It's been a while since Boozhound Labs came out with a new design... but the wait is going to be worth it :)
Introducing the BHL Crossover. This is a 2-way 12dB/octave active crossover that can be configured for any crossover frequency by selecting the proper capacitors and resistors. It uses all discreet components - no opamps! The filters are sallen-key implemented with JFET buffers. It uses the same great parts as the rest of the kits.
Choosing a crossover frequency is simple, using a chart provided in the assembly manual. Changing this frequency once it is built will require replacing parts.
The boards are just over 4"x4" and you will need one board per channel. The price has yet to be set, but this is a much more complex design and requires more than twice the number of parts as the phono stage, so I expect it to be somewhere in the $199 range.
I just ordered a set of prototype boards, so it will be a couple weeks until I can offer a fully tested design.
If you would like to be an early-adopter, please email me. I can probably swing a preorder deal.
Gavin McKenzie has built a very clever phono stage for 78 rpm records using the Boozhound Labs moving coil pre-preamp.
Many 78s were made before there was an accepted standard for the EQ curve applied to the cutting heads that creates the master record from which the rest are copied. Therefore, there is no standard for the playback phono stage like the RIAA curve for LPs.
Gavin found an old, passive, Master Record Compensator that provides a switched set of various EQ curves for 78s. The problem was that this is just the EQ, and needed external gain stages to turn it into a phono stage. Gavin originally was planning to use a BHL Phono stage and bypass the EQ section, but since he only needed 1 channel for mono, the MC pre-pre gave him 2 simple gain stages between which he could sandwich his EQ.
Basically this is the left channel of the pre-pre, then the EQ section, then the right channel. A nice simple design with a minimum of wasted parts. This could be built as a stereo unit using 2 of the pre-pre boards.
Thank you Gavin for the email and the clever phono stage!
To get the photos of the kits, I used one of these light tents. Basically the idea is that the indirect light eliminates any harsh reflections and shadows. The strobes on both sides add to this effect and overpower the ambient light so that the light reaching the object from the overhead fluorescents I have in the basement doesn't cause harsh reflections. The result is that you get a ton of color and detail.
To make the image as sharp as possible, I use a manual focus 50mm lens (Nikon 50mm/f2 on an adapter for my 40D) at f8 for plenty of depth of field. It's not a macro lens, and only focuses to 2 feet, so it's not ideal, but is cheap and works great. I also use a tripod and shoot everything with the self-timer to eliminate any camera shake. The strobes are triggered with a cheap wireless remote trigger (Yongnuo RF-603), and the strobes themselves are $40 manual strobes (Neewer TT560). As with all of my projects, the goal is low budget, hi fidelity :)
Ian sends a video of his phono integration into an existing preamp. I love garage systems! Especially when they involve a gigantic Adcom amp.
"Great success" indeed.
Another great biscuit tin build. A perfect example of how simple this DIY stuff can be - a couple RCA jacks and a pair of 9V batteries in an old tin and we are in business.
As you might have guessed, Nelson Pass is one of my favorite audio designers. He follows the principles of simplicity and elegance and applies then to solid state gear. Lots of guys are doing this with tubes, but very few with transistors.
He has a project out there that would pair amazingly well with my phono stage. The Amp Camp Amp
! It in minimalistic, inexpensive, and best of all uses a +19V power supply that would be quite compatible with the BHL Phono stage
. Kits are available from the DIY Audio Store
There is also a Universal Power Supply
kit that could be used for the BHL Phono
RMAF June 24 2013
Is anyone going to RMAF
, and would you like to share a room? I would obviously be showing a phono stage and playing a stack of albums. Do you have something complimentary that you want to show? This means speakers, amps, preamp, turntable of sufficient quality to integrate nicely with my stuff. Lemme know.
Wire June 24 2013
So the last few hundred kits I have shipped have been sent with some really nice Teflon insulated, tinned wire. Unfortunately that wire was obtained (as with most of my stuff) from surplus sources. A nasty side effect of awesome surplus deals is that at some point, you run out. That just happened.
So now I am sending kits with wire that might sound a bit better, but is slightly harder to work with. The new wire is Teflon insulated (the best) but the insulation is somewhat thin (better sonics, but harder to strip) and the wire is not tinned (better sonics but harder to solder). These drawbacks are probably worth it to have really amazingly good sounding wire for no additional cost.
Yes, it comes from plenum rated Teflon insulated CAT-5 cable. Stripped and coiled by loving hand by yours truly. Best wire ever.
Caps! June 13 2013
I now (finally!) have more caps so I can offer more kits! Hooray! There was a fire in the Moscow post office, so the package took an extra week or 2 to get here, but those of you who are across various oceans know how that goes.
In other - bad - news I have had lots of packages get lost in the mail. I now have a process to send tracking numbers with everything, where most of the old packages were sent blind. My apologies to everyone who has not received what I have sent - thank you for your patience!
Here are some photos of your pre-amp in a biscuit tin.
Hope you like them.