Beta testing the new BHK Preamp

Audio Components Amplifiers
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The input name editor has to be fixed. Either that or every BHK preamp owner needs a ration of sedative. Not only can you not edit an existing label without retyping the entire label, but:

If you type too long of a label, you overwrite the first characters of the field. Not a big deal until you save and realize that some of the extra characters are still getting appended to the end of the label. This is easy to correct with a few spaces, but you have to retype everything and be careful not to add too many spaces otherwise the first few characters of the field get overwritten with spaces.

If, on the tenth or twentieth iteration of trying to enter a label, you get a bit frustrated (just speculation - I remained perfectly calm and used absolutely no vulgar Anglo-Saxon terms) and spin the selector knob fast, you either get an endless alphabet or a selection of characters that are not in any language with which I am familiar.

At very least, provide a ‘return to default label’ option for those who eventually see the folly of attempting to edit the input labels.

And, while I’m thinking of it, how do we upgrade firmware? I don’t see a USB port anywhere; there’s no Ethernet port; no SD card. Do we have to ship the unit back to Boulder for new smarts?

-Pb

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We’ll look at the editor. Thanks for the info.

Indeed, software updates are done at the factory only.

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Peanut Butter said

And, while I’m thinking of it, how do we upgrade firmware? I don’t see a USB port anywhere; there’s no Ethernet port; no SD card. Do we have to ship the unit back to Boulder for new smarts?

-Pb


Would you mind indicating software that could be updated (not that shipping back to factory is remotely practical) ?

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I have had the pre-amp in my system since Saturday. I am due to get the Mono blocks back from their trip to Boulder for repairs today. Once they are back in, the serious listening can begin.

On first impression, I would have to say my 35 year old solid state amp (Apt 1) has never sounded so good. It was easier to pull this out of the basement than the amps that were directly replaced by the BHK mono blocks (Musical Fidelity NuVista 300).

One criticism of the remote control. I have a P5, a P10, the PWT and DS DAC all in the system. When I press the Dim button, the displays on the PWT, DS Dac and the Pre Amp all turn off but not the P5 nor the P10. I need to use the older remote to turn off those two displays. Here is the interesting part. When I change the volume or unmute the pre amp, not only does the display on the Pre Amp turn on for a short time, but so does the PWT, DS Dac (as was noted by Micheal above) and the P5 and P10. I think I will tire of watching all five boxes turn on for a short period of time when I use the volume or mute buttons. I wonder if the remote can be updated so this does not happen? Particularly, I wonder how it is that the P5 and P10 cannot be dimmed by the remote but will turn back on for a short period of time when using the remote.

Alan

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Alan W said

One criticism of the remote control. I have a P5, a P10, the PWT and DS DAC all in the system. When I press the Dim button, the displays on the PWT, DS Dac and the Pre Amp all turn off but not the P5 nor the P10. I need to use the older remote to turn off those two displays. Here is the interesting part. When I change the volume or unmute the pre amp, not only does the display on the Pre Amp turn on for a short time, but so does the PWT, DS Dac (as was noted by Micheal above) and the P5 and P10. I think I will tire of watching all five boxes turn on for a short period of time when I use the volume or mute buttons. I wonder if the remote can be changed so this does not happen. Particularly, I wonder how it is that the P5 and P10 cannot be dimmed by the remote but will turn back on for a short period of time.

Alan


I think this could be categorized as a bug

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It’s no bug, it’s intentional. The idea is once the units are in DIM mode, press any button on any remote and they all come back to life and then return to their original state. Not sure how all this developed over time but it was intentional.

It could be modified but only by updating all units concerned, and not the remote.

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When I press the Dim button, the displays on the PWT, DS Dac and the Pre Amp all turn off but not the P5 nor the P10

Paul shouldn’t all the displays dim when the button is pushed, I can understand the displays coming on for a few seconds but not just some of the units going Dim

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Note-- what follows below is my original post that i meant to place in this preamp beta testing chain, but inadvertantly posted it as a separate topic. If you’ve already seen it in the original location, sorry for the repeat.

Group: I just received my preamp beta unit yesterday. It was supposed to be shipped out on May 31 but some production issues (component supplier failure I think) delayed the ship out until June 8. Frustrating only in that I was chomping at the bit to join the party, and experience some of the revelatory sound you all have been reporting!

