Smoking Advents

[real1shepherd]

Hi All,

For many yrs I have been the designated "DJ" for a youth group. We always got by with my various receivers and four Advent Loudspeakers hooked up like the original Absolute Sound article designates. The only problem over the yrs was clipping my receivers in the large space with the techno and house music they like. The last receiver I used was the Onkyo TX8500. 110Watts RMS/channel. Still clipped it.

So I bought a QSC GX5 amp...Chinese DJ amp. Somewhere in the neighborhood of 500-700 watts/channel depending on how they write their specs. Anyway, everything was going great for the first hr. 

Then as you might imagine, the back of the speakers started to smoke and the crossover switch would burn your flesh to touch. Only the woofers were still working at this point and stayed that way the rest of the dance. Afterward, I got some DJ Peavey speakers and all has been good.....but at my expense.   

I'm hoping it's just the crossovers that got burned up. Is there a way to test the tweeters themselves to see if they survived? I replaced all the original tweeters with the newer style domes many yrs ago.

 

Kevin

 

 

[RTally]

Testing the tweeters is easy if you have an ohmmeter. Remove the tweeter, disconnect at least one wire from the tweeter terminals, and measure VC resistance with an ohmmeter. If you put in 8 ohm tweeters, they should measure about 5 to 7 ohms resistance. If you don't have a meter, get down to Harbor Freight and buy a cheap $2.99 meter. Those are fine for troubleshooting and quick checks.

While you are removing drivers, pull the woofer and inspect the crossover components. Look for any discoloration of the resistors. Measure the resistors to see if they are still resisting properly. Hopefully, you just burned up a resistor.

You don't say if you have the original (OLA) or the new (NLA) advents. Check out the crossover info at http://baselaudiolab.com/ADVENT_LA_XO.html

Post pictures. The pics could be a lesson for others.

 

[real1shepherd]

Thank you. I have an old working Fluke.

OLA's all of them....vinyl and wood veneer.  All have the Masonite woofers.

The tweeters were the recommended domes replacements way back in the day.

If I haven't destroyed the tweeters, this would be a good time to update the crossovers. Supposedly, you can just punch then out fwd form the back using a blunt piece of wood?

I will happily include pics when I get the crossovers out.

 

Kevin

[JKent]

Vintage speakers will not take that kind of abuse. Nor will the kids' ears, but that's another issue.

The Peavy speakers are the way to go.

[real1shepherd]

The Advents worked very well for yrs & yrs if I watched for clipping.....but bringing in the big DJ amp was my mistake. I really thought the Advents could take it. I remember in college seeing double Advents hooked up to Phase Linear 700 systems. But there's dampening issue differences and I don't think rock has the music dynamics of techno and house music.

Just like we didn't want to be told not to listen to loud music when we were kids, the same applies today. We do have some kids on the autistic spectrum (as they call it) and so they limit the really loud stuff in severity.

 

Yeah, the Peavey's are awesome in this application....and there is a light show I can attach to the bottom with laser lights changing to the music. 

 

Kevin

 

[JKent]

People have reported very good results using those QSC (and Crown) amps with power-hungry 4 ohm speakers like the AR-3a, but that's at normal listening levels. You were remarkably fortunate for years. Playing the Advents at ear-splitting levels should have fried them. Your switch to PA speakers was a good choice.

I would bet money that the tweeters are fried. but if you do decide to rebuild the crossovers, take a look at Pete's excellent page on that subject: http://baselaudiolab.com/ADVENT_LA_XO.html

[real1shepherd]

It's just been a clipping issue all these yrs and I would back down the volume. The Advents showed no signs of fatigue or the crossovers heating up. I used to use fast blow fuses on the speaker wires, but stupidly didn't have them on when I switched to the QSC. That might have saved the Advents.

If the tweeters are fried, I might just part out all the speaker parts. Unless quality dome tweeters are readily available that sound similar. I'll still have the issue of the fried crossovers most likely. I think I do have all the original tweeters but I think that's a step backward.

Yeah, saw the page about crossovers, thanks.

 

[ra.ra]

1 hour ago, real1shepherd said:

I used to use fast blow fuses on the speaker wires....

My first thought reading the original post was curiosity about whether external fuses had been in use. Without them, driving (four) vintage loudspeakers from a single source of amplification while blasting techno music for a youth dance sounds to me like a recipe for disaster.

1 hour ago, real1shepherd said:

...but bringing in the big DJ amp was my mistake.

