I’m still trying to wrap my head around the concept that DSJ vol=100>BHK pre-amp set to unity gain>amplifier would sound any different to DSJ vol=100>amplifier.
As a very simple example if the DAC and preamp had identical output sections and if you had very long interconnect cables, putting a buffer in the middle will double the frequency where any rolloff due to cable capacitance happens. The DS and probably any given preamp have different output stages so any interactions with interconnects are expected to be different with a preamp in the middle. That difference is often minor, but not always. Adding a preamp will also change the topology of any interference from groundloops, etc. and once again may be better or worse, but each resultant loop (usually) has a smaller area and affects a different part of the system.
The passive output section of the DS is great for many purposes, low noise generation, common mode noise suppression, etc. But not all systems. The output of the DS can be affected by high capacitance interconnects, very long interconnects, potentially by very low input impedance down stream (not a likely scenario)…
If your amp is sensitive to any ultrasonic frequencies from the DS or simply from some RF or other EMI over the output interconnects, a preamp can filter those out and help the amp…
All of this is assuming that you don’t really need any volume control. If you do the DS’s output has a constant noise floor no matter the volume setting and most preamps have a noise floor that tracks the input level for a larger volume range than the DS output.
Similarly all of this is assuming that the DS output, the amp sensitivity, your speaker sensitivity, where you sit in your room relative to the speakers, etc. are optimally matched for your favorite listening levels, if anything is too far off a preamp can be a good thing.
brodricj said I'm still trying to wrap my head around the concept that DSJ vol=100>BHK pre-amp set to unity gain>amplifier would sound any different to DSJ vol=100>amplifier.I fully understand. It is akin to the differences in cables; why should one pair of wires sound any different than another? They are just wires.
Even after possessing a rough understanding of both wires and active components and their impact on the sound, I remain dissatisfied with the explanations. My lizard brain apparently does not grok the why.
Yet, I have experienced improved sound with wires and with inserting a preamp, to the great annoyance of the lizard brain.
My experience is that a good active preamp improves the sound more often than the explanations suggest. I have also yet to hear a passive preamp used as a volume control which does not suck some of the life out of the sound.
For me, it remains one of the many minor mysteries of the universe.
I seem to find that dynamics in the lower ranges are less than impressive without active amplification even with well matched impedances. The addition of a preamp below 150Hz has improved the experience my little ears have had. I do not mean that I just turn the preamp up louder (oh sometimes I do
) but even with a similar swept sine wave profile the experience is more satisfying with the preamp “in”.
Did I miss it or was there a link to the preamp review at TAS?
No review yet. TAS stated way back in January that the review was coming. Little did we (us regualr folks) know that the first beta units wouldn’t be delivered until late May. I wouldn’t expect a review for a few more months…
Ted Smith said
The output of the DS can be affected by high capacitance interconnects, very long interconnects, potentially by very low input impedance down stream (not a likely scenario)…Ted what would you consider high capacitance interconnects
Magicknow
Hmm, I knew someone would ask that 
When we removed 1nF protection caps from outputs we could hear a difference, but it wasn’t night and day. I’d expect that most people can hear 1nF - 10nF or greater capacitance on the outputs, note that the change isn’t necessarily bad for everyone or every system.
Noticing:
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that the BHK Mono are in Stereophile’s Class A
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that while very positive, TAS didn’t put the BHK 300’s into the 2016 list of most recommended amplifiers, published in an edition with the XA 160.8 both reviewed and in the list and the BHK300 review also included (the Directstream continues to be listed in the corresponding 2015 list for digital components)
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PSA marketing material states the Pre-Amp is best pre- that Bascom has ever designed and ever heard (not sure whether the design comments cover the Constellation Herc I, but it would surely include hearing it)…
Then, 1) other than the BHK 300’s, is there is a particular type or style of amplifiers to which the BHK Pre- might be well suited ?
- What’s the BHK 300’s capacitance rating ? It’s not in the marketing material listed on the website. Output impedance at 0.1 Ohm is included.
Paul McGowan said We didn't actually build to a price point - though the opposite is true - we didn't force every dollar we could on it. There's setting a budget–don't spend more than this–and then there's making a conscious decision to set a high price point–what can we do to justify a $40,000 price point?Our directive to Bascom was simple. Design the very best preamplifier you know how and make it fit into this box. He had full carte blanche after that - and he spent far more than we would ever have imagined.
Yes, this is well-stated. But the “fit into this box” part is tricky with a pre-amp, especially one in which the design emphasizes the role of an over-built power supply. Putting that supply into a separate outboard chassis couldn’t help but improve the sound, no?
Probably - if just for the freedom to use a bigger transformer if nothing else. There’s plus and minus attributes to external power supplies - the long cables, the extra chassis can be a bad thing, but properly done and taking advantage of a larger transformer, I would guess it would sound better.
Digital is where this really comes into play. DACs are noisy and affected by power supply proximity more so than analog devices - and a DAC is where one might really benefit from a separate power supply box.
Paul McGowan saidPaul was your unit the Aesthetix Calypso Signature preamp?The Calypso has long been my favorite. What a stellar sounding preamp - best I have heard - until the BHK. As soon as I have moved from a prototype BHK preamp to a production unit, the Calypso is for sale. Anyone interested should contact me.
Paul, am I correct in assuming the BHK preamp built as a hybrid has lower noise, and better low and high frequency extension as compared to the Aesthetix Calypso? Is that want you were looking for when you voiced the BHK?
It was the Aesthetix Calypso but not the Signature. I don’t want to really get in the position of comparing the two - the Calypso is an extraordinarily good sounding preamp, best I ever heard until the BHK came knocking.
Both are extraordinary products.