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    VTA PH16 Phono Preamp Show and Tell

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    TMadden

    Posts : 99
    Join date : 2011-12-22

    VTA PH16 Phono Preamp Show and Tell

    Post by TMadden on Mon May 25, 2015 11:28 am

    I just finished building my personal PH16 with MC step-up transformers (Lundahl LL9226 at 26 db gain), and she sounds fabulous! Wonderfully musical, revealing, spacious.
    With a Benz Micro Glider SM cart, it's simply leaps and bounds better than my Shure V15 type 3, AT 150MLX or Ortofon 2M Black. Mids are absolutely lucid,
    highs super clean, bass is powerful,  low and defined. Micro detail in spades, it's like a whole new system! With my better LP's, the realism is uncanny! Am I in the studio? As I type, I  keep looking over at my system in amazement! Happy-Happy!
    Anyone who has built a phono preamp can tell you the challenge is to build a quiet one, well this one is DEAD QUIET, and that's with 70 db of gain!
    A properly built PH16 is dead quiet, but maintaining that noise level with high gain SUT's requires that all EMF be contained. Layout is critical, all wires carrying AC are twisted, all ground paths must be right, power and step-up transformers are shielded in steel enclosures.
    So anyway, this was my Memorial weekend project, and I couldn't be happier! Here's a few pics of the internals.



    wgallupe

    Posts : 81
    Join date : 2014-05-18
    Age : 62
    Location : Central Mass.

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by wgallupe on Mon May 25, 2015 5:05 pm

    Hey Troy, that looks really nice! I see that you eliminated the resistors and dip switches. I assume they are not needed due to the SUT. Is that the 16" chassis?

    Is it really 70db gain? That sounds like a lot for a medium output Benz MC. Based on your description of what you are hearing, obviously is not too much gain...

    I'm still enjoying my little PH12 but this PH16 sure is tempting...

    Have a great Memorial Day...

    TMadden

    Posts : 99
    Join date : 2011-12-22

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by TMadden on Mon May 25, 2015 5:35 pm

    wgallupe wrote:Hey Troy, that looks really nice! I see that you eliminated the resistors and dip switches. I assume they are not needed due to the SUT. Is that the 16" chassis?

    Is it really 70db gain? That sounds like a lot for a medium output Benz MC. Based on your description of what you are hearing, obviously is not too much gain...

    I'm still enjoying my little PH12 but this PH16 sure is tempting...

    Have a great Memorial Day...


    Hi Wayne,

    Yes, I don't really need the cartridge loading options for this application. I just installed the 47K load resistors, which gives me a 117.5 ohm load through the SUTs.
    70db is more than enough gain for the medium output Benz, but this way I can also use low output MC cartridges. As long as you don't have noise issues, I have found that having a lot of gain tends to really bring out low level detail in the music. And, some of the faults in the recording process, I can hear tape hiss, mixing glitches, master tape print through, and on one album, what must be rumble in the cutting lathe! On a good LP I get the impression I am listening to the master tape!
    The PH12 is a great phono pre, a lot of people have been surprised at just how good it is, but the PH16 is really special. I built a PH16 just like mine for a fellow who uses low output MC's, he also has a Krell Reference phono pre, he tells me his PH16 is just as quiet, and sounds better! I am having have a great Memorial Day, thanks, I hope you are as well. OH, yes, that is the 16" chassis, I wouldn't attempt the SUT's in a 12", too close to the power transformer, it would be very difficult to keep hum at bay.

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by deepee99 on Mon May 25, 2015 6:04 pm

    She's a beauty, Troy.

    TMadden

    Posts : 99
    Join date : 2011-12-22

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by TMadden on Mon May 25, 2015 7:31 pm

    deepee99 wrote:She's a beauty, Troy.

    Thanks David, the only problem now is I'm really curious how some of the other MC carts sound and they are a whole lot more expensive than MM's to experiment with!
    Champagne taste, beer budget! LOL! I guess maybe if I sell off my MM carts I can justify another MC! Keep reading very good things about the Dynavector 20X2, supposedly much like the Benz, only even better.

    mijohn

    Posts : 33
    Join date : 2013-06-19

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by mijohn on Mon Jun 15, 2015 2:12 am

    TMadden wrote:
    deepee99 wrote:She's a beauty, Troy.

    Thanks David, the only problem now is I'm really curious how some of the other MC carts sound and they are a whole lot more expensive than MM's to experiment with!
    Champagne taste, beer budget! LOL! I guess maybe if I sell off my MM carts I can justify another MC! Keep reading very good things about the Dynavector 20X2, supposedly much like the Benz, only even better.

