Feature Set: New Preamp

Yes, essentially, the front end of the power amplifier but much more power supply intensive.

Paul McGowan said Yes, essentially, the front end of the power amplifier but much more power supply intensive.
Hi Paul

what is the target price for the preamp?

magicknow

I don’t really have a target price because that isn’t typically how we do things. I have hopes. Once the bills of material and labor estimates are in we have an idea of what it’ll cost to build and that’s basically what sets the price on a PerfectWave product. Others, like Sprout or a NuWave product we definitely set a target and do our best to meet it. With the preamp I just work on designing in what we want, that will sound best, and let the chips fall where they may.

I’ll try and be a bit more informative when we get the schematics finished.

Any updates on this Paul? A preamp is one thing I don’t currently have (running DS directly to power amp right now). I’m really, really picky with how transparent my preamp needs to be, but my amp likes a little more juice then the usual 2v - so I’ve always got my ear to the ground for a preamp that might sway me from the direct connection.

The preamp? It’s been designed, PCBs are being laid out, we should have our first prototype perhaps in February. Can’t suggest a release schedule but I am hoping for end of the summer. No promises.

Excellent!

Elk said Very neat.

How is volume itself controlled? The description of employing a stepper motor sounds like you are using discrete resistor switch attenuation.

Yes, but very unique. Perhaps we should start this thread in the BHK section?

Paul given you are building parts of the ampere do you have target price yet?

magicknow

MSRP on the BHK Signature preamp looks like the same as DirectStream, about $6K. It is based on the same zero feedback balanced differential tube stage used in his design of the amplifier, feeding MOSFET outputs. Inside is a killer headphone amp as well. The volume control, as I have mentioned in an earlier post is quite a work of art. Controlled by a stepper motor used in reverse and displayed by a nice little OLED display with big numbers for us old guys, the knob has an amazing silky detented feel to it. The remote control also works, of course.

The heart of the volume control is a combination of things, some proprietary. As those who know my posts for a long time probably remember, I consider the volume and balance controls in a preamplifier the biggest point of degradation. The volume change is the area of greatest concern and where the most care must be taken to get it right. It’s where everything that can go wrong, sonically, will.

The BHK preamp uses a combination of solutions gathered through years of experience in building such things and the discussion between Bob Stadtherr, myself and BHK was long on this very subject. We spent more time mapping out the particulars of the volume control than the amplification circuitry of the preamp itself. One part of the volume control is, as Elk speculated, PRP resistors in a ladder of sorts, switched in with relays, the other part is proprietary but somewhat like the original Gain Cell we invented some time ago.

More to come and perhaps when we do the close-up interviews with BHK he’ll explain in greater detail than I have here.

This is probably not feasible at this time but It would be amazing to be able to synchronize the volume control (and possibly input switching) so that a stack of the preamps could be used for multi channel or multi driver systems with digital crossovers and outputs in jriver for multiple ds units to feed multiple preamps. I wonder if the new bridge card can synch multiple dacs, but if not a rednet could feed multiple aes outputs synced.

Paul McGowan said One part of the volume control is, as Elk speculated, PRP resistors in a ladder of sorts, switched in with relays, the other part is proprietary but somewhat like the original Gain Cell we invented some time ago.

More to come and perhaps when we do the close-up interviews with BHK he’ll explain in greater detail than I have here.


Fascinating. I cannot wait to learn more.

@adminpaul

Paul what is the latest estimate as to when the Preamp will be available?

magicknow

My goal is to have the prototype playing in Munich at the high end show in May. We’ve finished the PCBs and building them so Bascom can start his tweaking cycle. The chassis are on order and hopefuly we’ll have something on time but it will be tight and hand carried.

Will the new preamp use Urushi output caps?

Paul McGowan said My goal is to have the prototype playing in Munich at the high end show in May. We've finished the PCBs and building them so Bascom can start his tweaking cycle. The chassis are on order and hopefuly we'll have something on time but it will be tight and hand carried.
What is your performance objective? I presume it would have to beat at least your Aesthetix - are there other reference preamps available for comparison during development you are gunning for?

The preamp hasn’t any caps on its output. It is direct coupled, one of the advantages of a solid state MOSFET output, yet maintaining the musicality and zero-loss of the input vacuum tube.

Yes, the Aesthetix will be the first to knock off. It’s the finest preamp I have ever heard and that in itself is a major challenge.

If you can get it to the performance level of say ARC Ref 5SE (which I owned in the past) at half the price I’d be a happy camper.

How many balanced inputs will the preamp have? Hopefully at least two (DS and NPC).

edorr said If you can get it to the performance level of say ARC Ref 5SE (which I owned in the past) at half the price I'd be a happy camper.
This would both be a significant achievement and wonderful for audiophiles.

Having never heard one I cannot say but I’ll bet we do pretty well.

stevem2 said How many balanced inputs will the preamp have? Hopefully at least two (DS and NPC).
I believe it has 5 balanced and 5 RCA inputs. Here's a picture of the board on Bob's test bench. The RCAs come after solder.

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