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November 25, 2020, 03:33:35 AM

Author Topic: The New BeePre Pure Speculation Thread  (Read 1288 times)

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Offline makarushka

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Re: The New BeePre Pure Speculation Thread
« Reply #45 on: October 23, 2020, 08:34:20 AM »
Great to hear regarding the improvements in microphony reduction! My original BeePre was one of the best preamps I've owned overall, including many custom DHT units of various designs, a purist but really insane build based on we437a with Tango NP-126 outputs -- real "wire with [a lot of ] gain", and several commercial units of certain pedigree like EAR 912 and AtmaSphere MP-3. Excessive microphonics was the ONLY reason I ended up selling the BeePre -- was just too much for me to live with. The sound otherwise was just sublime -- had everything: transparency, bloom, phenomenal bandwidth, just the right amount of gain, etc. In retrospect, I should have re-worked that unit further to produce better mechanical isolation but I felt that with all the tweaks I made I got close to limit.

With that in mind, would you guys -- Doc and Paul -- consider some further mechanical isolation for the 300B socket mounting? Or at least, make the opening just large enough so that the base of the tube can go through just so we can mount the socket on rubber standoffs ourselves? Or do you feel strongly that with the new design even this is not needed?

As far as the sound, and this is of course very subjective, no loss of clarity/immediacy/transparency with the extra follower stage? That was the beauty of the old one -- nothing but a DHT in the signal path. But if you guys say it sounds good, it sounds good -- I've built a couple of your kits and I trust your sonic reference -- and like it a lot.

I am pretty sure I'll be ordering this one :)
« Last Edit: October 23, 2020, 08:35:51 AM by makarushka »

Offline Doc B.

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Re: The New BeePre Pure Speculation Thread
« Reply #46 on: October 23, 2020, 09:11:17 AM »
I may have some experiential advantage here due to having taken a pragmatic approach to dealing with the issue. The amount of suspension necessary to effectively limit vibration transfer from the chassis to the socket would have the socket bouncing around like a baby in one of those Johnny Jump Up suspended chairs. With a top heavy 300B this floppy suspension would be a recipe for disaster. A tighter suspension won't do much more than the O ring we provide to put under the tube base. The very best way to reduce the vibration is to isolate the preamp from the rack shelf with something very squishy and add mass to the top of the tubes in the manner I did, with the vinyl coated lead flask weights.  When I say mass, I mean MASS. The mass right on the tube envelope has the advantage of reduction of both groundborne and airborne vibration. Mass added to the chassis panel may help a little too.

Obviously keeping the preamp away from speakers, out of corners or areas of the room with antinodes is a useful thing as well.

Perhaps the most effective method to reduce groundborne vibration is to have a listening room with a concrete floor. That will limit the vibration transfer to higher frequencies that are usually easier to address.

Another possible solution would be an isolation platform on an inner tube. Haven't tried that, but with enough mass in the platform on top of the tube it should be fairly resistant to groundborne vibration as well.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline makarushka

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Re: The New BeePre Pure Speculation Thread
« Reply #47 on: October 23, 2020, 10:36:02 AM »
While "Johnny Jump Up chair" is only a vaguely familiar reference to me, I do get the point :) I had me a feeling. I did what was possible with my BeePre -- dual lead rings on each tube, rubber band under the base (made the least difference), top plate dampened with dynamat and then isolated from the chassis with sorbothane, sorbothane under the chassis, etc. It all helped but fell short still.

Concrete floor indeed would be a solution but is a no-go in my housing situation. A high-end Minus K or Vibraplane isolation platforms would also do the trick, I suspect. Unfortunately, the impossibility of the former and the cost of the latter make a different preamp a more feasible solution :)

I will give a shot to the new one regardless based on the killer sound of the 1st generation. 13dB of microphony reduction as per Paul's post's scenario -- which is likely in my system's gain structure -- is a lot and most likely will make it a non-issue.

Thanks for replying!

Offline Doc B.

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Re: The New BeePre Pure Speculation Thread
« Reply #48 on: October 23, 2020, 11:03:56 AM »
Re the CF I had the same concern that the sound might suffer. That actually led to this most recent listening session. I had not heard the earlier prototypes in some time and so PB brought over a basic BeePre 2 prototype along with parts for every possible upgrade version of the new design. This new preamp has a better focused image, cleaner highs that make vocals sound more natural, and quite a bit more punchy bass than the limited edition BeePre 1 I have in my system presently. All in all it gives a more relaxed and natural presentation. I would not have expected this based upon my previous experience with CFs, it was quite a surprise. That's why I refuse to sign off on a design unless I can give it some comparison with a known quantity. You can only think you know what might sound better unless you actually listen and compare. Sometimes you get a surprise.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline makarushka

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Re: The New BeePre Pure Speculation Thread
« Reply #49 on: October 23, 2020, 11:20:35 AM »
That sounds killer! I am very ready to be surprised -- bring it on :)

And in response to the earlier post regarding messing up tubes by running wrong filament voltage via a switch -- I am that rare individual who's had all manner of gear with switchable filament and B+ voltages, and managed to not mess up once. Yet. It's probably in my future :) So to be able to run a 2A3 as well may seem like a cool option. With that said, personally I would not expect (or desire necessarily) a massively different sound from a [typical modern] 2A3 in a line-drive design that is ultra-optimized for 300B. Unless it was 2A3-40, which is a bit of a waste at regular 2A3 op. points anyway [it can be argued]. Even then, should curiosity become unbearable, I could always try it by stuffing a different set of regulator boards in there that I already have, Coleman or Pete Millett's, depending on what's desired. Probably a switch of a cathode resistor, too -- although maybe not even?

As long as there is enough room inside. For all those fat polyprops and vitreous non-inductive wirewounds and other some such jibberish :)
« Last Edit: October 23, 2020, 11:23:48 AM by makarushka »

Offline Paul Birkeland

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Re: The New BeePre Pure Speculation Thread
« Reply #50 on: October 23, 2020, 12:54:14 PM »
2A3s will not work in the design and there isn't a good way to make that work without providing a different power transformer and a different circuit.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Alby0521

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Re: The New BeePre Pure Speculation Thread
« Reply #51 on: November 04, 2020, 03:43:08 PM »
Hello

Will the upgrades come available at release date or will you release them later on?

 I already made some space on my rack which is allocated to the beepre ii :) and yes at the moment I became beepreless...
Can’t wait for this winter project.

Best

AB

Offline Paul Birkeland

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Re: The New BeePre Pure Speculation Thread
« Reply #52 on: November 04, 2020, 03:44:59 PM »
The upgrades will come a bit after the kit is released. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Sp33ls

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Re: The New BeePre Pure Speculation Thread
« Reply #53 on: November 16, 2020, 12:06:55 PM »
I went to go place an order on the BeePre and was wondering why it was "Out of Stock". Queen pointed me here, and now I'm even more excited. :)

Building this over Xmas would be amazing...  ;) :P