The Mighty AU-X1

What series is the WIMA 0.33µF capacitor for the phono cards?

I use FKP if I want to replace an old polystyrene.

To bridge the gap in the modification above I used an MKS.

According to their respective data sheets:

FKP
Typical Applications
For high frequency applications e.g.
  • Sample and hold
  • Timing
  • LC-Filtering
  • Oscillating circuits
  • Audio equipment
MKS
Typical Applications
For general DC-applications e.g.
  • By-pass
  • Blocking
  • Coupling and decoupling
  • Smoothing
  • Timing
 
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Thanks Ron. It gets confusing on what the internet says what to use where. I want to order these parts so that they are here. They wont go in now but I want to do this mod. This post is great and you have been a great help.
Cheers,
 
Thanks Ron. It gets confusing on what the internet says what to use where. I want to order these parts so that they are here. They wont go in now but I want to do this mod. This post is great and you have been a great help.
Cheers,

Cool! Take pictures!
 
Ron,

I always replace polystyrene with polystyrene since they seem to be the best film caps in teams of sound quality, just after polycarbonate and teflon. The later two are very difficult to find. Otherwise i also like to use the Panasonic pp and metalized pp film caps.

For the mod you are describing i used a vishay mkp that i had available.
 
At the moment i have my hands full on some Sony gear, actually two turntables (tts4000 & tts8000), after that i can really start testing the phono section of the au-x1. I have two MC cartridges, a Sony xl55pro and a Monster Genesis 2000. For MM i can use a Technics EPC 205mk3. I wonder now they match with the Sansui.
 
Ron,

I always replace polystyrene with polystyrene since they seem to be the best film caps in teams of sound quality, just after polycarbonate and teflon. The later two are very difficult to find. Otherwise i also like to use the Panasonic pp and metalized pp film caps.

For the mod you are describing i used a vishay mkp that i had available.
You’ve done the Kuehne F-2770/71 mods? Please post some pics and details if you can.

At the moment i have my hands full on some Sony gear, actually two turntables (tts4000 & tts8000), after that i can really start testing the phono section of the au-x1. I have two MC cartridges, a Sony xl55pro and a Monster Genesis 2000. For MM i can use a Technics EPC 205mk3. I wonder now they match with the Sansui.
Sounds like a real interesting thread to come.
 
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Ron, maybe you can help me something. I placed some additional caps on the backside of the f2918/2917 boards, just as was done in the later boards. Now I am not sure if I did this correctly. I looked at the amp8 website. Do you have original boards that have these caps on the solder side?

Regards

Harold
 
i had a look again at these caps, these are just 0.22uf caps over the larger 1000uf caps. So that is ok.
 
View attachment 1098967 View attachment 1098968

Ron, maybe you can help me something. I placed some additional caps on the backside of the f2918/2917 boards, just as was done in the later boards. Now I am not sure if I did this correctly. I looked at the amp8 website. Do you have original boards that have these caps on the solder side?

Regards

Harold

Yes. On my version of the F-2917/18 boards the film capacitors were already factory installed on the trace side of those boards.

They bridge / smooth the capacitors C-05, 06, 08, and 09. So as long as your installations are on or near (on the same traces as) the pads used by those capacitors, it is correct.

The code on those film caps is 224K or .22uF.

BTW: Is it safe to assume that your X1 had DC drift on the EQ boards?

If not, was doing the Kuehne modification just an insurance policy of sorts?
 
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Hi Ron,

Thx for the info, I installed them correct, just wanted to be sure.
i performed the modification to remove drift i had on the board. I did have some drift and after the mod there is almost no drift left.


regards
 
Hi Ron,

Thx for the info, I installed them correct, just wanted to be sure.
i performed the modification to remove drift i had on the board. I did have some drift and after the mod there is almost no drift left.


regards

Thanks for the update Mr. Harolda.

It is great to have another confirmation that the mod is good and a great improvement.

I wonder if most issues of DC drift can be solve by using a similar approach.

Confirmation appreciated!

Ron
 
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Question for the experts. As you know, I always listen to the X1 bypassing the flat amp- would that increase it's longevity?

Not that it matters, I prefer the sound in the "Jump" mode but I was just curious.
 
Question for the experts. As you know, I always listen to the X1 bypassing the flat amp- would that increase it's longevity?

