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I've decided to get rid of those big caps and inductors in signal line and I'm planning to immplement a PLLXO.
The thing is that Davey's .ods files are nowhere to be found and I'm stuck.
Can anyone help ?
Follow Ups:
I would recommend an active crossover if you're handy and have the skills to assemble/test it. Much cleaner conceptually and operationally. Also easily transportable if you change preamp or poweramps.
The page I posted 13 years ago is still there in the tweaks section with examples of both PLL and active versions.
http://www.integracoustics.com/MUG/MUG/tweaks/davey/mg1.6xo.htm
Cheers,
Dave.
Davey, did you try both and came to this conclusion ?
There are some people that gave up on active and settle down with PLLXO (more pleasing soundwise)
The active circuit could easily implemented on a breadboard. I'll give it a try along with PLLXO.
BTW, the level control in active schematic is sort of useless if use same amps, isn't it ?
I find that the highs are much more sensitive than the woofer on my 3.3s. The high out needs attenuation for me. So no level control would be a mistake.
Thanks for the feedback guys,
I guess level control stays,
and while we are at it, what's your favorite opa for this job ?
I never find level controls useless. In this case it allows to use amplifiers with different voltage gains, but even if the amps are identical it allows fine adjustment for personal preference. No drawbacks to level controls at all.
I don't have 1.6's but have numerous MMG's. I used PLL and active and DSP gadgets with those. The simple active circuit I've shown is the best for sound quality and consistent performance for various preamp and amp combinations. It's also really cheap to build too. :)
Cheers,
Dave.
Not necessarily.
If, as in the case of the MG1.6, you have an inductor of 0.4ohms in Series with the bass panel, removal will result in slightly HIGHER bass output. The inductor represents about 10% of the total DCR of the bass circuit.
An attenuator in the bass part of the crossover could be used to bring it back to the same level as the HF part of the panel.
I'll be curious what Davey has to say, and if we agree or he has another take altogether on the level control in active crossovers.
Too much is never enough
I use the level controls as tone controls. Particularly for bass.
What speaker are you implementing? Or what slopes?
MG 1.6, IIRC 500hz
First goal, eliminate the need for powerfull amp which troubled me enough already (don't have the money for BAT, Pass and the likes)
I believe the "ods" files that you are referring to are mine not Davey's. Here is a link to my PLLXO spreadsheet but it it is designed only for those models with 1st order LP and HP filters, like the MMG or MG-IIb. I do have a model for the 1.6 but it is in pretty rough form and while it works for me, it probably would not make sense to anyone else.
As you know, each PLLXO is unique to the the preamps and amplifiers that one uses - change the amps and you need to change the PLLXO. I would be happy to email you the schematic and components if you let me know (email) what the output impedance of your preamp and input impedances of your amps are. Also let me know if you want it single-ended or balanced.
Thanks neolith,
it might be that those files are yours
my amp has input impedance of 19.5kOhm
and my preamp output is 137 Ohm
I want to have the files so I could calculate these myself not to mention that I'll be changing preamp (I think the zero gain B4 won't cut it)
my email is jkemail at gmx dot com
Using my LT Spice and neolith's spreadsheet you might try starting with the following circuit. You can see the Spice run and circuit diagram below.
just found the .ods file in the Tweaks section
my bad
nnnnooowww it's work time
will report when done
thanks guys
Do you have the spreashee handy ?
My email is jkemail at gmx dot com
I'm curious about the result
I've tried a DBX in the past with not great results and got tired and sold it.
I did not use a spreadsheet to come up with my recommendations for you. I used LT Spice. Here are the instructions on how to run it yourself as well as a Spice file I created for your Zpre and Zamp values.Here is how to use the spice file:
1. download LT Spice free here:
http://www.linear.com/designtools/software/2. download the asc file link with this post.
3. Run LT Spice and "file" menu "open" the asc file.
4. From the menu, select "simulate" and then "run" (the running man)
5. Hoover the mouse over the left Y axis and right click. Select "visible traces" and make sure the V_oem V_neo traces are selected.
6. For best viewing, hoover the mouse over the left Y axis again and right click. Select "manual limits" and then set the Y axis as follows: 0db, 3db, -42db (left side) and 120, 30, -120 (right side).
7. Note that R13 and R15 are the Z input of the power amps. R14 is the Z output of the preamp. These values have been set to 137 ohm and 19,500 ohm for your setup.
8. You can change the values of the C and R components by hoovering the mouse over the components and then right clicking. After each component change you have to go back and select the "running man" again to see the changes.
9. The circuit on the top is the "OEM" speaker level crossover that you can use for comparison as you tweak the PLLXO values for the circuit on the bottom.
Also note that this circuit does not have a trim adjustment in it. I have found that when I used this circuit I did need to adjust the volume level of the bass vs tweeter panels of my Magnepan 1.6. So at least for me, there was some sort of behavior that was not being modeled correctly. However, this circuit should get you close. I recommend you prototype the board as I did before committing to a soldered PCB.
Edits: 03/28/14
Very good.
Minor notes:
R14 should be wired in series with the signal source (V2) vice shunting it.
Also, you could include a resistor in series with L1 to simulate DCR.
Dave.
note updated LT Spice file with davey recommended fixes.
again,
thanks guys, you are most helpfull
best regards to everyone
With neolith and davey's help I went PLLXO with my 1.6's.
You can read about it here:
http://db.audioasylum.com/mhtml/m.html?forum=mug&n=196102
also, in that thread you will find instructions and my LT Spice files for simulating the PLLXO and OEM XO networks.
Yeah dumpingground I've seen that
most informative I must say,
I'm thinking of putting the xo inside amp (no humming I hope) what do you say ?
I wanted to go the PLLXO way since paco did that some aeons ago
...
and away we go
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