Hello Big Guy,
Top of line audio system; wao. I googled all the devices therein! I guess you are streaming analog or digital music into the Mytek.
Can you estimate the maximum level of H2 at the input of XA60.8s; which has a voltage gain of 26 dB or a 20X Vinput. It seems to me that % H2 used is low; because I am thinking the output power delivered to the loudspeaker is ~1 W rms.
Best
Anton
Top of line audio system; wao. I googled all the devices therein! I guess you are streaming analog or digital music into the Mytek.
Can you estimate the maximum level of H2 at the input of XA60.8s; which has a voltage gain of 26 dB or a 20X Vinput. It seems to me that % H2 used is low; because I am thinking the output power delivered to the loudspeaker is ~1 W rms.
Best
Anton
Thanks, Anton.
Yes, I am using a PC tweaked for audio and running JRiver Music Center to feed digital to the Mytek via an Adnaco fiber to USB device to galvanically isolate from PC. Interconnects are Harmonic Technologies "Photon" which also provide galvanic isolation between Mytec & Pre as well as Pre & Amps.
The preamp is similar in concept to the Tortuga LDR designs but is a custom build from a DIYer in our audio society.
I did not mention that I am also using 2 HSU and 1 Velodyne sub to add weight and presence since the CLX only goes down to about 50 Hz tho' I may need to drop their levels given the weight added by the H2.
Re the amount of H2, I do not have any measurement gear to give you a number. Sorry...
Hello Big Guy,
You have done a lot of detailed homework to assemble your high caliber audio system. Truly most interesting.
A noise which is hum is attributed to 60 Hz and a buzz is/maybe 120 Hz [ripple]. Ground loops, and/or pickup of radiation?
H2 Preamp V1 is noiseless in my audio system. I replaced the 24 VDC switching PSU with a linear non-regulated one. This switcher had flooded the H2s with high frequency noise which was readily visible on the scope.
Best wishes, and happy holidays,
Anton
Yes, its been a work in progress for about 40 years! Two constants however are that I am "poster child" for both Pass and Martin Logan which, together, make beautiful music, IMHO. Have owned both for 20+ years.
Interesting about the noise introduced with the wall wart! Thanks!
Pretty sure its not ground loop or radiation since system is dead quiet without H2.
Which 24V power supply did you wind up using to replace it?
I hard wired the supplied wall wart but it would be easy enough to replace with something more quiet. That plus Nelson's future tweaks to the LM317 noise filtration sounds like great revisions.
I had replaced the old switching PSU with a [remote] non-regulated linear one. It is from a spent Radio Shack receiver. I control the 24 VDC output voltage to the H2s via a variac in the AC power circuit of the receiver. This PSU is quiet.
Your system has 4 pairs of RCA cables whereby noise can find its way in their shields. You may consider trying the following diagnosis to pinpoint the origin/cause of the buzz. Priority one is to protect the loudspeakers.
1. Disconnect the RCA cables from the H2s to the XA60.8s.
2. Disconnect the hot output of XA60.8s from the loudspeakers [protect].
3. Power up the XA60.8s and H2s and stabilize.
4. Disconnect both RCA cables from the volume control to the inputs of the H2s, and then connect the H2s' outputs to the power amps.
5. Finally connect the loudspeakers to the XA60.8s. The moment of truth is: buzz or not?
6. If no buzz, repeat a subset of the above and continue to methodically introduce the remaining RCA cables towards the laptop.
Hope you'll nail down the culprit.
Best
Anton
Did not have a RS receiver to pirate so wound up buying this LRPS since I thought that you had a great idea...
https://www.amazon.com/gp/product/B00B88EGM6/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
Will also spend time with your suggested noise-shooting protocol.
Thanks.
Hello Big Guy,
I look forward to your noise-shooting results, and all additional H2 impressions.
Please go to the site High performance audio transformers and ground isolators.. It [Jensen] has white papers [e.g. an004.pdf] which discuss hum and buzz noise. Maybe applicable.
Best
Anton
Will check the link, Anton.
I do not understand the intricacies of grounding...earth vs chassis, etc.. Reading most articles makes my head hurt!
Do wall warts need to be grounded somehow? Most that I have seen are only 2 prong.
Does it help to have the wall wart cable shielded with the shield grounded somehow?
Rather than hard wiring the SMPS to the H2, I have ordered mini-XLR jacks and plugs to provide some flexibility in powering the H2.
Your tutelage is appreciated.
Hello Big Guy,
Thanks for your post. I have my suggested answers in your post above.
Mr. Pass has suggested the SMPS: TRIAD WSU240-0500 in his second H2 article; but not in his first one. Its case appears to be made of plastic.
