CHR-70 bass reflex

[markaudio]

Originally Posted by Andy17

Yes, for such a low frequency (40Hz) you need these values.
Of course no air-coils. I do not know US shops and parts.
Here are e.g. Mundorf coils quite commen.
http://www.mundorf.com/english%201.1/spulen-kern.htm
FERRIT-core coils > 10mH are about €10.

Hi Andreas, Guys,
Many thanks to Andreas for making the time to design this filter.

Looking at the values on Andreas's drawing, the pricing for this filter component set will be mighty expensive. I checked the Erse site and a 15mH solid core is US$35 (US$50 with the shipping - see screen pic). 2 of these would be needed to get close to one of the values on Andreas's drawing. Add in the cost of the other filter components, the project costs shoot through the roof.

Being a purist, I've not put much time into filter design (busy working on drivers), so other members will likely have more experience.

I get nervous when seeing so many components on a filter. Markaudio driver cones are very micro-resonant sensitive. What filters of this size and type do the input signal............ummmmmmmph. Having listened to several multi-way systems recently, I personally remain planted in the "minimalist" audio camp. But I also appreciate for others, designing and making filters is an interesting part of the hobby.

Cheers
Mark.

[Einric]

How about one of these maybe?
Line Driver With Subsonic Filter

[markaudio]

Originally Posted by Einric

How about one of these maybe?
Line Driver With Subsonic Filter

Hi Einric,
Not recommended. I guess you're looking at the "sub-sonic" part of the device, but there's no advantage that I can see in using this device as signal boost is not the challenge in this case. I'm very weary of devices such as this one. They are rarely get close to being "audiophile" grade.

Thx
Mark.

[Andy17]

If someone is unsure about the values, at
2-Way Crossover Designer / Calculator
Crossover Design Chart and Inductance vs. Frequency Calculator(Low-pass)
you can calculate a 2nd order Butterworth around 40Hz.
(Here you need the Highpass!)
It is clear that a passiv filter is not good choice
I think the only solution, if someone really wants a filter, is an activ filter in front of the power amplifier.
I think some information can be found at the "Digital Line Level" part at this forum?

[planet10]

I would like to note that any passive filter in the region where the impedance curve looks like a roller coaster is going to have very irregualr performance. You would be much further ahead -- both performance wise, and in the pocket-book -- to filter at line level.

dave

[chrisb]

Originally Posted by Einric

How about one of these maybe?
Line Driver With Subsonic Filter

Originally Posted by markaudio

Hi Einric,
Not recommended. I guess you're looking at the "sub-sonic" part of the device, but there's no advantage that I can see in using this device as signal boost is not the challenge in this case. I'm very weary of devices such as this one. They are rarely get close to being "audiophile" grade.

Thx
Mark.

also note this appears to be an automotive system black box - (the inline fuse holder kinda gives it away) - this is an environment in which for the vast majority of listeners the deleterious effects such gadgets might bring to the table are likely swamped by the environment

I mean, I've heard some wonderful sounding "car audio" when the vehicle's standing still - but unless it's a Rolls Royce or other such mobile cocoon, once underway, the finer subtleties can be buried under a noise floor that can easily exceed 70dB SPL.

[Andy17]

So, after >50 hours operating I think could say a few words
First, as you can see, I'm not a professional cabinet maker
Talking about the sound quality is a bit difficult, as, till now, I only used it as center, and I have only one speaker.
As center it really fulfill (beats) my expectation, the voices are "clear" and "full" !!!
It seems that the sounds get more "potent" "stronger" (don't know the right english word) the longer it operates. Maybe I can reduce the resistance of the filter a bit!? But I will wait some hours of operation.
When I have some time I will put it at the Hifi amplifier ... but with one speaker I don't think that I have a lot to say.

[Andy17]

Yesterday I had some time and so I test the speaker with music.
First, I think its nothing complete wrong with the speaker (Well I have no measurment equipment)
I test with all kind of music, even ACDC
With "small" sounds - few instruments/vocals - I find it really great!
With "complex" sound I find it a bit to "cold/thin ?!?"
I think the 200-500Hz is a bit to gentle - or around 1000Hz a bit to much - I have to test it.
The bass is really "incredible" for the small chassis/enclosure.
Ok no deep bass of course (with 59Hz reflex) but there is a clear fine bass!
Mids and highs sound really good, especially the highs are "airy".
(didn't thought that FRs are so good at the highs! And as I read, the Alpairs shoud be better)
With total cost less than €70 (incl. wood, filter components, ...) I am really satisfied with the result!!!

If I find time (and money) I will build a pair of FR speakers.

[Spec]

Im planning to build a pair of these for monitors for my computer.

Would you suggest lowing the port freq from 59hz to something a little lower? say 40 to 45?

Any idea how long the port would have to be then?

[zman01]

Originally Posted by Spec

Im planning to build a pair of these for monitors for my computer.

Would you suggest lowing the port freq from 59hz to something a little lower? say 40 to 45?

Any idea how long the port would have to be then?

Spec,

Arbitrarily lower port tuning for a certain design doesn't usually yield the best results - it can very well result in a spikes in the overall frequency response. Playing around with WinISD I've noticed that if I lower the tuning frequency, usually there is a dip in the 80-200 Hz area, which is not ideal, especially if you are listening to rock/metal. You can maybe do a correction via DSP, but that can sometimes lead to more cone excursion and distortion.

There's a bigger box called the "Half Towers" which is tuned to the mid 40s IIRC:

http://homepage.mac.com/tlinespeaker...aps-150909.pdf

There is a folded version of the half tower that is shorter in height - you can probably find that under "CHR-70 Application Thread" in the forum.