output matching

You might check the output spec/input specs:

Typically the Output spec lists a Maximum voltage out- so a full tilt signal would cause that 2 volt signal - the cannons going off in the 1812 Overture- Other passages would vary correspondingly....

Input spec - typically it is listed as "minimum input required for full output". Having said this - 150 mV is more like the output from an MC cart - not a Line Level source. It is common for a Pre-amp/receiver to take inputs in the range of 1.5-2 volts for full output [1.5V = 1,500 mV] - most line level sources (Tuners, Tape decks & CD players) have an output in the 1.5-2.0 Volt range.

Lastly- Unless there is a limiter in the input circuit of the receiver (unlikely) you can feed the CD into the Aux input - and you may just not use most of the Volume Pot range...
Happy Listening

RE: output matching, posted on April 1, 2017 at 13:47:33

walkstoslow
Audiophile

Posts: 277
Joined: November 18, 2012

Let me state this back to you to make sure I understand,the output of the cd player is proportional to the signal from the disc, with a 2v max for the cannon, being the signal with the most amplitude.
I checked again the input specs of my receiver(sansui 317)and the service manual reads aux, tape play 150mv/47kilo ohms, so this is the minimum signal to get full response.
I listening to a pair of utah coaxes in a ported box.
3 ticks up on my volume control (8:00) is too loud. I was thinking my input is too high, apparently this is not correct.
Do I just need less efficent speakers?
thanks

RE: output matching, posted on April 1, 2017 at 14:11:44

6bq5
Audiophile

Posts: 4391
Location: SF Bay
Joined: August 16, 2001

Well, yes, less efficient speakers might help-
you have created the perfect storm- in that you are using very efficient speakers, so you do not need much gain to drive them to pleasant levels-
and yes, the Sansui has a very low input sensitivity -

You have a couple of choices-
You can live with letting the amp loaf along and enjoy unparalleled headroom (because you are not taxing the amp)
Or you can add some resistors to reduce the output of the CDP and go to town-

I would leave it, and not crank up the Volume pot-

Happy Listening

RE: output matching, posted on April 1, 2017 at 14:30:23

Jonesy
Audiophile

Posts: 3156
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
Since: March 1, 2018

Back in the day of your Sanusi, most cd players came with a variable out. Now the cd players or dvd blu ray just have a direct out of 2 volts. Conversely today's amps today have around 300 mv input sensitivity. So you have more steps on your volume control. It doesn't help your specific case, except for an explanation.

Cheers

Jonesy

"I know just enough to get into trouble. But not enough to get out of it."

Cable, posted on April 1, 2017 at 14:37:52
djk Manufacturer Posts: 6135 Joined: June 17, 2000	Make a patch cable with a 10K resistor in the hot lead going to the CD player, and a 1K resistor from hot to ground at the amp end. 1/8W are small enough to fit.

RE: output matching, posted on April 1, 2017 at 16:00:15
walkstoslow Audiophile Posts: 277 Joined: November 18, 2012	thanks everyone, i have been sat at ease...

RE: Cable, posted on April 2, 2017 at 06:59:26
walkstoslow Audiophile Posts: 277 Joined: November 18, 2012	thanks, one of my hobbies is making cables. This is a voltage divider?

RE: Cable, posted on April 2, 2017 at 13:28:40
djk Manufacturer Posts: 6135 Joined: June 17, 2000	Yes, it will knock the signal down about 20dB, or from 2V to about 180mV.

RE: Cable, posted on April 3, 2017 at 16:48:46
Old SteveA Audiophile Posts: 648 Joined: March 27, 2011	If you weren't apt at making up cables,couldn't you just use some Rothwell Inline Attenuators instead ?

RE: Cable, posted on April 3, 2017 at 16:55:32
djk Manufacturer Posts: 6135 Joined: June 17, 2000	They are stupidly expensive, and only 10dB. 2V -10dB = .664V

RE: Cable, posted on April 3, 2017 at 17:03:55
walkstoslow Audiophile Posts: 277 Joined: November 18, 2012	i am going to try this, Now my volume control is stepped and the sound is either too low or too loud, thanks again.

RE: Cable, posted on April 3, 2017 at 17:07:29
Lou S Audiophile Posts: 3164 Location: Ohio Joined: February 26, 2001	Double down on stupid and buy 2! ;-) Best Regards, Lou

RE: Cable, posted on April 3, 2017 at 18:40:45
Old SteveA Audiophile Posts: 648 Joined: March 27, 2011	Seriously.... Is it ever necessary to call anything "Stupidly" expensive ! I do realize this is the Tweakers Asylum but a lot of people could call just about anything to do with our Audio Hobby "Stupidly Expensive" (A simple "They're a bit insufficient for the job & "pricey" would have sufficed)

RE: Cable, posted on April 4, 2017 at 14:54:35
djk Manufacturer Posts: 6135 Joined: June 17, 2000	Perhaps I should have said "inordinately" expensive instead (USD 43.79)? Harrison Labs are less expensive (~$25), but they don't make a model with the correct attenuation either.

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output matching

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