Bee2Quiet Stepped Attenuator/Constant Current Source Upgrade for BeePre2
This upgrade kit is for the current production BeePre2 only (10″ x 16″ chassis). It will not work at all with the original BeePre (12″ x 12″ chassis).
When we were developing the BeePre 300B preamp kit we built the prototype preamp circuit itself on a pair of chassis, and we built several outboard chassis platforms that allowed us to try various attenuator schemes. We tried all sorts of schemes – inexpensive carbon potentiometers, our old standby Sweetest whispers attenuator, high end stepped attenuators from other manufacturers, transformer volume controls, ladders, shunts, series steps, etc., etc.
Our old faithful Sweetest Whispers attenuator floated to the top of these various setups. But we felt the Whispers had room for improvement in two areas. One was that the steps were rather big. The other was that we had always used inexpensive switches to keep the price reasonable.
Save 10% when you buy 2 or more (when not on sale). Shipping can take from a couple of days up to 6 weeks here’s why.
We felt that an “ultimate” attenuator for the BeePre needed to be done to a higher standard and we felt that it would be reasonable to make the kit similar in price to the other high end attenuators on the market. So we got very high quality rotary switches and PB put his math degree to work coming up with a very useful thirty-six 1.5dB steps, yielding a total -52.5db of attenuation. Yes, you read that right, 36 steps. We accomplish this with two six position switches, one a stereo coarse control with 9db steps and the other a stereo fine control with 1.5 db steps. Simply set the coarse control in the general range you want to listen and then use the fine control to get the level perfect.
The switches are populated with Vishay Dale metal film resistors, a resistor that has remained a favorite of ours over the years for attentuator use. The BeeQuiet coarse and fine stereo switches replace the stock carbon pot volume and balance controls in the BeePre.
With the new BeePre 2.0 circuit, we redesigned the BeeQuiet to work appropriately in its new circuit position. When the BeeQuiet attenuator and C4S active loads are added simultaneously, we are able to further optimize the attenuator impedance characteristics compared to only offering the attenuator as a stand alone upgrade
This manual is divided into two sections, as the C4S active loads can be installed and evaluated on their own prior to installing the BeeQuiet attenuator.
As always the kit comes with an extensive, detailed manual. Assembly and installation is probably a one or two evening affair.
And now to address the question in everyone’s mind – why install this upgrade?
When we put the protoype in our production prototype BeePre the bass punch and dynamics became like Wow! Can’t say for sure why, as both the stock pots and the BeeQuiet are about the same impedance at around 50K ohms. So this is another case where we won’t try to come up with some far fetched theory. We will just suggest strongly that you build the BeePre with the stock volume and balance pots first, then install the BeeQuiet upgrade and share your impressions.
Installed the BeeQuiet and upgraded the caps to ClarityCap MR 10uf 400V.
I am sure it is a combination of both upgrades, but WOW does it sound great. Clarity, and detail is vastly improved from the stock configuration, very immersive sound stage, and the caps have not had any time to open up yet. I am impressed, it blows my Extended Foreplay III out of the water.
Bottlehead, what an incredible preamp you came up with, I couldn’t be happier!!!!