The good news on the delay is I can confirm the unit does now have a time counter for the tubes. I can’t comment in more detail beyond that right now as I am manual challenged (as in didn’t receive one in the box), but that is the least of my threshold issues…

So last night at 9 pm I finally had the chance to unpack her and begin. I can echo the comment that the trampoline type packaging setup is pretty slick to see, but in my case, opening the box revealed that the system didn’t function as it should. The preamp was twisted in the “hammock” such that the front corner (volume pot) was pushed up against the cardboard frame of the trampoline and not suspended in free space as intended. Lifting the upper trampoline I noticed that the plastic bag covering the unit was torn irregularly at the volume knob (not a clean slit, more like a tear from impact/abrasion) but a quick check for cosmetic damage or wobble or play in the pot was negative, although the plastic bag still kept everything pretty snugged up.

Now I don’t know if anyone else experienced this, but simply removing the preamp from this plastic bag proved unusually challenging. In my case, the vinyl protector for the piano black top plate had peeled up at the edges and adhered itself to the outer bag, so the process entailed gradually pulling the two plastics free enough to allow the tight plastic bag to incrementally slip off. (In the future, I would recommend one of those thin cotton wraps be used between the two plastics to speed this process.) to accomplish this separation I had to (gently) stand the unit alternately on its right and left sides, while separating the plastics and then incrementally inching the outer bag off. And in flipping the unit from left end to right end is when I heard it–loose rattles. Something small is loose inside (first thought) followed by no– several things are loose inside.

OK. deep breath… work problem #1- remove bag. Finally off, I peeled back the vinyl protector and inverted the unit so anything loose could fall out, and it did–they did. 3 items: a machine screw, a nut and a black washer. Further tips to right and left revealed no more sounds.

I next realized that instead of the manual for the preamp, I received the manual for the BHK amp. No big deal, the other insert said the manual is online at the PS Audio site. Um, no– its not. At least not yet. great. Lets see what I can figure out using the remote and the front panel button.

So I think– what to do? Apart from the loose hardware and the bag abrasion at the volume pot, nothing else seems physically imperfect. So I decide to stick to my game plan unless any other issue arises: I will hook up my 3 redbook CD players and my SACD player into the 4 inputs, connect my Little dot Mk. III OTL tube headphone amp to the unbalanced outs, and my pro sound headphone monitor/ distribution amplifier to the balanced outs. That way I let it run in, with music running (alternatively) through all 4 inputs and both outputs driving as well, and I can evaluate the sound of the headphone output of the BHK against the two headphone amps (both driven off the preamp outputs, and also driven by the CD players directly) plus I could compare the BHK to the headphone outs on 2 of the CD players. With 6 different headphones available(Denon, Sennheiser, Beyer, Grado, Goldring, and AT) I’d have plenty of choices.

So over the next 3 hours I do this. couple observations, which I would love to hear feedback on: the volume pot may not be physically loose, but it seems to have right/left “play” in that you can rotate it right or left a click and nothing happens. I also noticed that its a bit finicky– if you try to just move it one “notch” (say from 60 to 61) occasionally one “click” to the right accomplishes it, but at other times it takes two or 3 clicks to get it to move the one increment up– a couple times it actually took 5 or 6 clicks for it to respond! also, if you deliberately move the pot up to a predetermined point (say, from 25 to 65) in a smooth rotation, at some point (around the 50s) the sound temporarily drops out– as if the pot lost its connection or skipped a beat. Is this supposed to happen?

Last mechanical point– hum. At exactly volume position 85, hum enters the scene from the headphone output. Whether I have the output connected or not, or 4 players on inputs or just one connected, when I stop the CD and turn up the BHK’s volume to 84, its dead quiet, but at 85 the hum jumps in– prominently. I isolated it to the right channel: if I shift balance to the left to at least 18, the hum is imperceptible (and the unit is dead quite all the way up to 100), but from balance 17 left through zero, to 48 right, the hum is constant and does increase in volume from 85 to 100.

