250.2 with Supernait as a pre- want to use flatcap also

Posted by: rega1 on 07 March 2018

I Posted a few days back about utilizing a hicap in my system with a Supernait/lp12/ NDX. Now my dealer has allowed me to demo a 250.2that has been recapped, upgraded, and was part of his personal kit until he moved to a 300 years ago, and it has been sitting. I can’t afford both the 250 and hicap dr, and I am leaning toward the 250 now, as it really is a nice addition for my lp12. 

My problem is that my Supernait 1, does benefit from the flatcap and yes, I do prefer it over the hicap, sorry about that, and I know it is not the right path according to opinion and white paper. I would like to use the flat cap to power the prefix and the Supernait preamp, but when I follow the pictorial diagram in the manual that shows the Supernait connected to the hicap and the 200 connected to the hicap signal out......and I apply that cable routing and socket configuration to MY Supernait / flat cap 2x / 250.2, I get a low hum in the bass speakers. 

Any my help would be appreciated. I think I am missing something here. For now I have the link plug in, and I am using the bi-amp socket out to the 250.2, which is working fine, and other are doing based on my forum search. 

Scott

Posted on: 08 March 2018 by Richard Dane

Scott, when you have the pre section of the SN powered by the Flatcap2x with signal then taken from the FC2x to the NAP250, how do you have the Prefix connected? I assume you are using Power Out A for the SN and Power Out B for the Prefix? If you disconnect the Prefix (signal and power cables) does it still hum?

n.b. Only ever connect or disconnect SNAICs etc.. with the power amp OFF.

Posted on: 08 March 2018 by rega1

I do power everything off sir, I have been taught that is a must, and follow the protocol. I have the prefix being powered by one section of the flatcap 2x, but would like to power the pre amp in the Supernait to gain the benefit of sound quality from the flatcap2x for my NDX. Sound. 

I do not have the Supernait powered by the flatcap 2x as you normally would. I was attempting to follow the diagram in the manual that shows the HiCap between the Supernait and a NAP200. 

 

Posted on: 08 March 2018 by Richard Dane
rega1 posted:

I do power everything off sir, I have been taught that is a must, and follow the protocol. I have the prefix being powered by one section of the flatcap 2x, but would like to power the pre amp in the Supernait to gain the benefit of sound quality from the flatcap2x for my NDX. Sound. 

I do not have the Supernait powered by the flatcap 2x as you normally would. I was attempting to follow the diagram in the manual that shows the HiCap between the Supernait and a NAP200. 

 

OK thanks.  Let's concentrate on the SN - FC2x - NAP200 first then and see whether the hum crops up when correctly connected.  So..  Power everything down.  Remove the Prefix connection from the FC2x and remove any sources from the Supernait other than the NDX, to take it out of the equation for the moment.  Connect the Supernait's link plug.  Connect the Supernait Pre-amp OUT to the Flatcap POWER OUT A via SNAIC5 (band at the SN end).  Then connect the Flatcap SIGNAL OUT A to the NAP200 via SNAIC4 (band at the FC end).  Reconnect power leads etc..  Power up.  Is there still hum? 

Posted on: 08 March 2018 by rega1

I apologize for any confusion, I do not have a NAP200, but I am trying to set up a 250.2 with Supernait as a preamp only.

Posted on: 08 March 2018 by rega1

I am at work right now, but will test your theory when I get home this evening. 

Posted on: 08 March 2018 by Richard Dane

OK apologies:  So Connect Flatcap2x SIGNAL OUT A to the NAP250 via white banded DIN-XLR lead.

Posted on: 08 March 2018 by Dave***t
rega1 posted:

Now my dealer has allowed me to demo a 250.2that has been recapped, upgraded

Upgraded how, if it's still a 250.2?

Just wondering about potential resale issues/bargaining chips.

Posted on: 08 March 2018 by rega1

I was just sent the certificate filled out by Chris West who did the work, have not read it yet. 

Posted on: 08 March 2018 by rega1

Richard,

tested your experiment, still the same low hum. I have a 5pin to 5 pin black Snaic from preamp out, but without the link plug in. I can’t run the trial you suggest with the link plug in, otherwise my only option is to plug into the preamp out/ biamp socket on the Supernait, and into the flatcap power out A .  Toning else is connected to the Supernait or flat cap as a source. Mains are dedicated, and have had no issues, at all. Even hooking up the hicap dr to Supernait, with prefix powered by flatcap, no hum....

 

scott

Posted on: 09 March 2018 by Richard Dane

Sorry Rega. Auto correct error. Should have read Disconnect link plug. 

It may be you have a faulty Snaic in there. Do you have any extra to swap in? 

Posted on: 09 March 2018 by rega1

I do not, and it needs to be a 5 pin, to 5 pin correct?

I also tried another test last night. I did the same test with the hicap dr I am also home demo-ing. I removed all other cables and kit from my supernait, plugged in the hicap and the 250.2 as shown in figure 20-5 in link, same low hum.

supernait 1 to hicap manual link

So the flatcap, and the hicap, with the same cables, no prefix plugged in or powered, no NDX plugged in or powered, produce the same low hum.

Here is the twist, I can remove the 250.2 out of the equation, power the supernait pre-amp from the flatcap as directed, power the prefix from the flatcap, and there is no HUM issue at all. I can even power the supernait, or the prefix with the hicap, and use the flatcap to power the other component and no hum.

So, I am left with link plug and biamp out only as shown in figure 20-4 from link above.....There is a ground loop issue with the 250-2 possibly?

 

 

Posted on: 09 March 2018 by Richard Dane

It would appear you have narrowed it down the either the NAP250 or possibly the DIN-XLR lead as possible cause of the problem.  Time to chat with your dealer.

Posted on: 11 March 2018 by rega1

Richard, quick update

It is an earthing problem, or something with too many grounds, and it is still not solved, and I did not want want to use link plug and pre-out socket for biamp. So as it stands now, the Supernait will go on the auction block and it just so happens that another customer switched to tube amps, and there was a mint condition NAC 282 at a great price to try andpotentially buy, to match up with the 250.2. Lets just say none of the kit is going back, and I have the 282 scheduled for service with Mr. Chris West in early May. Nice upgrade!