Call Us: +1 720-406-8946

BHK Phono preamplifier | BHK Power and Preamp Forum | Forums

A A A
Avatar

Please consider registering
guest

sp_LogInOut Log In sp_Registration Register sp_MemberList Members

Register | Lost password?
Advanced Search

— Forum Scope —




— Match —





— Forum Options —





Minimum search word length is 3 characters - maximum search word length is 84 characters

sp_Feed Topic RSS sp_TopicIcon
BHK Phono preamplifier
Topic Rating: +3 Topic Rating: +3 (3 votes) 
June 19, 2016
6:53 am
Avatar

PS Expert
Forum Posts: 5463
Member Since:
July 8, 2013
sp_UserOfflineSmall Offline
1sp_Permalink sp_Print
+2

For those wondering about the upcoming BHK phono preamplifier, I include a photo off Bascom’s bench.

I love this photo. Bascom and I design the same way, with porcupine wires and push board for components. It’s a thing of beauty as you can see, though some might be horrified at the mess – just think of it as genius at work.

In the back with the chassis on its side is where two tube sockets can be connected to the breadboard in front of it, and behind that the chassis is the heater supply (bottom) and a high voltage supply on top. In the foreground is a simple solid stage phono preamp breadboard Bascom uses for the RIAA EQ and its output stage for testing the tube and FET input stage. To the right are additional power supplies for that SS phono preamp and for circuitry on the tube breadboard.

Bascom’s big challenge at the moment is lowering noise when using a tube/FET input stage.

Just thought you’d all enjoy a peek into the working of BHK as he moves forward with yet another design.

Phono-preamp-Kludge.JPGImage Enlarger

sp_PlupAttachments Attachments

The following users say thank you to Paul McGowan for this useful post:

magister, DoggieHowser, jazznut

Co-founder and CEO of PS Audio. Hobbies (other than audio) include cooking, artisan bread baking, writing The Carbon Wars, hiking and inventing stuff. Infinity IRSV, MG Audio Designs and Audioquest cables, five P10 Power Plants, DirectStream DAC, NuWave Phono Converter, Clear Audio Master turntable, Lyra Cartridge, BHK Monos and BHK preamp, LANRover USB Transporter. I live in Boulder Colorado with my wife Terri, both of us are vegetarians for many decades. If you want to see support my first shot at writing a novel go here.

June 19, 2016
7:18 am
Avatar
Waynesville, Ohio

PS Contributor
Forum Posts: 1828
Member Since:
December 24, 2011
sp_UserOfflineSmall Offline

I guess the pill bottle is for headache medicine.4_gif

Very cool, thanks!

PC Server--Bridge II/DS DAC--BHK Preamp--BHK 250--RD-75 based bipolar line array above 150Hz. Low frequencies via PSA 4.5 Preamp--dcx2496--Bryston 3B-- Hawthorne Audio based OB dual 15" woofers and HSU SW Amp--dual HSU 120HO Subwoofers. Belden ICONOCLAST cabling and Nordost power cabling plus some other crap I bought that makes me feel better but I'm not entirely sure works...

June 20, 2016
6:43 am
Avatar

Member
Forum Posts: 82
Member Since:
February 6, 2015
sp_UserOfflineSmall Offline

Is the new phono preamp going to include an A to D converter for ripping vinyl like the NuWave Phono preamp?

June 20, 2016
6:53 am
Avatar

PS Expert
Forum Posts: 5463
Member Since:
July 8, 2013
sp_UserOfflineSmall Offline

No, it’s purely analog.

Co-founder and CEO of PS Audio. Hobbies (other than audio) include cooking, artisan bread baking, writing The Carbon Wars, hiking and inventing stuff. Infinity IRSV, MG Audio Designs and Audioquest cables, five P10 Power Plants, DirectStream DAC, NuWave Phono Converter, Clear Audio Master turntable, Lyra Cartridge, BHK Monos and BHK preamp, LANRover USB Transporter. I live in Boulder Colorado with my wife Terri, both of us are vegetarians for many decades. If you want to see support my first shot at writing a novel go here.

