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Chris661's HiFi

chris661

Well-known member
Oct 30, 2019
191
116
270
Hi all,
One of my first posts here, so thought I'd kick things off with some snaps of my current HiFi system:

Sources: Half a laptop (running Spotify, iTunes, and VLC player for movies), GL75 turntable into a NAD PP1 phono preamp
Amp: Cambridge Audio CXA80
Speakers: Custom designed/built, 8" 2-way with Seas aluminium coned midbass and a 1" compression driver.



Turntable with a dusty record:


With a cheapie Audio Technica stylus. I've taken the time to set it up properly, and it does well on a vinyl test disk (playing test tones at various frequencies and places on the record).

Crossover:


Outboard for now, but I'll build it into the speakers eventually.

For the 8": 3rd order lowpass, parallel "bottomless" notch to kill the primary breakup mode of the aluminium cone (it shouldn't be surprising that they literally ring like a bell, in this case at 4.5kHz, so that needed attenuating strongly to make sure the resonance didn't poke through into audibility), and a Zobel filter since the voice coils are fairly large and inductive.
For the compression driver: 3rd order highpass, series notch to dip the 3.5kHz range a little, and an L-pad which attenuates by about 20dB.

The idea behind these speakers is as follows: the cones and domes are acting as pure pistons throughout their operating range. Paper cones are often run up in a region where the cone itself is starting to bend and deform, which to me is inherently a compromise. I also wanted a horn to cover most of the range to cut down on near reflections from side walls etc. A pair of 8"s can put out enough low end for me, so it was straightforward to make it a 2-way design. The compromise for these speakers is the complexity of the crossover.

The overall sound is excellent - clean, neutral, and if you turn it up, it keeps getting louder and louder. These speakers aren't choosy over the music - you can play Rage Against the Machine and crank it until you feel the impact of the drums. You can then turn the volume down and play something intimate and acoustic, resulting in the singer coming to visit the living room for a song or two. In short, if it's on the recording, you'll hear it.
The compression driver has a very easy life in this system - the 8" drivers will give up long before the tweeters start to struggle - so even at high volumes, the sound never turns harsh.


The amplifier is nice and easy to use, too. I have the laptop connected via USB to the amp's built-in DAC, and often just use Spotify (controlled from another device) to play music. If I want to listen more seriously, though, I use high-quality digital files.

I think that's everything for now.

Chris
 

scene

Moderator
Sep 25, 2008
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19,070
Nice homemade speakers (y)

I think you should make a design statement of the alfresco crossovers - maybe mounted in a perspex box with lighting :)
- I'm guessing you have no cats or small people...

Have you tried measuring the response curves of the speakers?
 
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chris661

Well-known member
Oct 30, 2019
191
116
270
Hi Scene,

Yeah, the speakers measure well. I had to use a measurement system to come up with the crossovers in the first place, too - the online calculators assume an 8ohm resistor when they spit out their values, and real loudspeakers are much more complex than that.

The in-room low-frequency response looks like this:


Which I flatten out on the laptop using a program that sits between the media players and the USB output. Net result is flat to 10Hz, which is cool. The 8" drivers don't get loud at 10Hz before they're distorting, though - you need to move a lot more air if you want to feel frequencies that low.

I'll see if I can dig up a full-range measurement.

Chris
 

Tonestar1

Moderator
Nov 4, 2008
182
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18,670
Looks great. I know little about active crossovers but I'd be moving the speakers a little bit out from the wall and trying to get the left one out the corner a bit, it's almost in a box. Room placement makes a big difference in my experience.
 

chris661

Well-known member
Oct 30, 2019
191
116
270
I designed these so they'd be happy near the side/back walls. I do agree that the shelves come a bit further forward than would be optimal, but that's life.

The high-frequency horn (which covers 900Hz and upwards) keeps good control over where the sound is/isn't going, so there's not much energy being thrown at the nearby reflective surfaces. The result is that the sound isn't affected much by nearby objects. More conventional speakers (B&W 685s, for example) throw a lot more sound sideways, which will mean they suffer much more if they're placed sub-optimally.

The hope was that I could make a speaker that works well in a position that would normally be considered a compromise, and I think I've succeeded in that. Those that have heard the system seem to agree, although it's entirely possible they're just being polite!


Chris
 
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scene

Moderator
Sep 25, 2008
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19,070
The hope was that I could make a speaker that works well in a position that would normally be considered a compromise, and I think I've succeeded in that. Those that have heard the system seem to agree, although it's entirely possible they're just being polite!
Always possible - they might be finding it hard after you've demoed the loves of your life and explained all the hard work you put into them to say "Actually, they don't sound that great" ;-)

Naah - sure they sound the great. Horns are great to direct sound - and you've been managing the resonances as you said. So should sound pretty sweet. And loud...
 

Gray

Well-known member
Nov 27, 2015
888
513
5,770
Is that a 4-pole Speakon plug & socket in amongst your crossover Chris?
Making for a neat 4-core cable out of the plug....because you wouldn't want things looking untidy ;)
 

chris661

Well-known member
Oct 30, 2019
191
116
270
Yeah, I run a live sound business most of the time, so SpeakOn connectors are always on-hand.

The crossover as-is was a rig-up to make sure the simulators were doing what they ought to be doing. After a couple of tweaks, it sounded so good that I didn't want to stop listening.

Since the photos, I've mounted the crossovers on the back of the cabinets with heavy-duty double-sided sticky tape. Works for now.

Eventually I'll buy some nice birch plywood and re-build the cabinets with the crossovers inside, and a simple set of binding posts (or SpeakOn sockets) on the back.

Chris
 

scene

Moderator
Sep 25, 2008
766
168
19,070
Yeah, I run a live sound business most of the time, so SpeakOn connectors are always on-hand.

The crossover as-is was a rig-up to make sure the simulators were doing what they ought to be doing. After a couple of tweaks, it sounded so good that I didn't want to stop listening.

Since the photos, I've mounted the crossovers on the back of the cabinets with heavy-duty double-sided sticky tape. Works for now.

Eventually I'll buy some nice birch plywood and re-build the cabinets with the crossovers inside, and a simple set of binding posts (or SpeakOn sockets) on the back.

Chris
Looking forward to seeing photos of the finished speakers (y)
 

insider9

Well-known member
Sep 20, 2016
739
298
5,270
Hi Scene,

Yeah, the speakers measure well. I had to use a measurement system to come up with the crossovers in the first place, too - the online calculators assume an 8ohm resistor when they spit out their values, and real loudspeakers are much more complex than that.

The in-room low-frequency response looks like this:


Which I flatten out on the laptop using a program that sits between the media players and the USB output. Net result is flat to 10Hz, which is cool. The 8" drivers don't get loud at 10Hz before they're distorting, though - you need to move a lot more air if you want to feel frequencies that low.

I'll see if I can dig up a full-range measurement.

Chris
Wow that's some SPL you're pushing out. I'd turn it down quite a bit. I'm sure you can feel 110dB at 40Hz in your chest 😁
 

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