    Troy, I'm in the process of constructing a PH16 and are using a Par Metal 12" chassis and have installed a full length and height aluminum divider between the PSU and preamp. I've lined this on both sides with mu-metal. I'm also thinking of using copper Pearl Tube Coolers earthed to the PCB doubling as EMF shields (I hope).

    Like you I am also considering the Dynavector 20X2, which is available in high (2.8mV) and low (0.3mV) output versions. I'm agonizing over whether to buy the high output version and save several hundred dollars on SUT’s, or install SUT’s in the PH16 and go with the low output version. I have read that the 20X2L (Low) is theoretically better because of the lower mass of smaller coils and if one has a good phono stage and turntable combination, this is the best option. What do you think?


    Last edited by mijohn on Mon Jun 15, 2015 11:00 am; edited 1 time in total

    TMadden

    Posts : 99
    Join date : 2011-12-22

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by TMadden on Mon Jun 15, 2015 8:24 am

    mijohn wrote:
    TMadden wrote:
    deepee99 wrote:She's a beauty, Troy.

    Thanks David, the only problem now is I'm really curious how some of the other MC carts sound and they are a whole lot more expensive than MM's to experiment with!
    Champagne taste, beer budget! LOL! I guess maybe if I sell off my MM carts I can justify another MC! Keep reading very good things about the Dynavector 20X2, supposedly much like the Benz, only even better.

    Troy, I'm in the process of constructing a PH16 and are using a Par Metal 12" chassis and have installed a full length and height aluminum divider between the PSU and preamp. I've lined this on both sides with mu-metal. I'm also thinking of using copper Pearl Tube Coolers earthed to the PCB doubling as EMF shields (I hope).

    Like you I am also considering the Dynavector 20X2, which is available in high (2.8mV) and low (0.3mV) output versions. I'm agonizing over wether to buy the high output version and save several hundred dollars on SUT’s, or install SUT’s in the PH16 and go with the low output version. I have read that the 20X2L (Low) is theoretically better because of the lower mass of smaller coils and if one has a good phono stage and turntable combination, this is the best option. What do you think?

    Sorry, but I can't offer much in the way of advice. My experience with MC carts is pretty limited. The reason I built my PH16 with SUT was based on hearing my Benz Micro
    Glider SM with an identical PH16 I built for a customer. The sound was so good I couldn't build mine fast enough! My Benz was getting worn however, so I sent it to Benz for a rebuild. In the mean time I bought a Ortofon Quintet Black low output MC cart, based on the excellent reviews and the moderate price. So far, it's just not nearly as good as the Benz, esp at the top end, but maybe it needs some break-in time. At this point I would rather listen to my AT 150MLX than the Ortofon. So, for me anyway, there no substitute for actually hearing the cartridge/SUT/preamp combo. One thing is for sure, the PH16 will easily reveal the differences in every cart you try with it!

    mijohn

    Posts : 33
    Join date : 2013-06-19

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by mijohn on Mon Jun 15, 2015 11:28 am

    Thanks Troy, I have found this thread very interesting and hope you and your Benz are reunited soon!

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by deepee99 on Mon Jun 15, 2015 12:12 pm

    Good morning Troy, et. al,
    I would shure (pardon the pun) give the Ortofon a little burn-in time. Maybe a lot. My experience is limited mostly to MM carts, though.
    I bought a Dynavector 20x2 that still sounded like cats having sex after maybe 50 hours of run-in, NeedleDoc was good enough to accept a return, went back to an Orto and am very happy with it.
    I can't shatter the neighbours' windows on 1812 Overture with the best CDs, but gimme vinyl and run for your life. bounce

    TMadden

    Posts : 99
    Join date : 2011-12-22

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by TMadden on Mon Jun 15, 2015 12:49 pm

    deepee99 wrote:Good morning Troy, et. al,
    I would shure (pardon the pun) give the Ortofon a little burn-in time. Maybe a lot. My experience is limited mostly to MM carts, though.
    I bought a Dynavector 20x2 that still sounded like cats having sex after maybe 50 hours of run-in, NeedleDoc was good enough to accept a return, went back to an Orto and am very happy with it.
    I can't shatter the neighbours' windows on 1812 Overture with the best CDs, but gimme vinyl and run for your life. bounce

    Yes, I will break it in, I wish I could just hit play and let it run, nothing's easy with vinyl, but it sure sounds great once you find the right components!

    mijohn

    Posts : 33
    Join date : 2013-06-19

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by mijohn on Wed Jun 17, 2015 11:05 am

    Troy,
    Are the shields on all the wiring to and from the inputs, MM/MC switch, SUT's and PCB grounded at both ends? They appear to be from looking at your photos.

