Bee Pre input selector switch

[fritzthecat]

Does anyone have experience with replacements for the stock bee pre input selector switch? I am just building a bee pre and ordered it with the bee quiet upgrade and to be somehow consitent I'd like to replace the stock input selector switch as well. I got a TKD input selector switch I didn't use in a former project - see pic - I think this one should be okay. Does anyone have experience with this or other options? Thanx a lot, Chris

[Paul Birkeland]

You'll have to drill several extra holes in the attenuator overlay that comes with the Beequiet to use that TKD selector switch.  It also will not provide ground switching like the stock switch will.  You'd also want to be very, very sure that it isn't too large to interfere with the Beequiet. 

[fritzthecat]

Thank you Paul - I just realized again that I really have to learn a lot about audio circuits...

Talking about the ground switching the stock switch provides - What exactly does this mean or what ecactly is the difference between the two switches?

Still I would like to try another input switch as the stock one - but with aequivalent switching options like the stock switch. What type of switch do I exactly have to look for?

Regarding the three holes I'll try to go another way - I'd like to position the switch and the be quiet at the back of the Bee Pre - as close as possible to the inputs. Therefore I'll use rods, shaft couplers, ball bearings and will have to produce some metal parts from stainless steel and Aluminium (Including a back and front panel and a new top plate without mounting holes for input selector and bee quiet switches as they will sit at the front).

I'd like to have more than three inputs as I have more sources - do you see any problems to do so with the solution I just described?

I hope the three rods somehow will fit, else I'll build a new a bit higher chassis from slate.

One more question regarding the EL84 tubes being used within the Bee Pre - I know, they are part of the Shunt regulator - I just wonder what EL84 (in terms of standard or custom values) I might be able to use? What are the critical values for EL84 tubes in the Bee Pre?

And a last one: I have a matched pair of PSvane Hifi Series mesh plate 300B/N tubes which should fit within the standard 300B specs and a pair of EH Gold 300B and a pair of unused PSvane 300B WE replicas -  are these all okay to be used with the Bee Pre?

By the way - built two Kaijus - amazing kit!!! Soon get a third one...:-)

Thank you so much!

Best,

Chris

[Paul Birkeland]

There are some odd 300B tubes that aren't really 300B's which can cause problems, but they are not among those you listed.

The EL84's are enormously flexible and any variant will work very well.

[fritzthecat]

Hi Paul,

thank you for your answer regarding the Tubes working with the BeePre. In the meantime Imfigured out about the input selector switch and got myself a TKD 4R6 that should do the trick with ground switching as it has 4 instead of only 2 switching levels.

Looking forward to get it done.

Thank you for helping.

Best regards,

Chris

[fritzthecat]

You'll have to drill several extra holes in the attenuator overlay that comes with the Beequiet to use that TKD selector switch.  It also will not provide ground switching like the stock switch will.  You'd also want to be very, very sure that it isn't too large to interfere with the Beequiet.

Hi Paul

just wanted to get back to you regarding your very much apreciated advices - thank you so much! I am really, very happy I discovered Bottlehead and your beautifully designed kits - it's an amazing experience for me and even some of my friends started to build BH kits! Thank you for the great work you guys do and the support you provide to Bottlehead youngsters like me!

Regarding the replacement of the stock selector switch I am totally aware of the points you mentionned regarding drilling additional holes for the TKD and the size of that TKD switch. In the meantime I even got a bigger one as you raised the ground switching issue I would run into when usimg a 2R6 I got a 4R6 that solves that issue.

I am just about to figure out how to wire it properly.

I am thinking about a custom made mounting plate (sorry I'm not native English speaking but try my best) for the whole BeePre circuit. I am planning to have it lasered from stainless steel in mirror quality. As my neighbour and best friend Urs (he ordered several BH kits himself - actiually BeePre, Eros and Kaiju) has extended experience in laser cutting and metal construction including drawing 3D construction plans and so on.

The plan is to design our own BeQuiet overlay - maybe including six input positions and if possible backgroung illumination and custom knobs. This will take some time but we hope to be able in early to present first results in early 2018.

I have some questions regarding what I wrote above:

- Regarding TKD 4R6: To have proper ground switching I guess that I can use one of the additional 2 switching layers (4R6 offers 4 instead of 2 the of the 2R6) or am I thinking in a wrong direction? Oversee something?

- To satisfy the big child inside me in a further step I'd like to replace the Cat5 signal wiring running from inputs to selector switch / volume control returning to the outputs. I would like to replace it by a selfmade solution using teflon insulated solid core silver wiring done analog to the construction of the stock Cat5 cables; should I do separate paths (one for inputs to selector/volume and a separate one back to the outputs or do you see any issues by putting them all together into one french braid shield?

