Issue with Avantgarde Acoustic DUO XD >>> Power amplifier getting super hot after 5mins of usage

[FredJ]

Hi all,

first of all I have to mention that I love the whatsbestforum! A lot of helpful information been discussed amongst people who share the same lovely hobby

Why I am reaching out (issue): I received my DUO XDs last night and installed them right away. They look great and also sound was good from the start! After listening for approx. 1hour we were about to leave and come back later, so I was switching off the gear. Surprisingly I recognized then that my stereo power amplifier Burmester 911 MK3 was freaking hot!!! Until then nothing was recognizable, it was playing fine and It did not switch off or anything like that.

Which gave me a little shock honestly and never ever happened before, while previously, I was driving it much heavier with bigger volume with my other pair of speakers (89db efficiency 3-way ETON chassis treble ER4 + mid 7inch + bass 11 inch). The maximum there was a bit of casual little warmth after 4-5hours of continuous listening...

Later same night, I plugged in my other speakers again and the 911MK3 it was playing fine w/o any temperature - kind of business as usual.

I tried another time to run the DUO XDs (connected as per manual means preamp > power amp > via speaker cables to mid range input > via jumper cablse to sub/treble inputs) and the 911 MK3 started getting hot again immediately after ~5mins!!

I am puzzled honestly as I connected everything as it is explained in the manual from Avantgarde as well as Burmester - see attached pictures. Also the DUO XDs should not demand any relevant power from the power amplifier as they have the active Bass Modules and the external amplifier only needs to drive the Mid/ Treble as far as I understand.

Has anyone a clue or idea why this happens and the 911 MK3 is getting hot after 4-5mins?

What's happening? Thanks a lot in advance for any helpful guidance here everyone!!

Kind regards and a great start into the weekend everyone,
Frederik

 

[sujay]

Strange! It shouldn’t happen. I have been running my 911s for over 15 years. They do occasionally require rebiasing when they run hotter than usual. The newer power amps like 226/218 don’t need this.
The only other occasion my amps ran hot was when I was passive biamping them using the jumpers.
Get the amp checked please. How old is it? The 911 is an ultra reliable amp

 

[FredJ]

Thanks Sujay!

The 911 MK3 has been manufactured 2018. And it l‘s running fine right now again for already 1.5h again with my other speakers.

Thea‘s why I am 100% sure its nothing about the 911 but within the circuit/ connection with the DUOs…

 

[Hear Here]

From your first sentence, I understand you have just taken delivery of used Duo XD speakers. Is that right?

It seems you have them connected up properly, so let's do a bit of experimentation to find out where any fault may be:

1. Check that polarity is constant and correct to both speakers and to both sections of each speaker
2. Disconnect speaker cables and using a standard multi-meter, check the DC resistance of the Duos, both at the mid and the bass/top terminals. - Strangely, with my Duos, I get about 12 ohms on the mid and nothing on the bass/top
3. Turn off the Duo's internal amps and play music as you normally do. It will sound OK, but lacking in bass. Does the amp get hot?
4. Connect only the amp to the bass / treble connectors on the Duos. This isolates the mid-horn, so music will sound poor. Does the amp get hot?5. Connect only the amp to the mid horn on the Duos. The sound will lack treble and bass. Does the amp get hot?

By doing these tests (one speaker at a time) you should establish where any fault may lie. AG speakers are very easy to drive so your problem seems odd. Perhaps there's a fault with the built-in bass amps or a crossover component within the speakers,.

I had a different problem with my earlier Unos (nasty thump when amps switched on and a "scratching" noise from the bass section) and I wrote to AG in Germany about it. Via the UK distributor at the time, the problem was identified to a "missing" small resistor and poorly adjusted DIP switched on the internal amp board. Fixed for a couple of quid and the problem was resolved for good.

Good luck - I hope you get the problem fixed as you have great speakers. I hope the previous owner hasn't neglected to mention a known fault.

 

[FredJ]

Thanks for your reply Hear Here!

And yes correct, bought used but from a professional high end shop (not close to my place but received via shipment). So worst case will need to return.

I partially did what you recommended as checks, but will run through again later today. Right now not at home.

Will let you know. Thanks again and have a great start to the weekend! Fred

 

[FredJ]

From your first sentence, I understand you have just taken delivery of used Duo XD speakers. Is that right?

It seems you have them connected up properly, so let's do a bit of experimentation to find out where any fault may be:

1. Check that polarity is constant and correct to both speakers and to both sections of each speaker
2. Disconnect speaker cables and using a standard multi-meter, check the DC resistance of the Duos, both at the mid and the bass/top terminals. - Strangely, with my Duos, I get about 12 ohms on the mid and nothing on the bass/top
3. Turn off the Duo's internal amps and play music as you normally do. It will sound OK, but lacking in bass. Does the amp get hot?
4. Connect only the amp to the bass / treble connectors on the Duos. This isolates the mid-horn, so music will sound poor. Does the amp get hot?5. Connect only the amp to the mid horn on the Duos. The sound will lack treble and bass. Does the amp get hot?

By doing these tests (one speaker at a time) you should establish where any fault may lie. AG speakers are very easy to drive so your problem seems odd. Perhaps there's a fault with the built-in bass amps or a crossover component within the speakers,.

I had a different problem with my earlier Unos (nasty thump when amps switched on and a "scratching" noise from the bass section) and I wrote to AG in Germany about it. Via the UK distributor at the time, the problem was identified to a "missing" small resistor and poorly adjusted DIP switched on the internal amp board. Fixed for a couple of quid and the problem was resolved for good.

Good luck - I hope you get the problem fixed as you have great speakers. I hope the previous owner hasn't neglected to mention a known fault.

4. I checked on this and connected the amp with only mid and only Bass Module.
> Connected to mid only - no prob and no heat.
> Connected to Bassmodule only - amp starts to get warm after 1.5mins (!) and is hot after 5mins

Also when connecting pre-amp via XLR with the Bassmodules - there is hardly any sound eve if you bump up db on the DUO Terminal.

>>> all-in-all this clearly indicates an issue with the Sub/bassModules right?

 

[Hear Here]

> Connected to Bassmodule only - amp starts to get warm after 1.5mins (!) and is hot after 5mins

Is that with the AG's amp switched on?

Try with the AG amps switched off. This should indicate a problem with the AG's amp or XO.

Did you try with each speaker separately? If so, do both speakers overheat your amp?

I'd be surprised if both AG amps have a fault.

 

[FredJ]

Is that with the AG's amp switched on?

Try with the AG amps switched off. This should indicate a problem with the AG's amp or XO.

Did you try with each speaker separately? If so, do both speakers overheat your amp?

I'd be surprised if both AG amps have a fault.

Same happens either way…AG amp switched on or off and with both or single speaker connected unfortunately…with single speaker the respective side of the amp statts heating up

 

[Hear Here]

Same happens either way…AG amp switched on or off and with both or single speaker connected unfortunately…with single speaker the respective side of the amp statts heating up

All very odd. I suggest a call to AG may be the best place to start. If amp getting hot when not sending music to the speakers, the implication is a partial short. The nominal impendence of these AGs is 18 ohms so they should be an easy speaker to drive. The mystery remains unsolved and it's most odd that both speakers seem to upset your amp. I hope you get it resolved.

 

[SlapEcho]

If amp getting hot when not sending music to the speakers, the implication is a partial short

Possibly also due to high frequency oscillation instability into this particular speaker impedance.