John Curl's Blowtorch preamplifier part II

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31697B

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Free MLS software -

I mentioned this on another forum awhile ago but forgot until today --- Get MLS while it is still free and use it on a crossover (as well as a driver/speaker system):
Free MLS software at:



Might need Google translator.

Thx-RNMarsh


KSTR said:
I'm saying that desiging a conventional symmetric Linkwitz-Riley XO generally gives the best compromise for the drivers overall (this is agreed on by many people), its only drawback is the allpass behaviour making it non transient-perfect, and that can be eliminated by preprocessing the input signal with an analytically derived FIR -- "non-causal" -- filter (no artifact), giving a linear phase Linkwitz-Riley XO. The filter kernel for convolution is simply the time inverse of the allpass impulse response. This is probably one of the few things where a free lunch can actually be had, the main downside are latencies of the filter itself and of the digital processing and a slight loss of headroom / dynamic range. Typically one has to lower input level to the convolver by 6dB or so to avoid digital clipping.
A tool to play with, for these matters, is rePhase (freeware, there's a thread on it here at DIYA).

For a real world example, look up the white paper on the Grimm Audio LS1 monitor speaker, albeit IIR filters are used for the driver EQs and XO instead of analog ones (but they behave the same), and ahead of that is a small FIR filter that undoes the allpass phase.
Click to expand...
 
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KSTR

KSTR

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Joined 2007
RNMarsh said:
I mentioned this on another forum awhile ago but forgot until today --- Get MLS while it is still free and use it on a crossover (as well as a driver/speaker system):
Free MLS software at:



Might need Google translator.

Thx-RNMarsh
Click to expand...
That's nice, but it looks like it is lightyears behind other freeware of this genre, like HolmImpulse and especially REW (Room EQ Wizard, don't get fooled by the name, this is a freeware that eats many older 10k$++ "pro"-software for breakfast).
 
gpapag

gpapag

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john curl said:
Too much is implied that BS is dominant in hi end audio. They mostly mean well, and those who insult them are insulting everyone in the trade, rather than just the true BS'ers.
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IMo, some mean well and these who mean well, better keep distance from those who don’t mean well instead of feeling insulted by the remarks or critique directed toward those who don’t mean well.

George
 
EUVL

EUVL

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xen-audio.com
> Well, everybody out of 'questions'?

I have one, slightly out of topic, but I think nevertheless interesting (I hope at least).

How to make a constant current source, ideally 2-terminal, that is low noise, temperature and long term sable, and yet simple ?

Take some target specs :

Current 8mA
Current stability <+/-0.1% over time
Room temperature 18°C~28°C
Voltage headroom 3V min, 9V max
Current noise <<-120dB over audio band

I have looked at Walt Jung's article, scientific journals, .......
There does not seem to be a clear winner.

At first instance I would have done it with a heavily degenerated JFET.
It satisfied many of the requirements, but the current changes with room temperature.

Any good suggestions or pointers ?


Patrick
 
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31697B

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KSTR said:
behind other freeware of this genre, like HolmImpulse and especially REW (Room EQ Wizard, don't get fooled by the name, this is a freeware that eats many older 10k$++ "pro"-software for breakfast).
Click to expand...

Great to get even more examples of free software that can do MLS measurements. Try them thru all electronic audio gear and the whole system for the fun of it.... not just for room/speaker application.

No reason for anyone to say they couldnt afford it so they never tried MLS tests in various apps.


-THx-RNMarsh
 
jan.didden

jan.didden

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linearaudio.net
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EUVL said:
> Well, everybody out of 'questions'?

I have one, slightly out of topic, but I think nevertheless interesting (I hope at least).

How to make a constant current source, ideally 2-terminal, that is low noise, temperature and long term sable, and yet simple ?

Take some target specs :

Current 8mA
Current stability <+/-0.1% over time
Room temperature 18°C~28°C
Voltage headroom 3V min, 9V max
Current noise <<-120dB over audio band

I have looked at Walt Jung's article, scientific journals, .......
There does not seem to be a clear winner.

At first instance I would have done it with a heavily degenerated JFET.
It satisfied many of the requirements, but the current changes with room temperature.

Any good suggestions or pointers ?


Patrick
Click to expand...

Patrich hgave you tried a diode as part of the degeneration to cancel tempco?

Jan
 
scott wurcer

scott wurcer

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Joined 2004
john curl said:
Too much is implied that BS is dominant in hi end audio. They mostly mean well, and those who insult them are insulting everyone in the trade, rather than just the true BS'ers.
Click to expand...

I'm not sure I agree with "mostly mean well" but the case of Feastrex is different. The washi paper cones handmade by a national treasure is a classic mix of ritual and hobby. They make no extraordinary claims in fact it could very well be the best paper for a paper cone. The leather suspention is anyone's guess but all in all this seems similar to buying a $3500 kitchen knife made by a national treasure sword maker in his spare time (you can spend a lot more BTW).
 
KSTR

KSTR

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RNMarsh said:
Great to get even more examples of free software that can do MLS measurements.
Click to expand...
Most of todays software use Farina log sweep and convolution as it proved to be much more robust than MLS techniques and it also measures/isolates distortion components directly... MLS systems were common because they were easiest to implement in hardware 30yrs back, MLSSA being the best known system.
 
a.wayne

a.wayne

Member
Joined 2008
EUVL said:
> Well, everybody out of 'questions'?

I have one, slightly out of topic, but I think nevertheless interesting (I hope at least).

How to make a constant current source, ideally 2-terminal, that is low noise, temperature and long term sable, and yet simple ?

Take some target specs :

Current 8mA
Current stability <+/-0.1% over time
Room temperature 18°C~28°C
Voltage headroom 3V min, 9V max
Current noise <<-120dB over audio band

I have looked at Walt Jung's article, scientific journals, .......
There does not seem to be a clear winner.

At first instance I would have done it with a heavily degenerated JFET.
It satisfied many of the requirements, but the current changes with room temperature.

Any good suggestions or pointers ?


Patrick
Click to expand...

I was thinking along these lines ...

Take some target specs :

Current 22A
Current stability <+/- 5% over time
Room temperature 18°C~28°C
Voltage headroom 3V min, 9V max
Current noise <<-120dB over audio band
 
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