Here is a nice example of a biggish 3 way project of much a moderate cost. The final performance is very high. The units used are mostly discontinued (woofers still on Madisound catalogue, midwoofer ??? tweet available).
So what do you do when some stock of Audax plastic chassis units is being cleared on nice price plus some nice Czech class A/B professional amps are on special offer? Time to build some system I guess.
OK, so my economically challenged young friend got a low budget chance for his 40sqm living room finally…his KEFs were somewhat small for his space.
Those last left drivers were:
Only 2 HP210G0, some 8 AP170Z0, a couple of Morel MDT30 leftovers….hmmm
I cooked a 2 box 3 way with 4 series parallel 6.5’’ woofers, an 8 inch mid and a Morel MDT 30 per side. Having a bigger mid than the woofs posed an aesthetic challenge. I arranged the woofs (see pictures) so they sat easy to the eye on a wider baffle, matching the 8 inch box with a cool tech advantage…Evened out the diffraction pattern seriously.
Low box is 70litres with a 10cm X 7cm flared port stuffed by 20% with Dacron.
High box is 20litres with a 5cmX9 cm backside port stuffed by 20% with Dacron.
Both ports are trimmed for real room performance after simulations, measurements and auditions. Nothing hangs, it’s tuneful.
For some long period I used a Behringer for bass to mid cross duties since 2 amps were available, but after time it got clear that it gave bad service to music. The sysytem was destined for full passive biamping…
Not only dynamics were not lost in the end but the musicality, staging, and information retrieval leaped to warp 3!
The full passive system has 91dB / 2.83V, 5 Ohm nominal characteristics and a real 30Hz in room bottom reach. 300W true RMS power handling per channel also.
4 channels of 200W @ 4 Ohm RMS are driving it. 500Hz and 1800Hz are the crossover points. Low / top box crossovers are located in bottom boxes, mid / tweeter crossovers in top boxes. Vibration challenges less the top box components and 3M low profile, button like, elastic feet are used between them. Same decoupling is used between bottom box and a granite slab.
During Sheffield Drum and Track CD, before even momentarily clipping indication on the amps red leds dared to show, and while we could not detect any serious woofer travel, a woman from 2 stories above came to ask what shakes her ceiling in the fully concrete and marble building…
The performance is really good, on par with many pricey ‘Hi-End’ big ones, but alive and creamy and musical too. The bass unit is fast due to low mass multiple cones.
I include the crossover schematics in case someone has the Audax units or some of them and still can find the rest, plus needing a cheap big good speaker.
In the midrange part there is a 1+1 Ohm resistor combination. If the full 2 Ohm is used, the system is warmish. If the +input is connected to the second one and only 1 Ohm is used, then it’s neutral.
This is for system matching, room matching, distance of auditioning, and musical taste option. Listen to both.
The top box is polarity inverted for input.
Caps used are Chinese MKT (maybe Bennic) bypassed by Mundorf Mcap Supreme for mids, MKT Mcap bypassed for lows, SCR MKP, bypassed with SCR Tin Foil for tweeter, and the coils are air core.
Please keep the gauges as they are if somebody is going to build it, its all in the recipe. Wire is Belden 2X4mm2 professional type.
Same wire is used connecting to the amps speakons. Any 2x100W and higher stereo amp with good current can bring serious SPL as long as the biamping /biwiring inputs are bridged. I recommend 2x200W just because you gonna like it. The distortion of the speakers is very low, they can take stick.
The frequency response chart is for the real living room at 3 metres from a speaker. Reflections, room modes, and all, on tweeter axis. It’s for the warmish setting.
You get about 2 dB presence and highs output boost in neutral.
Top box is designed to be always upside down. Else lobe suffers.
So to recap, we have a biamped 3 way system based on Audax plastic chassis stock cleared drivers, 2 Czech budget professional amps, an OPA 627 & 637 DIY preamp, a Creek CD 50 MKI second hand CD player, wired with DIY interconnects in pseudobalance and Belden professional audio installation copper speaker wire. After I listened to it well enough, I was amazed of what can be achieved by a sound and humble approach, save for my friend’s constant grin. A happy, not empty pocketed DIY convert indeed.
He listened to a Bryston 2X400W based system driving Danish brand name big 3ways using Scanspeak, with cool $$$ sources and Siltech cabling at a point in a friend’s house, seasoned and carefully setup by a serious geek.
He called me and started describing the brand name system…I thought he was going to tell me in despair that his low $ mostly DIY system sucked in comparison….But he told me to go out instead, he was buying the drinks!
Cheers
Salas
So what do you do when some stock of Audax plastic chassis units is being cleared on nice price plus some nice Czech class A/B professional amps are on special offer? Time to build some system I guess.
OK, so my economically challenged young friend got a low budget chance for his 40sqm living room finally…his KEFs were somewhat small for his space.
