Search found 11 matches

by tmuikku
Thu Sep 26, 2013 12:15 pm
Forum: Build
Topic: Dual Class-A Line and Headphone Output Board Documents
Replies: 125
Views: 201559

Re: Dual Class-A Line and Headphone Output Board Documents

Yello! Here is my headamp x 4 box. Works fine at least at the moment 8-) Have to run it some more hours to see if the PSU regulators stay on. The regulator heatsinks are a hack of two small ones, not sure if they are enough... Still have to drill some more holes on top panel, this thing heats up! Al...
by tmuikku
Fri Sep 20, 2013 6:17 am
Forum: Build
Topic: Dual Class-A Line and Headphone Output Board Documents
Replies: 125
Views: 201559

Re: Dual Class-A Line and Headphone Output Board Documents

The output to feed the top track of the pot from the 1240 is labeled "O" the wiper which feeds the DRV134 is "I." Hehe, I thought the opposite in haste and not checking the PCB. Thanks! Sounds very good. Now three more and then see if the PSU holds up. I'm hoping I could get away with standard LM31...
by tmuikku
Fri Sep 20, 2013 4:15 am
Forum: Build
Topic: Dual Class-A Line and Headphone Output Board Documents
Replies: 125
Views: 201559

Re: Dual Class-A Line and Headphone Output Board Documents

Alright got the first one working :) I adjusted as per build document with +-15V supply and then changed it to +-18V. The pin4 on IC1 and IC2 was now measuring around 410mV. Between TP:s I got ~200mV and adjusted that to around 250mV for first test. Sounds good! :shock: But, got problem with pot. I ...
by tmuikku
Fri Sep 20, 2013 2:54 am
Forum: Build
Topic: Dual Class-A Line and Headphone Output Board Documents
Replies: 125
Views: 201559

Re: Dual Class-A Line and Headphone Output Board Documents

Hi! I'm finally putting these together. Its been over a year since I purchased some PCBs :) I've got some questions: I have purchased 18VAC mains transformer for the project. Running the PSU with +-15V DC for four head amps will get the regulators run very hot... I could run the PSU with +-18V to sa...
by tmuikku
Fri May 11, 2012 1:51 pm
Forum: Build
Topic: Dual Class-A Line and Headphone Output Board Documents
Replies: 125
Views: 201559

Re: Dual Class-A Line and Headphone Output Board

Yello! Few questions: 1. Got email from Wayne that a board eats around 200mA current in headphone use with 30V supply. Is this the idle, Iq? Is 500mA +-15V power supply good? 2. How about the volume pot. I'm using DRV134 as output chip and datasheet says input impedance is ~10k. I'm not good enough ...
by tmuikku
Mon May 07, 2012 12:40 am
Forum: Build
Topic: Dual Class-A Line and Headphone Output Board Documents
Replies: 125
Views: 201559

Re: Dual Class-A Line and Headphone Output Board

In a headphone amp, I suppose you would have more room anyway, or just bolt them to the front panel, which would make a super HS! I'll order one small box from here for testing: http://modu.it/galaxyeng.html the sides should be ok for heatsink. If it works ok, I'm building the headphone amps in the...
by tmuikku
Sat May 05, 2012 3:39 am
Forum: Build
Topic: Dual Class-A Line and Headphone Output Board Documents
Replies: 125
Views: 201559

Re: Dual Class-A Line and Headphone Output Board

I'm following with great interest :)
by tmuikku
Sat Apr 21, 2012 10:54 am
Forum: Build
Topic: Dual Class-A Line and Headphone Output Board Documents
Replies: 125
Views: 201559

Re: Dual Class-A Line and Headphone Output Board

mediatechnology wrote:How many do you think you might need tmuikku?
Probably 5 boards since I need 4 headphone amps and the fifth for experimenting, maybe as line driver for a monitor output.
by tmuikku
Sat Apr 21, 2012 10:15 am
Forum: Build
Topic: Dual Class-A Line and Headphone Output Board Documents
Replies: 125
Views: 201559

Re: Dual Class-A Line and Headphone Output Board

Roger, cool stuff!

May I ask what are the dimensions of the PCB? Also, is it considered ok to bolt the transistors to chassis instead of separate heatsink? I know regulators must be insulated from chassis but not sure of the BD139/BD140.

Wayne, I'm ready to buy if you get some boards manufactured ;)
by tmuikku
Tue Apr 17, 2012 10:42 am
Forum: Build
Topic: Dual Class-A Line and Headphone Output Board Documents
Replies: 125
Views: 201559

Re: Dual Class-A Line and Headphone Output Board

Thank you for joining us and posting. Thanks for keeping up very good forum!:) Sounds like they would be perfect other than the combined input impedance issue. The THAT1240 can only drive 2K loads. What you could do however is switch the 1240 inputs to the various sources (balanced) with each pot c...