June 20, 2016
7:37 am
Avatar

Member
Forum Posts: 30
Member Since:
September 11, 2012
sp_UserOfflineSmall Offline

Paul McGowan said

I love this photo.

 

Me too.  When I was an engineer still in my 20’s my boss tasked me with designing a simple circuit.  I remember my own workbench looking something like your photo.  However, it didn’t work.  It didn’t do remotely anything that even my sainted mother would construe as ‘working’.  It was the last time I ever tried my hand at electronics design :)

June 20, 2016
7:50 am
Avatar

PS Expert
Forum Posts: 5463
Member Since:
July 8, 2013
sp_UserOfflineSmall Offline

That’s a shame – you’re so damned talented! Though I understand. I once took great pleasure in smashing to bits an entire power amp circuit board with a hammer so it would never cause me grief again. 

Then I discovered the variac and life changed.

Co-founder and CEO of PS Audio. Hobbies (other than audio) include cooking, artisan bread baking, writing The Carbon Wars, hiking and inventing stuff. Infinity IRSV, MG Audio Designs and Audioquest cables, five P10 Power Plants, DirectStream DAC, NuWave Phono Converter, Clear Audio Master turntable, Lyra Cartridge, BHK Monos and BHK preamp, LANRover USB Transporter. I live in Boulder Colorado with my wife Terri, both of us are vegetarians for many decades. If you want to see support my first shot at writing a novel go here.

June 20, 2016
8:10 am
Avatar

Newbie
Forum Posts: 8
Member Since:
May 9, 2013
sp_UserOfflineSmall Offline

Paul, in viewing the prototype I didn’t notice any tubes in the circuit.  Perhaps it is too early in the design.  Will the BHK phono preamp include tubes in the circuit? Thanks. 

 

The tubes are on the top of that aluminum chassis and face away from view.  And yes, it will have tubes in the input  and output stages of the circuit.  And like my previous BHK designs, will also have MSFETs and JFETs where needed.

BHK

Analog Front End: Merrill Heirloom table (with outboard speed control, record weight, outer peripheral record clamp), Well Tempered Lab arm and Grado Ref Sonata cartridge, VPI 16 Record Cleaner; Phono Preamp: PS Audio NuWave Phono Converter.

Digital Front End: PS Audio PerfectWave Memory Player on PowerBase and DirectStream DAC;

Speakers: Martin Logan Ethos; Power Amps: Cary Audio SLM200 Mono Blocks; Preamp: Cary SLP05; Power Components: PS Audio P10 Power Plant on PowerBase, PS Audio P600 Power Plant, five PS Audio Ultimate Outlets,

June 20, 2016
8:30 am
Avatar

Up and Coming
Forum Posts: 540
Member Since:
October 12, 2015
sp_UserOfflineSmall Offline

Great news, you’re also working on a phono amp, so even if it means a few k$ more for add. cabling compared to a one box solution, I’ll possibly also have an extended PSA chain sometimes ;-) Probably instead of a headphone amp a phono stage wouldn’t have fitted into the preamp anyway.

There are three questions I’d like to ask at the moment:

  • will it have tubes (as tubesrule asked) and balanced inputs?
  • often, like my current one, preamps or phono amps have a separated power supply (even if in a smaller, less costly chassis). My understanding is, this helps avoiding interferences. You didn’t choose so with your preamp and I wonder if you’d do with the phono amp. Is it a matter of cost vs. effect?
  • do you already have design goals like a very flexible design in terms of adjustments like a Manley… or a reduced, no-nonsence design that fit’s all?

Hobby musician, music lover, long time audiophile, jazz-, vinyl-, and tube nut (but not dogmatic), now also CD/Hires/DSD nut. I use the Directstream DAC on Redcloud with Bridge II, a galvanic isolation device for LAN connection, a Monster High speed CAT6 LAN cable, a NAS drive QNAP TS253pro with 8TB WD red pro drives and Jriver for QNAP on the NAS with an *.aif/*.dsf library behind. I also use a power line separated from the rest of the house supply and from network components, a few active HF field protectors, a molecular reformatted complete signal chain as well as very sophisticated cabling throughout.

