We just used one of these for the 1st time (3160 model) and it has zapped 2 Episode amplifiers. When hooking up a multimeter, it is displaying 2 ohms. It is a 4 ohm speaker but that seems very low and might explain why it has killed 2 amplifiers.

Anyone know if that reading seems abnormal? I don't have another unit to test at the moment.

Thanks in advance

I’m not sure if this is exactly the speaker that you are using. Down the page are some impedance graphs. Personally, I’d like to see the speaker rated at less than 4-Ohms.

[Link: erinsaudiocorner.com]

I've never used an Episode amplifier.

Note that multi meters won't give you as accurate a reading of a loudspeakers impedance as an impedance bridge.

I'd recommend going to an amplifier like the KEF Kasa500, or an amplifier along the lines of something from Crown, or LEA, or QSC that's specifically made to drive difficult loads.

Your meter only measures DC resistance, which is always lower than the nominal impedance. I would want to know the crossover and level settings for the amplifiers, ventilation, how many pieces of equipment were powered by the circuit, etc. We don't really have enough info to work with. Which Episode amplifiers?

Is there a specific reason the Kasa500 amplifier wasn't used? Snap AV carries that, too.

If you followed my link above, you’ll notice that the magnitude of the impedance varies with frequency. A DC ohmmeter cannot measure this.

By the way, we talk about the “magnitude” of the impedance because we could replace our mystery box with a resistor of that value and dissipate the same amount of power — but only at that specific frequency.

This is a situation where a client moved into a home with existing gear. We had never had issues with 4 ohm loads with other in-wall installs so we tried the Episode.

I've had many times where 4 ohm speakers test at 3.2-3.5 but 2 ohms seems too low. Before I throw a KASA on it, I want to try to test another 3160 to see if it also shows something in the 2 ohm range as I don't want to blow it up as well.

This is a scenario with:

Plenty of ventilation.
DSP: I think we set it to flat with frequency adjustments as the stock DSPs on the Episode offerings are limited and don't match a 3 X 6.5" set-up. I'd have to check with the guys.

Thanks for the feedback

NO!!!

There is a VERY distinct reason why many (not just KEF) speaker manufacture have "paired" subwoofer amplifiers to match to their in-wall subwoofer products. Many of these amps have custom EQ & Filter settings for the matched drivers - such as subsonic filters at certain frequencies, which not only are needed for the sound quality but also to keep an amp from trying to drive a woofer in a region it might dip very low in impedance at. Also custom EQ notches for flat in-room response.

It says very boldly in the KEF Ci3160RLB-THX manual = "...must be matched with KEF's powerful KASA500 system amplifier."

Read "MUST" not recommended! There are also several DIP switches on the back that have to be set for this very particular setup.

Put the proper amp in!!!

And no, 2Ω isn't a crazy reading to get on a DMM (DC reading) for a 4Ω woofer. Depending on the type, a range from 2Ω to 6Ω is possible. With most being in the 3Ω to 4Ω range.

Still need to know which Episode amplifiers were used.

Were the Episode amplifiers in bridged/mono mode? If so, it's likely that the failures were caused by low impedance, since the bridged amplifier will react to the impedance as if it's 1/2 of the real value.

Hopefully, the amps weren't the EA-DYN-2D-200 because the spec sheet shows "Bridged Power Output, All Channels Driven- N/A" and the EA-RSP-2D-200 spec sheet shows "Minimum impedence- 1 ohm for this one and 2 Ohms for the other multi-channel amps, but there's nothing about Stereo or Bridged Mono mode. Tech support confirmed that the spec sheet should have made this distinction and that none of these amplifiers should be driving a 4 Ohm load.

They were the 500 watt version (SUB-1D-500R) and not bridged. There was only 1 sub and it was hooked up in the correct location (SUB1 vs SUB2).

Brad,

If I can get my hands on another 3160 and test it and it comes in at 2 ohms, we'll pop a KASA in there. I appreciate the info.

On a side note, I like many of you have been installing these way before DSP amps came to the market. In the past, you could use virtually any amp with any subwoofer as long as you set frequencies where it made sense.

I understand the concept of DSP amps and why they are touted. However, speakers are speakers and haven't changed over the years. Why would DSP amps be so crucial now when they weren't in the past?

We had to deal with product shortages during Covid and used mismatched amps on a number of occasions. We have replaced amplifiers for existing in-wall solutions that weren't matching many times over the years. I understand the theory of DSPs and how they can optimize sound but is there any science to the claimed concept of "you must use our amplifier"?

It's not the DSP that matters, it's the amp design and this one isn't the cleanest I have seen, although that's academic in most situations, but I also haven't seen many amplifiers that can actually double the power with half of the impedance, either. They don't state minimum impedance and this should be shown.

The KEF sub has three woofers, so they're either having the voice coils wound to their spec in order to achieve 4 Ohm impedance, or they dip below what most amps can handle/design their amp to handle it. It wouldn't be unimaginable if they stuck a 1 Ohm resistor in series, either- Carver did that in their amps that were sold as 'sound more tube-like', IIRC.

This sub is made for in-wall use- not how I would prefer to use a sub, but with the DSP, it can be made to work with the goofy impacts a stud cavity can cause.

“I understand the theory of DSPs and how they can optimize sound but is there any science to the claimed concept of "you must use our amplifier"?”


Bose?

Bang Olufsen?

JBL Synthesis?

?

My take on it is that anytime the speaker designer knows the amplifier designer, you're going to get a better match.

I ended up getting my hands on a 2nd 3160...2 ohms! This was a good learning process. I'll definitely match up the manufacturer's amp next time.

Thanks for the feedback.

2.0 Ohms or somewhere between 2 and 3 Ohms? Using a multimeter to measure resistance of many 8 Ohm speakers will show about 6.7 Ohms, but again, that's DC resistance, not impedance- however, it's pretty typical.

Both of them were 2.0 ohms.