Over the past couple of weeks I have been busy constructing a pair of bass reflex desktop speakers using MarkAudio's CHN-70 driver. As soon as the polyurethane had dried, I eagerly mounted the drivers and connectors, plugged them in, and had a listen. Something was very wrong 🙁 ... I waited till the morning, leaving BBC radio 2 on at a low level, but they still sounded quite horrid when I got up the next day.
It seems these drivers have an unbelievably brash 10dB boost in the 1-5kHz range, culminating in a 12dB peak at 5.6kHz. Needless to say, this does not sound very nice at all. Interestingly, this is completely absent from the published frequency response 😕 .
I'd invested a great deal of time into this build (especially with the veneer) and wasn't going to put up with a tinny, shouty sound for all of my effort 😡 . With this in mind I came up with a passive line level equaliser to compensate for this, while also providing a little baffle step correction, along with some extension of the top end, taking into account pre-amplifer output and power amplifier input impedance. It's fairly straightforward to place this between the pre-out-power-in terminals on most integrated amplifiers.
With this in place, they sound rather good, as far as a 4" full range driver can. A stark improvement over what they sounded like previously. If you've invested your time with these drivers, then all is not lost! Give it a try 😀 .
It seems these drivers have an unbelievably brash 10dB boost in the 1-5kHz range, culminating in a 12dB peak at 5.6kHz. Needless to say, this does not sound very nice at all. Interestingly, this is completely absent from the published frequency response 😕 .
I'd invested a great deal of time into this build (especially with the veneer) and wasn't going to put up with a tinny, shouty sound for all of my effort 😡 . With this in mind I came up with a passive line level equaliser to compensate for this, while also providing a little baffle step correction, along with some extension of the top end, taking into account pre-amplifer output and power amplifier input impedance. It's fairly straightforward to place this between the pre-out-power-in terminals on most integrated amplifiers.
With this in place, they sound rather good, as far as a 4" full range driver can. A stark improvement over what they sounded like previously. If you've invested your time with these drivers, then all is not lost! Give it a try 😀 .
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I'm afraid I designed this circuit using measurements made by others, one from a comparison thread on this forum and one from the parts express forum, then factored in the baffle step. I simply calculated the values so as to flatten those measurements as best as possible with a first order function.
I'm afraid I designed this circuit using measurements made by others, one from a comparison thread on this forum and one from the parts express forum, then factored in the baffle step. I simply calculated the values so as to flatten those measurements as best as possible with a first order function.
Montypig,
It's a well-known issue that the CHN70 has a terrible frequency response - with an elevated 10dB Mesa plateau and dips an peaks. It was the subject of this thread and quite a bit of controversy in a previous thread. My measurements were confirmed by others independently and don't agree with the factory measurement.
http://www.diyaudio.com/forums/full...parison-3in-4in-class-full-range-drivers.html
http://www.diyaudio.com/forums/full...nd-comparison-3in-5in-full-range-drivers.html
Here is response and HD from a sealed Nautaloss rear chamber and trapezoid baffle:
It is said that the driver was voiced for the Japanese market - apparently they like their speakers to sound like muted wailing banshee.
However, there is a redeeming value to this driver. It's low cost, quite sensitive, and affords pretty deep bass. Now if you put it in a mini Karlsonator, the K aperture essentially reverses all of the bad traits and makes it very listenable. In fact, it's my daily listener at work. I use it with an ACA class A amp and it sounds great.
The trick is the mini Karlsonator.
http://www.diyaudio.com/forums/full-range/280669-improving-chn-70-a-5.html
Response in 4pi space with no BSC - pretty deep bass that is balanced level wise with rest of response. Nor HiFi by any means - but very listenable.
It's a well-known issue that the CHN70 has a terrible frequency response - with an elevated 10dB Mesa plateau and dips an peaks. It was the subject of this thread and quite a bit of controversy in a previous thread. My measurements were confirmed by others independently and don't agree with the factory measurement.
http://www.diyaudio.com/forums/full...parison-3in-4in-class-full-range-drivers.html
http://www.diyaudio.com/forums/full...nd-comparison-3in-5in-full-range-drivers.html
Here is response and HD from a sealed Nautaloss rear chamber and trapezoid baffle:
It is said that the driver was voiced for the Japanese market - apparently they like their speakers to sound like muted wailing banshee.
However, there is a redeeming value to this driver. It's low cost, quite sensitive, and affords pretty deep bass. Now if you put it in a mini Karlsonator, the K aperture essentially reverses all of the bad traits and makes it very listenable. In fact, it's my daily listener at work. I use it with an ACA class A amp and it sounds great.
The trick is the mini Karlsonator.
http://www.diyaudio.com/forums/full-range/280669-improving-chn-70-a-5.html
Response in 4pi space with no BSC - pretty deep bass that is balanced level wise with rest of response. Nor HiFi by any means - but very listenable.
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I suppose they'd sound 'edgy' with the sort of simple 'girl-and-guitar' type music that seems to be popular over there.
Do you have a plan for your karlsonator? How directional is it? It looks like you still have a rather intrusive peak at 5.5kHz.
Do you have a plan for your karlsonator? How directional is it? It looks like you still have a rather intrusive peak at 5.5kHz.
The plan is literally the title of the above referenced post: 0.44x scale in height and depth and 0.55x scale in width. Go to the mini K'nator thread and use GregB's plans for the full scale K'nator (designed for 12in driver). Scale height and depth by 0.44x and widh by 0.55x. Preserve internal dimension if using thinner material.
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds.html
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds.html
Can we rephrase post #5 above to state that this driver's FR was tailored for a particular demographic?
I personally don't find them as objectionable as some folks, but then my main exposure to them has been in the Planet10 Castle Microtower, and with subwoofer dialed in by ear.
That said, there are other drivers in the MA pantheon that I prefer.
I personally don't find them as objectionable as some folks, but then my main exposure to them has been in the Planet10 Castle Microtower, and with subwoofer dialed in by ear.
That said, there are other drivers in the MA pantheon that I prefer.
And then misrepresented in the datasheet 😉 ? I think I shall put this down to incompetent measurement more than anything else.. Not bad faith on the part of MarkAudio, but error in measurement or manufacture.
Thanks, Chris! Pine is a very underrated veneer IMO 😀 . I did originally plan on doing them in MDF and getting the graining roller out, but raw pine just looks so good (and I had enough hide glue left over to hammer it on).
I should have probably got the router out and chamfered around the edges, but I didn't want to spend too much time on a £45 pair of drivers.
I think I'll use shellac for my next build, polyurethane has a nice tough gloss sheen, but it's a little too 'in-your face' for me. More suited to kitchen tables and floors than full-range cabinets, which should be all about finesse 🙂 .
I should have probably got the router out and chamfered around the edges, but I didn't want to spend too much time on a £45 pair of drivers.
I think I'll use shellac for my next build, polyurethane has a nice tough gloss sheen, but it's a little too 'in-your face' for me. More suited to kitchen tables and floors than full-range cabinets, which should be all about finesse 🙂 .
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