June 20, 2016
8:38 am
Avatar

Newbie
Forum Posts: 3
Member Since:
May 1, 2014
sp_UserOfflineSmall Offline

I hope the stereo/mono switch isn’t overlooked.

June 20, 2016
8:39 am
Avatar

PS Expert
Forum Posts: 5463
Member Since:
July 8, 2013
sp_UserOfflineSmall Offline
10sp_Permalink sp_Print
0

tubesrule said
Paul, in viewing the prototype I didn’t notice any tubes in the circuit.  Perhaps it is too early in the design.  Will the BHK phono preamp include tubes in the circuit? Thanks. 

If you look closely near the back of the bench you’ll see an open chassis sitting on its side and facing us are two tube sockets (well, the wiring side). It might be hard to see.

But yes, by all means, there’s two tubes inside.

Co-founder and CEO of PS Audio. Hobbies (other than audio) include cooking, artisan bread baking, writing The Carbon Wars, hiking and inventing stuff. Infinity IRSV, MG Audio Designs and Audioquest cables, five P10 Power Plants, DirectStream DAC, NuWave Phono Converter, Clear Audio Master turntable, Lyra Cartridge, BHK Monos and BHK preamp, LANRover USB Transporter. I live in Boulder Colorado with my wife Terri, both of us are vegetarians for many decades. If you want to see support my first shot at writing a novel go here.

June 20, 2016
8:39 am
Avatar

PS Expert
Forum Posts: 5463
Member Since:
July 8, 2013
sp_UserOfflineSmall Offline
11sp_Permalink sp_Print
0

bfotk said
I hope the stereo/mono switch isn’t overlooked.

Good point.

Co-founder and CEO of PS Audio. Hobbies (other than audio) include cooking, artisan bread baking, writing The Carbon Wars, hiking and inventing stuff. Infinity IRSV, MG Audio Designs and Audioquest cables, five P10 Power Plants, DirectStream DAC, NuWave Phono Converter, Clear Audio Master turntable, Lyra Cartridge, BHK Monos and BHK preamp, LANRover USB Transporter. I live in Boulder Colorado with my wife Terri, both of us are vegetarians for many decades. If you want to see support my first shot at writing a novel go here.

June 20, 2016
1:04 pm
Avatar
Santa Barbara, CA
Admin
Forum Posts: 70
Member Since:
September 15, 2014
sp_UserOfflineSmall Offline
12sp_Permalink sp_Print
+1

A note on the experimental breadboard setup in the initial post on this subject, that is a one channel circuit, not a working stereo one.

I thought I would clarify the intentions for this phono preamp design.  First it is to be a fully balanced circuit that would allow the cartridge to be floated off of signal ground – or not.  There will be a tube differential amplifier first stage that may or may not be augmented with some FETs below it for lower noise.  Following the input stage will be a passive RIAA equalizer that may be the full network or just the 2120 Hz rolloff part. If a partial equalization network, the output stage will have active feedback to generate the 500 -50 Hz bass boost.  If the equalizer is the full network, the output stage is flat in frequency response.  This describes the main signal circuitry and is setup for MM gain.  For MC inputs, a stepup transformer of suitable quility will be used.

There are a lot of considerations in all of this.  First is the issue of input noise.  I am most familiar with the work of John Curl and James Bongiorno in achieving super low noise MC input stages.  Personally, I am not all that worried about a little input noise if the sound is better.  I once made a tube MM/MC phono preamp using very low noise 7788 tubes. The MM 2120 Hz HF rolloff was with a series 47K resistor and a suitable capacitor at the input of the tube. Heresy!  All of those 10’s of K of noise resistance !  This also provided the essentially 47K loading for the cartridge up in the 20 kHz range.  It was quiet enough to not be audible at the listening position at normal playing gain.  I also did the same thing for MC use by  a much lower impedance RC input network.  That also worked pretty dammed good with the same circuit.  So bottom line on this, this preamp circuit may not end up as the lowest noise circuit on the block but it going to sound dammed good and serve the music. 