- Regarding short signal paths the best solution would be to move input selector and volume control to the back of the chassis and use extension rods, ball bearings and to construct some supports to make the whole thing stable and reliable. Then the knobs have to be moved (turned by 90 degrees) to the frontplate (would laser a separate inlay plate to mount at the front) of the wooden chassis.
As our plan includes a custom mounting plate for the BeePre circuit anyway this would actually be the best solution in my opinion - or am I wrong??? I am aware that this would change the dimensions of the BeePre causing lots of redesign and construction work - but maybe a special Swiss edition of the BeePre could raise the awareness of Bottlehead as a supplier of beautifull DIY kits among the Swiss tube amplification enthusiasts community?

=> I am very unterested to have your opinion regarding this option my thoughts and am sorry for having written almost a novell here and hope not to get on your nerves with all my questions and non existant know how and very little experience. Iit would be great if you somehow could find the time to read all this and drop a reply.

Thank you very much for enabling me and my friends to build amazing audio gear!

All the best,

Chris
-

[Doc B.]

The ideas you have are pretty involved. We're happy to offer an opinion of one well defined change to the circuit like the installation of a different switch, or changing a cap value. But when you take something this far from the original layout and components it's pretty difficult for us to be able to assure you that everything will work as expected. I'm not saying the ideas are at all bad, or that they won't work. Just that this extensive modification would be beyond what we can predict. Once you get to that level of modification you have to just try it and see how it works.

That said I have done preamps with controls back from the front panel with extended shafts and so on. The thing you have to keep in mind is the potential to introduce noise into the circuit that the stock circuit may not have. A short signal path is one consideration, but the physical distance between components that generate noise, like a power transformer, and a component that is sensitive to noise pickup, like a volume pot or a selector switch, is fairly critical. One can offer some general rules about component placement - which have been used in the stock design - but beyond that you have to put it together the way you plan and see if it works right.

What I'm getting at here is the general idea that the farther you deviate from what we deliver, the more you will have to take responsibility for the outcome. Your basic ideas are sound, but we can't say if they will make the preamp sound better. So you don't need our blessing as much as you need some willingness to try out and then refine your ideas until they give the result you desire.

[Paul Birkeland]

I agree with what Dan says.  When you move off into this direction (which I did myself in roughly 2006), you're really on your own!   

That's not to say that you shouldn't do this, but rather that you should be well prepared to encounter some bumps along the way.

[fritzthecat]

Dear Dan
Dear Paul

Thank you so much - I totally agree - it will be a trial and error approach my friend and me have to go throug...:-)

And please don't get me wrong, I am not the one to make anything better than you guys do and I actually don't even have the know how yet - it's more for the sake of it and because I have the possibility to use my friends abilities in terms of lasering and construction skills - we'll just try it.

I will soon start a blog in the internet to share the experiences and to let others know what mistakes we made so others may be able to avoid bad experiences we have to face.

Is it okay with you to publish links to the Bottlehead website and to promote Bottlehead a bit here in the german speaking part of the world? Actually my experience regarding your products and the amazing support one gets is just wonderful and I would love to share it with fellow audiophiles here in my region?

Regarding the introduction of noise into the switches by moving them closer to the power transformers I thought that shielding may be a solution - but there is a BUT: which material to use (aluminium is no solution as the magnetic fields just go through) - so I will do some further research... So far I found a material called "MU-Metall" in german - it is used for transformer shielding applications and I think is worth further research.

The shielding topic raises my next question: Should the shield for the selector switch and volume controls connect to ground and if so where?

You see the way to get there is really far and I have to learn a lot! Thank you so much for your very apreciated input and support!

Maybe you may give me a hint regarding sources for know how regarding parts placement, component shielding and grounding?

Thank you very much for enabling us DIYers to build amazing high end audio gear! It is such a great experience to me and makes me very happy and to me it is as Bottlehead really opens a new window to the music I love and to be able to hear details I never did before - since integrating the Kaiju amplifiers into 3 ways (low midrange, midrange and tweeters - for the bass channels I am still using Silvercore 822c monos) of my system songs I thougt to know very well  really touch me emotionally - in a way I never thought to be existant in music reproduction at home! Thank you for making this possible!

All the best to you and the whole Bottlehead team,

Chris

ps: attached a pic of the power amp section of my system - now there are 3 Kaijus and I am planning to get two more and to set them up as monoblocks for the Klipschorns - that raises the next question I have to bother you with soon regarding the the international availability of the Bottlehead speaker kit....