[titaniumheads]

So I Bi-amped my Elixers and used a Micro Zotl as the Pre-amp. It has a big turn on thump if you dont turn it on before the amps. So now my tweeters are not working in both speakers. I read there are no fuses and I also believe the tweeters are ok but just not getting a signal. Any ideas? The mids and woofers are fine.

[HAL]

The ribbon tweeters do not like transients.  Take a close look at the elements and see if they have changed.

If the ribbon elements have been damaged, replacements for them might be available from Parts-Express. 

[titaniumheads]

The ribbons seem fine, the tweeters are not getting a signal. I checked them and they ohm out ok and when I connected a different tweeter I know works there was no sound from it.

[Evoke]

The ribbons seem fine, the tweeters are not getting a signal. I checked them and they ohm out ok and when I connected a different tweeter I know works there was no sound from it.

If you have connected an audio signal directly to the tweeters and they work, it may be the L-Pads. Turn them back and forth a bunch of times. If you get sound at different levels, and/or it sounds scratchy, it is the L-Pads. There are 2 fixes. Get some circuit board or "pot" cleaner and spray them clean while turning them back and forth. The other thing to do is to replace the L-Pad. While you're at it, double check the ribbons in the tweeter to make sure they are fully intact without tears, stretching etc.


I have spare RMX tweeters if you need. Be advised that I suggest you only buy them in pairs so speakers match. Private me if you need,.


Hope this helps,
Mark

[John Casler]

All good advice and suggestions.

Take a flashlight and examine the ribbon for rips, tears, sag, or completely detached.

Could be the L-Pad, as Mark suggested, in which case you might hear the tweeter cut in and out over burned and non-burned sections.



Good luck

[ZAKski288]

Hello Titaniumheads, I would check the tweeter crossovers (capacitors) if everything else checks out.  I had a friend that he just noticed that his tweeters weren't playing any more. In his case one capacitor was burnt. Good Luck Zak

[Stimpy]

I second checking the capacitors.  The capacitors can take a beating, especially with Brian's 1st Order crossover design.  Even more so, if the owner likes loud, realistic playback levels.

Oh yea, amps get turned on last, turned off first!  Always!  Otherwise, you can pass damaging transient spikes through to the speakers!  Ribbons don't like transients.   

[srb]

Oh yea, amps get turned on last, turned off first!  Always!  Otherwise, you can pass damaging transiant spikes through to the speakers!  Ribbons don't like transients.

Preamplifiers and amplifiers without muting relays are lacking in design IMO.  Shit happens.

[audiomagnate]

If the tweeters are dead and the ribbons aren't open then it is most likely the transformers inside the tweeters. I agree with srb that a preamp that can wipe out your speakers with a turn on transient is a crappy design. With all due respect EVOKE, if it is the tweeters I would be EXTREMELY surprised if it turned out they weren't off the shelf unmatched Aurum Cantus ribbons available from Parts Express, where Brian bought most of his stuff. I've worked on and torn apart my fair share of VMPS speakers and subs and crossovers and never saw any evidence of precision matching (despite the literature) of anything. To anyone who has worked on VMPS speakers, "precision" is not the first word that comes to mind. I've measured significant variations in supposedly matched crossover components. If it's the L-Pad I would be shocked if it isn't an off the shelf inexpensive unit from PE as well.

Don't get me wrong, I love my VMPS speakers and have nothing but respect for Brian (whom I knew from support calls) and his achievements, but there was huge amount of BS the literature.

[titaniumheads]

I am driving the mids and tweeters with a tube amp and the woofers with a solid state amp. The ribbons are completely intact and I did the 1.5 volt battery test and they make a popping sound. I will have more time to investigate this weekend after I get 2 men and a gorilla to help me lay them on their side.

[titaniumheads]

I am thinking of possibly converting these to active with Hals dspMusak if I cannot find out what is wrong. The capacitor for the tweeter Meters out fine. The tweeter when connected to another speaker works , just not when connected to the VMPS speaker. I replaced the L pads with new ones. The mids and woofers work as normal. Stuck in mud.

[ZAKski288]

Can I ask what was your meter reading on your tweeter crossover capacitors? Also did you check the wire , with a meter (continuity test) from the L-pad to the top of the speaker  where the tweeter connects.            Good luck Zak

[James Romeyn]

RM/X tweeter is crossed high, around 6k IIRC.  IIRC Brian did not succumb to pressure to add LP crossover to the planar drivers till well after the RM/X, meaning RM/X planar mid extend quite high. 