Aside from considerations of shielding a power transformer from hum radiation in the same chassis and issues of power supply regulation, the main issue for me in this initial circuit experimentation is the design of the second gain or output stage of the circuit.  First is the matter of whether it is a bass boost equalizer or flat amplifier.  The output devices in this proposed output amplifier are P channel MOSFETs that would be operated in the common source mode with attendant high output impedance.  Overall output circuit feedback will reduce this to a sufficiently low value.  Now if it is the flat response version where the RIAA equalization is all done in the interstage network between the input and output amplifier, all is well. However, if it is configured as the 500-50 Hz bass boost part of the RIAA equalization, the output impedance is going to rise as frequency goes down below 500 Hz because the amount of feedback is going to decrease.  This will have the effect of the very low bass frequencies will rolloff more with low impedance loading on the output of the preamp.  Also there will be different amount of input signals available to the output stage in each case.  Less signal for the full interstage EQ and more for the 2120 HF rolloff case.

More on the circuit for the output amplifier.  It is going to have a differential tube input stage.  Unlike the first stage of this phono preamp and the tube stages of the BHK preamp and power amplifiers where the tube stages stand alone outside of any including feedback loops, this first stage of the output amplifier will be included in the circuit’s overall feedback loop.  Servo circuits will keep the output phase to phase and each phase to ground close to 0 VDC.

This is enough for now and I realize it is too technical for some but not others.  If there are good ideas to consider in this and perhaps alternative circuits to consider, chime in to contribute!

BHK

The following users say thank you to BHK for this useful post:

pmotz, jazznut, magister

I have worked my entire career with tube and solid state circuitry for companies such as Marantz, Great American Sound (GAS), Sumo, BGW, Infinity, Counterpoint, Genesis Technologies, Conrad-Johnson, Audio Alchemy, Forssell Technologies, and Constellation Audio. I was responsible for the Marantz 1120 Integrated amplifier, Infinity HCA hybrid Class A power amplifier, Conrad-Johnson Premier 350 power amplifier, various accelerometer woofer servo systems, and Constellation Audio products.

June 20, 2016
2:27 pm
Avatar

Up and Coming
Forum Posts: 540
Member Since:
October 12, 2015
sp_UserOfflineSmall Offline
13sp_Permalink sp_Print
0

Thanks a lot for this insight!  Although I understand way too little about the technical details, it’s great to read and I wish I studied electronic engineering and I could participate more in detail.

I look forward to reading more about this project.

One thing, that’s interesting for me in theory, someone like you or Paul maybe could answer:

We know a preamp can add benefit to a source like the DS DAC, especially a certain richness and headroom, maybe even preserving or even adding transparency, although it means an add. circuit.

In my case as in your planned phono stage, the phono stage adds another 2 tubes to the circuit. Does this make a better result or worse than if it would be possible to connect phono directly to the preamp?

Or said another way very theoretically: would a low output DS DAC, connected to a similar pre preamp stage and then to the preamp sound better or worse than connected as high output directly to the preamp?

Hobby musician, music lover, long time audiophile, jazz-, vinyl-, and tube nut (but not dogmatic), now also CD/Hires/DSD nut. I use the Directstream DAC on Redcloud with Bridge II, a galvanic isolation device for LAN connection, a Monster High speed CAT6 LAN cable, a NAS drive QNAP TS253pro with 8TB WD red pro drives and Jriver for QNAP on the NAS with an *.aif/*.dsf library behind. I also use a power line separated from the rest of the house supply and from network components, a few active HF field protectors, a molecular reformatted complete signal chain as well as very sophisticated cabling throughout.

