Blog Pages

6/28/17

Universal Audio M610 Tube Preamp

Inside The Universal Audio M610 Vacuum Tube Preamp

The M610 preamp is the same tube preamp used in the LA610,  LA610 MKII and 2-610. The preamp is made up of two separate feedback gain stages that are cascaded one after another.


The UA M610 Circuit

The first feedback gain stage can be adjusted with the "GAIN" switch on the upper left of the front panel. This switch selects a feedback resistor that can add or subtract gain to the circuit. The first tube in the circuit (left tube) is a 12AX7 dual triode.


The following feedback gain stage uses a 6072 (right tube). The 6072 is similar to the 12AT7 dual triode. Notice that the big knob says "LEVEL". This is because it acts like a volume knob and not a gain knob in the circuit.

The first feedback gain stage feeds the 250k ohm "LEVEL" potentiometer and you adjust the input level to the following 6072 feedback gain stage.


More info and measurements coming soon.
Thanks for reading,
Trenton


6/15/17

12AX7 Vacuum Tube Breadboard Adapters On Ebay

BB-NOVAL TUBE ADAPTERS ON EBAY

These are now available on Ebay at this link: BB-NOVAL Breadboard Adapters


They also work with other tubes such as 12AU7, 12AT7 and the EF86 Pentode.  You can learn how to design your own 12AU7 gain stage by reading my white paper 12AU7 Gain Stage Example.

Thanks for reading,
Trenton

12AX7 Vacuum Tube Breadboard Adapter On Ebay

BB-X7 VACUUM TUBE ADAPTERS ON EBAY

These are now back on Ebay at this link: BBX7 Breadboard Adapter.


Find out how to design your own 12AX7 Gain Stage by reading my white paper "12AX7 GAIN STAGE EXAMPLE on my website at trentonblizzard.com .


If you have any questions you can comment here or contact me via my web page.
Thanks for reading,
Trenton


6/13/17

Orange Dual Discrete OpAmp

Orange - Dual Discrete Audio OpAmp

Orange has a new discrete opamp available for purchase. According to Orange, "it's among the most musical sounding dual discrete op-amp out there."


https://orangeamps.com/shop/components/op-amp/#top
SPECS:
Unity gain stable
Rail Voltage: +/- 18 volts max
Current Draw: 18mA
Slew Rate (min): 38V/uS
Open Loop Bandwidth: 48kHz
Open Loop Gain: 112db

PACKAGE SIZE:
Common DIP-8 pinout.
PCB height is 22mm. So, you will need to check for any clearance issues inside your gear.

APPLICATIONS:
According to the Orange web page, it uses low noise JFETS in the front end. It can be used in any CD player, DAC, or preamplifier that currently runs DIP 8 based IC dual op-amp types.

Since JFETS have inherently low current noise, this opamp could be a good choice for the front end of a DI as well. However, 18mA might kill your battery fairly quickly.

It is reported that it can replace the following dual opamps: (clearance accounted for)
    OPA2604
    OPA2134
    TL072
    NE5532
    LM4562
    OP275
    OP285

COST:
£42.00 | $55
Available from the online Orange store.

Thanks for reading,
Trenton

6/7/17

How To Build A 12AX7 Gain Stage Part 4 (Measurements)

Part 4 of my video series on How To Build A 12AX7 Gain Stage. This video covers DC measurements, AC gain measurements, and frequency response measurements. SPICE simulation is then compared to the real-world tube circuit.



Thanks for watching,
Trenton