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Thread: Bang and Olufsen Icepower tech support?

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    Bang and Olufsen Icepower tech support?

    Anyone know if B&O will give tech support on their Icepower products? I have a 700asc/x in my Ashdown Retroglide 800 that goes into protect mode because of Zobel network oscillation but only with some speakers. The website for the Icepower division doesn't have any contact info for tech support, and only contact for sales outside of Denmark. I'll probably give the Americas sales office a call tomorrow and ask, just wondering if anyone has any experience.

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    Lifetime Member Enzo's Avatar
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    Seems if I recall properly, some amplifier OEMs who use the ICE units do not even get schematics and documentation. As far as I know they intend the boards to be replaced like a part.

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    Add to or mess with the values on the Zobel. Can't hurt, can it?

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    Amazing!! Who would ever have guessed that someone who villified the evil rich people would begin happily accepting their millions in speaking fees!

    Oh, wait! That sounds familiar, somehow.

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    Quote Originally Posted by R.G. View Post
    Add to or mess with the values on the Zobel. Can't hurt, can it?
    If I can't get any support that is what I will do. Looks like this board may have been early development, there is quite a bit of hand rework around the class D driver ICs, and there are already two big caps that have been added in parallel to the originals in the Zobel network. Want to find out if they have figured out a better zobel recipe or if this is problematic early production maybe they will replace it with a newer model that is more stable at something less than full retail cost.

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    Master Destroyer nosaj's Avatar
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    Quote Originally Posted by glebert View Post
    If I can't get any support that is what I will do. Looks like this board may have been early development, there is quite a bit of hand rework around the class D driver ICs, and there are already two big caps that have been added in parallel to the originals in the Zobel network. Want to find out if they have figured out a better zobel recipe or if this is problematic early production maybe they will replace it with a newer model that is more stable at something less than full retail cost.
    I would check with AShdown first. The rework you are talking about could be their handiwork for the speakers they included with the amp.
    nosaj

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    Quote Originally Posted by nosaj View Post
    I would check with AShdown first. The rework you are talking about could be their handiwork for the speakers they included with the amp.
    nosaj
    I guess it is possible that they would have reworked, but it didn't seem like there was ever a specific cabinet associated with this head (Retroglide 800). Maybe Ashdown can at least confirm if there were any issues with this head, but it seems like it was pretty short lived and low production.

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    Master Destroyer nosaj's Avatar
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    Quote Originally Posted by glebert View Post
    I guess it is possible that they would have reworked, but it didn't seem like there was ever a specific cabinet associated with this head (Retroglide 800). Maybe Ashdown can at least confirm if there were any issues with this head, but it seems like it was pretty short lived and low production.
    Well they had to test the head with something. Sometimes short lived and low production is just turning away from a bad design.

    nosaj

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    Old Timer tedmich's Avatar
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    from the board's manual
    Click image for larger version. 

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    here
    seems like this is a bit of their secret sauce, but they imply a symmetric circuit, what values do you have?

    Is it the powered board AS1 right?

    Any trend on speakers what "don't" vs do work?
    These amps can be very touchy on outputs they aren't "power anything" IME.

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    Quote Originally Posted by tedmich View Post
    here
    seems like this is a bit of their secret sauce, but they imply a symmetric circuit, what values do you have?

    Is it the powered board AS1 right?

    Any trend on speakers what "don't" vs do work?
    These amps can be very touchy on outputs they aren't "power anything" IME.
    Looks like the top side "stock" cap values are .68 and .1uF, resistors look like 3.3 ohm (?). The back side added caps (in parallel to the .68uF) are 1uF. Check my values, I have gotten too used to just reading off a schematic.

    I don't know what the AS1 powered board means, this board has the smps from the mains and the class D sections.

    Don't see much of a trend on what works and what doesn't. A little 6" 10 watt 8 ohm speaker is fine, my SWR Jr. 2x10 4 ohm is fine, 12" Peavey Scorpion Ultra is fine, but a Boss Chaos 15" speaker or some cheap PA speakers send it to protection (there was another bass cab I had that did it too, maybe a Fender Rumble 410). I am measuring 50Vpp at about 62kHz (which is about half of the class D switching freq) probing on the big red caps when it is protect mode, nothing there when it is not in protect.

    Someone on MEF had given me a contact at Ashdown to try, I emailed him and will see if he has any info on this.

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    Last edited by glebert; 07-29-2019 at 07:05 AM.

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    Old Timer J M Fahey's Avatar
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    The Zobel is "symmetrical" because itīs a bridged amp, so each half needs its own.

    Modding just one half but not the other will not work.

    In any case, try to make it work with the customerīs cabinet and leave it there.

    As Enzo says, "we are here to repair, not to reengineer".

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    Last edited by J M Fahey; 07-30-2019 at 02:51 AM.
    Juan Manuel Fahey

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    Quote Originally Posted by J M Fahey View Post
    In any vase, try to meka it work with the customerīs cabinet and leave it there.
    Ay, this customer is a real PITA (hint, it's me )

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    Old Timer J M Fahey's Avatar
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    Don't see much of a trend on what works and what doesn't.
    Well, I do
    A little 6" 10 watt 8 ohm speaker is fine, my SWR Jr. 2x10 4 ohm is fine, 12" Peavey Scorpion Ultra is fine,
    Those are all *speakers* .


    but a Boss Chaos 15" speaker
    that is just car audio crap.

