Lord Jims Updated PCB
The green PCB shown in your message is identical to the blue PCB I recently received from Douk. It is the latest/current MX50 SE model.
On the underside there is text with instructions about amplifier gain (330R/470R) and the limits on the supply voltage (12 < VDC < 45)
The green PCB shown in your message is identical to the blue PCB I recently received from Douk. It is the latest/current MX50 SE model.
On the underside there is text with instructions about amplifier gain (330R/470R) and the limits on the supply voltage (12 < VDC < 45)
That is roughly what I had calculated when figuring out which filter caps to use in the first rectifier board.
Any advice on how to make the load safe even up to and at the limit of the MX50SE (around 45V)? Not sure introducing actual speakers into my situation are going to help anything if I am trying to use that driving signal for low distortion measurements and calibration. For most people that is the obvious answer, for me, I guess I need to use power inductors or capacitors for a safer load?
I have recently read back up on phasor diagrams and how impedances workout with AC signals. However, I would really appreciate a little guidance on this topic. I'm in the middle of writing a calibration guide for the Potomac AA-51, which links to this great thread for finding help on the "47 Ohm Fire Resistors", lol! I'm a 1st Semester Jr in EE, but I'm switching to Electrical Tech next semester because of what my interests are turning to. So, I know more than the average bear, but far from being a "real engineer", perhaps one day!
Thanks in advance for any help!
That means a 10k pot on the input is not a good solution to reduce sensitivity.
What consequences can it take to increase the 470R resistor in feedback to 1K?
Quick look at the schematic of MX50SE shows that there is 100k resistor in front of input filters, so, yes, it is possible to use 10k pot at the input of MX50SE to reduce sensitivity. But it is also possible to reduce gain of amp by using 1k gain setting resistor instead of 470R.
I would suggest that you use pot because if you lower the gain of amp it could become unstable. Lowering the gain rises HF response of amp and that is risky if you don't want to redesign the whole amp.
I would suggest that you use pot because if you lower the gain of amp it could become unstable. Lowering the gain rises HF response of amp and that is risky if you don't want to redesign the whole amp.
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Thanks! Understand that buffer will be the very best in this case. Increasing the 470R in the feedback is also not a good idea. The purpose of C7 (100pF) will change if the source impedance becomes too high - so 1K is a good proposal for the upper limit of source impedance.
Does not find that the SELF "bible" refers to this, other than a potmeter at the output of the source can make some cable problem.
Does not find that the SELF "bible" refers to this, other than a potmeter at the output of the source can make some cable problem.
10k log pot will see 100k as load. The loading of the pot will be correct. I am not educated in electronics, so I may be wrong. Pot solution is simplest but not the best. Buffer is better, but if you make buffer than output impedance will be defined with series output resistor which can be as low as 50 Ohms. No need to make output impedance of buffer so high as 1k.
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Welcome everyone! Which preamplifier is used for the mx 50 se panel at the factory?
I've already tried this: LJM PREAMP 9 Single-Ended Class A Transistor Preamplifier 2018 Version | eBay
But that did not work well! The 10R1w resistance was hot.
that's what I tried:Aiyima NE5532 HIFI Lossless Audio Treble Bass Adjustment Tone Board Amplifier | eBay
But this did not amplify anything! It's as if there was not a preamplifier.
Is such a preamplifier solved this problem?
LJM Mini P7 Preamp Kit For MX50 L20 L6 Power AMP DIY AMPLIFIER KIT J163 6976350784522 | eBay
I've already tried this: LJM PREAMP 9 Single-Ended Class A Transistor Preamplifier 2018 Version | eBay
But that did not work well! The 10R1w resistance was hot.
that's what I tried:Aiyima NE5532 HIFI Lossless Audio Treble Bass Adjustment Tone Board Amplifier | eBay
But this did not amplify anything! It's as if there was not a preamplifier.
Is such a preamplifier solved this problem?
LJM Mini P7 Preamp Kit For MX50 L20 L6 Power AMP DIY AMPLIFIER KIT J163 6976350784522 | eBay
İ have 2x24v 300vac toroidal transformer for poweramp ljm mx 50se and 2x12v 30vac for p7 mini preamp. İ measure ac voltage difference between grounds of two transformer. As a result i cannot use the preamp... There is a phase difference between two transformer i think but this is not make sense to me.
Any idea to overcome this situation??
Any idea to overcome this situation??