    Mike

    TMadden

    Posts : 99
    Join date : 2011-12-22

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by TMadden on Wed Jun 17, 2015 12:04 pm

    mijohn wrote:Troy,
    Are the shields on all the wiring to and from the inputs, MM/MC switch, SUT's and PCB grounded at both ends? They appear to be from looking at your photos.

    Mike
    Good question, as you know ground loops will definitely cause hum. All the shields (except the short jumper from MM input to switch) are connected , but not grounded actually, at both ends.
    The RCA jacks are isolated from the chassis, so their only ground reference is the ground trace on the PCB (via the shields), which is in turn grounded at the power supply, at the same point the ground from the AC power connector grounds. The input and output windings of the SUT's are grounded only at the RCA jacks (via the shield). The black wire connected to the turntable ground post grounds the SUT cases, only. Originally the PCB the SUTS are mounted on connected the input and output grounds, and the case grounds, I cut the traces on the SUT PCB so I wouldn't have ground loops. The next problem was the SUT's picking up leakage flux from the power transformer, that was solved by enclosing all transformers in steel enclosures.

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by deepee99 on Wed Jun 17, 2015 12:23 pm

    TMadden wrote:
    mijohn wrote:Troy,
    Are the shields on all the wiring to and from the inputs, MM/MC switch, SUT's and PCB grounded at both ends? They appear to be from looking at your photos.

    Mike
    Good question, as you know ground loops will definitely cause hum. All the shields (except the short jumper from MM input to switch) are connected , but not grounded actually, at both ends.
    The RCA jacks are isolated from the chassis, so their only ground reference is the ground trace on the PCB (via the shields), which is in turn grounded at the power supply, at the same point the ground from the AC power connector grounds. The input and output windings of the SUT's are grounded only at the RCA jacks (via the shield). The black wire connected to the turntable ground post grounds the SUT cases, only. Originally the PCB the SUTS are mounted on connected the input and output grounds, and the case grounds, I cut the traces on the SUT PCB so I wouldn't have ground loops. The next problem was the SUT's picking up leakage flux from the power transformer,  that was solved by enclosing all transformers in steel enclosures.
    Good info, But talk to an airplane pilot some time about ground loops. They are far more interesting, if you survive.

    mijohn

    Posts : 33
    Join date : 2013-06-19

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by mijohn on Thu Jun 18, 2015 6:47 am

    Troy,
    Thanks for the explanation, just a couple of more questions please:
    Is the black wire connection from the turntable ground post terminated at the pad on the SUT PCB labeled 'case gnd' and is the black case that the PCB is mounted in, physically/electrically connected to the chassis?

    I haven't received my SUT's & PCB yet so only going from the attached photo, where did you cut the traces on the PCB?



    TMadden

    Posts : 99
    Join date : 2011-12-22

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by TMadden on Thu Jun 18, 2015 7:27 am

    mijohn wrote:Troy,
    Thanks for the explanation, just a couple of more questions please:
    Is the black wire connection from the turntable ground post terminated at the pad on the SUT PCB labeled 'case gnd' and is the black case that the PCB is mounted in, physically/electrically connected to the chassis?

    I haven't received my SUT's & PCB yet so only going from the attached photo, where did you cut the traces on the PCB?



    Is the black wire connection from the turntable ground post terminated at the pad on the SUT PCB labeled 'case gnd' and is the black case that the PCB is mounted in, physically/electrically connected to the chassis? Yes, and yes the black case is screwed to the chassis.
    where did you cut the traces on the PCB? On the other side of the PCB there is a trace that connects all the "grounds" together, it actually has narrowed spots on the
    trace to indicate where to cut the trace if you want to separate the grounds.

    mijohn

    Posts : 33
    Join date : 2013-06-19

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by mijohn on Fri Jun 19, 2015 2:44 am

    Thanks Troy, I hope my PH16 ends up as quiet as yours, noise wise that is!!!  Smile

    TMadden

    Posts : 99
    Join date : 2011-12-22

    Re: VTA PH16 Phono Preamp Show and Tell

    Post by TMadden on Fri Jun 19, 2015 9:10 am

    mijohn wrote:Thanks Troy, I hope my PH16 ends up as quiet as yours, noise wise that is!!!  Smile


    Take care with grounding, shielding and layout, and it should be!

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