To insure audible signal past the RM/X xo, I suggest warble tone approximately 10k @ low to moderate level.  The goal is to use a test signal that is audible past the tweeter xo.  You want to avoid using a music program with so little energy >6k that it's inaudible during your test.     

If you know tweeter X works, as it seems you confirmed, then connect tweeter test leads as close as possible to RM/X full range inputs (the above described test signal is OK full range to the tweeter at low/moderate level).  Then just continue by increasing steps, working farther from RM/X input and closer to the original wire terminals connected to the tweeter.  Somewhere along the line the signal fails, confirming the failed part(s). 

Considering the voltage values of the xo parts, it seems odd an input voltage spike could or would cause something to fail IFO and before the tweeter itself.  Me thinks something is amiss in Denmark!     

[fredgarvin]

If the tweeters are dead and the ribbons aren't open then it is most likely the transformers inside the tweeters. I agree with srb that a preamp that can wipe out your speakers with a turn on transient is a crappy design. With all due respect EVOKE, if it is the tweeters I would be EXTREMELY surprised if it turned out they weren't off the shelf unmatched Aurum Cantus ribbons available from Parts Express, where Brian bought most of his stuff. I've worked on and torn apart my fair share of VMPS speakers and subs and crossovers and never saw any evidence of precision matching (despite the literature) of anything. To anyone who has worked on VMPS speakers, "precision" is not the first word that comes to mind. I've measured significant variations in supposedly matched crossover components. If it's the L-Pad I would be shocked if it isn't an off the shelf inexpensive unit from PE as well.

Don't get me wrong, I love my VMPS speakers and have nothing but respect for Brian (whom I knew from support calls) and his achievements, but there was huge amount of BS the literature.

Nothing in this post is helpful to the op nor informative on the subject.

[HAL]

If you do decide to go fully active, I have a measurement system to send to measure the existing crossovers.  That will help diagnose the tweeter circuit problem.

It is a very simple process to measure the existing crossovers at the terminals of each driver section.  This will show if signal is getting through the crossover circuit in the tweeter section.

[titaniumheads]

So I finally discovered that it was my tweeter capacitor that was bad. When I had originally taken it out and checked it with a meter it tested good or so I thought. I went on to other areas looking for the problem. It wasn't until I jumpered where the capacitor had been when checking for the problem that I discovered the tweeter worked. I put in a temp capacitor of a higher value and it also worked so I ordered the correct capacitors and will install those this weekend. I also have two CSS APR 12 passive radiators that I am going to install in place of the original ones. They are on the bottom of the cabinet and come with 20-45 gram washers. Any idea on where to start with the amount of washers? The original passive only has a small amount of putty on it. maybe 10 grams or so.

[John Casler]

I also have two CSS APR 12 passive radiators that I am going to install in place of the original ones. They are on the bottom of the cabinet and come with 20-45 gram washers. Any idea on where to start with the amount of washers? The original passive only has a small amount of putty on it. maybe 10 grams or so.

I have used the "slightly modded" CSS 15" and 10" to a good result. but not the 12".

Keep in mind, that these PR's are far stiffer, and have more mass, than the lighter, more compliant VMPS PR's Brian actually made himself.

On the 15" PRs we used 3-5 washers to a good result, but you will need to experiment.

If a PR is "down firing" you use LESS washers, than if "side firing".

[Evoke]

So I finally discovered that it was my tweeter capacitor that was bad. When I had originally taken it out and checked it with a meter it tested good or so I thought. I went on to other areas looking for the problem. It wasn't until I jumpered where the capacitor had been when checking for the problem that I discovered the tweeter worked. I put in a temp capacitor of a higher value and it also worked so I ordered the correct capacitors and will install those this weekend. I also have two CSS APR 12 passive radiators that I am going to install in place of the original ones. They are on the bottom of the cabinet and come with 20-45 gram washers. Any idea on where to start with the amount of washers? The original passive only has a small amount of putty on it. maybe 10 grams or so.

I am so happy to read this post! Getting an answer like that must be a total relief to you. If you need any advice on caps let me know. I'm pretty familiar with that tweeter