Ohm Walsh Micro Talls: who's actually heard 'em?

10:1 is based on reasonable power loss across the preamp output: the pream-amp circuit is a power divider. At 10:1 preamp to amp impedance only about 10% of the voltage signal is "wasted" in the preamp output stage. However, no preamp has a perfectly falt output impedance across the audible frequency range. The 10:1 should be applied to the peak output impedance of the preamp, not the manufacturer's stated nominal impedance. Impedance mismatch is a predictable source of coloration. The preamp is a voltage source that prefers to see an infinite impedance so that it is not loaded down which results in voltage sags and distortion.

The best SS amps use FETs for differential input stage for this reason.

BTW: My Walsh 5 Mk IIIs will be going back to Ohm for repairs on one driver. I spoke to John and decided to upgrade to the Walsh 5000. John says the improvement in sound will be "evolutionary," and they have double the peak power handling and go a little lower. I'll take any improvement I can get with these most fantastic loudspeakers.

Everybody,

Thanks for the advice. There's a Manley Shrimp up on A'gon right now. A little pricier than I'd like (and no remote) but output impedance is only 50K ohms, so I'm seriously considering it.

Fascinating discussion, by the way. I've learned a ton from you guys!

"output impedance is only 50K"

You meant 50 ohm, I assume, right Rebbi?

Mamboni,

You are using the 500w/ch Wyred4Sound amp these days I think I recall?

How do you like it?

Any chance this is too much power for the 5s resulting in the driver damage you report?

The 500w/ch Wyred is probably the most powerful amp option out there that I have considered and I'm wondering if it is overkill, and 250w/ch or so is plenty.

Mapman said:
You are using the 500w/ch Wyred4Sound amp these days I think I recall?

How do you like it?

Any chance this is too much power for the 5s resulting in the driver damage you report?

The 500w/ch Wyred is probably the most powerful amp option out there that I have considered and I'm wondering if it is overkill, and 250w/ch or so is plenty.

Yes, I am using the Wyred4Sound St-1000 which is nominal 550W/ch into 8 ohms. These amps are the first to really take hold of the power-hungry Walsh 5's and put them through their paces. The Walsh 5's have peak power in excess of 500W so I do not think this is too much power. I certainly am careful not to overdrive them. However, I have played full orchestral works with organ where there are rare 95-100 db peaks. But the average sound level is typically 75 db and typical peaks around 95 db.

The problem is in the left channel head unit. The woofer and tweeter sound perfectly fine, so this is not a case of fried driver or damaged voice coil per se. There is a buzz coming out of the speaker, centered around 1-2 khz I'd estimate, that occurs intermittently and is hightly frequency dependent. The following source materials evince this buzz, which sounds like a resonance:

1. Piano - only some recordings and at one keyboard note
2. female soprano voice on some recordings
3. french horns and trombones playing around concert Bb (horn's F at the top of the staff)
4. some organ recordings

My guess is that is is a loose soldier joint, board component or even a loose screw or plug - that's what the buzz reminds me of. I don't abuse my Walshs but they do get a lot of use. I log easily 3-4 hours listening per day; on weekends that might be 6 hours. And I lean towards full orchestral and organ recordings, so the Walshs get a workout. I've owned Ohm loudspeaker for many years and they are true workhorses - well engineered to operate trouble-free in the field. But after several thousands of hours of being subjected to vibrations, something is bound to loosen.

I'm compiling a CD with various tracks that evince the "buzz" so John at Ohm can hoepfully identify the fault.

BTW: I spent several weeks doing inventory on my listening, moving and removing any object which might be resonating and the source of the buzz - to no avail. I am fairly certain it is coming from the driver head unit.

I discovered the problem several weeks ago when I was driving the Walshs with my Sumo Andromeda II amps (240W/ch into 8 ohms). When I described the problem to John at the time he suggested that the amp might be clipping - he informed me that the power peaks on piano strikes and female soprano can be wicked, even at moderate listening levels. Nevertheless, the problem is virtually the same with the much more powerful ST-1000, so I don't think clipping is the problem. And I never had this problem with my original (classic) Walsh 5's.