I am unable to comment on the suitability of this particular amp for this application, but I think the mistake was not providing fuses in the first place and unrestrained use of the volume control. Playing techno and house music with significant dynamic peaks at high decibel levels can be dangerous for aged speakers not intended to handle such material. I have owned audio gear for near 50 years and have never blown a speaker driver due to abusive behavior, but then I've never had much interest in trying to recreate stadium sound levels from equipment intended for home use.

The Advents are probably worth restoring, and the tweeters are not all that hard to find for replacement. During this process, you'd be well-advised to inspect all internal components and refresh noticeably aged or damaged parts. And don't forget to install some external fuse blocks on backside with appropriate fuses. 

[real1shepherd]

3 hours ago, ra.ra said:

My first thought reading the original post was curiosity about whether external fuses had been in use. Without them, driving (four) vintage loudspeakers from a single source of amplification while blasting techno music for a youth dance sounds to me like a recipe for disaster.

I am unable to comment on the suitability of this particular amp for this application, but I think the mistake was not providing fuses in the first place and unrestrained use of the volume control. Playing techno and house music with significant dynamic peaks at high decibel levels can be dangerous for aged speakers not intended to handle such material. I have owned audio gear for near 50 years and have never blown a speaker driver due to abusive behavior, but then I've never had much interest in trying to recreate stadium sound levels from equipment intended for home use.

The Advents are probably worth restoring, and the tweeters are not all that hard to find for replacement. During this process, you'd be well-advised to inspect all internal components and refresh noticeably aged or damaged parts. And don't forget to install some external fuse blocks on backside with appropriate fuses. 

I'm amused there is all this judgemental chastising when I freely admit it was a dumb thing to do. I'm 70 yrs old.....I'm gonna make mistakes like this I didn't in my youth....especially when pressured at one of these dances. We only do it twice a yr, but every yr it gets harder for me. I have to set up everything but the food concession. If you've ever done a lot of volunteer work you know that if you do something well, you're hammered to do it yr after yr......lack of resources, lack of help etc.

So please,  let's not go on and on about what you would have done and certainly would have fused them etc, etc. My actual fuse blocks and speaker wire got misplaced and so I just bunted at the last hr...bad call.  Let's try to stay on focus to the actual damage done and rest assured these Advents will never again run un-fused and with this kind of music & volume levels.

I had asked the question earlier if I could just take a block of wood and drive the crossover base out through the front without incident?

 

 

Kevin

[JKent]

Kevin,

I apologize if I chastised you. The trouble with written communication is we miss all the non-verbal cues. You were doing a good thing for a good cause.

When I worked on my Advents I did the xo work through the woofer hole, following Pete's recommendations regarding new inductors. I also added bracing. Sorry I don't know if you can knock the xo out with a block of wood but working through the woofer opening isn't all that tough (and I'm also a septuagenarian).

Kent

[Guido57]

The crossovers are held by both staples and hot glue. At least they were on mine.  If you just punch them out you may take some fiberboard with them.  I pulled the crossovers instead of working through the woofer hole just because I though there was too much going on in a limited space for my soldering skills at the time.  Note: my OLA's had their crossovers mounted on a metal plate and isolated by spacers( at least that's how I remember it).  Whether or not putting the original tweeters is a step back is a matter of opinion.

[real1shepherd]

Thanks guys. Good looking work, Kent!

The higher range of the OLA's was always subjective against other speakers of their day. Personally, I think the 'fried egg' tweeters had a lot to be desired.

Next step is to test the dome tweeters and then see what has become of the crossovers.

The vinyl pair I bought in college new, so there's a lot of history there....lol. Be a shame not to restore both sets if at all possible. A Double Advent system is sort of a niche in audio history.

 

Kevin

[ChrisM]

14 hours ago, JKent said:

Pete's recommendations regarding new inductors

I looked at Pete's page but didn't see the recommendations. I saw in the picture you posted that you used an air core for L1 (the big one). What was the DCR of the coil you used?

[JKent]

My mistake. Pete's inductor recommendations were in the thread I started twelve years ago: 

 

These are the L1 inductors I used: https://www.parts-express.com/erse-15mh-14-awg-perfect-layer-inductor-crossover-coil--266-360

The thread I linked had no real closure but in the end, despite the crossover rebuild with air coil inductors and film caps I didn't love the Advents. To my ears the AR-2ax was superior so I sold the Advents (and eventually sold the 2ax's to make room for 3a's).

Hope this helps.

[Markkb]

Very cool, I can visualize the party with the Advents! I love how they play loud. I think you would be creating more work for yourself if you bust the crossover plate out. Reapplying the plate may not allow a good acoustic suspension seal. You'd have to work from within the woofer hole anyway. I see two options, remove the crossover components and update the components. If you do this, you could mount everything on another board that would attach inside, leaving wires to the switch long enough to allow mounting the switch in its hole. 

