T15 built and working, but ?s about pops and +48

[radrobot]

Had fun building the T15, especially now that it works.

Question 1: When I turn the gain knob, it sends a pop noise through the monitors when clicking to each gain stage. Is this normal? Have I done something wrong?


Question 2: My phantom power readings are +45.4 when on and .4 when off. Is this normal?

Thanks for your help.

[tpryan]

What voltage do you measure between U1, pins 1 and 8?

Your phantom voltages are fine.

[radrobot]

Voltage from pin 1 to 8 on U1 is .023

I'm assuming the pin configuration is:

notch
1 8
2 7
3 6
4 5

I'm placing the black (-) lead on the DMM to pin 1 and the red (+) lead to pin 8.

[radrobot]

I've edited the above reply a couple of times because of my ignorance.

[tpryan]

Does the voltage between pins 1 and 8 change as you switch gain?

[radrobot]

Today I'm getting a reading of .026 to .027.

No, voltage does not change when switching gain.

[mikew]

What is the acceptable range for the phantom power? I usually get about 46.5 or so as well.

Thanks,

- Mike

[tpryan]

46.5V is perfectly OK.

[evolver]

Had fun building the T15, especially now that it works.

Question 1: When I turn the gain knob, it sends a pop noise through the monitors when clicking to each gain stage. Is this normal? Have I done something wrong?

hey there i am in the same boat. i just finished building a T15, all measurements checked out and when i plug in a mic it sounds clear and has plenty of gain, however when i turn the gain knob i get a loud popping that i don't get from my A12 and N72 modules.

did you resolve this ?

[tpryan]

Measure the voltage between U1, pins 1 and 8. It should be very close to 0V. If it isn't, check your soldering around U2, R22, R23, R6, R7, C8, and C9.

[Joel C]

Had fun building the T15, especially now that it works.

Question 1: When I turn the gain knob, it sends a pop noise through the monitors when clicking to each gain stage. Is this normal? Have I done something wrong?

hey there i am in the same boat. i just finished building a T15, all measurements checked out and when i plug in a mic it sounds clear and has plenty of gain, however when i turn the gain knob i get a loud popping that i don't get from my A12 and N72 modules.

did you resolve this ?

Same pop sounds over here.
Anyone solved the issue?

[tpryan]

Measure the voltage between U1, pins 1 and 8. It should be very close to 0V. If it isn't, check your soldering around U2, R22, R23, R6, R7, C8, and C9. If it is close to 0V, the circuit is working properly and whatever pops you're hearing are normal.

[dblair]

I had the same issue of sounding fine but getting pops when switching gain. My Conn 1 readings were also low around 25v. So I re-soldered U2, R22, R23, R6, R7, C8, and C9. When I powered back up. the gain switch popping was gone But now everything is distorted on any setting whether it by phantom or dynamic mics. Totally unusable sound.
To be more specific it goes between almost clear to distorted sound to cutting out completely at random intervals of a couple of second between.

Conn 1 readings are still low at about 27-29v, when off about -55 mv. And measuring across U1 pin1-8 I get -6 to -8 v sometimes more.

I then unsoldered and resoldered the above mentioned connections with the same results. Except now the popping on the gain switch is back.

My other T1 that I built right after this one works perfectly.

What would cause this type of problem?