May 20, 2017
11:14 am
Avatar

Newbie
Forum Posts: 7
Member Since:
May 6, 2017
sp_UserOfflineSmall Offline
14sp_Permalink sp_Print
0

Hi..

Almost one year since the last post from Paul..any news on BHK Phono Preamp?

May 20, 2017
3:15 pm
Avatar
Raleigh, N.C.

Up and Coming
Forum Posts: 942
Member Since:
October 20, 2012
sp_UserOfflineSmall Offline
15sp_Permalink sp_Print
0

Or the speakers ?

UpToneLPS-1/ISORegen/microRenndu/USB>PSA DirectStreamDAC>PSA BHK SignaturePreAmp>qol>NCore400 w/P.I.Audio mods>Sophia3's/JL f112's; SonicTransporter/Synology 412+. VPI TT>PSA NPC; OPPO 103D/Vanity HD; AppleTv>Integra80.2>HT mode BHK; Epson 5030 Video; Seven PSA PowerBases; Iconoclast TPC XLR IC's;Three P.I.Audio DgiBUSS's, power cables & UBERBUSS; AirPort Extreme. Dedicated 16x23X10 room w/ ASC treatment/double walled/2 ply Iso-Wall Construction.

May 21, 2017
7:14 am
Avatar

PS Expert
Forum Posts: 5463
Member Since:
July 8, 2013
sp_UserOfflineSmall Offline
16sp_Permalink sp_Print
0

PCBs for the phono preamplifier are finally in process but not production. Darren made PCBs for Bascom so he can start building the prototype on a single board instead of the wired kludge he has now. So, still a work in progress but at least progress is being made.

Arnie’s speakers are finally moving forward and the drawings for extrusions and cabinet are done and at the manufacturer who is trying to get us a quote for the cabinets. Frustratingly slow. Hopefully within another month or two we can get cabinets and drivers for Arnie to start his magic.

The following users say thank you to Paul McGowan for this useful post:

rogerdn, magister, den

Co-founder and CEO of PS Audio. Hobbies (other than audio) include cooking, artisan bread baking, writing The Carbon Wars, hiking and inventing stuff. Infinity IRSV, MG Audio Designs and Audioquest cables, five P10 Power Plants, DirectStream DAC, NuWave Phono Converter, Clear Audio Master turntable, Lyra Cartridge, BHK Monos and BHK preamp, LANRover USB Transporter. I live in Boulder Colorado with my wife Terri, both of us are vegetarians for many decades. If you want to see support my first shot at writing a novel go here.

May 22, 2017
8:54 pm
Avatar
Richmond, VA USA

Up and Coming
Forum Posts: 344
Member Since:
July 7, 2016
sp_UserOfflineSmall Offline
17sp_Permalink sp_Print
0

 This is timely as I’m thinking of a phono pre upgrade. Paul, do you have any rough idea of price point and ETA? 

Music lover, amateur musician, physician, bulldog lover, and audiophile. PS Audio is integral in my system starting with P10 with PSA AC12 cable, a Directstream DAC, three separate M700 monoblocks and an S300 powering a hybrid 2 channel/HT setup, NuWave Phono converter, and LANRover. System also includes an Anthem AVM60, Mac Mini with Roon, B&W 804 D3 speakers, dual JL Audio Fathom subs, Fern & Roby Montrose turntable with Soundsmith Zephyr MIMC Star cartridge, and Gold Note PH-10 phono stage. Oh, and let's not forget about various and sundry ridiculously priced interconnects, USB, and power cables. 

May 22, 2017
11:11 pm
Avatar
Australia

Member
Forum Posts: 95
Member Since:
May 9, 2015
sp_UserOfflineSmall Offline
18sp_Permalink sp_Print
0

Paul

May I recommend getting some audio research Ref 2SE/3 phono preamps as a benchmark.

Not for sound quality :) heck no. I trust Bascom and you have enough experience but in terms of the user interface.

The ability to change the gain using a remote control and change the loading on the cartridge via the remote is a godsent when trying to set up the cartridge right from your seat. 

