Hi Mark.
Well if they need 200hrs then there's some way to go!
I'm using LM3875 amps (one for each driver), solid copper CAT 6 cables. The source is a very good NOS TDA1541A DAC by ECDesigns.
I recently made a pair of CHP-70 speakers for my son and they didn't have this brightness. They were theBlue Planet "Sahara" design which have a couple of parallel LCR networks connected in series with the drivers.
John
Well if they need 200hrs then there's some way to go!
I'm using LM3875 amps (one for each driver), solid copper CAT 6 cables. The source is a very good NOS TDA1541A DAC by ECDesigns.
I recently made a pair of CHP-70 speakers for my son and they didn't have this brightness. They were theBlue Planet "Sahara" design which have a couple of parallel LCR networks connected in series with the drivers.
John
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have you tried a different amp (one channel per enclosure with the drivers in series)
many of us tend to favor FR systems without passive compensation/EQ, and Mark certainly engineers the drivers with that in mind
I haven't tried a different amp yet, but I've tried a single LM3875 per channel (Peter Daniel's kit) with the drivers in series. However that sounds to me slightly congested and 'shut in' compared to one amp per driver.
'Castle' microTowers with CHP-70
Happy to say I'm beginning to get a much better balance of sound now. I guess it's largely to do with break-in, but different room placement, plenty of toe-in and placing the boxes on carpet rather than hard surfaces have all helped move things in the right direction.
I'm beginning to listen to the music again, rather than the speakers.
Happy to say I'm beginning to get a much better balance of sound now. I guess it's largely to do with break-in, but different room placement, plenty of toe-in and placing the boxes on carpet rather than hard surfaces have all helped move things in the right direction.
I'm beginning to listen to the music again, rather than the speakers.
...its just so cold in the workshop I'm finding it hard motivate myself
Glue them up in the kitchen while she's out?
It seems that there is an error in equation from the microTower plans (http://homepage.mac.com/tlinespeakers/FAL/downloads/microTower-maps-150909.pdf).
Lv = (23562.5*Dv^2*Np/(Fb^2*Vb))-(k*Dv)
For halfTower project:
Lv = 5.72 cm
Dv = 3.56 cm
Np = 1
Fb = 42 Hz
k = 0.732
With these parameters Fb should be 20.34L but according to plan it's more like 12.6L. I know that damping material virtually enlarge net volume but isn't 61% too much?
And with second suggested port size: Lv=15.24, Dv=5.08 >>> Fb=18,18L (!?)
Lv = (23562.5*Dv^2*Np/(Fb^2*Vb))-(k*Dv)
For halfTower project:
Lv = 5.72 cm
Dv = 3.56 cm
Np = 1
Fb = 42 Hz
k = 0.732
With these parameters Fb should be 20.34L but according to plan it's more like 12.6L. I know that damping material virtually enlarge net volume but isn't 61% too much?
And with second suggested port size: Lv=15.24, Dv=5.08 >>> Fb=18,18L (!?)
Thanks, I mistyped that.
Still don't know why is in the MLTL speaker project plan and how did Dave actually calculate port dimensions.
Hi djanci,
My apologies! I did not read your orignal message properly, but now I see the classic vent formula on page 8 of the PDF you linked to. Sorry I did not read your original message properly!
I also get Vb of 20.3 liters by the formula, and the halfTower seems to have a Vb of about 17.9 liters? My math is pretty bad though.
My apologies! I did not read your orignal message properly, but now I see the classic vent formula on page 8 of the PDF you linked to. Sorry I did not read your original message properly!
I also get Vb of 20.3 liters by the formula, and the halfTower seems to have a Vb of about 17.9 liters? My math is pretty bad though.
As i understand it, once you have a proper ventsize, the classic calculation can be used to convert one size port to another size port. If you do it right Vb & Fb cancel and are not in the equation. Guess i should do the gymnastics to remove that.
The goal is to calculate a new Lv', Dv'.
Lv = (23562.5*Dv^2*Np/(Fb^2*Vb))-(k*Dv)
Let Np=1 Let 23562.5 = a
Lv + (k*Dv) = a*Dv^2/(Fb^2*Vb)
Fb^2*Vb = a*Dv^2/(Lv+(k*Dv))
then a*Dv'^2/(Lv'+(k*Dv'))= a*Dv^2/(Lv+(k*Dv))
(Lv'+(k*Dv'))/Dv'^2 = (Lv+(k*Dv))/Dv^2
Lv'/Dv'^2 + k/Dv' = Lv/Dv^2 + k/Dv = constant = X
choose a convienient Dv'
Lv' = (X - k/Dv')*Dv'^2
(someone double check my algebra?)
dave
The goal is to calculate a new Lv', Dv'.
Lv = (23562.5*Dv^2*Np/(Fb^2*Vb))-(k*Dv)
Let Np=1 Let 23562.5 = a
Lv + (k*Dv) = a*Dv^2/(Fb^2*Vb)
Fb^2*Vb = a*Dv^2/(Lv+(k*Dv))
then a*Dv'^2/(Lv'+(k*Dv'))= a*Dv^2/(Lv+(k*Dv))
(Lv'+(k*Dv'))/Dv'^2 = (Lv+(k*Dv))/Dv^2
Lv'/Dv'^2 + k/Dv' = Lv/Dv^2 + k/Dv = constant = X
choose a convienient Dv'
Lv' = (X - k/Dv')*Dv'^2
(someone double check my algebra?)
dave
Dave, your algebra is 100% correct. Now lets solve k from the equation:
(Lv'+(k*Dv'))/Dv'^2 = (Lv+(k*Dv))/Dv^2
Dv'^2* (Lv+(k*Dv))=Dv^2*(Lv'+(k*Dv'))
k=(Dv^2*Lv'-Dv'^2*Lv)/(Dv'^2*Dv-Dv^2*Dv')
Substituting values from table at page 8 for CHR-70 halfTower:
Dv=35.6 Lv=57.2
Dv'=50.8 Lv'=152.4
k=5.37 (too large value for end correction!)
That means either Lv or Lv' is incorrect. If Scott is right than Lv' value is incorrect. Dave, can you double check values in the table?
(Lv'+(k*Dv'))/Dv'^2 = (Lv+(k*Dv))/Dv^2
Dv'^2* (Lv+(k*Dv))=Dv^2*(Lv'+(k*Dv'))
k=(Dv^2*Lv'-Dv'^2*Lv)/(Dv'^2*Dv-Dv^2*Dv')
Substituting values from table at page 8 for CHR-70 halfTower:
Dv=35.6 Lv=57.2
Dv'=50.8 Lv'=152.4
k=5.37 (too large value for end correction!)
That means either Lv or Lv' is incorrect. If Scott is right than Lv' value is incorrect. Dave, can you double check values in the table?
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