Those last left drivers were:
Only 2 HP210G0, some 8 AP170Z0, a couple of Morel MDT30 leftovers….hmmm
I cooked a 2 box 3 way with 4 series parallel 6.5’’ woofers, an 8 inch mid and a Morel MDT 30 per side. Having a bigger mid than the woofs posed an aesthetic challenge. I arranged the woofs (see pictures) so they sat easy to the eye on a wider baffle, matching the 8 inch box with a cool tech advantage…Evened out the diffraction pattern seriously.
Low box is 70litres with a 10cm X 7cm flared port stuffed by 20% with Dacron.
High box is 20litres with a 5cmX9 cm backside port stuffed by 20% with Dacron.
Both ports are trimmed for real room performance after simulations, measurements and auditions. Nothing hangs, it’s tuneful.
For some long period I used a Behringer for bass to mid cross duties since 2 amps were available, but after time it got clear that it gave bad service to music. The sysytem was destined for full passive biamping…
Not only dynamics were not lost in the end but the musicality, staging, and information retrieval leaped to warp 3!
The full passive system has 91dB / 2.83V, 5 Ohm nominal characteristics and a real 30Hz in room bottom reach. 300W true RMS power handling per channel also.
4 channels of 200W @ 4 Ohm RMS are driving it. 500Hz and 1800Hz are the crossover points. Low / top box crossovers are located in bottom boxes, mid / tweeter crossovers in top boxes. Vibration challenges less the top box components and 3M low profile, button like, elastic feet are used between them. Same decoupling is used between bottom box and a granite slab.
During Sheffield Drum and Track CD, before even momentarily clipping indication on the amps red leds dared to show, and while we could not detect any serious woofer travel, a woman from 2 stories above came to ask what shakes her ceiling in the fully concrete and marble building…
The performance is really good, on par with many pricey ‘Hi-End’ big ones, but alive and creamy and musical too. The bass unit is fast due to low mass multiple cones.
I include the crossover schematics in case someone has the Audax units or some of them and still can find the rest, plus needing a cheap big good speaker.
In the midrange part there is a 1+1 Ohm resistor combination. If the full 2 Ohm is used, the system is warmish. If the +input is connected to the second one and only 1 Ohm is used, then it’s neutral.
This is for system matching, room matching, distance of auditioning, and musical taste option. Listen to both.
The top box is polarity inverted for input.
Caps used are Chinese MKT (maybe Bennic) bypassed by Mundorf Mcap Supreme for mids, MKT Mcap bypassed for lows, SCR MKP, bypassed with SCR Tin Foil for tweeter, and the coils are air core.
Please keep the gauges as they are if somebody is going to build it, its all in the recipe. Wire is Belden 2X4mm2 professional type.
Same wire is used connecting to the amps speakons. Any 2x100W and higher stereo amp with good current can bring serious SPL as long as the biamping /biwiring inputs are bridged. I recommend 2x200W just because you gonna like it. The distortion of the speakers is very low, they can take stick.
The frequency response chart is for the real living room at 3 metres from a speaker. Reflections, room modes, and all, on tweeter axis. It’s for the warmish setting.
You get about 2 dB presence and highs output boost in neutral.
Top box is designed to be always upside down. Else lobe suffers.
So to recap, we have a biamped 3 way system based on Audax plastic chassis stock cleared drivers, 2 Czech budget professional amps, an OPA 627 & 637 DIY preamp, a Creek CD 50 MKI second hand CD player, wired with DIY interconnects in pseudobalance and Belden professional audio installation copper speaker wire. After I listened to it well enough, I was amazed of what can be achieved by a sound and humble approach, save for my friend’s constant grin. A happy, not empty pocketed DIY convert indeed.
He listened to a Bryston 2X400W based system driving Danish brand name big 3ways using Scanspeak, with cool $$$ sources and Siltech cabling at a point in a friend’s house, seasoned and carefully setup by a serious geek.
He called me and started describing the brand name system…I thought he was going to tell me in despair that his low $ mostly DIY system sucked in comparison….But he told me to go out instead, he was buying the drinks!
Cheers
Salas
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After everything is well run in now, I have decided its final hf balance.
Because I liked the mids in the warmish setting but I missed the added definition of neutral setting I experimented with a bypass cap so to retain the neutral hf avoiding possible clinical effects in the mids.
The cap is 5,6uF Mundorf Mcap across the 1+1 Ohm resistors.
You can see the modification and how it affects hf in room (3m on TW axis) in the pic below:
Because I liked the mids in the warmish setting but I missed the added definition of neutral setting I experimented with a bypass cap so to retain the neutral hf avoiding possible clinical effects in the mids.
The cap is 5,6uF Mundorf Mcap across the 1+1 Ohm resistors.
You can see the modification and how it affects hf in room (3m on TW axis) in the pic below:
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