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x250.5 - meter going full scale - whaaaaat ?
x250.5 - meter going full scale - whaaaaat ?
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Old 20th September 2018, 05:02 AM   #1
Old'n'Cranky is offline Old'n'Cranky  Australia
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Default x250.5 - meter going full scale - whaaaaat ?

Friend of mine has an x250.5
He recently got some second hand ribbon speakers.
We believe they are faulty as the gauge on the amp is going almost full scale while trying to get 'reasonable' volume from them.
He has no issues with any of his other speakers.

He also has a parasound A21 that goes into protection well before what the x250.5 can deliver.

So, question is, just how much power / current is being generated by the amp to get that needle right up near the end of the scale ?
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Old 20th September 2018, 03:25 PM   #2
vdi_nenna is offline vdi_nenna  United States
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x250.5 - meter going full scale - whaaaaat ? Send a message via Yahoo to vdi_nenna
I'm curious. Have you tried to measure resistance of the ribbon speakers while not connected to the amp? How about measuring from the speaker cable disconnected from the amp?
What is the brand of the ribbon speaker?
I've seen Parasound mono-blocks go into protection with 7" tall ESLs.
Not fun.

Have you measured the AC at the amp's output posts?
Be careful. I imaging what your are seeing is dangerously high voltage and current.


X250 SPECIFICATIONS
All figures obtained after 1 hour warm up, with regulated 120 VAC power line. See manual notes about AC power line regulation.

Power Output 250 watts maximum @ 1% THD, 1 kHz, 8 ohms

Maximum Output Voltage plus, minus 65 volts

Maximum Output Current plus, minus 20 amps

Power Consumption 270 watts idle, 1200 watts maximum
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Last edited by vdi_nenna; 20th September 2018 at 03:27 PM.
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Old 20th September 2018, 05:17 PM   #3
Nelson Pass is offline Nelson Pass  United States
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x250.5 - meter going full scale - whaaaaat ?
High current. Either because the ribbons have very low impedance,
or because there is a short in the wiring somewhere.

Probably this is not the right amplifier for very low impedance ribbons.

XA60.8 is probably best for that.
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Old 21st September 2018, 01:48 AM   #4
Old'n'Cranky is offline Old'n'Cranky  Australia
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Friend has limited tools and skills
And I'm too far away to drop everything and go there often..

Speakers are (second hand) Ambience 1800 Reference

Sensitivity. 96dB @ 1metre, 2.83volts input.
Power handling 150 watts RMS (long term)
Crimped metal ribbon type.
Twin 180mm SEAS woofers, custom made
specifically for Ambience loudspeakers.
Rear ported bass reflex design.
Nominal impedance 4 ohms.
Crossover 3rd order @ 420Hz
Minimum amplifier power 10 watts RMS/channel.
Ideal Amplifier power 30-70 watts RMS/channel.
* Specifications subject to change without notice


He has more gear than rooms.
Hes aiming to use the x250 in the main room with his normal passive speakers.
In this task it works reeeeally nicely

He then bought the ribbons to be powered by the parasound in another room.
When he tries to get "decent volume" the parasound goes into protect.

So his first thought is, lets plug them into the x250.
No comment.............

Hes been in touch with Ambience and they are going to walk him through narrowing down the exact issue.
They believe (as do I) that one or both panels are shorting.

I like the fact that the x250 still managed to drive them
Long term I wouldn't place bets though...
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Old 21st September 2018, 05:18 PM   #5
Nelson Pass is offline Nelson Pass  United States
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x250.5 - meter going full scale - whaaaaat ?
It's probably only one of the panels. If you run it with one speaker at
a time, then you can isolate the speaker that might have a short.
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Old 21st September 2018, 10:46 PM   #6
Old'n'Cranky is offline Old'n'Cranky  Australia
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My thoughts exactly.
I did mean to suggest that to him, but we've both been busy with other things.
At least I know I tend to forget things when busy and stressed.

Only real issue is, until you get the full story, then your chasing geese
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Old Yesterday, 11:58 AM   #7
Old'n'Cranky is offline Old'n'Cranky  Australia
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Update.
I have the speakers here at last.
The crossover can be bi-wired, makes for easy testing.

The panel section on both are perfect. A nice even 4ish ohms across their range.

The bass sections on both have been over driven for a looooooong time.
Both bass systems when swept with dats drop to 0.1ohm around 4khz.
The primary inductor (3rd order crossover) for the bass section on both speakers are no longer inductors.
More like crispy lumps of metal.
My LCR meter and the dats system refuse to even recognise them as inductors

Even though their long out of warranty the manufacturer has very generously offered to rebuild both crossovers with all the latest updates as well.

Some companies really do care about after sales service.
Helps to somewhat restore your faith in humanity.
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Old Yesterday, 05:52 PM   #8
Nelson Pass is offline Nelson Pass  United States
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x250.5 - meter going full scale - whaaaaat ?
Quote:
Originally Posted by Old'n'Cranky View Post
Some companies really do care about after sales service.
Helps to somewhat restore your faith in humanity.
It is my experience that those companies tend to stay in business.

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Old Yesterday, 07:59 PM   #9
Bfpca is offline Bfpca  Canada
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x250.5 - meter going full scale - whaaaaat ?
It’s a tribute to the toughness of the X250 that it could drive that load. The way you describe that inductor it sounds like there may have been DC put on it at some point. I can’t imagine how much music power on average it would take to burn up an inductor like that. I can’t imagine it would sound very nice while smouldering and smoking either.
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Old Today, 12:43 AM   #10
Old'n'Cranky is offline Old'n'Cranky  Australia
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In no particular order;

Pass labs and Ambience seem to be willing to go WELL beyond realistic levels for customer service.
I know a guy with a newish PL amp, and lets just say, I am astounded by what is being done by Kent to sort this guy out.
Um, That's in a good way that is

There are others, but this isn't a 'who is who' post

The inductor in question is held to the board with cable ties, they have melted through.
There's also a wire running past them, these have had their insulation melted through completely and are showing a good 3+mm of bare copper.

Note that all the inductors are good air core ones that are very well wound.
Nice and square, even, uniform winding.
Now have a closer look at the pics attached........
And no, thats not glue you can see on the inductor. It's melted wire enamel.

I would suspect that a previous owner may have been bi-amping, and either pushing the life out of the bass system, or had a faulty amp delivering some level of continuous dc.
Attached Images
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File Type: jpg 10.jpg (472.0 KB, 5 views)
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