New 300B pre-amp?

[Paul Joppa]

The LDRs that have been published are quite low impedance, making them less than universal with respect to sources (e.g. Seduction and Eros for example). They also appear to have tracking issues, usually approached by ruthless sorting and rejecting a large majority of devices. Both make them mostly useful to DIYers who have the time and patience, and who understand the impedance issues and can work around them.

That said, we haven't tried any yet.

[earwaxxer]

Hey Chris - here is a post on that topic.

http://rockgrotto.proboards.com/index.cgi?board=m&action=print&thread=4066

I would agree with Paul. Opto pots are not without their own problems. I would go stepped attenuator if you are looking at optimal sound quality.

[Doc B.]

For what it's worth - while we decided not to try LDRs we did listen to a lot of different attenuators before deciding on the coarse/fine one that will be the upgrade option. That would include TVCs, Alps Blue, PEC, Goldpoint, Sweetest whispers, some old Davens, etc., in various configurations - stepped, shunt and ladder.

[dbishopbliss]

At last year's Linestage Competition, I threw in a Lightspeed.  If I recall, it didn't make it into the final round of listening.

[debk]

Will the upgraded fine/coarse attenuators be available when the preamp ships or will it be an upgrade available sometime in the future.

Deb

[Doc B.]

We just got the high grade switches in to try today. Looks like they will require an adapter to mount them, so the release of the attenuator may follow the shipment of the preamp kits by a bit while we work out the details.

[Chris]

Wow, superb stuff from all of you!! My question was answered in spades... and dbishopbliss' comment for me says it all... If LDRs were that great and worth using, Paul and  Doc would have recommended them... Thank you guys...

[John Roman]

Any update on the attenuator upgrade?

[4krow]

There are different configurations for the fine/coarse controls that I have seen. Right now, I am using a mono (two controls per channel), but I have yet to try one that adjusts volume normally,both channels at once-coarse, and then one fine tune volume, per channel. What type might you be using?

[Doc B.]

The plan was to work on the prototype today, however we have a very large order of finished amps that needs to be completed a couple days before we had anticipated. Hope to get to the attenuator by Friday. It is stereo, both coarse and fine.

[4krow]

Ahhh, Yet another combination. Sounds practical to me. The two mono coarse/fine adjustments per channel is a bit much unless you are using it to set volume from say, a buffer amp to an integrated amp. That is how I am using mine, but it would drive crazier with that much on a pre-amp. The beauty of the arrangement is that there are many more volume positions possible with the c/f setup than a typical 12 step attenuator.

[Doc B.]

Yes, there are 36 steps. Steps are 1.5 dB apart.

[islanddave]

Does the new Bee Pre use a solid state power supply?

Dave

[Doc B.]

The power supply is solid state. The high voltage shunt regulator is a tube/SS hybrid, using an EL84. The filament supply regulator is SS, and uses a special "noise shunt" circuit that PB and PJ cooked up.

[islanddave]

Was the previous incarnate the foreplay was it...........was that a solid state power supply too?

Thanks Dave