Ohm Walsh Micro Talls: who's actually heard 'em?
I’ll take the first stock Flat cheap tweeter I think. You also should do some off axis measures if that matters for you. I’d like to know how the folded ribbon compares in particular. Also have you seen the audio frequency response chart online? That would be helpful for assessing frequency deviations at certain frequencies with ear sensitivity at same and also how those relate to various instrument frequencies heard in music. |
How do you make five hours fly by fast..... Man I love fiddling with stereo equipment. The smell of hot tubes, transistors and power supplies brings back memories from the mid seventies when I was a spry teenager. I walk by the stereo shop on the way to school everyday and finally I decided to enter the inner sanctum of my dreams.....Ahhh that smell from the tubes, transistors and power supplies were intoxicating and with that the beginning of a lifelong quest for better sound. When I started to take apart 4/5k's it really wasn't because I didn't love the way they sound, but because I took apart the Micros. The shock seeing the mess of a badly built speaker with parts so cheap rattled me, so my curiosity was peeked and the 4/5k project took a on a life of its own. Today was an eye opener again, but in my infinite wisdom I decided to use a different software to measure the frequency response. The software is great, but transfer the graphs in to a file that a human can see was another matter. So I am going to have to take pictures of the screen and then post them as soon as possible. What new things did I learn today? How about the speaker measures better with more dampening in the cabinet. A little bit of EQ will go a long way for perfection. No output beyond 2.5k on the Walsh driver. A non resonant cabinet sounds better. And much more. I manage to massage out a perfectly (or close to it) frequency response. The ribbon tweeter sounds and measures great even when I'm over 20 degree of to the side but not as great vertically. I also believe an electronic X-over is a must for this design if you want to squeeze out maximum performance. So that's how I manage to spend five hours nerding out on drivers, EQ's and acoustic sound dampening.......🇸🇪 |
Here I am with some more info to add to our arsenal of knowledge and understanding about our beloved Ohm speakers. It took some extra time to pull together additional charts to show what really is happening through the frequency sweep. I always suspected the Walsh driver to be great but not fantastic in the upper frequency region. After looking closely at the Walsh driver the conclusion must be that the application is brilliant, but not the latest in resolution or frequency extension. The Walsh driver works like an “F” driver but nowhere near it’s extension in the treble region, and if you are really honest at all, there’s very little difference between a front firing woofer/midrange driver and the Walsh driver. The difference is a removed dust cap and some tacky glue on the lower (bass) part (for damping I suspect). The 360 degrees off radiating sound is certainly one of the appealing reason for getting the Ohm’s. Let’s take a look at the different readouts. The first will be a 3D plot that shows both time and frequency in a dimensional way. The brighter the sweep is the more energy is emanating from the driver, you can also see valleys which are low energy areas. These measurements were taken at approx 15 inches from the drivers so I don’t think the room boundaries made any difference at all. The driver was the original soft dome tweeter, no extra EQ the only difference would be that it’s not confined behind foam, paint, perforated steel and speaker cloth I.E. no CAN. (4 layers) Image one: The Walsh driver no tweeter. Volume would be at about mid 80db, loud but not overly so. The bass frequency is a seams a bit on the plump side and then a suddenly a drop in energy way earlier then expected. (wideband Pink Noise). https://www.flickr.com/photos/147883144@N08/shares/D26z27
Image two: Here you have a full frequency sweep allowing you to really see what’s going on, and suddenly it drops of the cliff at 16k. (wideband Pink Noise). https://www.flickr.com/photos/147883144@N08/shares/b1976f
Image three: Walsh with stock tweeter, no EQ, padded cabinet but no OE padding which would consist of a 3 inch layer of re-constituted (shredded and glued together) denim, fluffy Dacron and an upper layer of netting separating the fluffy stuff from the Walsh driver. The graph confirms the 3D plot, very bass heavy and then it falls of pretty fast. These measurements were taken approx 1meter from both drivers. Frequency sweep 20-20khz https://www.flickr.com/photos/147883144@N08/shares/WrD31L
Image four: Walsh driver, stock tweeter, EQ and complete stuffing. 20-20khz Wow look at that curve, so much better…Way better and more midrange/treble energy. And the bass is under control. Very little smoothing as I really like to see all the ripples warts and all. The EQ was used with a tender touch nothing heavy handed. https://www.flickr.com/photos/147883144@N08/shares/8Y1zqV
Image five: (white trace) Walsh driver stock tweeter, no EQ, light stuffing 20-200hz https://www.flickr.com/photos/147883144@N08/shares/7fGU4j
Image six: (yellow trace) Walsh driver, stock tweeter, no EQ, complete stuffing 20-200hz A small but clear difference if you look closely, a slightly flatter curve, but remember this is a very small slice of the whole frequency curve. https://www.flickr.com/photos/147883144@N08/shares/5ffK60
Image seven: Walsh driver, ribbon tweeter, EQ and complete stuffing 20-20khz As mentioned earlier the impedance value is 5 ohm’s on this tweeter, so that will certainly add to some compatibility issues. But looking at the curve it’s pretty darn good and I think with some additional tweaking I could have done more. Below you’ll find an additional image of the same setup but 20 degrees off axis. https://www.flickr.com/photos/147883144@N08/shares/k4b4M0 https://www.flickr.com/photos/147883144@N08/shares/b5016x |