The second option is to work through the woofer hole. maybe one of the kids would be interested in helping to restore these. 

I'm more restore oriented, leaning toward using original fried egg tweeters. How about some pictures of the workhorses?

mark

[real1shepherd]

22 hours ago, Markkb said:

Very cool, I can visualize the party with the Advents! I love how they play loud. I think you would be creating more work for yourself if you bust the crossover plate out. Reapplying the plate may not allow a good acoustic suspension seal. You'd have to work from within the woofer hole anyway. I see two options, remove the crossover components and update the components. If you do this, you could mount everything on another board that would attach inside, leaving wires to the switch long enough to allow mounting the switch in its hole. 

The second option is to work through the woofer hole. maybe one of the kids would be interested in helping to restore these. 

I'm more restore oriented, leaning toward using original fried egg tweeters. How about some pictures of the workhorses?

mark

Hey Mark....will takes pics of everything when I get to it. I'm rebuilding a work truck transmission and clutch at the moment. Also trying to reconcile the notoriously bad motor that drives the capstan flywheel for a Tandberg 10XD reel to reel.  The little Hall effect motor they used is giving me fits. The Advents will come after that.  

I probably won't punch out the crossover plates then....I think one of the woofer sets has the wrong surrounds.  Classic case of someone  selling surrounds that weren't correct for the OLA's.

Does anyone have a good source for the correct surrounds on the Masonite woofers?

 

Kevin

[JKent]

Many people recommend Rick Cobb https://www.ebay.com/str/looneytune2001

[real1shepherd]

Thanks for the link. I'll probably buy a set and compare to what's on there. I'm pretty sure what's on there is wrong for one set, but the other set is OK....been too long to remember that stuff.

 

I use Boston Acoustics's T-1030 for my reference set now. I have one woofer that makes a mechanical BLAAAAT sound @high volume. Thanks to a forum member here,  there's a guy that will repair the voice coil. Simply Speakers determined the voice coil was the problem, but couldn't fix it. They wanted to throw it away....I said NO....sure there was someone redoing voice coils out there and indeed there was.

 

I got lucky on my second set of OLA's. They must not be that far apart in their production scheme of things, as they both have the fiberglass batting and the Masonite woofers. They actually look identical inside. Can't speak for the xo's because I don't remember comparing. For yrs I remember everyone talking about that 'foam' they used and had no idea what they were talking about until I saw a pic....LOL.

Kevin

[ra.ra]

Looking over previous posts, I realize I should've worded my comments differently - - - there was no intention to ruffle any feathers - - - my aim was not to tsk-tsk the OP, but to alert future users of the dangerous combination of unfused speakers at high volume levels with this type of program material. I still doubt that the amplifier was the problem here.

On a pair of Smaller Advents I restored last year, I removed the crossover panels to facilitate the installation of new caps and wiring. Like Guido has already noted, these 1/8" Masonite panels are typically installed with both glue and staples. After carefully removing all staples and cutting thru any exposed glue residue, I was able to easily push these free with a light tap-tap-tap from the backside using a block of wood to cover as much of panel area as possible. When re-installing, I used compressible foam strips for the air seal and small machine screws/washers for attachment.

  

[real1shepherd]

Lol....of course that high power Chinese brute amp smoked the Advents. Every single xo switch would burn the flesh off your fingers, they were so hot. A combination of the synthesizer used to make techno and house music dynamics along with all that power just fried things. There was never a problem with the Onkyo amp other than clipping it @110watts RMS/channel with the exact same music.

Let's not go another round with the fuses advice, as I'm the one that brought them up in the first place. As I said, the speaker wires with the fuse blocks had been misplaced and there wasn't time to rig new ones.  I took a chance as we often do in life and I lost.

Let's try to figure out the damage now and move forward, thank you.

I'll see if I can work through the woofer hole, but my hands are pretty big. I like Marks advice of maybe making another board and attaching it to the existing one....maybe with some grommets on each corner with a screw through the middle. I also don't know if I can get the return on my investment/ears by using all those fancy components Kent pictured. They look fantastic....but the tweeter upgrade I did probably did more. They sure sounded a lot sweeter on the top end.

 

Kevin

[JKent]

3 hours ago, real1shepherd said:

I also don't know if I can get the return on my investment/ears by using all those fancy components Kent pictured. They look fantastic....but the tweeter upgrade I did probably did more. They sure sounded a lot sweeter on the top end.

