BeePre Pre-Build Questions

[Gerry E.]

Hi:

I finally pulled the trigger and ordered a BeePre to go along with my Paramount 300B amps.  My friend Boulos, who has built a S.E.X. amp and then added the C4S upgrade, will be doing the build for me.  He has additional electronic/soldering experience including replacing my stock Paramount transformers with the Magnequest full-nickel upgrade transformer set.

I have been in the passive attenuator camp for a while (most recently with a LDR-based unit) but recently heard what an active preamp can do for my system.  Before Boulos gets started, I would like to ask some questions:

1.  We will go with the stock volume controls instead of the BeeQuiet which we can always add later.  I just want to confirm that if you add the BeeQuiet, you lose the balance control functionality, correct?

2.  I purchased the BeePre without tubes and was thinking of purchasing a pair of JJ 300Bs for it.  They JJ 300Bs appear to be both a good choice and good value for the BeePre - any thoughts on this?

3.  I know the BeePre comes with excellent parts but are there any must-have part upgrades you can suggest?  I assume capacitors would be the most likely but which ones?

4.  I'm a single input guy.  Um, I mean I only want/need a single input and two sets of outputs.  How difficult would it be to build with just a single input vs. the stock multiple inputs?  Would it actually be easier to build and possibly sound better?  I'm more curious about those last two questions than either mattering that much.

5.  Excluding the 300Bs, what is the full tube compliment and quantity of each tube?   

6.  Any other advice or tips about the build that you can think of?

Any information or thoughts would be very much appreciated - thanks!

Gerry

[Paul Birkeland]

1.  We will go with the stock volume controls instead of the BeeQuiet which we can always add later.  I just want to confirm that if you add the BeeQuiet, you lose the balance control functionality, correct?

Yes

2.  I purchased the BeePre without tubes and was thinking of purchasing a pair of JJ 300Bs for it.  They JJ 300Bs appear to be both a good choice and good value for the BeePre

[STURMJ]

Im using jj 300Bs in both my paramounts and beepree, and am very happy with yhem in both applications.

[Gerry E.]

Thank you PB and STURMJ!  Both the BeePre and JJ 300Bs are in transit.  I was pleasantly surprised how quickly the BeePre was shipped.  I expected it to be another month or so.   

The JJ 300B appears to be an ideal low cost option for the BeePre due to their very low noise

[Paul Birkeland]

One question I didn't ask was if the BeePre comes stock with two set of outputs.  I re-read the product description the other day and it mentions two sets of outputs.  Pierre Sprey's advice notwithstanding, I like running my subwoofer at line level vs. speaker level.  In case you don't know, Pierre is the very opinionated man behind Mapleshade and he says that you must only use speaker level inputs to subwoofers.

It does come with both an unbalanced and balanced output.  You could easily use two unbalanced output or two balanced outputs without much extra trouble, or you could just make a woofer cable that adapts the balanced output. 

[boulos]

If connecting two unbalanced outputs, do I simply jumper the signal and ground of the two outputs? That is, I wouldn't need the 604ohm, 475Kohm, and 10uF components that would otherwise connect to terminal 3 of the XLR output, correct?
Thanks

[Paul Birkeland]

Yes, that is correct.

[Gerry E.]

Hi PB:

Boulos, who is building the BeePre for me, and I are double-teaming you a bit here.  In an earlier post, you wrote:

"There are 10uF coupling caps.  Since you have Paramounts, these can be smaller if you like.  The voltage rating should be 100V or more.  We strongly suggest building the kit in stock for first, then upgrading later, and we have left a good amount of space to make this easy."

Can you explain why one can use smaller coupling caps when they will be using the BeePre with Paramounts?  Also, how low could I go without compromising performance?  The reason for the latter question is the lower I can go, the better cap I can buy.  Thanks for all your help!

Gerry       

[Paul Birkeland]

You can read through this page for a bit of an explanation on how this works:
http://www.v-cap.com/coupling-capacitor-calculator.php

FWIW, even though the calculator will give you a very small value to use in conjunction with the 249K input impedance of the Paramount, I would use a minimum value of 1uF.

[johnsonad]

HI Gerry, I played around with smaller caps and will say from experience that 10uF is a sweet spot.  Dan has posted a few times that 10uF is minimum for bass respose.

I'm using Russian KBG 10uF in mine and really like them.  I've got a pair of Jupiter's (10uF) collecting dust if you are interested.  If I were to try any others they would be the Rike Audio PIO's.  I'm really liking them in my SEX amp. 

[Gerry E.]

HI Gerry, I played around with smaller caps and will say from experience that 10uF is a sweet spot.  Dan has posted a few times that 10uF is minimum for bass respose.

Hi Aaron:

I thought Doc's 10uF recommendation was for the Paramount? I just want to make sure we are talking BeePre here.  Maybe it applies to both?

OT - Did you get my e-mail about Open Baffles?

Gerry   

[johnsonad]

Definitely the BeePre and not the Paramount.

No open baffled yet. I'm patiently waiting on boxes to be finished.

[boulos]

Not sure if I should start a new thread, but I will start here.

For the low voltage DC supply, page 42 specifies that one should user 10,000uF 10V capacitors.  However, the kit came with 10,000uF 6.3V capacitors (and only 2 instead of 4).  Has something changed in the build without an update to the manual? Or does this specific kit not include the correct parts?  I believe Gerry emailed replacementparts but afaik haven't heard back, so I thought I'd inquire here in case this was not a mistake.

Thanks
Boulos

[Paul Birkeland]

There should be four 10,000uF/10V caps and two 10,000uF/16V caps.  The 10,000uF/6.3V caps are a packing error, and likely came in place of the 10,000uF/16V caps. 

[boulos]

Thanks!  That's what I thought there should be.  What was packed instead were two 10,000uF/6.3V and two 10,000uF/16V.

So then I won't do anything with the 6.3V caps and wait for a response from replacementparts.