seth@miro.Berkeley.EDU (Seth Teller) (03/11/91)
i've been fooling with /dev/audio for the first time and there seems to be an awful lot of noise coming from the 'out' port. i've got a six-foot patch cord leading from that to an active (i.e., amplified) speaker, and a continuous low-frequency rumbling comes from the speaker. i think it's related to the power supply, since when i run a grfix program or even press carriage return in my wsh, the sound changes. finally, this happens whether or not anything is plugged into the 'mic' or 'in' ports, and whether or not /dev/audio is being read or written at the time. thanks for any help or advice. seth
SCHMIDT@SCHMDT.FNAL.GOV (Boy Programmer) (03/11/91)
Its been my experience when using the audio port of the sgi that the gain must be reset to zero when you are done using it. = Jack C. Schmidt "Nagy Commando" = Fermilab Computing Division/Distributed Computing Dept/Special Projects Grp = HEPnet/SPAN: FNDCD::SCHMIDT (43123::SCHMIDT) or FNAL::SCHMIDT (43009::SCHMIDT) = Internet: SCHMIDT@FNAL.FNAL.GOV = BitNet: SCHMIDT@FNAL = USnail: Fermilab POB 500 MS/234 Batavia, IL 60510
msc@ramoth.esd.sgi.com (Mark Callow) (03/12/91)
In article <1991Mar10.235452.13067@agate.berkeley.edu>, seth@miro.Berkeley.EDU (Seth Teller) writes: |> i've been fooling with /dev/audio for the first time and there |> seems to be an awful lot of noise coming from the 'out' port. |> i've got a six-foot patch cord leading from that to an active |> (i.e., amplified) speaker, and a continuous low-frequency |> rumbling comes from the speaker. |> This is typical of PI audio. It is not of very high quality. If you have a serious interest in audio I recommend you get a 4D/35 upgrade. The 4D/35 audio is completely new and is of high quality (AES/EBU digital input/output, 16 bit A/D for analog input, >18-bit 8X oversampling D/A for analog output etc.) We hired an Audio Engineer this time. Please note that initial shipments of the 4D/35 will not have the audio board due to various in-house delays. An audio kit will follow later. -- Captain Multi-Media (aka Mark Callow) msc@ramoth.sgi.com, ...{ames,decwrl}!sgi!msc "Spirits of genius are always opposed by mediocre minds" - Albert Einstein
jack@cwi.nl (Jack Jansen) (03/13/91)
Both sound input and output are noisy on the 4D25. I get an average of 2 bits of noise when recording with a mike that is switched off, and an audible hiss out of the speaker even when the output gain is set to zero (it is worse with non-zero gain, obviously). Everything the machine does effects the noise (moving the mouse, computations, network traffic), so I assume that it is not a question of improper shielding, but more one of coupling through the power supply. I guess they should market it as 'a 6 bit audio interface' in stead of an 8 bit one. I'll just wait for my 4D35 to arrive before doing any real audio work. The quality is good enough for my audio-biff, though. -- -- Een volk dat voor tirannen zwicht | Oral: Jack Jansen zal meer dan lijf en goed verliezen | Internet: jack@cwi.nl dan dooft het licht | Uucp: hp4nl!cwi.nl!jack