Now I realize that this might be normal, or due to several possible factors, but I wanted to ask my beta teammates to check this if they can and let me know what they find. I am in the mode of trying to determine if my unit is faulty or not; at this point I don’t think its fair to provide sonic observations or comments if I don’t have a properly functioning unit. Obviously, parts falling out of a statement/signature/$6000 component is cause enough for pause; but these volume pot and hum issues may be additional symptoms that something’s not right. As you might have guessed, my first 3 hours of listening was in some respects satisfying and impressive, but not in all ways, and I don’t want to indict the design before giving due consideration that this particular execution isn’t what it should be. I will call PS Audio to consult with them later this AM about next steps.

One last question–the unit was supposed to have switchable phase, but the phase buttons on the remote are labelled for DAC and PHONO, and neither functions. Is there some trick in the manual to enable phase inversion anywhere (hopefully on the remote, as it was described?)

Thanks, and I’ll keep everyone updated– John

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Good sleuthing, John. This si good feedback for PSA. Haven’t noticed the dropouts myself, but I’ll check when I get home. Does the dropout occur in sync with the relay “click” in the fifties?

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wglenn-- thanks for the support. I am not familiar with this relay “click” you point out but it could be associated with what I observed. I’ll review the posts tonight to familiarize myself with this relay click and then see what I hear and when exactly I hear it. I’ll report back.

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petrojo said

. . . the volume pot may not be physically loose, but it seems to have right/left “play” in that you can rotate it right or left a click and nothing happens. I also noticed that its a bit finicky– if you try to just move it one “notch” (say from 60 to 61) occasionally one “click” to the right accomplishes it, but at other times it takes two or 3 clicks to get it to move the one increment up– a couple times it actually took 5 or 6 clicks for it to respond!


The volume knob on my BHK will rotate approximately 0.5 degrees before clicking and making a volume change - much more responsive than what you describe.

. . . at some point (around the 50s) the sound temporarily drops out– as if the pot lost its connection or skipped a beat. Is this supposed to happen?
No dropouts noted on my unit.
Last mechanical point– hum. At exactly volume position 85, hum enters the scene from the headphone output.
As I noted in my previous posts, there is audible and constant hum when listening to sensitive headphones throughout the entire volume range on my unit. Does the hum change depending on the headphones you are using?

-PB

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I’m not noticing dropouts in volume but I do have relay-ish noises from the chassis at 1, 25 and 53. I am thinking that these are the “steps” that Paul referred to. Anyone else?

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Yes, since you asked me to check, I do notice the a dropout of the sound at 25 and 53. This is more noticeable with changing the volume with the remote. I do not get the dropout everytime but when it is not there, I am getting the same noises you describe.

Changing the volume with the knob, I am more aware of the “clicking” sound from the pre-amp and cannot say I notice the dropout.

Alan

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Since I am online, I thought I would add a couple of photos of the Pre Amp in its new home.

Paul, these are for you since you mentioned in the speaker project post that one day you hoped to have an all PS Audio system. This is probably as close as one can get for now.

IMG_1483-5.jpgIMG_1486.jpg

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I thought that looked like a Peter Max.

So you are saying that when there is no chassis click, there is dropout and when there is the click, no dropout?

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This is my first time posting to this forum. I’ve had the beta unit in my system for nearly a week and I thought I would take a shot at describing my experiences. I have the BHK Preamp connected, on the front end, to a rebuilt and modded Thorens TD-124 in a custom plinth, a Durand Talea tonearm, and the Soundsmith Strain Gauge SG-400, and amplified by a BHK Stereo amp. Before the beta unit arrived, I was running this combination with a Crayon Audio CFA-1.2. My speakers are Volent Paragon VL-3s.

The unit is well-packaged and I like what others, here, have referred to as the “hammock” packaging, which nicely suspends the unit in the double-boxes, safe from the inevitable bumps and dings from FedEx. While hefty and well-built, the unit is not so heavy that you need to have your younger and stronger cousin help you get it up on the rack. While the rubber feet are serviceable, in the future, I plan on experimenting with various footers.

