pauln Posted February 8, 2011 Share Posted February 8, 2011 The design ethics of the manufacturer is one of the most important "specifications" of an amplifier. I have a Sansui integrated amplifier from the early 70's. It is rated at 28W, but the transformer and power supply caps are the size and value you find in other amps rated at 100W. The Sansui literature at the time was critical of the "turn it up 'til it clips" version of amp testing. They didn't feel it was proper to offer a product where volume levels offered by the volume control would be distorted. They said their Sansui amps were designed to use any and all settings of the volume control, including full up without exceeding their distortion specs. I suppose what that means in practice is that their amp specs power ratings were under-rated? I notice that this amp has +/-30V supply rails... If the maximum unclipped sine wave could be +/-30V (60V peak-to-peak), its Vrms would be 21V, which into 8 ohms is 55W average power. Average power means there is still 3dB of headroom, right? 20*log(30/21)=3dB 55W+3dB=110W Should this amp have been rated as a 55W amp or did Sansui choose to rate it as an overbuilt 28W with 6db headroom? The 3A quick acting fuses on the outputs would open around 110W into 8 ohms (3.7A), which may support this idea? Anyway, the point is that some amps are build better than others, and the specs may not tell the whole tale. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted February 9, 2011 Share Posted February 9, 2011 How about using Volts and Min Z. Then with a little math you can find most anything else you want. +1 No second guessing, and the warranty departments would be happy campers. Quote Link to comment Share on other sites More sharing options...
Don Richard Posted February 9, 2011 Author Share Posted February 9, 2011 The design ethics of the manufacturer is one of the most important "specifications" of an amplifier. I have a Sansui integrated amplifier from the early 70's. It is rated at 28W, but the transformer and power supply caps are the size and value you find in other amps rated at 100W. The Sansui literature at the time was critical of the "turn it up 'til it clips" version of amp testing. They didn't feel it was proper to offer a product where volume levels offered by the volume control would be distorted. They said their Sansui amps were designed to use any and all settings of the volume control, including full up without exceeding their distortion specs. I suppose what that means in practice is that their amp specs power ratings were under-rated? This amplifier looks like it was designed and manufactured before the FTC standard for home stereo equipment was implemented. Back then it was fairly common knowledge that Sansui equipment was conservatively rated. Since they didn't publish their specific testing methods it is difficult to know whether the amplifier could pass the FTC preconditioning test or not, so it would be difficult to determine why Sansui chose to rate that product the way they did. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.