Chokes, resistors, tweaks, and an EL84 question

P

Paully

New member
There are a large number of tweaks for the Bee Pre such as boutique wire, pots, etc...  It’s what happens when you market to people who can solder.  I was really just considering one or two, besides the obligatory Bottlehead coupling cap swap, and had some questions:

A Pair of 157M chokes in the power supply.  Are these the best to use?  I see that the 159M has 15H / 100ma / 256 ohm / 500V just as a thought.

Mills 8 Ohm 10W resistors – any other resistor swaps people have done to consider?

General question: there was a hierarchy of tube importance in the Eros with the EF86 and 6DJ8 being important and the 12BH7 much less so.  I assume that NOS versus new production EL84 in the Bee Pre isn’t going to have much of an impact and NOS wouldn't be worth the expense.

I have some Shuguang 300B coming, off to order some JJ!  Thanks!
 
That choke will be about right.  The slight increase in raw B+ would be within the limitations of line voltage variation.  (If you have 130V AC at your outlets, you wouldn't want to do this)

Some people have swapped the cathode resistors out.  We use good quality parts here, so this seems unnecessary. 

The 10,000uF 16V cap that sits across the filament supply resides in the signal path.  Most of the substitutes available are of inferior quality to what we provide, but there may be a better sounding cap out there.  (Nichicon KA?)

The EL84 is in the power supply, so its influence on the sound will be roughly equivalent to the 12BH7 in the Eros.  If you feel the need to be different, the socket can be rewired for the 6S4 pretty easily.

-PB 
 
Paul is using a P500 and sets the voltage on 120V AC.  He could set it at 117V AC.

Are the cathode resistors the 10 Ohm resistors?  I would think that the cathode bypass cap is more important to the sound.
 
All right then, I will just stick to the chokes and use the 159M.  I will most likely not worry about the Mills and definitely won't worry about the 10K cap.  And there really wasn't much else I was curious about.

We do like to be different however.  Grainger and I can look at rewiring for the 6S4 just for fun.  Don't know that tube at all and what it entails.  But I would think we (i.e. he) can figure it out.
 
If you read my thread all the way through, I did most of what you are thinking of. I replaced those big lytics with KA's, cathode resistors are mills and for El84's, I've tied a few varieties and didn't notice a difference. I'm using some Ruskies now that work well. I highly recommend the BH attenuator.  The chokes made a very small, if any difference. As I'm running hotter than most pushing the limits of the amp with EML tubes, I couldn't afford any more heat under the chassis and swapped back to resisitors. You and I are using regulated clean power so the chokes probably won't make too much difference in your system either. They are easy to put in later as you need only 4 holes. Xavier's photos show where to mount them. I've got a pair if your heart is set on them. I use them as paper weights :)

The number one thing you can tame from the beginning is microphonics. They will drive you crazy if you are used to a dead quiet preamp. Again my lengthy isolation is outlined in the post.  I recommend the Dynamat extreme from the beginning as it's a PITA to apply after the build is done.
 
I have read through your post (twice!).  That's where most of the ideas came from.  I am set on the chokes, was thinking the 159M, I don't know what difference the 157M vs 159M would really make.  I was planning on putting the chokes on top of the chassis so heat shouldn't be a problem.  I can't get any of the photos to load from the forum on multiple different computers to see where xcortes put them.

The attenuator will have to be on hold as funds are approaching depleted for audio gear.  But I will keep your recommendation in mind.  Funny, after Paul mentioned the 6S4 I went down and checked my stash for EL84 and found a quad of GE oval plates, a quad of Tesla, a quad of Tungsram, and a handful of Soviet 6n14n.  Given what everyone says, I will just stick with the stock tubes coming with the amp and then use the Russians like you are doing.  No point wasting the NOS.
 
From what I am reading, the biggest  bang for the buck is the attenuator. I might put the funds for the chokes and such towards it and revisit the parts down the road...John
 
2wo said:
From what I am reading, the biggest  bang for the buck is the attenuator. I might put the funds for the chokes and such towards it and revisit the parts down the road...John
Click to expand...

I appreciate the input, I will have to see how my audio priorities shape up.  I would like to buy some records too!
 
I bought the 159M chokes.  Might have been a mistake, they're frickin' huge.  We'll see during the build whether they can fit on top or have to go in a separate box.

I ordered the KBG caps and am ordering the Obbligato 15u 250V from Partsconnexion.  I am picking up the 8R Mills, but mainly because I am ordering from PX and it was no big deal to grab two.  I am also ordering two Kiwame 5w 47R resistors to put in front of the chokes to put them at the 300R mark.  I just rather run things at the design parameters.

Not going to order a selector switch.  Grainger has a big 'ol Russian industrial silver selector switch that we may use, but it is big and complicated, so we may not.  That remains to be seen.

Definitely following PB's advice and going to leave the inputs and outputs stock with 3 in and two out with one out balanced.  I'll get an adapter for the balanced outs if I ever need to.  Doubt it will be necessary.

I haven't worried about the 10K cap.  Don't know that I ever will.

I have a set of Shuguang 300B coming, have an older pair sitting by along with a new pair of JJ 300B.  And lots of EL84 in my stash.  Seems I am good on tubes.

That's where it stands.  Seems good to me!
 
Aaron,

Just because I can't leave well enough alone, what made you pick the KA vs something like the Mundorf M-Lytic AG?
 
A couple of reasons. First, PB recommended it and it's and the top of that line of lytics. Second, the Japanese do lytics very well and I've always had great results with them; I would choose Elna, Nichicon and Sanyo over Mundorf for lytics.
 
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