to have the drivers discontinued by the manufacturer after the first production run.

As far as the center, the issue of matching, comes down to error matching, to make sure all the speakers are as lousy as each other and lousy in the same way.

Unfortunately center speakers are hard to design and most hobbled from the start because they lay out the speaker with tweeter in the middle and the drivers either side.
This creates extensive vertical dispersion and poor horizontal dispersion, which is the opposite of what is required. So centers need to be either coaxial designs, which I prefer, or three way with the tweeter above a midrange, and woofers either side. They do not have to come from the same manufacturer, or even use the same drivers, as long as all the speakers are really good speakers in every aspect. I use speakers that are MTM right and left, and use a coaxial design for the center. But everything combines to work with seamless synergy.

So as far as your speakers are concerned, I would get the left and right speakers upgraded, and if you get the itch to upgrade the center later, which you probably will, we can advise you then. Good center speakers are far and few between, and I have to say that they present a huge design challenge for multiple reasons.
 
D

Danzilla31

Audioholic Spartan
Well while I have your expertise...can we talk speakers?

I have a Marantz SR5005 for a receiver. I'd probably cap my budget off at $2000 for a new pair of speakers, unless extending slightly would be a significant upgrade. I'm also fine spending less if there is truly a Diamond in the rough less than that. As you can see I have extensive amount of replacement to do. Assuming my receiver can power a nice set of speakers I could plug in my Ps5 direct to my Samsung curved 4k and use ARC for the time being. Any speaker recommendations?

Will I need to upgrade my center channel and surrounds to match? Thought I read at one time not to mismatch speaker brands. I have a Mythos 7 center channel and Def Tech Pro Monitor 800s for the rears.
On a 2000 budget I'd go with Monoprices monolith lineup they are on sale right now.
 
D

Danzilla31

Audioholic Spartan
Well while I have your expertise...can we talk speakers?

I have a Marantz SR5005 for a receiver. I'd probably cap my budget off at $2000 for a new pair of speakers, unless extending slightly would be a significant upgrade. I'm also fine spending less if there is truly a Diamond in the rough less than that. As you can see I have extensive amount of replacement to do. Assuming my receiver can power a nice set of speakers I could plug in my Ps5 direct to my Samsung curved 4k and use ARC for the time being. Any speaker recommendations?

Will I need to upgrade my center channel and surrounds to match? Thought I read at one time not to mismatch speaker brands. I have a Mythos 7 center channel and Def Tech Pro Monitor 800s for the rears.



 
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D

Danzilla31

Audioholic Spartan
Well while I have your expertise...can we talk speakers?

I have a Marantz SR5005 for a receiver. I'd probably cap my budget off at $2000 for a new pair of speakers, unless extending slightly would be a significant upgrade. I'm also fine spending less if there is truly a Diamond in the rough less than that. As you can see I have extensive amount of replacement to do. Assuming my receiver can power a nice set of speakers I could plug in my Ps5 direct to my Samsung curved 4k and use ARC for the time being. Any speaker recommendations?

Will I need to upgrade my center channel and surrounds to match? Thought I read at one time not to mismatch speaker brands. I have a Mythos 7 center channel and Def Tech Pro Monitor 800s for the rears.
Out of the options I listed the Encore speakers are awesome! I own 3 of those towers BUT

The THX versions are even better and at they're sale price they are at right now you can get 2 of the towers and the center channel for under your 2000 budget

They will outperform your Mythos speakers by a long shot and I believe can compete with or even best many more expensive speakers out there.
 
D

Danzilla31

Audioholic Spartan
2 THX 460T towers $650 each and 1 THX 365C center channel is $450 that's $1750 for all 3 I don't think you will find a better deal out there in my opinion
 
N

NDyse10

Junior Audioholic
$ 2000.00 is bit lean for decent speakers, but I can get you close. In a way I am not may be the best to advise, as I don't shop for speakers. I design and build my own.
However I can give your a very solid recommendation, the SALK BMR monitors designed by a fellow member here, Denis Murphy. These are thoroughly well designed speakers, that measure superbly. I don't think you will need to replace these, probably ever. Dennis has had the courage to actually market his design. I did it once only to have the drivers discontinued by the manufacturer after the first production run.

As far as the center, the issue of matching, comes down to error matching, to make sure all the speakers are as lousy as each other and lousy in the same way.

Unfortunately center speakers are hard to design and most hobbled from the start because they lay out the speaker with tweeter in the middle and the drivers either side.
This creates extensive vertical dispersion and poor horizontal dispersion, which is the opposite of what is required. So centers need to be either coaxial designs, which I prefer, or three way with the tweeter above a midrange, and woofers either side. They do not have to come from the same manufacturer, or even use the same drivers, as long as all the speakers are really good speakers in every aspect. I use speakers that are MTM right and left, and use a coaxial design for the center. But everything combines to work with seamless synergy.

So as far as your speakers are concerned, I would get the left and right speakers upgraded, and if you get the itch to upgrade the center later, which you probably will, we can advise you then. Good center speakers are far and few between, and I have to say that they present a huge design challenge for multiple reasons.
Interesting. I like the idea of buying something and never having to upgrade again. I will do some research on those.

I knew the Def Techs wouldn't be that but got them for $600 for the pair so was a great deal.
 
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