    Do you REALLY expect a serious amp to drive that?
    * Impedance will probably drop below 1 ohm at some frequencies to win car SPL competitions.
    * half pound copper voice coil inductance will be high enough to filter a Twin Reverb power supply.
    * dynamic energy accumulated in that high Q (to win car SPL competitions) voice coil + *heavy* cone must send back flyback pulses high enough to electrocute a mouse.

    Your amp entering Protection is its way of crying FOUL!!!!!

    or some cheap PA speakers
    those with 7 piezos in parallel?

    Just use a real speaker and all will be fine.

    And donīt waste time solving a problem which does not exist.

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    Juan Manuel Fahey

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    'Tis a silly speaker indeed. 2 ohm if you parallel the voice coils. Resonant frequency an idiotic 26Hz. The unimpressive 86dB sensitivity is telling. The gap must be 3/4"+ to accommodate 2 voice coils wound of romex.

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    Master Destroyer nosaj's Avatar
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    Quote Originally Posted by The Dude View Post
    'Tis a silly speaker indeed. 2 ohm if you parallel the voice coils. Resonant frequency an idiotic 26Hz. The unimpressive 86dB sensitivity is telling. The gap must be 3/4"+ to accommodate 2 voice coils wound of romex.
    So the final synopsis is that USE guitar speakers and not anything else an you'll be ok.

    nosaj

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    Supporting Member The Dude's Avatar
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    ...... or a REASONABLE bass speaker.

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    Got a reply back from Ashdown, he said that the added caps were done after if left the factory, as neither they nor B&O have done any mods on this module, and that they have had no problems with it at all. He suspects that someone blew the module and did a home repair on it and then had to add the caps to get it stable. There are no schematics available to see if the FETs match up with design, there definitely has been rework around the class D driver chips. His thought is that the module will have to be replaced. I think I may give it a bit of a torture test with a resistive load, and then just use it as a practice amp with an expendable bass cab. I'll be curious to see what kind of power I can get out of it into a resistive load, it has always felt a bit weak-kneed to me.

    Thanks for inputs.

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    Old Timer J M Fahey's Avatar
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    Cool.
    Please measure it, the old way, which matches "our" PA/Stage use.

    I read Class D amp datasheets end to end and most say something like:
    "500W RMS 1% distortion" ... cool.

    "After 30 seconds 400W RMS"

    After 5 minutes it may self turn off for thermal reasons

    **Continuous** power available: 275W .
    WTF?

    As of the disposable speaker: no need to if you add a DC protection board with a relay or at least a TRIAC crowbar , Peavey style, between power module and speaker out terminals.

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    Juan Manuel Fahey

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    As an update, I ran this into my space heater load (10 ohm) and was able to maintain 50 vrms clean, maybe 53 at the onset of clipping, so it can put out full amplitude at some load (I haven't gotten around to making a second load to get down to 5 ohm). I ran a few different sine wave freqs and no stability issues or drop in power. I had it at that level for at least 5 minutes. Seems like it will be good enough for my use, as long as I am careful with my load and avoid cheap speakers.

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    Old Timer J M Fahey's Avatar
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    Cheap by itself is not the problem; but weird impedance is.

    B&O, Ashdown, all other users are not fools and must have extensively tested the modules with all kinds of reasonable speakers.

    Just guessing, but problem seems to be weird impedance, which must trigger all kinds of protections.

    In any case, copy the Peavey Triac crowbar, cheap and simple.

    Just thinking aloud, but since that is a bridged output amp and the crowbar does not really need reference to ground, I bet you can wire it "floating" across the speaker, so "just one" protects speaker from DC across terminals, no matter where that comes from, including two amplifiers driving it.

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    Juan Manuel Fahey

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    Was working on my latest class D bass amp, an Acoustic BN6210, and noticed that there was a small circuit board before the piezo tweeter. I did not verify if the amp module was B&O, but it looked very similar to their 500W Icepower module. I am guessing this board is to keep the class D amp from seeing the impedance of the piezo, which I think looks mostly like a capacitor. The Icepower module does have a capacitive load spec. I hadn't paid much attention to it since it said "purely capacitive" but maybe that means something different in German.

    I think this would support Juan's assertion that cheap speakers with multiple piezo tweeters are inappropriate for class D amps. BTW, those speakers have been sent off to the thrift store in hopes of frustrating some garage band's dreams of stardom.

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    Last edited by glebert; 08-07-2019 at 01:50 AM.

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    Old Timer J M Fahey's Avatar
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    Thanks.
    Piezo being capacitive, typically .1 or .22uF and sometimes up to.35uF (depending on piezo disk diameter) and even worse in cheapie multi piezo PA/DJ cabs, I have seen some with 2 "midrange horns" and 5 round Tweeters ... all in parallel, just do the Math, they can make a MESS with Impedance.

    Doubly so with Class D amps which even without signal in have a full rail to rail signal out at switching frequency ... anything from 33kHz to 500kHz ...... a perfect storm

    So cheapest solution is to add a series resistor, most common value being 47 ohm ... I see 3 of them there plus a toroidal inductor and 2 caps.

    If you still have it outside, please add a copper side picture so I try to draw the schematic; if not, donīt worry.

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    Quote Originally Posted by J M Fahey View Post

    If you still have it outside, please add a copper side picture so I try to draw the schematic; if not, donīt worry.
    flipped around horizontal axis, so inductor still towards the left.

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    Thanks

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    Juan Manuel Fahey

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    BTW, the one cap you can see is labeled as .47u the other two are .33u.

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