Hifi Preamps for your Record Player

By: skrodahl | October 16, 2018

Several people have been in touch lately with questions on how to modify the PCB into something it isn't right now. Popular requests are balanced inputs and/or balanced outputs, and DC servo on the outputs.

The PCB itself doesn't really lend itself to any of the modifications above, but you could always try doing add-on boards or roll your own from the open source freely available schematics.

An explanation of the Muffsy Phono Preamp PCB layout can come in handy for such alterations. And wouldn't you know, here it is:

Muffsy PP-4 PCB Layout
The Muffsy Phono Preamp PP-4 PCB Layout

Modifications you can do are changing the input impedance and altering the variable gain. I'm also happy to announce that the gain calculator has been updated to show the output voltage and voltage gain:

Muffsy PP-4 Gain Calculator
Muffsy PP-4 Gain Calculator

Finally, if you want to make major modifications, a way of simulating the circuit would really come in handy. Well, here's the Muffsy Phono Preamp LTSpice simulation file.

Muffsy LTSpice Simulation
Muffsy Phono Preamp LTSpice Simulation

By: skrodahl | June 27, 2018

Behold the new Muffsy Phono Preamp!


It'll be available on Tindie, very soon. Actually, it is available: https://www.tindie.com/products/skrodahl/muffsy-phono-preamp-kit/

The new Muffsy Phono Preamp PP-4

What's New?

These are basically the same circuits as before. The focus has been on making the build experience even easier than before, and improve noise prevention.


  • The op amps are OPA2134 and LM4562
  • SNR improved by 2.9 dB, from 79.4 dB to 82.3 dB
  • No screw terminals facing the side walls of the enclosure
  • The AC power cables do not cross the input
  • The DC power cables do not cross the output
  • The AC and DC power connectors line up on the PP-4 and PSU boards
  • The signal inputs and outputs line up with the RCA connectors on the back panel
  • The grounding scheme is redesigned to avoid ground loops
  • The input impedance switches are grouped together
  • The gain switches are grouped together
  • The back panel has a ground pad in one of the corners, to ground the cabinet
  • The back panel now has gold pads and the golden "M" logo
  • The power supply now has the golden "M" logo
  • There's room for heat sinks on the power supply voltage regulators (if needed)
  • The solder pads for the screw terminals are beefier
  • The mounting holes have been increased from 2.8 to 3.0 mm
  • The board width is approx 0.5 mm narrower for a better fit in the B0905 cabinet
  • The board's corners are even more rounded to make it easier to insert into the B0905 cabinet

Built-in Grounding of the Enclosure

One prime example of the thought that's gone into this new version is the fact that the back panel connects to the enclosure for improved grounding and shielding from noise:

 
Back Panel ground pad
 
Grounding the Muffsy PP-4

Crisp, Clear Pictures

I've put my new lightbox to good use, and produced some really nice pictures for the instructions.


Here's one of the new photos compared to the corresponding old phono. Judge for yourself:

New Power Supply Instructions
Old Power Supply Instructions

Thanks

This new version of the Muffsy Phono Preamp couldn't have been created without the (without exceptions) enjoyably long and fruitful email conversations with so many people. Keep using the contact form.


A special thank you goes to the loyal customers who helped me test the prototypes and provided valuable feedback, you know who you are. ;)

Category: News 

Tags: muffsy, phonostage, vinyl, launch, pp-4 

By: skrodahl | August 31, 2017

YouTube user Blake G has posted a couple of vinyl-rips using the Muffsy Phono Preamp onto the video site. Although YouTube probably alters the bitrate, you can still get an idea on how the Muffsy Phono Preamp performs in his setup. His setup, btw, is:


    • Turntable: Sony PS-X500
    • Cartridge: Empire 999ve/x
    • Phono Stage: Muffsy PP-3
    • Line In: Behringer UCA202

Muffsy Vinyl-rip on YouTube

Here are the links to Blake G's two rips:

 
 

Category: News 

Tags: muffsy, phonostage, vinyl, youtube, rip 

By: skrodahl | September 26, 2016

UPDATE:

Since only one extra resistor value is needed to get the higher impedances, it's been added to the kit. Now you can choose between these two options.

The input impedances on the Muffsy MC Head Amp can be changed to your liking. To help you find the right values, here's a nifty input impedance calculator.

Muffsy MC Head Amp - Default Input Impedances

You can play around with the values for R1, R2 and R3, and the calculator will show you what the input impedance choices will be. With all the switches set to OFF, the input impedance will be equal to R3.

The picture shows the values that are included in the kit.


PLEASE NOTE:
The resistors R3 MUST be installed, or you risk that the Muffsy MC Head Amp won't function.

Here's a suggestion for other component values, if you need a bit higher impedance:

Muffsy MC Head Amp - Alternative Input Impedances

By: skrodahl | September 21, 2016

After a lot of testing, ordering of components, assembling kits, more testing and writing build instructions, the Muffsy MC Head Amp kit has finally launched!

If you're looking for a way to use low output MC cartridges with your Muffsy Phono Preamp, or any other MM phono stage, look no further! 
Get it on Tindie today for only $79!

You can now build your own MC Head Amp

One very important requirement before launching the kit was to have a section in the build instructions on testing the circuit before you power it on, and troubleshooting the head amp if the tests fail. That all came together last night, and then it was just a matter of opening the gates at Tindie.


The build instructions for the Muffsy MC Head Amp contains every step from start to finish, including customization, testing and troubleshooting, all in one single page. This makes it easier to build than ever. And remember: If you don't know how to solder, EEVBlog's videos will get you going  in no time at all.

next>>