New Aleph J build

[buzzforb]

I am preparing to build an Aleph J for my first amp. I have most of the parts on order with the exception of the capacitors. I have found plenty of info to support Nelson's choice of the Elna Silmics II as a wonderful sounding electrolytic cap. The cap i have a question about is the Input Cap C1. I have a frien who is helping me with the build who says that if there was one to upgrade, it would be this one. But, he also says that Nelson's stuff doesn't really need expensive caps to sound really good. I tend to agree but would like to hear opinions. Why pay more for a boutique cap and will it really sound different.

[massimo]

I think Nelson Pass is using this component in his commecial amp:
Digi-Key - BC2076-ND (Manufacturer - BFC241671005)
If not, this model is ok, as well as an equivalent WIMA MKP10 (generally 250V or 400V and thus much bigger).
I you want a "cheap but chic" boutique cap, try Obbligato Premium (search for it on ebay), they worth the money.

[buzzforb]

Massimo,
Thank you for the reply. I think you are right about the Wima being used in the Pass amps. At least that is what I ordered. My question was not which one he used, but is it worth it to buy a more expensive replacement. I was hoping for an explanation as to why one works better than another and whether the difference is that significant. If a 20$ capacitor sounds that much better, why did Nelson not use it. From what I have read, his choice of Elna Silmics, makes perfect sense. This article may help with making my point.

http://tech.juaneda.com/en/articles/...apacitors.html

Reading the above article, the choice of Elna's makes sense. But, they are also many articles saying similar things about the different polypro caps that are best to use, yet you do not find these in his euipment, as far as I know. It would seem that he doesn't believe it would be different enough to warrant the cost or else he would have included them. This is of course speculation on my part and he amy have a perfectly good reason for not including them. I was hoping for opinions of others.!

[bobodioulasso]

If your source presents no DC, why not to simply take the input cap off.

[massimo]

I was probably misunderstood.... NP is using BC MKP, possibly because of availability in U.S., small size (for a MKP), or.... whatever.
I suggest the Wima MKP10 (not MKP4) as alternative, beacause I think it's slightly better, but it's also bigger.
The Silmic is a very good cap, but is an electrolytic one and I won't use it where I can use a good film cap.
If the vaue were 47uF, no choice: go for the Silmic, but for 1uF, much better a film cap.
In the article you linked, at the end, the author stated: If you search for better capacitors from Elna, look for metalized polypropylene capacitors.

P.S. the cap is on the signal path only if you use the balanced input, thus if you think you will mainly use the SE input, don't worry too much about it.

[buzzforb]

Thanks for the info Massimo. I had a feelign bobodioulasso was trying to get me to think about the circuit. I have ordered the WIMA already, but was considering upgrading and wanted to know if it was really necessary. What are the benefits of XLR? I will try to do some reading. I was going to buld either an Aleph P or Zen Mods Pumpkin.

[Bill Fuss]

Originally Posted by bobodioulasso

If your source presents no DC, why not to simply take the input cap off.

If you eliminate C1 and short the neg input to ground to run single ended you will disrupt the output offset control.

[bobodioulasso]

I meant shorting it. The 22 k will be inserted between negative input and ground.
Or this is not working anyway?

[Bill Fuss]

You would still be shunting around 90% of the DC feedback to ground. I'm sure it would still work marginally, but not be totally effective. I'm sure someone has tried it, but I have never seen NP use an unneeded component.

It could also disrupt the AC feedback using the amp balanced, depending on source impedance and other things.