Thanks for the song - very nice. I also like this one for testing head phone amps.
https://www.youtube.com/watch?v=s6_B1AB9nu8&sns=em
Just listened to it on the 770s. Yes good on the Beyer's sonic style indeed.
I have a problem
I just measured the spectrum of my DCG3 and it looks like there are some oscillation issues. I can't really hear it all that well but it shows up like a xmas tree on the FFT. My simple 2 transistor amp measures clean so I know the rig and software are not at fault. Using UCA202 and RightMark software.
What do you all think could be causing this?
As a comparison of a clean amp, the same rig measures this:
I just measured the spectrum of my DCG3 and it looks like there are some oscillation issues. I can't really hear it all that well but it shows up like a xmas tree on the FFT. My simple 2 transistor amp measures clean so I know the rig and software are not at fault. Using UCA202 and RightMark software.
What do you all think could be causing this?
As a comparison of a clean amp, the same rig measures this:
Attachments
Are you sure that you don't ovedrive the unit?Let me try a better PSU and in different room. There seems to be RFi in that room.
Pay attention on RMAA vu-meter
Regarding the signal wiring, if running twinax with a sheild should I connect the shield at both ends on all connections inside the amp or just connect it at the source end? Is it better to "complete" the shield throughout the input signal wiring or leave each individual sections with the shield only connected at the source end? Iam thinking it's better to connect all the shields except the one to the amp board input so it all drains to the source. Any opinions?
I set it up in another room with a known good PSU (7815/7915 based with CRCLC filtering good for solid 150mA bias). Unfortunately got the exact same HD xmas tree bloom. So I added a 50k pot and below a certain level (-2.7dB on VU meter - it says -1dB should be good), the HD goes nuts - just explodes. But a tad below and it vanishes. There is a minimum input load that is required to keep the amp stable. I should measure what that setting on the pot is and just add a hardwire resistor to ground to keep it from happening.
Here is the new FFT with the pot set so that the distortion doesn't blow up. Much better - this amp is predominantly H3 and H7 - I suppose having a differential input pair does that?
Here is the new FFT with the pot set so that the distortion doesn't blow up. Much better - this amp is predominantly H3 and H7 - I suppose having a differential input pair does that?
Attachments
Don't you have single coax for each channel signals? Its better.. Connect all shields to the PCB common. I would connect both ways the amp's wire shield too. I would try differently only in case of hum loop.
Seperate twinax each channel. 2 wires plus shield each channel.
In this diagram should I connect the shield at the vol pot and amp or leave it disconnected at the amp to "drain" like some interconnects do?
For the psu I will probably just connect the shield at all connections.
Attachments
- Home
- Source & Line
- Analog Line Level
- Salas DCG3 preamp (line & headphone)