Bridging is possible as long as output current stays within the limits of 8 Aeff, now calculate. 🙂
Don't know for L.C, but, on my opinion, with digital sources, this kinf of thing:
Dale 23 Step Ladder Type Potentiometer Volume Control LOG 10K Ohms Stereo | eBay
is the most transparent and long lasting device you can find.
(Take attention to of the quality of the resistances.
Just set with it your level a little louder than you need, and fine tune down with your digital source.
If you need more channels, this kind of stuff:
Search in ebay for:
LCD volume control preamplifier board+Remote control
http://6.taoxiaobao.net/2011/06/starlidd1234/%E9%BE%99%E5%8D%8E/16.jpg
can work well, with little modification (quality caps etc...)
btw, LC, Did-you had my PMs and E-Mails ?
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Is this becoming a french bar here ?
Bobo The Cat, are you in also ? Don't you have some unfinished Panson Stuff ?
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Hi Christophe, i like something like this.Don't know for L.C, but, on my opinion, with digital sources, this kinf of thing:
Can you comment if this solution need a buffer between the step ladder and input of VSSA. Based on what i seen i imagine it needs a buffer especial for good low z to go into VSSA 10K input and not interfere VSSA input filter calgutated cutoff.
If it needs buffer do you have circuit suggestion you would share ? Imagine a LME49710(VFB)/LME49713(CFB) could do.
Regards Ricky
Actually the more transparent (and In my opinion more interesting) option is the circuit that Bruno Putzeys published in Linear audio.
Thanks for the hint, i will read that article later. For others if interested it is Linear Audio Volume 5. Available at www.linearaudio.net.
Regards Ricky
Is there something more transparent than a non magnetic thin metal resistance ?
Exactly there is the problem. Personally I agree with Putzeys on the matter, as he writes about it in the Linear audio article.
Input of the ladder shorted (low output impedance from your preamp), the max output impedance of a 10K volume control will be 1.4K at full power-1. Less than 1K at normal levels.
According to the 100 Ohms, 100pF provided in the L.C. schematic, it will give you a -3db cutoff at ~1MHz and a phase error of < 1.2° at 20KHz.
You can use-it without any active device between Ladder and VSSA for an unmatched transparency.
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AS long this volume control is in the amplifier case itself, of course.
If it is in a preamplifier, you will need a buffer after-it.
On my side, i prefer a Current feedback OPA, buffered with two discreet transistors in push-pull, inside the feedback loop.
Then i protect the output with a 100/150 Ohms resistance, both against the short circuits and EMI/RFI returns in the feedback loop itself.
Thanks for explanation.
Is it possible to get data for output impedance from preamp you use in calgulation, it is for learning about calgulation.
See #post830 for input filter change later than #post300 schematic.
Post 2374, i have seen such circuits here in domain somewhere.
I start with 10K just before VSSA, and later will do some test if it needs buffer.
Must solder this weekend, now i have all stuff VSSA/Hypex/heatsink and small parts arived today. 🙂
Ricky
Is there any documentations on using the amp ?
Hello,
I am awaiting the arrival of the these boards and would like to do some read up in the meantime.
Details such a s the parts to order, the heatsink requirements, the power supply and the necessary adjustment before hooking up to sepakers.
Please point me to the relevant threads
thanks
kp93300
Hello,
I am awaiting the arrival of the these boards and would like to do some read up in the meantime.
Details such a s the parts to order, the heatsink requirements, the power supply and the necessary adjustment before hooking up to sepakers.
Please point me to the relevant threads
thanks
kp93300
kp93300, the boards LC supplies include everything except for 8 capacitors, listed here:
http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-114.html#post3486981
http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-114.html#post3486981
Well, i thought about this and made some sims. (Can interest L.C. as well).
It is about the C4/C6 caps. in the VSSA (see http://www.esperado.fr/fr/temp/compare_vssa/vfa-schematic.gif).
BRYTT, you noticed a little change in the group delay at low frequency, due to the low pass filter they introduce. I answered it was not a real issue.
But, looking to the descending distortion curves in simulator, i realized it has a direct influence on distortion, even at 1000Hz, due to the little phase turn they introduce in the loop. Trying to increase the value to 100 000 µF and the distortion at 100Hz goes from 0.0032 to 0.00048 %.
I don't know if it will make a real difference in real the world we are living-in, so far from the perfect simulator one, but may-be...
Considering the few DC mV on this cap, it would be interesting to try a super/ultra capacitor (double layer) here and listen if any difference?
A transformer based (some say an autoformer) volume control would be better, IMHO.
There are some not so expensive autoformer sellers in Europe.
Salutations,
M.