Which PSU did you use on your first generation H2 which caused the buzz?
Best
Anton
I read the link you provided but will need to revisit and also read more about the Iso-Max (Jenson Transformers).
I used the suggested Triad which is a SMPS that you note but have not identified it is the source of the noise heard with H2 Ver1 in the system. Nelson had indicated that the LM317 regulator was not particularly quiet and indicated that additional filtration could be added to the H2 Ver1 circuit. He said the revision is in progress as time permits.
I thought your use of a Linear Regulated Power Supply was a good one so purchased this LRPS to replace the Triad...
https://www.amazon.com/gp/product/B00B88EGM6/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
I also ordered these small XLR connectors to replace the standard wall wart plug and jack on the chassis...but only plan on using 2 of the 3 pins for the supply.
I DID put a copper braid shield on the SMPS as you have noticed but it is NOT attached at either end...like running the cable thru a tube.
Hello sarathssca. The voltage gain of H2 is not as high as 26 dB. Mine has ~15 dB.
The voltage output of H2 maybe 0.5 V rms. Thus, it generates a desired level of distortion which can be read on the graph on page 7 of the article by Mr. Pass which correlates %distortion with its output voltage.
Of course it'll drive a voltage follower; except the voltage output of the follower [buffer] will still be 0.5 Vrms to drive a loudspeaker. The resultant power output of the follower across a 4 Ohm loudspeaker will be 63 milliWatts.
Best
Anton
ADDENDUM: Forgot to mention that even tho' the shield is not attached at either end, there is a copper pigtail that runs along the shield terminate in a 3-prong plug with the shield/pigtail connected to the ground pin. There were extensive posts on a thread suggested this to be very effective.
Hello Big Guy,
Please find attached the schematic of the on-board [LM317]-regulated PSUs for H2 Preamp V1 and below it that of the Original H2. Note:
1. The on-board regulated PSU for H2 Preamp V1 has a PRE-LM317 and a POST-LM317 low pass filters which are comprised of R1=R2 = [33.2 Ohms] and C1=C2= [1000uf]. Very effective!
2. My RS linear and unregulated PSU brings to my H2 Preamp V1 a 40 mVp-p sawtooth ripple as seen on the scope. This noise became a diagnostic tool.
3. The first R1C1 pre-filter drops the magnitude of the parent ripple to ~2 mVp-p.
4. The second R2C2 filter wipes clean all ripple at the +V output as seen by a flat scope trace.
5. The on-board regulated PSU of the Original H2 is shown below that of H2 Preamp V1. It is simpler and may appear less potent than the later. BUT the +24 V output of the suggested SMPS [TRIAD..] is already pre-regulated as shown in paragraphs [4 and also see 5] on page 6 of the parent H2 article.
IF the noise in your system is riding the +24 V output of the SMPS [or the new linear PSU] as determined by scope, then this suggested solution will knock its amplitude way down. Parallel a 1000uF with the existing 10uF; by example/copy of points 1-3 above done by Mr. Pass. This new pre filter is comprised of R=68 Ohms and C =1010 uF. It has an F3 of 2.3 Hz.
IF the amplitude of the above noise; say is 1 mVp-p, it'll be amplified by 20 times from XA60.8 times 2. A net 40 mVp-p emanating from both loudspeakers maybe audible.
Best
Anton
Attachments
Phew! Did NOT understand much of what you wrote, Anton. Sorry.
I do not have scope or access to one so much of your commentary is not relevant for me. That being said, I am OK with "Betty Crocker" instructions...I CAN follow directions.
Given that my LRPS wall wart just arrived, it makes sense that I should use the circuit mods that you show for linear PS. I will compare the original with your schematic to see if I understand.
BTW, how can I print the schematic in your post?
Please pause any proposed changes and do the following simple diagnosis to your system starting with LDR [Optical Volume Control]. The acronym HTI used below stands for Harmonic Technologies Interconnect. It is an optical galvanic isolator which connects any two devices.
1. The music signal currently flows from: LDR via HTI to H2 via RCA coaxial cable to XA60.8.
2. Instead of point 1 above, reconfigure the signal flow from: LDR via RCA coaxial cable to H2 via HTI to XA60.8. Will this kill the buzz?
The use of TRIAD WSU240-0500 PSU in the original H2 which you have has been suggested and cleared by Mr. Pass.. Best to use it because its output is already regulated. Its specs are at the TRIAD website.
This begs the question to users of the Original H2. Did anyone encounter any hum/buzz in your loudspeakers like in Big Guy's system.
Best
Anton