Having dual inputs, XLR inputs from the tonearm would also be nice. 

Analog: Sumiko Pearwood Celebration II, Project RPM10.1, Bel Canto Phono 3 --- Digital: PS Audio DirectStream, EMM Labs XDS1, Playback Designs MPS-5, Ayon CD-5S --- Computer: MacMini 2012 i7 2.6GHz and CAP Zuma derived Haswell-E i7 both with linear PSU, Windows Server 2012 R2 --- PreAmp: Audio Research Ref 5SE --- Power: Electrocompaniet Nemo --- Thiel CS3.7 and S1 Integrator with 2 x SS2.1

May 23, 2017
6:31 am
Avatar

PS Expert
Forum Posts: 5463
Member Since:
July 8, 2013
sp_UserOfflineSmall Offline
19sp_Permalink sp_Print
0

I doubt Bascom will have it finished and we release this calendar year. Look for 2018.

The following users say thank you to Paul McGowan for this useful post:

amgradmd, den

Co-founder and CEO of PS Audio. Hobbies (other than audio) include cooking, artisan bread baking, writing The Carbon Wars, hiking and inventing stuff. Infinity IRSV, MG Audio Designs and Audioquest cables, five P10 Power Plants, DirectStream DAC, NuWave Phono Converter, Clear Audio Master turntable, Lyra Cartridge, BHK Monos and BHK preamp, LANRover USB Transporter. I live in Boulder Colorado with my wife Terri, both of us are vegetarians for many decades. If you want to see support my first shot at writing a novel go here.

December 6, 2017
8:47 am
Avatar

Newbie
Forum Posts: 3
Member Since:
August 30, 2017
sp_UserOfflineSmall Offline
20sp_Permalink sp_Print
0

Will the new phono preamp have a mono button?

There seems to be no practical way to play mono vinyl without changing to a mono cartridge.  This is not a practical solution.  One option is to use y cables to sum the right and left signals.  I heard that this presents a problems since resistors should be introduced for optimal sound.  It also is not practical.  Back to the mono button… This would be the answer, it seems.  Any comments on how to best play mono without changing to a mono cartridge?

Any update on the release of the new phono preamp?

December 6, 2017
11:22 am
Avatar

PS Contributor
Forum Posts: 2633
Member Since:
December 6, 2012
sp_UserOfflineSmall Offline
21sp_Permalink sp_Print
0

I have mono buttons (well, in my case it’s toggle switches) on a Decware phono preamp and a Decware preamp. Definitely a more practical way to “go mono” than changing cartridges.

Decware:HR-1,ZP3,ZBIT, ZTPRE, ZROCK2, Torii Mk III amp,Taboo Mk IV amp;PS Audio:DMP+DSD DAC,P10,PowerBases,AC-12 pcs+HDMI cbl;Mapleshade Dbl Helix Plus;Magnum Dynalab: MD-90T SE;Cambridge Audio CXU;Rega:RP3,TTPSU,white belt,all Groovetracer upgrades,Exact2;VooDoo Cable:Cremona+Amati ics,Iso-Pods; Mapleshade:Samson v.2+v.3 racks;Audeze LCD-2;Oppo PM-1

December 6, 2017
5:50 pm
Avatar

PS Expert
Forum Posts: 5463
Member Since:
July 8, 2013
sp_UserOfflineSmall Offline
22sp_Permalink sp_Print
0

No updates still. Sorry.

Co-founder and CEO of PS Audio. Hobbies (other than audio) include cooking, artisan bread baking, writing The Carbon Wars, hiking and inventing stuff. Infinity IRSV, MG Audio Designs and Audioquest cables, five P10 Power Plants, DirectStream DAC, NuWave Phono Converter, Clear Audio Master turntable, Lyra Cartridge, BHK Monos and BHK preamp, LANRover USB Transporter. I live in Boulder Colorado with my wife Terri, both of us are vegetarians for many decades. If you want to see support my first shot at writing a novel go here.