Agreed. You had talked about upgrading the crossovers so I went into Pete's recommendations. But the inductor coils should be OK. As long as you have continuity that's all that's needed. Likewise the resistors. Look for signs of burning and if they look OK they're OK. I would recommend replacing the capacitors. One 8uF and one 16uF mylar cap per cabinet will cost under 10 bucks plus shipping.

http://www.erseaudio.com/Products/PEx250v/MET25-05-3-00

http://www.erseaudio.com/Products/PEx250v/MET25-05-16-0

http://www.erseaudio.com/Products/PEx250v/8uF-250-volt-Metallized-Polyester-Mylar-Film-Capacitor

[Pete B]

If you are up for it the Econowave Mod makes a lot of sense for your application.  You

could use one waveguide tweeter with two woofers.  I can explain it if you are interested.

https://audiokarma.org/forums/index.php?threads/zilchs-ak-design-collaborative-econowave-speaker.150939/

If you don't want to do that, then the first question is what revision of the OLA are your

speakers?  The first revision with the very light weight red dot inductors were known 

to have the wire burn up and possibly short out.  There was a tech note from Advent

about measuring the DCR of the inductor when replacing tweeters.  I would just replace

the tweeter inductors with 18 or 20 ga air core if you have the dot type inductors.

Some of the tweeter resistors are near the switch and they were probably the source

of heat.

I've been writing this assuming you want to use them as PA speakers, are the Peavy s good 

enough so that the Advents are going back to home use?  I'll bet that the Advents had 

better bass.

 

[JKent]

Glad you chimed in Pete. As I understand it, the Peaveys will remain for the "rave" and the Advents will be home speakers, so we're looking at a restoration (although I should let Kevin speak for himself). Good point about that red dot tweeter inductor. I had forgotten how frail they are. So Kevin could replace just those if they got fried.

Kevin--check whether your xo uses 16, 8, 4uF; 16, 16, 3uF or 16, 8, 4uF capacitors (so don't order the ones I suggested unless they match) and check Pete's site for what the DCR of the little coil should be.

[real1shepherd]

1 hour ago, Pete B said:

If you are up for it the Econowave Mod makes a lot of sense for your application.  You

could use one waveguide tweeter with two woofers.  I can explain it if you are interested.

https://audiokarma.org/forums/index.php?threads/zilchs-ak-design-collaborative-econowave-speaker.150939/

If you don't want to do that, then the first question is what revision of the OLA are your

speakers?  The first revision with the very light weight red dot inductors were known 

to have the wire burn up and possibly short out.  There was a tech note from Advent

about measuring the DCR of the inductor when replacing tweeters.  I would just replace

the tweeter inductors with 18 or 20 ga air core if you have the dot type inductors.

Some of the tweeter resistors are near the switch and they were probably the source

of heat.

I've been writing this assuming you want to use them as PA speakers, are the Peavy s good 

enough so that the Advents are going back to home use?  I'll bet that the Advents had 

better bass.

 

Thanks for chiming in, Pete. I think for the OLA's probably just replace the caps and anything not to spec and/or fried. No, these will never leave the house environ if I get them working again.  

Yes, the Double Advent system kicked the Peavey's butt in bass....but only for an hr until meltdown. The Peavey's have a very directional horn for the highs.....it is what it is.....the kids love them and they're great for a PA system.....not for a house room. They have a lot to be desired but they are LOUD and they take the amp's power without a complaint.

The youth group I helped found about 12 yrs ago. It's now under the umbrella of a regular children's center. They did buy the Peaveys, but I bought the stands, the cables and the Chinese amp.  And I furnish a sort of Rube Goldberg laser light show with disco ball. There's a YouTube vid of the Peaveys with a great light show fastened to their bottoms, syncopated with the music. 

I honestly don't have the time to push the Advents to some newer dynamic never heard before by me. I think it's great Pete, that you have taken them as far as you have.  But I'm quite happy with the BA T-1030's for my main speakers. I don't know what I'd do with the Advents if i took them to the next level. So......I think I'll just bring them back to the level they were before the meltdown. Now if the tweeters are all fried....maybe I'll go for something more. 

 

46 minutes ago, JKent said:

Glad you chimed in Pete. As I understand it, the Peaveys will remain for the "rave" and the Advents will be home speakers, so we're looking at a restoration (although I should let Kevin speak for himself). Good point about that red dot tweeter inductor. I had forgotten how frail they are. So Kevin could replace just those if they got fried.

Kevin--check whether your xo uses 16, 8, 4uF; 16, 16, 3uF or 16, 8, 4uF capacitors (so don't order the ones I suggested unless they match) and check Pete's site for what the DCR of the little coil should be.

 

Will do Kent. I'll take some pics once I get inside, thanks.

 

Kevin

[Doug G.]

Just for reference, it should not be all black when you get inside.

Doug