Infinity powered tower sub issue!

[Dan Madden]

I have Infinity Interlude IL50 powered towers (circa 1992/3). I noticed recently that the left sub power light is always on. Normally after 5mins or so of inactivity, the sub powers into standby mode. Also, there is a low volume pink noise kinda' 'rumble' coming from the sub. From the listening position, I can barely hear it. The subs on both sides are set for RCA line LF/LFE in connections from my AVR. If I remove the line in connection, the rumble is still there. Also, if I switch the sub for direct speaker wire line in connection, the rumble is still there.

I opened up the back panel and blew it out with compressed air and then applied contact cleaner to the various switches and connections but the sub still stays powered on and the low volume rumble is still there.

Bare in mind that the sub still works and sounds fine........it's just not powering down and the low volume rumble still persists.

Any ideas or info you can give me on how to fix it??

 

[TLS Guy]

I have Infinity Interlude IL50 powered towers (circa 1992/3). I noticed recently that the left sub power light is always on. Normally after 5mins or so of inactivity, the sub powers into standby mode. Also, there is a low volume pink noise kinda' 'rumble' coming from the sub. From the listening position, I can barely hear it. The subs on both sides are set for RCA line LF/LFE in connections from my AVR. If I remove the line in connection, the rumble is still there. Also, if I switch the sub for direct speaker wire line in connection, the rumble is still there.

I opened up the back panel and blew it out with compressed air and then applied contact cleaner to the various switches and connections but the sub still stays powered on and the low volume rumble is still there.

Bare in mind that the sub still works and sounds fine........it's just not powering down and the low volume rumble still persists.

Any ideas or info you can give me on how to fix it??

Obviously one of the early stages in the sub amp has become noisy, which is making the LF noise and keeping the sub powered on.

The amp needs checking with an O-scope to identify the source of the noise and then the components in that stage need checking to find the faulty component.

 

[Dan Madden]

Obviously one of the early stages in the sub amp has become noisy, which is making the LF noise and keeping the sub powered on.

The amp needs checking with an O-scope to identify the source of the noise and then the components in that stage need checking to find the faulty component.

Heheheee......Oh ya, that sounds easy !!

 

[Dan Madden]

UPDATE!!

Ok.......Now the sub has failed completely! No power....no light....no sound (I checked the fuse and it's fine). That being said, I'm perplexed as to whether to have it fixed or to just buy another sub. The amp itself could be toast!! The other sub in my right tower still works fine and as I stated earlier, I'm shocked at how little difference the lack of the left sub makes to the overall LF/LFE sound performance.

The tower weighs 80 pounds so I'm reluctant to bring the entire thing in for repair and I am thinking that I could just bring in the back control panel, which houses the amp, crossover etc for the entire speaker. Could that work? Who could do that work is another question??!!

OR.......I could just buy another.....better.....bigger sub. I'm figuring it would cost in the $200+ bucks to have it fixed right?

What are your thoughts my Audioholic friends??..........HELP??!!

 

[TLS Guy]

It is now very hard to find independent local repair guys. The other issue is whether there is a service manual for it. Since it was noisy and has now failed totally, my best guess is that it is an opamp failure. This would be a typical sequence, noise and then failure. So then the next question is if it is an IC opamp failure, is that chip still available? I have to say the odds are against it.

I'm very busy right now packing everything away and servicing it and getting equipment ready for snow and cold. When I get a chance I will see if I can find at least a circuit.

That is an integrated unit. I think if you do use another sub, it will not sound the same.

I have to say I'm a huge believer in totally integrated systems rather than any speakers any sub. I do think you can get a much more realistic sound presentation with total system design.

I'm not surprised you notice little difference with only one sub. You have only lost 3db. However you have lost half your power handling in the last octave or two.

This may take me a while. But I will look into it. For now I would just run with one sub. You have one of the better speaker systems from years gone by, and it is worth taking a little time to see if it can be preserved.

Best option would be repair if possible, or seeing if another amp could be used and or adapted to duplicate the performance of the original.

 

[Dan Madden]

It is now very hard to find independent local repair guys. The other issue is whether there is a service manual for it. Since it was noisy and has now failed totally, my best guess is that it is an opamp failure. This would be a typical sequence, noise and then failure. So then the next question is if it is an IC opamp failure, is that chip still available? I have to say the odds are against it.

I'm very busy right now packing everything away and servicing it and getting equipment ready for snow and cold. When I get a chance I will see if I can find at least a circuit.

That is an integrated unit. I think if you do use another sub, it will not sound the same.

I have to say I'm a huge believer in totally integrated systems rather than any speakers any sub. I do think you can get a much more realistic sound presentation with total system design.

I'm not surprised you notice little difference with only one sub. You have only lost 3db. However you have lost half your power handling in the last octave or two.

This may take me a while. But I will look into it. For now I would just run with one sub. You have one of the better speaker systems from years gone by, and it is worth taking a little time to see if it can be preserved.

Best option would be repair if possible, or seeing if another amp could be used and or adapted to duplicate the performance of the original.

Thanks TLS !! I have no intention of replacing My all around Infinity Interlude 5.2 channel setup (Including 3 IL36C speakers) and will sit happily with one sub if necessary. Preferably, I would like to get the unit repaired and I'll contact Infinity to see if there is any repair options available locally (probably not!).

I too also have thought of the possibility of powering the sub with another amp but I'm not sure how that would work?