Not that it matters, I prefer the sound in the "Jump" mode but I was just curious.

Hmmm...that is a question.

I say, amature musing here, you are extending the life of the flat amp. Since Mr. Kuehne discovered that the destructive oscillation that the X1 was notorious for originated in the flat amp,
then perhaps bypassing it is "best practice" until you install his anti-oscillation modification.

You could super baby it (like turning off the amp before switching sources) but if you just use it normally and un-abusively, it should be good for at least a couple decades. Especially considering the work you have had done on it.

Really the best insurance is to let your tech check it's health once every 2 years.
 
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How do I love thee? Let me count the ways...

More than 2 years in and my restored X1 never ceases to amaze me. This unit is so versatile that it's almost a shame to call it an integrated amp, it really does provide the versatility and SQ of separates (more so than any other high quality integrated amps I've come across). As those of you that have read through this thread know, I've been using this amp with the "Jump" switch "On" (-14dB gain bypassing the flat amp) but recently I brought the Flat Amp into the mix. I was curious to see if I could get closer to the presentation of my a A-S801. With the "Jump" Off setting there is clearly more hiss at moderate high output by the tweeter than with the "Jump" switch On but I'd say it provides more "punch', "snap" & "forwardness" to the presentation which I would say is similar to a typical integrated like the 801.

As you know, I primarily use the X1 to power my Bowers & Wilkins 805D2 & REL S/2 sub (it's my best set-up) and I'm very satisfied with the combination. With the "Jump" switch off setting (with a modern 2V source) it was too much in my opinion so I dialed back the Power Amp Levels until I found the sweet spot. In my room I'm currently at ~ -14 to -16dB. While the dBs seem similar to the "Jump" switch on setting, this setting definitely does sound different to me even at the same SPL than the setting with the Flat Amp out of the picture. My question to the qualified expert techs here (we all know who you are) is what, if any are the differences in these settings (measurements or technical) that would cause this audible difference.

As you would expect, I've compared my Yamaha A-S801 to the X1 in the same room driving the 805D2s & REL S/2 sub (within the power limits of the 801). The X1 wins hands down. I also recently had two other highly regarded Integrated Amps in here, the Marantz PM-14S1 and the Yamaha A-S1100. They are both rated with less power than the X1 but I was driving them well below their limits. All I can say is that in my opinion and in the opinion of the owner of the 14S1 & 1100, the X1 was the clear winner. In addition, neither of the two modern integrated amps could compare to the pure silence of the X1 with the "Jump" switch engaged.

The X1 truly is a special amp that was way ahead of it's time.
 
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I agree with you. My 919 doesn't have more or less noise with the jump switch on or off. It does have a little more body (fleshed out) using the preamp (flatamp) section. Something may not be right in your preamp section.
 
I agree with you. My 919 doesn't have more or less noise with the jump switch on or off. It does have a little more body (fleshed out) using the preamp (flatamp) section. Something may not be right in your preamp section.

I don't think there's anything wrong with it because it's not like it get's noisier, on the contrary- the little normal noise that's there disappears. With the flat amp in the signal path and the volume level up high (nothing playing), the hiss at the tweeter is comparable to a the "Reference Class" PM 14S1.

The magic of pure silence happens when I hit the Jump switch. Even with the individual amp levels at max and the volume pot at 12 or 1 o'clock (this would equate to a high SPL) there is absolutely zero noise detectable from the tweeter. I have never heard an amp quieter than this X1 with the jump switch engaged.
 
I also notice how quiet the AU-X1 is, but didn't notice much if any difference in noise 'Jump off' // 'Jump on' with the controls set to 'normal' listening levels in each case. For me there was little or no difference in SQ with the Flat Amp in use (Jump off), or not (Jump on).
As you know, I always listen to the X1 bypassing the flat amp- would that increase it's longevity?
To answer a previous question.
I can't see that being a consideration for the use, or not, of the Jump switch.

The only thing I have noticed, which I think was first mentioned by Harold, is a certain sensitivity to the setting of the power amp attenuators. Namely, sounding very slightly harsh if turned fully up. (meaning zero attenuation). Backed off by the smallest amount and things were better, I have got used to listening to mine set to about -2dB according to the panel markings.
 
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