PassLabs X600

[RobertS61]

that chassis is connected to IEC mid pin, we know that

Ground is lifted inside the AC Cables of both amplifiers!
And still there's zero resistance between the ground of the AC receptacle and the chassis of both amplifiers.
That tells you IMO that there is a ground connection between XLR pin 1 and chassis because grounding now goes through the pre-amps chassis, the conversion RCA - XLR cable, pin 1 to ground and then to the chassis of the X600's. There's no other possibility.

In already cited in the manual Nelson Pass states that:
"The X600 and X350 have their circuit grounds attached to the chassis in the conventional manner."

what you need is to check connection between audio GND and chassis

practically XLR pin 1 and chassis

funny how you decided to mess with AC receptacle, instead of measuring at IEC on back of amp, or mains cable connected in/to amp

avoid dealing with AC receptacle, when you don't need to

The AC receptacle I have blocks the entries of the plus and minus poles when nothing is inserted so it's pretty safe.
I wanted to make sure that ground arrives where it should be thta's why I choose the AC receptacle...

 

[Zen Mod]

remove interconnects while measuring, that is logical

check again

or - simply lift amps from safety gnd, as I explained before (while being connected to preamp with interconnects) - you're safe having FID protector ..... in that case no need for any intervention inside amps

maybe is time to install ground thingie in preamp 🙂

 

[RobertS61]

remove interconnects while measuring, that is logical

check again

or - simply lift amps from safety gnd, as I explained before (while being connected to preamp with interconnects) - you're safe having FID protector ..... in that case no need for any intervention inside amps

maybe is time to install ground thingie in preamp 🙂

Yes indeed.

But Krell is from the Forbidden Planet so it doesn't like to be on the Earth's ground...

Thanks so far!
I feel safe now and very satisfied.

Now the only thing remaining to get some new Violet/Blue about 430nM LED's for the Krell to make it compliant to his masters!

 

[RobertS61]

Pass color LED's on Krell KRS-2

Bit trivial but as said I would replace the blue approx. 500nM wavelength diffuse 5mm LED's from the KRS-2 preamp with the same color as Pass Labs uses.
I managed to establish the right wavelength as 430nM and sourced the appropriate LED at Mouser.
The partnumber is 'BIVAR 5BWC' listed on Mouser as 749-5BWC.
https://www.diyaudio.com/forums/attachment.php?attachmentid=1000272&stc=1&d=1637839402

https://www.diyaudio.com/forums/attachment.php?attachmentid=1000269&stc=1&d=1637839150
https://www.diyaudio.com/forums/attachment.php?attachmentid=1000270&stc=1&d=1637839150

 

[Zen Mod]

wasn't it more cunning, to leave original Krell LEDs at home, and toss rest outa home?

 

[RobertS61]

wasn't it more cunning, to leave original Krell LEDs at home, and toss rest outa home?

You mean keep the LED's and throw away the rest of the Krell?

 

[nicoch58]

boat anchor

 

[Zen Mod]

You mean keep the LED's and throw away the rest of the Krell?

exactly

 

[RobertS61]

boat anchor

No no no, the boat anchors were the KRS-100's I had before the Pass X600's.
Well only the weight of 59 kilograms was like a boat anchor but they sounded great you Pass-snobs!

No I have a Krell KRS-2 for a pre-amp which is by the way a very delicate instrument and not a boat anchor at all. It is very pretty looking also and it sounds great in my ears complements the X600's just fine you Pass-epigons!

 

[nicoch58]

is full of useless stuff 😀😀

 

[Zen Mod]

(we are just jealous bstrdz 🙂 )

 

[nicoch58]

Nope after Papamp Vfet we are bstrdz happy.....plus dont need a pre 😀

 

[Zen Mod]

everyone needz a pre

 

[twitchie]

every pre needs a plank 🙂

 

[RobertS61]

every pre needs a plank 🙂

Every plank needs at least two columns or two brackets...

 

[RobertS61]

PassLabs X600 powermeasurements

With the Infinity Kappa 9A and Acoustat 2 + 2 loudspeakers, it is not that difficult to get that lazy meter moving. But because there's no decent scale it is guessing how much power the X600 delivers with the meter in a specific position. So I took some powerresistors configured 8 Ohms and let a 1KHZ running trough them.
At 10 Volts the meter on the X600 starts moving so that's 12 Watts Class A RMS at 8 Ohms, bit disappointing with the heatsinks reaching 48 degrees Celcius.
Well it is what it is.
Then meter exactly in the middle of the scale is 30 Volts or 112 Watts.
Then a 200 Watt and 312 Watt position. Resistors are "singing" at 312 Watts and got hot so I did not dare to go all the way and chickened out...
https://www.diyaudio.com/forums/attachment.php?attachmentid=1003082&stc=1&d=1638804582
https://www.diyaudio.com/forums/attachment.php?attachmentid=1003083&stc=1&d=1638804582
https://www.diyaudio.com/forums/attachment.php?attachmentid=1003084&stc=1&d=1638804582
https://www.diyaudio.com/forums/attachment.php?attachmentid=1003085&stc=1&d=1638804582

 

[MEPER]

Could you use some electrical train "break resistors" to test max. power from amp?

 

[RobertS61]

Could you use some electrical train "break resistors" to test max. power from amp?

Yeah sure, have a couple lying around...😉

 

[RobertS61]

No serious, I could reach 600 Watts probably for a short moment but I didn't dare...

 

[MEPER]

Something like this may do it 🙂
BRAKING RESISTOR 8 OHM 1200W - MEP Inc.

I wonder if an electrical toaster or electrical heating element could be used......maybe a couple in parallel to get low enough impedance 🙂