 

[TLS Guy]

Thanks TLS !! I have no intention of replacing My all around Infinity Interlude 5.2 channel setup (Including 3 IL36C speakers) and will sit happily with one sub if necessary. Preferably, I would like to get the unit repaired and I'll contact Infinity to see if there is any repair options available locally (probably not!).

I too also have thought of the possibility of powering the sub with another amp but I'm not sure how that would work?

Let me work on this. I have a source for a service manual, but they won't let me download it until I pass some type of exam. This is to make sure I'm not a guy who would kill myself or burn the house down!

When I see what we are dealing with I will let you know.

I have pretty good facilities here. When I see what we have, I will let you know if this is something I likely can fix for you.

 

[TLS Guy]

I have downloaded the manual and studied it extensively tonight.

The news is not good. This is a complex unit. It has a very complex power supply, class D amp, proprietary bass management, crossovers, limiter and compressor to prevent woofer damage and parametric Eq.

I suspect your problem is in the power supply. It seems these gave a lot of trouble and there were lots of revisions. The latest was 2005. The service manual states that all units needing service need extensive updating. This is very complex requiring the replacement of a lot of components and extensive calibration.

Servicing this unit is not a project I would want to undertake.

Now this unit was designed and produced after Harmon bought Infinity.

I was on their site and entered your speaker and then tried to find a service center. However I drew a blank as there is no service center listed for that product. This may be because there are a lot of proprietary parts which may be NLA.

I would contact Harmon and see if they have an option for service. Expect a big bill.

Now you can not use a different sub. This is more than a sub. The high pass filter to the mid is passive second order at 150 Hz. The speaker input is fed to the amp, and there is a low pass electronic crossover at 150 Hz. The LFE subwoofer in is mixed in with that signal. This is similar to what I did with the design of my speakers. There is a high pass filter at 32 Hz and a compressor limiter to limit driver excursion and damage.

I don't think it would be realistic to reproduce that in another amp. There would be extensive custom work and design.

So currently your damaged speaker is rolling off at 150 Hz, But in addition you have lost that channel below 150 Hz. The LFE signal is mono so left and right information is in the remaining speaker over the frequency range of the LFE signal.

I'm sorry to say that realistically, if Harmon can not provide you service for that amp, then it is the end of the road for those speakers unfortunately.

 

[Dan Madden]

WOW!! Thanks for all your input and research TLS. I can agree that this is a complicated unit as I popped off the back panel at the beginning of my troubles to blow out dust etc and saw how elaborate the electronics were.

I'll contact Infinity to see if there are any options available to me. Thanks for your help.

 

[TLS Guy]

WOW!! Thanks for all your input and research TLS. I can agree that this is a complicated unit as I popped off the back panel at the beginning of my troubles to blow out dust etc and saw how elaborate the electronics were.

I'll contact Infinity to see if there are any options available to me. Thanks for your help.

If Infinity are unwilling or unable to repair that unit, ask them if they will let you know the Thiel/Small parameters and acoustic responses of the woofer and mid range units, and also the internal box volumes of the enclosures those two units are in.

With that data we just might have a route to salvage and even improvement. However I will warn you this will not be easy or without significant expense.

That unit unfortunately has all the signs of being designed by committee. George you are in charge of this circuit, Bill you do this part and Jane this.
Quite honestly elegance is not that unit's middle name. I'm not surprised it failed, and it seems from all the extensive revisions a lot must have.

In the meantime you can soul search and really decide how committed you are to those speakers as opposed to starting over.

 

[Dan Madden]

Thanks TLS !

The Infinity repair people here in Montreal have agreed to look at it. Also, I will only have to bring in the back panel electronics (Amp..crossover etc) which is great because the whole speaker weighs 80 pounds or so.

The most it will cost me $45 bucks for them to look at it.

Wish me luck because I really love these speakers and would like my left sub back!

 

[TLS Guy]

Thanks TLS !

The Infinity repair people here in Montreal have agreed to look at it. Also, I will only have to bring in the back panel electronics (Amp..crossover etc) which is great because the whole speaker weighs 80 pounds or so.

The most it will cost me $45 bucks for them to look at it.

Wish me luck because I really love these speakers and would like my left sub back!

That is good news that they did not just decline. Lets keep our fingers crossed it does not need an NLA part.

 

[Dan Madden]

That is good news that they did not just decline. Lets keep our fingers crossed it does not need an NLA part.

Hi TLS,

Hey....any advice as to how I can figure out the wiring placements when I disconnect everything. There are A LOT of wires connected to the electronic box and I need to find a way as I disconnect everything to remember where everything re-connects when I get the unit back!!

I was thinking about masking tape and labeling each wire #1....# 2 etc and taking a picture of the unit with all those wires with the tape connected so I can re-connect everything in it's proper place after I get the unit back?

How would you do it?

 

[TLS Guy]

Hi TLS,

Hey....any advice as to how I can figure out the wiring placements when I disconnect everything. There are A LOT of wires connected to the electronic box and I need to find a way as I disconnect everything to remember where everything re-connects when I get the unit back!!

I was thinking about masking tape and labeling each wire #1....# 2 etc and taking a picture of the unit with all those wires with the tape connected so I can re-connect everything in it's proper place after I get the unit back?

How would you do it?

Are the wires different colors? If not make part of them a different color. Electrical tape comes is a lot of different colors. So wind different colors by winding electrical tape of different colors around part of the wires fairly close to the unit. If you run out of colors use combinations, like black/yellow, red/blue etc.

Now take a good marker pen and make the color by each connector on the chassis of the unit.

Now take your photographs. Take lots from different angles. Now disconnect the wires.

This should do the trick.

Good luck!