Though I, now, have maybe 25-30 hours on the preamp, I chose to listen to the unit at various points through the burn-in, rather than waiting until I’d gotten more hours on it, in order to hear how the sound might evolve over time. Right out of the box, I would describe the preamp’s sound as “delicate,” which is to say, a modicum of detail and upper-range extension, but lacking at the bottom end. I listened to a range of acoustic stuff and enjoyed what I heard, but the listening left me expectant about what might be to come rather than satisfied by what I initially heard.

Somewhere in the manual for the BHK Stereo amp, there is a recommendation that users put about 100 hours on the amplifier to hear what it is capable of doing. My own experience has been that by 100 hours, the amp sounds good, but it is between the 100 and 200 hour marks that the real awakening of the amplifier’s sound and character happen. By contrast, the BHK Preamp’s sound evolved much more quickly and by the 5-10 hour mark, I was beginning to hear some of the bass that Bascom King had mentioned in his account of the design and testing of this preamp. Since then, there has been a steady increase not only in the quantity of bass, but also a quickening that makes for a unit that yields both power and responsiveness — the kind of bass that you feel in your gut as much as with your ears. This leads me to my first, recommendation: in the manual include some guidelines as to burn-in time to allow users to temper their initial expectations.

Somewhere, at the beginning of The Great Gatsby, the narrator, Nick, refers to himself as “that most limited of all specialists, the ‘well-rounded’ man.” By contrast, what I find to be remarkable, is that while it is true that the preamp does virtually everything well, there’s no sense that it has achieved that balance through a series of compromises, but, instead, is a unit that simply excels in most, if not, all of the categories that audiophiles use to evaluate a component’s capacities. This is not a unit of artful or carefully-considered tradeoffs. And so, while I tried to remain attentive to the details of what I was hearing, so often in my auditioning I have found myself slipping into that glorious state of allowing the music to wash over me. Unlike some, I love a preamp that doesn’t call attention to its own performance, but pushes the source front-and-center, even as it does its magic behind the curtains. This is just such a unit.

I agree with others on the forum that the labeling control is clumsy. I noticed that when I dialed through the alphabet and numbers that it did not appear to move through the string of characters smoothly or predictably and I found myself inching the dial forward, moving the selection cursor one character at a time, to select the appropriate characters. Perhaps, a better solution would be to include labelling controlled by the remote.

I have seen some provide editing suggestions for the manual and I took the time to go through the entire document and provide editing suggestions, but I won’t bore forum readers with the details. Paul, if you’re out there and reading, I am happy to forward my comments (or to do a markup of an ms word doc). My suggestions have to do with things like the erratic deployment of hyphens and penchant for ending sentences with prepositions, which, though it may now be grammatically correct, does not necessarily make for good writing, etc.

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Welcome, Muralido!

Thank you for your thoughtful and detailed post.

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muralido said This is my first time posting to this forum.
Welcome to the forum, Muralido. You've provided some very good insights on the preamp and we look forward to more reports!

-Pb

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There may be some here who wish to see the unboxing photos I took tonight. Really handsome unit and first-rate packaging. http://americanmadeaudio.com/2016/06/16/ps-audio-bhk-signature-preamplifier-unboxing/

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Alan w and wglenn: I can now confirm the relay clicks at 1, 25, and 53 as you describe; and yes, I have the sound dropout or hiccup at the relay points, but nowhere else. Sounds like it may be just a characteristic of the volume control. I still have the up/ down play or rocking of the volume control (a back and forth looseness between clicks) that may be normal or a result of the unit shifting iN the hammock during shipment (when the volume knob banged up against the cardboard hammock frame and might have sustained a shock.) PB-- was able to confirm with 4 sets of headphones of varying impedences/sensitivities that my hum condition goes in/out at precisely 85 on the volume scale-- at volumes below 84 the unit is dead quiet regardless of balance position; at 84 a slight hum becomes audible in the right channel and at 85 the hum is in full song. At that point If I move the balance left to at least 14 on the 48 point scale, the hum vanishes; otherwise it is clearly noticeable.

jeremy and Jim at psaudio have emailed and called to say their engineering dept thinks the loose hardware belongs to a transformer heatsink, so they issued a call tag to get the unit back. I requested another unit ASAP so I could continue the beta testing with minimum delay (and to get all these issues and questions behind me)-- hopefully they can accommodate the request. So far they have been very invested in working the problems, which is all I can ask.