Air Cores in action
To John B, my enormous thanks for the design and your willingness to share and teach at the same time. Ditto to Pano.
I have just now finished building my Manzanitas at long last, and I am now listening while the last coat of varnish dries. Very impressed first up with how good they sound, so clear etc etc etc compared to my old 3 way, base reflex corals. They look good too, even if I say so myself.
I have followed the recipe fairly closely (I started with C = 5u6 but have 6u and 6u2 on standby) but the main change was to use air cored inductors and 2mm wire.
I soon found out 2mm is quite challenging to wind. So I designed and built a coil winder with enough torque to wind very tightly. (used a windscreen wiper motor from the wreckers and a home made pulse width controller to give a variable speed drive and re-wired the foot pedal from the sewing machine). The 20mH coils are both 19.95mH and about 0R9 after stripping off about 10 of the over-wind turns. Similarly the 2mH measured 2.04mH and 0R3. Weight is 5kg and 1.2kg. Measurement frequency 1kHz.
To John B, my enormous thanks for the design and your willingness to share and teach at the same time. Ditto to Pano.
I have just now finished building my Manzanitas at long last, and I am now listening while the last coat of varnish dries. Very impressed first up with how good they sound, so clear etc etc etc compared to my old 3 way, base reflex corals. They look good too, even if I say so myself.
I have followed the recipe fairly closely (I started with C = 5u6 but have 6u and 6u2 on standby) but the main change was to use air cored inductors and 2mm wire.
I soon found out 2mm is quite challenging to wind. So I designed and built a coil winder with enough torque to wind very tightly. (used a windscreen wiper motor from the wreckers and a home made pulse width controller to give a variable speed drive and re-wired the foot pedal from the sewing machine). The 20mH coils are both 19.95mH and about 0R9 after stripping off about 10 of the over-wind turns. Similarly the 2mH measured 2.04mH and 0R3. Weight is 5kg and 1.2kg. Measurement frequency 1kHz.
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That may be the biggest crossover coil I've ever seen.
Are you looking at the spool of wire that the coils are wound from?
Nice tightly wound coils there.
I have used an ordinary 5mm iron coach bolt to hold the 20mH coil in place and I will try to find a non magnetic stainless or brass equivalent to finish off properly. While measuring I checked the impact of the iron bolt - it adds only 0.4mH to the 1kHz inductance.
However I do not know what effect it would have at the operating frequencies and currents, nor if there will be any saturation effects. Does anyone have experience in this area?
Quote- You may have the start of a small cottage business there -
I guess I am open to requests, there is enough copper left for 2 more pairs. The 36kg mother reel cost me over AU$550 and that was a clearance price for a part used reel.
Quote - Nice tightly wound coils there
Thanks, I used the Brooks approximation for minimum copper length which gives a square profile - equal turns and layers. It was very challenging to get a perfect lay like that and I suspect there is a vastly diminished return on the effort. What you see is the first coil. The bobbin for the next one was made 2 turns larger but for some reason I could only fit one then zero extra turns on alternate layers. With extra spaces between each turn the lay became uneven and the finish was nowhere near as professional. However the roughy only had 5 extra turns on it get the same inductance.
My understanding is that excess inter-winding distance in an air core only affects the net inductance and not frequency or current responses of the solenoid - is this true?
However I do not know what effect it would have at the operating frequencies and currents, nor if there will be any saturation effects. Does anyone have experience in this area?
Quote- You may have the start of a small cottage business there -
I guess I am open to requests, there is enough copper left for 2 more pairs. The 36kg mother reel cost me over AU$550 and that was a clearance price for a part used reel.
Quote - Nice tightly wound coils there
Thanks, I used the Brooks approximation for minimum copper length which gives a square profile - equal turns and layers. It was very challenging to get a perfect lay like that and I suspect there is a vastly diminished return on the effort. What you see is the first coil. The bobbin for the next one was made 2 turns larger but for some reason I could only fit one then zero extra turns on alternate layers. With extra spaces between each turn the lay became uneven and the finish was nowhere near as professional. However the roughy only had 5 extra turns on it get the same inductance.
My understanding is that excess inter-winding distance in an air core only affects the net inductance and not frequency or current responses of the solenoid - is this true?
He-he, no.
I was looking at the inductor in back of the speaker. It looks as big or bigger than the Peerless woofer magnet.
He-he, no.
I think the biggest crossover coils I've seen were in the passive crossover for the Fried Model H: (!!)
te he he he - there is no use for a foot pedal because the motor is missing, I tried that first for the winding machine but nowhere near enough torque.
