Hi hope somebody can help with suggestions please. My phono stage and integrated amplifier are located some distance away from each other and for various room layout reasons I would like to retain that. The distance a cable would travel would be approx. 10M. If this is operating at line levels e.g. 200-300mV what cable type would be best to avoid noise pick up or system issues. Would standard twin individually screened audio cable be sufficient or would I need something special.
Thanks
Mark
Thanks
Mark
I had a 4 m coax rca plug cable carrying line level from the RA-88a mixer to the ST120 amp, and it was picking up AM radio. RA-88a had 33078 op amp single ended output on RCA jacks.
Twisted pair does better up to 33 m but it takes a differential drive on the two wires to work properly. You can do that with two op amps, one inverting, the other not. Twisted pair cable can have 1/4 phone plug both ends, or if 2 pairs, stereo 1/4 phone plug. Doesn't have to be shielded.
The cheapest way IMHO is to buy a mixer with stereo 1/4 phone plug to the power amp. I picked up a Peavey PV8 mixer $60 with freight. It came with a dead left output which turned out to be a bad via through the board. The master volume pot was bad. A new 10k bourns slide pot was $2 but the box of 2 mm screws to hold it to the panel was $6. When that was stolen I bought another PV8 with freight for $88. Turns out that one was working, at least as far as I've checked it. No charger but a 12 vac charger from the charity resale shop for $1 works for signals up to 9 vac. 16 vac chargers new are ~$30.
6 extra 4565 op amps in line made the signal quieter, go figure. Plus the PV8 had tone controls, which the RA-88a did not. The PV8 would mix a real mono signal if I was playing a LP that hat stereo problems. The Ra-88a had RIAA deemphasis on two channels, very rare for a mixer. Noisy though, took changing the 4558's to 33078's and removing the AC power transformer from the case to quiet it down.
Twisted pair does better up to 33 m but it takes a differential drive on the two wires to work properly. You can do that with two op amps, one inverting, the other not. Twisted pair cable can have 1/4 phone plug both ends, or if 2 pairs, stereo 1/4 phone plug. Doesn't have to be shielded.
The cheapest way IMHO is to buy a mixer with stereo 1/4 phone plug to the power amp. I picked up a Peavey PV8 mixer $60 with freight. It came with a dead left output which turned out to be a bad via through the board. The master volume pot was bad. A new 10k bourns slide pot was $2 but the box of 2 mm screws to hold it to the panel was $6. When that was stolen I bought another PV8 with freight for $88. Turns out that one was working, at least as far as I've checked it. No charger but a 12 vac charger from the charity resale shop for $1 works for signals up to 9 vac. 16 vac chargers new are ~$30.
6 extra 4565 op amps in line made the signal quieter, go figure. Plus the PV8 had tone controls, which the RA-88a did not. The PV8 would mix a real mono signal if I was playing a LP that hat stereo problems. The Ra-88a had RIAA deemphasis on two channels, very rare for a mixer. Noisy though, took changing the 4558's to 33078's and removing the AC power transformer from the case to quiet it down.
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Right now I'm testing audio server distributions and using an 10M standard twin RCA cable between my RPI4 & my Sony amp without issues.
I would be concerned if I would live near a radio or TV station.
There are however thicker cables with better overall shielding.
Pick a slight thicker cable, from a known brand or use mic cable. There is a thinner one which fits RCA connectors.
Try a standard cable first and stick with it if it works.
I would be concerned if I would live near a radio or TV station.
There are however thicker cables with better overall shielding.
Pick a slight thicker cable, from a known brand or use mic cable. There is a thinner one which fits RCA connectors.
Try a standard cable first and stick with it if it works.
Mic Preamp
Good Morning everyone, l apologize for diverting your attention, someone kindly assist. l would like to know how to calculate the gain of the following preamp schematic. which resistors do you use to determine the gain. l want to make some frequency response measurements, and would like to build a good mic preamp with a 6 position pole switch for the gain pot. great regards
Good Morning everyone, l apologize for diverting your attention, someone kindly assist. l would like to know how to calculate the gain of the following preamp schematic. which resistors do you use to determine the gain. l want to make some frequency response measurements, and would like to build a good mic preamp with a 6 position pole switch for the gain pot. great regards
