Ok, so it took me all of six and a half hours to get my butt into gear. I got my U-mik for Christmas 2 years ago and haven’t used it once. So here’s two images. The first is my XSim model. The second is my first ever speaker measurement. This is from listening position with both speakers active, with 1/6th smoothing. Looking at this I think I should cut the resistor on the mini k’s back to 8ohms. Curious to know what everyone else’s thoughts are.
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Nice work! That’s a very promising result, and as you say, boosting the output from top end would make sense to balance it. Try several values of R, and see what you like. Many people prefer a tilt of 5dB greater bass from 50Hz to 20kHz. Sort of like you have in Xsim.
Thanks X. After some experimenting I settled on 8 ohms for a flatter in room response. This is a great setup. Basically flat to just below 30hz on open Baffle. Not bad.
I also measured just the mini-k’s on there own just for kicks. The response above ~150hz was identical to my previous measurements. So I know my XO is doing exactly what I predicted in XSim. Pretty cool stuff.
I also measured just the mini-k’s on there own just for kicks. The response above ~150hz was identical to my previous measurements. So I know my XO is doing exactly what I predicted in XSim. Pretty cool stuff.
Here is the measurement with the 8 ohm resistor at the mini-k's. I was also curious about the FR I'm getting from the mini-k's. I feel it should be flatter. The dips at 500, 1,300, and 6-7k are much more pronounced than the data sheet for the 3fe's suggests. Is that just my room or a product of some combing affect from two full range drivers? I thought damping on the aperture may have an impact so I temporarily applied felt to the back and it had no measured affect. I'm open for other suggestions...
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Hey X, do you think changing my dual 3FE25-16 K's over to dual TC9s would be a huge hit in sensitivity? I'm building a tube amp that can put more power into 4 ohms than 8 for similar THD specs, and I already have a quad of TC9s I can swap in for the set of 3FE25. I figured it would be easier/less time consuming than building another set of K's for now.
A brief review of the dual 3fe25 mini Karlsonators...
(with bass support via GRS 15PF-8 on Open Baffle, F7 clone Class A amp, WHAMMY pre)
My friend and I spent some time last night listening to my mini-k's. For comparison, the last time we did a listening session, we have been using Joe Henderson's Lush Life, Track #1 as our standard for comparison. At the time we using his Paradigm Studio 60 v5 speakers to compare between his Line Magnetic 211ia integrated tube amp and my ALPHA 20W Class A amp.
Our last listening was is April so this is quite the subjective review. But take it for what it's worth. Also, I did bring the mini-k's along during that listening session and we briefly put them into the system. At the time we both noticed the sound of the foam core box and certain resonances, even buzzing, that took away from the experience. Not to mention, not much bass below about 100Hz in his space. Thankfully I've been able to address all those issues.
I spent about 10 minutes trying to quickly set up my equipment in my friend's living room while he put his kid to bed.
I think even in those 10 minutes I was able to dial the placement of speakers and listening position in pretty well. Right from the beginning he (professional music teacher) was beside himself with the level of realism, sound stage, imaging, and balance in sound coming from the mini-k/GRS combo. He said he had never heard anything that good before in his life. Or heard a system disappear like this one did. Let me say, the Joe Henderson recording is VERY good. The detail and top-end from the mini-k's was also plenty for both of us. My hearing goes to about 14kHz these days, so no super tweeters needed for this guy.
We continued with Santana's Abraxas. The percussion hits on this album are exceptional with the mini-k/GRS combo. My friend commented on this right away. Also, the panning done in the mastering of the album spins crystal clear images across the sound stage.
Things got a little interesting when we put on Cannonball Adderley's Live in Paris. On duller systems this album sounds good. On this system the recording was overly bright, bordering on harsh. We both found the sound a bit fatiguing. I concluded that this system is revealing of bad and mediocre recordings, while great recordings really knock you out of your chair.
We also played some Telarc compilations to get a feel for orchestral music. This combo handles complex music well. Knocking anything below 150Hz out of the mini-k's spectrum with the crossover allows them to play effortlessly to very loud volumes. My friend noticed later that we had the volume up pretty high and said he didn't notice because the sound was so clean.
We finished with Heavy Weather's Night Passage on vinyl. The last track on the album, Madagascar, features a great live recording of some unique sounds and instruments across a broad stage. A really great test track for any system. The same listening comments were made on this one. Great sound stage, pin-point imaging, good depth of field...
Over all he was blown away by what he heard from the mini-k's that night. I was proud to have really shown him what DIY was capable of. Thanks for all of your help to make that possible, X, Freddi and everyone else who has contributed to this thread along the way!
(with bass support via GRS 15PF-8 on Open Baffle, F7 clone Class A amp, WHAMMY pre)
My friend and I spent some time last night listening to my mini-k's. For comparison, the last time we did a listening session, we have been using Joe Henderson's Lush Life, Track #1 as our standard for comparison. At the time we using his Paradigm Studio 60 v5 speakers to compare between his Line Magnetic 211ia integrated tube amp and my ALPHA 20W Class A amp.
