The New BeePre Pure Speculation Thread

[Deke609]

So, we know a new BeePre is coming. What else do we know? Only this much:

A universal power transformer is indeed part of what's up.

Note the phrase "part of what's up".  So there's more. So let's speculate what it'll be! 

In the thread from which PB's above quote is taken, someone expressed hope that the filament regulator will be immune to mains voltage sag -- b/c when the reg drops out you get a lot of hum/buzz.  I think the new universal power trafo with different primary winding configurations will take care of this in most cases -- but perhaps the voltage of the LV secondary will get bumped a bit? And maybe permit a bit of smoothing before being sent to the reg?  I doubt this last bit b/c that would be overkill (which, of course, is why I included a CLC filter before the fil reg in my Beepre rebuild  ;D )

My biggest question is whether the attenuator will be moved from the input to the output to increase SNR, as in the Moreplay.  If yes, I really hope there's a mod to make this work with existing Beepre's.  IIRC, PB mentioned in another thread in the last year that to do this other circuit changes are needed to maintain the output impedance of the amp.  I'm not sure if moving the attentuator would make much difference for those who keep the Beepre attentuators turned up pretty high -- but I'm guerssing it might make an audible difference for those who only use the first two (highest dB reduction) positions of the coarse attenuator.

What else?  Let the wild guessing begin!

cheers, Derek

 

[Paul Birkeland]

There will not be any backwards compatibility between what we are up to now and what we are working on for the release.

 

[Deke609]

J. H. C.! I might be building a new Beepre next year!  With luck I can build the new circuit in my "BigBy" chassis.

 

[Deke609]

I take comfort in knowing that I am not the only recent Beepre builder that will likely be building the new version when it gets released.

I am all but certain that, like me, Jameson is  weighing whether he can make use of two Beepre's and I'd even guess that he's leaning towards (a) using the new premium preamp in his main rig; (b) in that same main rig, replacing the SII with Monomours to drive his Kaiju Jager tweeters; and (c) using the "old" BP and SII as a kickass secondary system -- perhaps office or for tv.

Jameson: am I close?  ;D

cheers, Derek

 

[Jameson]

I don’t want to talk about it

 

[Alby0521]

When is the new Beepre supposed to come out?

 

[johnsonad]

I predict it will sound fantastic, have a great manual and support from the BH team. If it improves on the BeePre that will be one nice preamp!

 

[Alonzo]

Here's a wild speculation:
Universal transformer, TI DC 6v boost circuit board added to power supply, extra input so now 3 in, 3 out, change out the 80 ohm resistors for Ohmite ceramic for a cooler top plate, individual pots instead of a balance circuit or maybe BeeQuiet being standard.

 

[Jameson]

If it’s anything like previous stepwise updates they’ve made to the Eros, it might just be a universal transformer and a change to the layout to make things simpler to construct and troubleshoot.

 

[Doc B]

Even I don't know what the final changes will be yet. We have a tentative plan to listen to a couple of prototypes next week, after which I will make some final decisions. The voltage sag issue has been addressed. The power supply is different than the one in the original BeePre.

 

[Deke609]

We have a tentative plan to listen to a couple of prototypes next week ...

Man, testing different PJ/PB prototypes ... that's a pretty sweet part of the job!

cheers, Derek

 

[raymondp1138]

Even I don't know what the final changes will be yet. We have a tentative plan to listen to a couple of prototypes next week, after which I will make some final decisions. The voltage sag issue has been addressed. The power supply is different than the one in the original BeePre.

Please post some pics of the prototypes, inside and out. To respect the theme of this thread, I speculate the new BeePre will be in my system in the future.

 

[Paul Birkeland]

Please post some pics of the prototypes, inside and out.

That's always an iffy proposition.  Some of the stuff we (more often than not me) build sucks horribly and should never see the light of day, and what we really wouldn't want is to get traction on a prototype that performs poorly!

 

[raymondp1138]

I saw a picture of a BeePree II prototype on the Bottlehead Instagram feed and was wondering what the chassis size is. (Gotta make sure I have space. )


BTW, that power transformer looks massive, like the Kaiju's.

 

[Paul Birkeland]

It is a 10x16 like the Kaiju with the same power transformer.

 

[Deke609]

So Doc B. has chosen the winning prototype?

When will we learn more? I imagine putting together the assembly manual will take a while. Any chance of a brief circuit description in advance, preferably highlighting changes from the previous version?

cheers and thanks, Derek

 

[Paul Birkeland]

Yeah, all of this started in April 2018 with this prototype.  Ultimately all I was really wanting to do here was to make myself a BeePre that looked more like my Kaiju and to mess with a BeePre  powered with the Kaiju power transformer.  I used the new Kaiju DC filament supply board instead of the specialty BeePre filament regulator which freed me up from being locked into the BeePre operating point and allowed a little extra flexibility.  Being able to adjust the operating point meant that I could move the attenuators to the output and not overdrive the 300B in the process. 

 

[Paul Birkeland]

After the red prototype, we explored the possibility of different packing and remote control options.  All those extra metal panels drove the cost of the kit way up, and the remote attenuator would have required me sitting down with the boards we ordered and doing surface mount soldering to each one to prep them before shipping, or paying a board house to do assembly.  Stuff like that really messes with lead times, and a $3000 preamp kit wasn't sounding like such a hot idea, so this one didn't make it to the public.

 

[raymondp1138]

The Bottlehead Instagram has a picture of the underside and showed a stepped attenuator. Is the stepped attenuator an upgrade kit? I hope the basic potentiometers with L/R balance control are still available.

 

[Paul Birkeland]

So now we arrive at the current design, which from my records is the 5th or 6th prototype (not all of them make it to getting built).  This iteration was inspired by the simplicity of the Moreplay, and in essence what I built could be called a BeePlay. It is a boiled down version of the circuit with the Kaiju DC filament supply but just a CRCRC high voltage supply.  Biasing and plate loading are done with resistors to dramatically decrease the amount of initial debugging, and we just plug/block off the holes for the extra tubes/jacks that come with the upgrades.  This will be the "stock" BeePre 2 offering. 

On Friday, I brought up this basic BeePre preamp and several of the upgrade modules, and we installed them and listened to the various options. 

Ultimately one upgrade will be a BeeQuiet attenuator with completely different values to better work with this new circuit, but this upgrade will also come with active loads for the 300B.  The combination of the lower impedance of the new BeeQuiet and the resistive loading in the stock circuit isn't optimal, hence the combination of the attenuator and C4S board offered together.

The second upgrade module will populate the rear two 9 pin sockets with a dissimilar dual triode that provide individual shunt regulators for both channels as well as adding a cathode follower buffered output that decreases the output impedance of the kit substantially.  This upgrade will also provide balanced outputs similar to the BeePre 1.

The primary benefits of the new design vs. the old are:
[list type=decimal]
[*]Replacing the two single voltage power transformers with a new universal power transformer.
[*]Reducing the severity of microphonics and apparent noise in the circuit through relocating the attenuator and using a different 300B operating point.
[*]Offering a far easier to build stock circuit and modularizing the more difficult components as future (optional) upgrades.
[*]Providing some additional space with a larger chassis plate that matches the Kaiju.
[*] Low line voltage regulator dropout is now nearly impossible through the combination of using the Kaiju DC filament regulator, the universal power transformer, and a different circuit design.
[/list]