Quick question on how to easily alter the gain. I built a friend one of these who also uses an Ellekit TU-8850Vk on Klipsch Chorus II. His cartridge is an Audio Technica Moving Magnet. So, a ton of gain and he barely turns the volume up on his Elekit before it gets loud.
He said sometimes when he lifts the tonearm it results in a loud thump that overloads the input of the Elekit and it indicates that with red ring around the volume pot and it distorts a bit until it turns back to green.
I told him each time he changes the record he needs turn the volume down on the Elekit first, but his Elekit isn’t near the turntable.
A couple options I thought of:
Thanks! I’m open to any other ideas.
He said sometimes when he lifts the tonearm it results in a loud thump that overloads the input of the Elekit and it indicates that with red ring around the volume pot and it distorts a bit until it turns back to green.
I told him each time he changes the record he needs turn the volume down on the Elekit first, but his Elekit isn’t near the turntable.
A couple options I thought of:
- lower it by adding a volume pot between the P3 and Elekit
- add a muting switch to the P3 but that could result in a thump too when switched
- or change a couple resistors on the P3 boards
Thanks! I’m open to any other ideas.
Hello All,
For grins and giggles I am going to do as @wayne suggests and reduce R22 to about 110R (place a second 220R resistor in parallel) to see what happens to the gain.
Thanks DT
Added note:
I am downloading Audacity to record some real tracks and visualize pops, clicks and such.
Don't you have an analog oscilloscope? I don't understand that.
By the way:
Wayne deliberately chose the open loop amplification of the first stage, and and and ... I think we should finally put an end to this egg dance.
If you would like a total of 36dB gain for your MM, then you have all the freedom you need to add the two stages -> but then the result is no longer a PEARL 3, but an offshoot or something completely unique.
I am looking forward to your results and thoughts, but at the same time I am also (somtimes) disconcerted.
Best wishes,
HBt.
Shout out to SB.
I sent a PM to SB, paid the money with PayPal and received some very nice looking professional quality P3 PCB's. Good timing I guess.
The idea is to experiment with different part values.
Thanks to SB
DT
Don't you have an analog oscilloscope? I don't understand that.
By the way:
Wayne deliberately chose the open loop amplification of the first stage, and and and ... I think we should finally put an end to this egg dance.
If you would like a total of 36dB gain for your MM, then you have all the freedom you need to add the two stages -> but then the result is no longer a PEARL 3, but an offshoot or something completely unique.
I am looking forward to your results and thoughts, but at the same time I am also (somtimes) disconcerted.
Best wishes,
HBt.
Hello HBt and All,
Yes there is an oscilloscope on the bench. Keysight MSOX3052A
My thoughts are still circling like dots in the Windows loading cursor.
I want to end up with some audio files to share on the big screen in the front of the classroom. I am always thinking lesson plans and visuals. I was a teacher too long.
Today I was poking around in the APx500 software. In addition to the ability to quantify there is also a recorder function that will record the analyzer input in a (.WAV) audio file.
I do have an interest in quantifying, seeing, and hearing all the vinyl noises including clipping. Then formulate an opinion about how much of the finite vinyl / cartridge dynamic range could or should be reserved for overhead margin.
Thanks DT
Hi Wayne, are these worth it for MC so that ideally the jfet input stage is essentially an MM phono preamp where it really shines https://catalog.triadmagnetics.com/Asset/A-11J-Datasheet.pdf
I recently measured the output of my pre-amp. A 45RPM 12in single reached 2.4V peak. A normal LP reached 1.2V peak. My pre-amp has a completely nominal gain of 40dB at 1KHz, and my MM cartridge has a completely nominal output of 5mV RMS at 5cm/s and 1KHz.
Rumble was visible but low in amplitude. I design for >20dB headroom, but the practicality is that any LP that could approach clipping would have a big enough scratch or boulder in the grooves to cause me to discard the LP.
Ed
I haven’t ever used a step up transformer. The Pearl 3 is really designed to be quiet enough for MC straight in.
SO, I looked at that BrownDog site.
https://www.cimarrontechnology.com/product/browndog-970601-so8-to-dip8-adapter
Looks like I can get some SOIC opamps already mounted on the DIP adapter.. Which ones should I try?
I took your approach exactly...and agree about the beauty of the "official" chassis combo.
Here is my completed build of the Pearl 3. I had to change the 220R resistor to 820R to get the current flow via R27 to 3.6mA left and 3.7mA right channel. Need to hear them now with my AT-VM95ML cartridge installed on my DIY TT, presently using a Schiit phonostage. Made a umbilical cord using 20awg cable wires, seems to be good inside the braided sleeve.
Thanks @birdbox and best of luck for your build.
Here you go - https://www.aliexpress.us/item/2251...A1OwqIZH&utparam-url=scene:search|query_from:
You get multiple options like latching, voltage, LED ring with/without the power icon symbol etc., I like the Lanboo branded ones been using them in all my builds since long never failed so far.