VHF man said:
It is, but this implies putting the attenuator at the wrong end of the cable.
VHF man said:
By the same token any decent power amplifiers input will accept a fair source
impedance without premature h.f. roll-off. An attenuator placed on its input
has no cable to drive, only any input capacitance of the amplifier.
We disagree perhaps, but I'm adamant the far end of the cable is
the best place for an attenuator. There is no technical arguement
that would suggest otherwise whilst there is a sound technical
argument it is superior in terms of driving cable capacitance.
Applies equally to CD player output to pre-amp in.
In reality probably does not matter where it goes ......
/sreten.Re: Re: reducing system gain
Read carefully. I said:
" Joe said: Hi SLR, The easiest way I have found to do this is I bought a 50K ohm passive preamp? from eBay and vary the CD player output level. "
This means put the attenuator BETWEEN the CD player output and the preamp input. Not the preamp and amp. Too much attenuation between the CD player and amp can change the dynamics of the music. Between the preamp and amp you have your pots and of course no change of dynamics would happen.
Joe
Read carefully. I said:
" Joe said: Hi SLR, The easiest way I have found to do this is I bought a 50K ohm passive preamp? from eBay and vary the CD player output level. "
This means put the attenuator BETWEEN the CD player output and the preamp input. Not the preamp and amp. Too much attenuation between the CD player and amp can change the dynamics of the music. Between the preamp and amp you have your pots and of course no change of dynamics would happen.
Joe
Re: Re: Re: reducing system gain
In general you will find that most preamps have their volume control at the input and not the output. Some have the volume pot at a mid point between a voltage amplifier and a buffer.
Therefore, if you simply add another pot between the CD player and the preamp input you actually haven't achieved anything. In fact you will possibly have degraded the channel separation and unless the pot is 1-2 % tolerance you may have also degraded channel balance.
Remember that the objective here is to adjust overal system gain for improved S/N without degrading any other parameters. By attenuating the preamp output we are using as much of the source voltage as possible. In this way any noise that's added by the preamp is also attenuated by the same amount as the wanted ac voltage.
This is basic fundamentals.
jrockhead said:
In general you will find that most preamps have their volume control at the input and not the output. Some have the volume pot at a mid point between a voltage amplifier and a buffer.
Therefore, if you simply add another pot between the CD player and the preamp input you actually haven't achieved anything. In fact you will possibly have degraded the channel separation and unless the pot is 1-2 % tolerance you may have also degraded channel balance.
Remember that the objective here is to adjust overal system gain for improved S/N without degrading any other parameters. By attenuating the preamp output we are using as much of the source voltage as possible. In this way any noise that's added by the preamp is also attenuated by the same amount as the wanted ac voltage.
This is basic fundamentals.
Hi all, I've got way to much gain from my cd player to pre and poweramp which means i can only use the first quarter of my volume control on my pre.
Hi again SLR, do you have other inputs to your preamp besides the CD player? Such as a tape machine or a tuner or a turntable.
If so it makes more sense to level match the CD player to the other inputs so they all play about the same level. Padding the output of the Pre would not help with the level differences and the CD player might overload the preamp input cuz' the volume control will allow a higher level to get to the preamp input.
Joe
Hi again SLR, do you have other inputs to your preamp besides the CD player? Such as a tape machine or a tuner or a turntable.
If so it makes more sense to level match the CD player to the other inputs so they all play about the same level. Padding the output of the Pre would not help with the level differences and the CD player might overload the preamp input cuz' the volume control will allow a higher level to get to the preamp input.
Joe
slr 5000 said:
slr 5000 said:
that metaxas opulence
have way to much gain for a normal preamp
normal gain for a normal line pre amplifier is 4-10 (+12 to +20dB)
one thing is
that modern CD-players will not need preAmp at all.
The output level is Nominally max 2 Volt RMS at strongest signal
and the average CD out is about 0.7-1.0 Volt RMS for most kind of music.
Most power amplifiers need like 0.7 - 1.0 Volt RM for MAX POWER out
(for example 100 Watt out of one 100 Watt power amp)
So, you see,
CD out - is made to fit Power Amp input.
This goes for modern CD-players + Modern Power Amplifiers.
You can & should connect CD -> Power Amp.
For best result audio.
Unless you have some special audio equipment that would require one preamp.
Lineup
hi all
thanks for all the help and advice
ive sold the pre and amps since this thread and have started on a slightly different path (active with dbx260)
i did however try the rothwell attentuators and did not like their effect ,both between the cd to pre and the pre to poweramps .
they seemed to really kill the dynamics of the system
thanks for all the help and advice
ive sold the pre and amps since this thread and have started on a slightly different path (active with dbx260)
i did however try the rothwell attentuators and did not like their effect ,both between the cd to pre and the pre to poweramps .
they seemed to really kill the dynamics of the system
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