Dishwasher Interference

[Lavcat]

Originally Posted by c2cthomas

Question? Did the interference with the phono stage start after you fixed the leak in the dishwasher????

The apartment superintendent replaced the pump, not I. I am just as glad to leave that kind of DIY to others. Though many, many years ago I did install a dishwasher in a house, with the next door neighbor's help. Last I looked that house had not burned down nor flooded.

[c2cthomas]

Errrrrrr - I wuz just fun'n around!!! The point being that maybe the leak was in some manner keeping the interference from affecting electronic gadgets in the area - in which case putting the leak back in might solve your problem. OF course - the people that live below you won't be real happy with that fix.

Sometimes people forget that I'm a dumb smart-azzzzz....

[Lavcat]

As an update, I have been listening to the phono input on headphones with the volume turned up and with no record playing. Pops from the dishwasher switching cycles are present but barely detectable. They are below the level of record noise.

Hiss and hum on phono are no more than on high level inputs. And there is no shortwave reception.

This is using the Sony cables.

[gootee]

That's good news! Your sound quality should be signficantly better now.

I would probably call it "good enough", if it were me. But there might be stronger RF in your future. And it doesn't always demodulate into things you can hear directly. Sometimes it just shifts the operating points of semiconductor circuits, or produces DC offsets, degrading things in ways that might not be obvious.

If you decide to try to make it "perfect", you could try some 22pF caps across the input jacks of the phono preamp, as suggested by indianajo. I would probably try to replace each of the 1K series input resistors with two 500 Ohm resistors and drop something like .001 uF to ground from between them, to make a low-pass RF filter, which should have a cutoff frequency of a little over 300 kHz (unless I got the capacitor size too small by half, again). [I guess then you could test it by connecting an antenna or length of wire to each input (grin!).]

If that doesn't kill the pop completely, then it's possibly the portion of the RF burst that's conducted through (or radiated into and then conducted through) the power system rather than radiated over the air directly into your phono system, or else it's getting in over the air through a different part of the system, which is also very likely. Have you tried it with the whole phono system unplugged from the main preamp? That might be interesting.

[Lavcat]

Originally Posted by gootee

Have you tried it with the whole phono system unplugged from the main preamp? That might be interesting.

With the phono system unplugged from the Threshold there is no audible dishwasher interference. This is from listening with headphones connected to output of Crown D-75A amp and gains turned up.

[tcunningham4]

Lavcat: Just ran into this post looking for something else. After reading the first wfew replies., I was going to suggest that it might be the cables, but I see you have come to that conclusion. I have found after many years of audio experience personally and professionally that the price of a cable means very little in the long run. In reality, if you were to try to buy a cable from Sony you might spend as much as for the Monster. The Monster design of a twisted pair with a shield attached at one end is relatively recent, and works better than a simple single conductor shielded cable at audio frequencies and medium impedances. It may be that the higher impedance of the Phono cartridge adn the capaciance of the twist actually caused more trouble than it solved. but I'd have to calculate it. EE classes were a long time ago.
I am surprised that nobody suggested trying different cables early in the discussion, but I have a good supply of spares and parts available whenever I setup a system.
(I do live sound for small venues, which are frequently challenging, but alway fun.)

Enjoy your 'new' system.

Vinyl Lives!!!

Tom C.

[Lavcat]

Originally Posted by tcunningham4

Lavcat: Just ran into this post looking for something else. After reading the first wfew replies., I was going to suggest that it might be the cables, but I see you have come to that conclusion. I have found after many years of audio experience personally and professionally that the price of a cable means very little in the long run. In reality, if you were to try to buy a cable from Sony you might spend as much as for the Monster. The Monster design of a twisted pair with a shield attached at one end is relatively recent, and works better than a simple single conductor shielded cable at audio frequencies and medium impedances. It may be that the higher impedance of the Phono cartridge adn the capaciance of the twist actually caused more trouble than it solved. but I'd have to calculate it. EE classes were a long time ago.
I am surprised that nobody suggested trying different cables early in the discussion, but I have a good supply of spares and parts available whenever I setup a system.
(I do live sound for small venues, which are frequently challenging, but alway fun.)

Enjoy your 'new' system.

Vinyl Lives!!!

Tom C.

Thank you for your reply. Not to hijack my own thread, but perhaps you could give me your thoughts on another cable question? Some while ago I started the following thread about connecting my Threshold preamp to my Crown amp:

unbalanced to balanced conversion

Initially I was biased against using transformers, but am now convinced transformers and galvanic isolation are the best way of making this interconnection, with the only ground connection through the safety grounds of the equipment.

This still leaves a lot of variables. For the interconnect between the Threshold (which has an unbalanced RCA output) and the transformer I could use coax or a twisted pair (with or without shield). I could terminate the transformer end either with RCA or XLR. I could also try bypassing the output capacitor of the Threshold if the DC wouldn't saturate the core.

For the connection between the transformer and the Crown (which has a balanced input) I could run straight balanced, with or without the shield connected on the transformer side, or I could run unbalanced by connecting the signal negative to the shield (which should be signal ground). What seems to be best practice is to run unbalanced, though I am not sure the reason.

Currently I am using an RCA to RCA cable of unknown construction, with a phono to phone adapter on the Crown. This works but it could be better. But at least there is no interference from the dishwasher.

[tcunningham4]

Personally, I'd just go with what you have -- You could also use a direct box like EBTech LLS2 Line Level Shifter at zZounds or build the unbalancer into a cable

RCA center - 10k ohm - pin 3
RCA gnd --- 10K ohm - pin 2
RCA gnd - - - - - - - - - - pin 1


Or Ebay:

2 PACK KIRLIN XLR MALE TO RCA FEMALE ADAPTER #3107 | eBay

Monster cable Z Series Z200i interconnect cable Male XLR / RCA Pair 1M | eBay

Let me know if you want me to make you a cable. tom@edentechs.com

[Lavcat]

Originally Posted by tcunningham4

Personally, I'd just go with what you have -- You could also use a direct box like EBTech LLS2 Line Level Shifter at zZounds or build the unbalancer into a cable

RCA center - 10k ohm - pin 3
RCA gnd --- 10K ohm - pin 2
RCA gnd - - - - - - - - - - pin 1


Or Ebay:

2 PACK KIRLIN XLR MALE TO RCA FEMALE ADAPTER #3107 | eBay

Monster cable Z Series Z200i interconnect cable Male XLR / RCA Pair 1M | eBay

Let me know if you want me to make you a cable. tom@edentechs.com

I appreciate your advice not to use transformers, but I probably won't take it. I have a Jensen ISO-MAX, which I'm using in another place, though I tried it between the Threshold and the Crown with good results. I'm building a box with the same transformers to go between the Threshold and the Crown:

http://www.jensen-transformers.com/datashts/11p1.pdf

Once I heard what the JT-11P-1 could do I could not go back. I don't need level shifting, by the way, I have plenty of gain.