OMG The last thing the boss wants is another speaker project and the need to buy more drivers, I do intend to make an :"Homage clone" tho using a set of woofers I have on the shelf " Eventually "
Thanks for sharing your build
Johno.... Thanks for sharing your build experience and pictures! Looks great!! Also great to know you like the sonic results.
Curious, what are the dcr values for your 2 custom coils? And what resistance value do you like on the Vifa? It will also good to know where you end up on the Vifa crossover components once the speaker has settled down. This is usually 100 hours or so of playing time. And one last thing, what distance from the rear wall sounds the best, most balanced to you? Hope I'm not being too much of a pest! Best and congratulations on your new creation! John
Johno.... Thanks for sharing your build experience and pictures! Looks great!! Also great to know you like the sonic results.
Curious, what are the dcr values for your 2 custom coils? And what resistance value do you like on the Vifa? It will also good to know where you end up on the Vifa crossover components once the speaker has settled down. This is usually 100 hours or so of playing time. And one last thing, what distance from the rear wall sounds the best, most balanced to you? Hope I'm not being too much of a pest! Best and congratulations on your new creation! John
Hi John, thanks for the kind comments....
My feedback
My amp has the volume knob about 40% higher to get roughly the same volume out as the old bass reflex speakers. OBs do indeed eat watts.
20mH has 0R95 dcr (compared to 0R56 for the recommended ERSE) and the 2mH has 0R27 (compared to 0R7 for the ERSE). Believe this giving me more high end and less low end and this is becoming more apparent as the speakers age.
I am currently using 5u6 with 4R7 on the pad and 10R in the trap per your spec, but to re-balance the output for the higher 20mH dcR I am planning to increase C to 6u2 and the pad to 5R6. Maybe the trap could increase to 12R. But I will let the drivers settle more first.
The rear wall distance is really fascinating.
WAF says as close to the wall as possible leading to harshness and diminished bass. Sounds horrid.
But 48 inches into room and about 18 inches in from the side and the bass returns and the treble mellows. So we are at an impasse of sorts. And she doesn't yet know about the sewing machine. However I have my eye on a lovely little red ducatti to buy her as a peace offering (and no, she doesn't ride - te he he he)
The room itself is L shaped with large curtained windows on both long sides. The stereo is currently in the shorter/narrower arm of the "L". I am going to reverse the position to the larger half which is about 14x19 feet vs 9x13.
Finally I am using a cheap karaoke amp while I finish the 5 a side Leach amp that I am building and I am certain its freq response is not too flash. This is probably having a negative impact on my listening impressions now, so at the least I need to measure its response and only fiddle accordingly.
More to come obviously. Thanks again for sharing the design.
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The Magnum 18 LF is a nice woofer with a smooth roll off similar to the Eminence 18241 originally used in the HE. Both have similar xmax. The Magnum is about 2 db less efficient, but a higher QTS and FS. (.22 vs .32 & 22Hz vs 32 Hz) Not enough to make a lot of difference. Anyway, the Magnum is closer than most 18's but would require some additional pad on the Seas 8" FR. The FR crossover cap may also require some adjustment slightly downward in value to retain the original crossover point. The Magnum also has a Faraday ring, the original 18241 does not.
If you are willing or able to do some crossover tweaks the Magnum should work reasonably well but the over all system will not be quite as efficient. Hope this helps.
If you are willing or able to do some crossover tweaks the Magnum should work reasonably well but the over all system will not be quite as efficient. Hope this helps.
My new Manzanita Ultra build.
Hello John and fellow diy builders. I have had the great fun of building the Manzanita Ultra's the last couple of weeks. I hooked up the speakers to my tube pre-amp and B&K ST202+ power amp yesterday night. First impressions are very good, with a very impressive bass and homogenous overall sound. Very low and clean bass notes. This is only my first listening impressions with new drivers, no proper burn-in period done. Thank you so much John for sharing this exciting and elegant design with the diy community! \Hans in Holmsund, Sweden.
Hello John and fellow diy builders. I have had the great fun of building the Manzanita Ultra's the last couple of weeks. I hooked up the speakers to my tube pre-amp and B&K ST202+ power amp yesterday night. First impressions are very good, with a very impressive bass and homogenous overall sound. Very low and clean bass notes. This is only my first listening impressions with new drivers, no proper burn-in period done. Thank you so much John for sharing this exciting and elegant design with the diy community! \Hans in Holmsund, Sweden.
