Bang and Olufsen Icepower tech support?

[glebert]

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.

[Enzo]

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.

[R.G.]

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

[glebert]

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.

[nosaj]

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

[glebert]

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.

[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.

Well they had to test the head with something. Sometimes short lived and low production is just turning away from a bad design.

nosaj

[tedmich]

from the board's manual

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.

[glebert]

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.

[J M Fahey]

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".

[glebert]

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 )

[J M Fahey]

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.

[The Dude]

'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.

[nosaj]

'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

[The Dude]

...... or a REASONABLE bass speaker.