RCA connection question

[muso37]

The Bushmaster documentation says it should be plugged into the CD or AUX input of an amp. I'm looking at a 2nd hand AudioLab 8000a amp on ebay with a broken CD input, but this classic model also had no Aux input, the only other inputs are labelled Video In, Tuner, Phono (MM & MC), Tape1 & Tape2. I know the Phono input is different, but how would an Aux input be different from a Tape, Video or Tuner input?

[YNWaN]

It's not -you can use Tape In, or Tuner if you want to.

[muso37]

That's as I'd always thought, I've used them interchangeably in the past, just confused as to why the Bushmaster recommendation is so specific.

[StanleyB]

That's as I'd always thought, I've used them interchangeably in the past, just confused as to why the Bushmaster recommendation is so specific.
That's because the Bushmaster output is 2Vrms, which is CD level. AUX Tape, Tuner etc. are 350mV to 1V. What that means is that you can lose up to 3dB of dynamic range with loud musical passages.

[muso37]

Thanks Stan, has this always been the spec for a amp's CD input? Even 20 year old amps?

[StanleyB]

You can look up the specs of your amp on line. Try the manufacturer's website.
Age is just another number. Official and unofficial agreed standards on output/input impedance and voltage levels for the different types of electronic equipment (from headphones to CD players) have not changed much since the 60's.

[DSJR]

Some amps with dedicated "CD" inputs used to put attenuation in to match volume settings for different inputs, most others don't bother. Since the line inputs on most proper modern amps have an overload margin of several volts input, all you need to worry about is the position of the volume control. Having used the 8000A in all its versions, there'll be no issue at all IMO. Just take care with matching interconnect or speaker cables, as it's an easy thing to get this amp to sound like a dogs dinner - it often does and gets bad opinions said and posted about it, quite often due to this simple reason.

[muso37]

I've checked the spec in the manual for my current amp I'm looking to upgrade (Marantz PM4001) - and all my inputs (Tuner/CD/AUX/Tape1/Tape2) have the following spec:

Input sensitivity impedance: 170mV / 20 k ohms
Signal to noise ratio: 104dB
Frequency response (-1 dB): 10Hz - 50kHz
Tone characteristics (100Hz and 10kHz) : +/- 10dB
Channel separation: 670dB

170mV! Nowhere near the 2V CD level standard. I may not be getting the best from my Bushmaster with this amp! But how much difference does this make in real audible terms for loud passages in music like Stravinsky's Rite of Spring, where the timpani and bass drum should be earth-shattering? I must say that I haven't noticed anything seriously lacking in such music, it does still sound impressive, so perhaps I'm reading too much into this.

[Yomanze]

I've checked the spec in the manual for my current amp I'm looking to upgrade (Marantz PM4001) - and all my inputs (Tuner/CD/AUX/Tape1/Tape2) have the following spec:

Input sensitivity impedance: 170mV / 20 k ohms
Signal to noise ratio: 104dB
Frequency response (-1 dB): 10Hz - 50kHz
Tone characteristics (100Hz and 10kHz) : +/- 10dB
Channel separation: 670dB

170mV! Nowhere near the 2V CD level standard. I may not be getting the best from my Bushmaster with this amp! But how much difference does this make in real audible terms for loud passages in music like Stravinsky's Rite of Spring, where the timpani and bass drum should be earth-shattering? I must say that I haven't noticed anything seriously lacking in such music, it does still sound impressive, so perhaps I'm reading too much into this.

170mV is the required input voltage for your amp to achieve full output, so there really shouldn't be any worries here.

[muso37]

170mV is the required input voltage for your amp to achieve full output, so there really shouldn't be any worries here.

I'm not an electrician, I'm only concerned about sound quality, and Stan's related comment about losing dynamic range if my input sensitivity is under 2V (if I understood that correctly!) - does this equate to a restriction in the amp's ability to get the most out of the DAC, or does it merely affect how the volume control knob position equates to loudness?

[Yomanze]

I'm not an electrician, I'm only concerned about sound quality, and Stan's related comment about losing dynamic range if my input sensitivity is under 2V (if I understood that correctly!) - does this equate to a restriction in the amp's ability to get the most out of the DAC, or does it merely affect how the volume control knob position equates to loudness?

Stan was talking about lower output components like tape or tuner, which can be as low as 350mV. 2V is more than more enough for your amp to achieve full output with no issues with loss of dynamic range.

[muso37]

Stan was talking about lower output components like tape or tuner, which can be as low as 350mV. 2V is more than more enough for your amp to achieve full output with no issues with loss of dynamic range.

I'm talking about using the Beresford Bushmaster (2V output) with an amp which only has inputs rated at 170mV sensitivity or lower - since the recommendation is to connect it to a CD or Aux port with the same rating (2V), rather than tape/tuner at 350mV, what issues are there if you only have 170mV inputs? Is it only a how the volume knob equates to loudness, or am I not getting the best from the DAC?

In my ignorance I'd expect it only to be a problem the other way round, i.e. if the DAC's output was less than the amp's required input. If it's more then I'm not sure if there is an issue!