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Yamaha R-N402D with JBL Stage A180 hiss/impendance

Nonick

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I recently got JBL stage A180 speakers (have auditioned them on couple occasions and chose A180 instead A190 - much more focused, clear bass and mids).
Since i couldnt wait for amplifier, i took "first in hand" - Yamaha R-N402D stereo receiver.
These are R-N402D specifications:
Minimum RMS output power (40 Hz to 20 kHZ, 0.2% THD, 8ohm) 100 W + 100W
Dynamic power per channel (IHF) (8/6/4/2 ohm) 125/150/165/180 W
Maximum powr per channel (1 Khz, 0.7%THD, 4 Ohm) 115 W
IEC power (1 Khz, 0.2% THD, 8 Ohm) 110 W
Damping factor (Speakers A) 1KHz 8 Ohm, 120 or more
Maximum effective output power (1 Khz, 10% THD, 8Ohm) 140 W
Total harmonic distortion CD, etc. to Speakers out (20 Hz to 20 kHz, 50W 8Ohm) 0.2% or less
Signal to noise ratio (IHF-A), CD, etc. (input shorted, 500mV) 100 dB or more


As stated in Yamaha manual - speaker impedance RN-402 is 8 Ohm or higher. If you connect speakers with an excessively low impedance, this unit may overheat.
JBL Stage A180 are 6 Ohm impedance. Due to lower impedance of JBL A180 (6 Ohm), will there be any damage to speakers or receiver (8 Ohm)?

Another thing which is "annoying": there is a slight hiss noise coming from speaker tweeters (while nothing is playing and volume set to minimum).
When i change the input source to CD - hiss is audible. When switched to Optical / Coax - the hiss is gone, theres just a slight high pitched noise). Is this hiss produced by low quality of Yamaha amp? Anyone with similar experience?

Final question: which receiver/amplifier can be recommended for JBL Stage A180 (that doesnt produce hiss or noise)?
I was thinking Yamaha R-N803 (reviewed here with passmark), or perhaps Denon DRA 800H, Topping PA5 with decent DAC (if Topping has enough power for JBL Stage A180)?
Thank you.
 
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Nonick

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In the avoidance of unbearable hiss from tweeters: I pulled out old n' dusty Denon AVR 3803 and connected it to JBL Stage A180.
Absolutely zero hiss from tweeters, sound is clean and crystal. This is an almost 16 year old AVR and it works perfectly. No hiss.
Yamaha R-n402D is going away, it will be replaced by CA AXR100D or Streamer + Topping PA5.
 

ZolaIII

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A) It drives 6 (and even 4) Ohm's speakers just fine.
B) Something is making a ground loop in analog input. Up to you to find is it a connection cable or something inside (R-N402D is AB class and zero twitter hiss).
R-N803 has identical power stage.
 

rwortman

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Ground loops cause hum, not hiss. You may have interference from a poorly shielded cable or maybe the amplifier simply has low level noise. Is there a cd player connected to the CD input? If no, try shorting the input. Nothing to do with speaker impedance and everything to do with noise level and speaker sensitivity. Poking around with an oscilloscope would be revealing.
 
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Nonick

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Nothing is connected to CD input, also there is no connection to Line 1 or Line 2 input.
When switched to Optical / Coax - the hiss is gone. As i wrote two posts above - i've connected old Denon AVR 3803 and there is zero hiss from tweeters.
It's the noise level of R-N402D, not so good. I'm reluctant to give a shot with R-N803D.
 

ZolaIII

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Ground loops cause hum, not hiss. You may have interference from a poorly shielded cable or maybe the amplifier simply has low level noise. Is there a cd player connected to the CD input? If no, try shorting the input. Nothing to do with speaker impedance and everything to do with noise level and speaker sensitivity. Poking around with an oscilloscope would be revealing.
Then pick the cable out on DAC side and twist the contacts with fingers to see how it blows out tweeters.
@Nonick R-N402D is dead silent to the extent that people either add 2~3 dB with input source or with analog input stage (volume trim). I say this because I have one. So it's either setup or something defective with unit. Try another analog input on it.
 

rwortman

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Nothing is connected to CD input, also there is no connection to Line 1 or Line 2 input.
When switched to Optical / Coax - the hiss is gone. As i wrote two posts above - i've connected old Denon AVR 3803 and there is zero hiss from tweeters.
It's the noise level of R-N402D, not so good. I'm reluctant to give a shot with R-N803D.
Noise is usually tested with shorted, not open inputs. How it performs with something connected to it is what matters.
 

ZolaIII

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Just did listening to one I own.
It has a lo hum (probably picking it up from power transformer [EMI]) but it's on the woofer driver and barely audible (had to put my head directly on the speaker and seal the other ear so that I can not hear buzz of other power supply two meters away that whose louder) and it's the same on all analog inputs.
 
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Nonick

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Then pick the cable out on DAC side and twist the contacts with fingers to see how it blows out tweeters.
@Nonick R-N402D is dead silent to the extent that people either add 2~3 dB with input source or with analog input stage (volume trim). I say this because I have one. So it's either setup or something defective with unit. Try another analog input on it.
To which speakers is R-N402 connected? Absolutely no hiss from tweeters?
I have JBL Stage A180 (rated 90dB sensitivity). Suppose this R-N402D is a faulty unit.
 

ZolaIII

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To which speakers is R-N402 connected? Absolutely no hiss from tweeters?
I have JBL Stage A180 (rated 90dB sensitivity). Suppose this R-N402D is a faulty unit.
Nope, put your ear to the speaker as described and listen it's IEM from power transformer impacting the analog input stage. Luckily I know a easy way to fix it all do it doesn't bother me at all (can't be audible even from 20 cm away as lo frequencies fade energy fast). If it bothers you return it (I doubt R-N803 will be any better in this regards but I could be wrong).
 

ZolaIII

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Shielding of the analog input path with a can of graphite spray (and while at it building a paper wall between the transformer and rest of the system and spraying it over other sensitive components including output transistors). But it's electrical conditioning and neads an layer of transformer varnish on sensitive parts (to prevent short circuit).
Well it's not all that easy but it's not complicated either. I whose looking for the reason to rip it open anyway and now I have it.
 

ZolaIII

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Not only it's great as EMI shielding and even against AC one (graphite) but it also improve heat dispersion.
 

maty

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You need a good DC Blocker.



20190917_154246-1.jpg
DCB_CMF.png
 

ZolaIII

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I didn't mention it but that other transformer I mentioned in listening test (that I had to block) whose a plate capacitor power conditioner and it didn't help. But again this really isn't problem (at least for me). It's under the level of ambient noise even when you put ear directly on speaker. Will try with shielding in generally to try to get the performance a bit better but not before spring probably. EMI hum from AC and transformer is very difficult one to block under 100 Hz (40 to 60 Hz especially).
 

ZolaIII

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Must see how grounding is done for analog line's input (it could be as trivial as that signal not power grounded) it's not related with analog stages (preamp, amp) that's certain and it ain't digital input either (DAC and DAC lines are silent). Hell you get me bugging now. :facepalm::);)
 

ZolaIII

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Which?

Usually, commercial power conditioners do not have a DC Blocker inside.
RUL old one but it doesn't matter. I need to rip it open and see what I can do on this part particularly,


1591422660537~2.pngboth regarding grounding and isolation (which won't happen soon).
 
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TheBatsEar

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R-N803 has identical power stage.
Nope. The R-N402D has identical power amp and power supply to the A-S201 and possibly the R-S201 and R-S202D.
It's rather weak, their smallest one.

The R-N803 shares power supply and power amp with R-S700 and A-S700/701/801.
 
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