Our last listening was is April so this is quite the subjective review. But take it for what it's worth. Also, I did bring the mini-k's along during that listening session and we briefly put them into the system. At the time we both noticed the sound of the foam core box and certain resonances, even buzzing, that took away from the experience. Not to mention, not much bass below about 100Hz in his space. Thankfully I've been able to address all those issues.
I spent about 10 minutes trying to quickly set up my equipment in my friend's living room while he put his kid to bed.
I think even in those 10 minutes I was able to dial the placement of speakers and listening position in pretty well. Right from the beginning he (professional music teacher) was beside himself with the level of realism, sound stage, imaging, and balance in sound coming from the mini-k/GRS combo. He said he had never heard anything that good before in his life. Or heard a system disappear like this one did. Let me say, the Joe Henderson recording is VERY good. The detail and top-end from the mini-k's was also plenty for both of us. My hearing goes to about 14kHz these days, so no super tweeters needed for this guy.We continued with Santana's Abraxas. The percussion hits on this album are exceptional with the mini-k/GRS combo. My friend commented on this right away. Also, the panning done in the mastering of the album spins crystal clear images across the sound stage.
Things got a little interesting when we put on Cannonball Adderley's Live in Paris. On duller systems this album sounds good. On this system the recording was overly bright, bordering on harsh. We both found the sound a bit fatiguing. I concluded that this system is revealing of bad and mediocre recordings, while great recordings really knock you out of your chair.
We also played some Telarc compilations to get a feel for orchestral music. This combo handles complex music well. Knocking anything below 150Hz out of the mini-k's spectrum with the crossover allows them to play effortlessly to very loud volumes. My friend noticed later that we had the volume up pretty high and said he didn't notice because the sound was so clean.
We finished with Heavy Weather's Night Passage on vinyl. The last track on the album, Madagascar, features a great live recording of some unique sounds and instruments across a broad stage. A really great test track for any system. The same listening comments were made on this one. Great sound stage, pin-point imaging, good depth of field...
Over all he was blown away by what he heard from the mini-k's that night. I was proud to have really shown him what DIY was capable of. Thanks for all of your help to make that possible, X, Freddi and everyone else who has contributed to this thread along the way!
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Thank you for the detailed account of your listening session. It sounds like the mini K’s knocked it out of the park! Congratulations!
Just to get the specifics straight. So is this a foam core dual 3FE25 with 15in OB woofer and passive XO (circa 150Hz) and powered by an F7 and Whammy pre?
Just to get the specifics straight. So is this a foam core dual 3FE25 with 15in OB woofer and passive XO (circa 150Hz) and powered by an F7 and Whammy pre?
You got it X. Those are the correct specs. Passive XO is per post #3491 with the exception of 8 ohms ILO the 16 Ohm resistor at R1. This did turn it into a 4 Ohm speaker though, so 16 ohms may be ideal for the system while using the room placement to tailor the bass to your liking.
A few more notes that I remember. We noticed that when listening it felt a bit like looking down at the stage or that the image was a little too low. I need to experiment with some short speaker stands to see if that changes things. Also, to get the full effect you really needed to sit in the sweet spot. Whether that came down to room effects I’d have to experiment more. Either way these issues didn’t detract much from the overall presentation, which was stunning.
A few more notes that I remember. We noticed that when listening it felt a bit like looking down at the stage or that the image was a little too low. I need to experiment with some short speaker stands to see if that changes things. Also, to get the full effect you really needed to sit in the sweet spot. Whether that came down to room effects I’d have to experiment more. Either way these issues didn’t detract much from the overall presentation, which was stunning.
Hi Jwjarch,
I have also noticed the tilted down soundstage you mention. It has to do with the Karlson aperture being up/down asymmetric. The wave launches up relative to the front. When they are on 30in tall stands, the effect is not as noticeable. I have not tried this but perhaps tilting the box down while on a stand might change this.
I have also noticed the tilted down soundstage you mention. It has to do with the Karlson aperture being up/down asymmetric. The wave launches up relative to the front. When they are on 30in tall stands, the effect is not as noticeable. I have not tried this but perhaps tilting the box down while on a stand might change this.
@Hugh - Thank you! Always enough getting a good listening session in and letting people know what can be achieved with these designs. I agree on the Class A percussion. A few months back I put my nice little T2 Tripath amp from HiFimeDIY in for some listening. After having listened to the ALPHA 20 for some time I couldn't listen to the T2 anymore. It just couldn't hold a candle to the ALPHA. There is something about the weight and breath of the sound from a good Class A amp. Not sure I'll ever go back!
@X - Thanks for the info and tips. I'll have to give the stands and tilting a try. I knew it had to have something to do with the aperture.
@X - Thanks for the info and tips. I'll have to give the stands and tilting a try. I knew it had to have something to do with the aperture.