Leaderboard

Golden Reference LV Build Guide Schematic for the golden reference LV: parts in green are new additions compared to the published schematic pdf in joamats post above. Parts in purple set the output voltage, parts in brown are the optional fine output adjust and parts in dark blue are the optional power led. Component Layout Optional parts and Options: 1. if you don't want to have a power led fed from the LV board omit the 2K resistors R13, R14 and the led D3 2. if you don't want very fine adjustment of the output voltage omit the 1M resistors R17, R18, R23, R24 and the trimmers RV2 and RV1. If you want more adjustment range reduce the value of the resistors. With 1M ohm resistors the fine adjust can only change the output voltage by a few mV. Replacing with 810K resistors provides a little more adjustment range ~ 20mV but at the expense of decreasing the temperature stability. A cheaper alternative for good output accuracy is to use 1/4W 0.1% low ppm e.g. 15ppm resistors for the voltage set resistors and omit the fine adjust completely - which is cheaper and improves the temperature stability. 3. if you have the dual output board (which has both positive and negative output rails) either you populate the middle diode bridge only and use a transformer which is centre tapped OR you populate the two outer diode bridges and use a transformer with two separate output windings. If use use synchronous rectifiers instead of diode bridges use must use the second option and use separate windings for positive and negative rails. Do not populate all three bridges. If you use a centre tapped transformer you must connect the centre tap to the middle screw terminal (which is connected to the GRLV ground plane) of the 5 terminal AC input block . Do not use a synchronous rectifier to the centre bridge it will not work correctly and can result in the driver mosfets of the synchronous rectifier burning. Note the GRLV cant output less than the voltage of the voltage reference (LT1021), ideally for proper regulation the output needs to be more than about 2V higher than the LT voltage reference. So for about 12V or less output it is recommended you change the 10V reference for a 7V and the zener diodes for a 7V. For 12V output 10V reference or 7V reference can be used but the 7V reference version may have less noise. Maximum output is constrained by the voltage rating of the caps and is about 30V without modifications. Setting the Output Voltage For the positive output R8 and R7 control the output voltage along with the voltage reference, the output voltage is ((R7+R8)/R7)*voltage reference output D5. Assuming you keep R7 at the stock value of 1.5K: output voltage change R8 to 3k = 30V 1.5K = 20V 750 = 15V 300 = 12V In general to calculate R8: ((Voltage required * R7)/voltage reference D5 output) - R7 = R8 For the negative output R10 and R9 control the output voltage along with the voltage reference, the output voltage is ((R10+R9)/R9)*voltage reference output D7. Assuming you keep R10 at the stock value of 1.5K: output voltage change R9 to 3k = 30V 1.5K = 20V 750 = 15V 300 = 12V In general to calculate R9: ((Voltage required * R10)/voltage reference D7 output) - R10 = R9 Photos of finished boards for reference: This version uses a single diode bridge so this is setup for a centre tapped transformer, also has the trimmers and resistors for the power led populated but no power led installed. The build uses 4700uF reservoir caps and silmic 220uf output caps and 1/4w resistors from vishay and dale. This is what you get using the BOM link in this post (see bellow) and is very close to the original BOM published near the beginning of this thread. This version is setup for dual separate transformer windings, and has no power led or trimmers implemented. It also uses synchronous rectifiers instead of diode bridges, nippon chemicon 10000uF reservoir caps, Panasonic FR series 220uF caps and 1/2W 50ppm 1% koa resistors. The resistors that set the output voltage are 1/4W TE 0.1% 15ppm for increased temperature stability and output accuracy. This is my current default build. BOM (based on 10V voltage reference and all options being populated) https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=edda1bdbf7 Component list with cap size information Br1,Br2,Br3 = 2 x 4A 100V RS402L use 2 for dual winding transformer use 1 for centre tapped transformer C,C = 2 x film 4.7uF 50V 5mm lead spacing 0.5mm lead diameter C,C,C11,C12,C14,C15 = 6 x film 0.01uF 100V 5mm lead spacing max size ~ 7.6mmx3mm 0.5mm lead diameter C1,C2 = 2 x 50V 4700uF 10mm lead spacing max diameter 25mm, 22mm more comfortable fit main reservoir cap I also use Nippon Chemicon 63V 10000uF which just fit. C3,C16 = 2 x Tantalum 35V 10uF ESR=2 Ohms 5mm lead spacing 0.5mm lead diameter C4,C5 = 2 x Multilayer Ceramic 50V 47pF 5mm lead spacing 0.5mm lead diameter C6,C10 = 2 x 220uF 35V silmic or Panasonic FR series 5mm lead spacing 12.5mm max diameter C7,C8,C9,C13 = 4 x tantalium 35V 47uF ESR=0.8ohms 5mm lead spacing 0.5mm lead diameter D,D,D,D = 4 x 1N914 D1,D2,D3,D8,D9 = 5 x 1.7V red led 4 are required one is for optional power led leally all 4 main leds should be from the same batch and have similar characteristics. D10,D11 = 2 x IN4007G 1A 1000V D4,D6 = 2 x IN4739A 9.1V 1W use 7V zener for <=12V output D6,D7 = 2 x lt1021-10 10V voltage reference use 7V for <=12V output Q4 = 1 x MJW21194G Q5 = 1 x MJF15031G Q7 = 1 x MJW21193G Q9 = 1 x MJF15030G Q1,Q3,Q6,Q13 = 4 x KSP92TA Q2,Q10,Q11,Q14 = 4 x KSP42TA Q8,Q12 = 2 x DN2540N3-G R1,R4 = 2 x 150 1/2W R13,R14 = 2 x 2K R15,R16 = 2 x 10K R17,R18,R23,R24 = 4 x 1M, 810K = +-20mv adj range optional for fine adjustment R2,R5,R11,R12 = 4 x 1K R20,R21 = 2 x 500 R3,R6,R19,R22 = 4 x 10 R7,R10 = 2 x 1.5K R8,R9 = 2 x 750 for 15V output change as necessary for your output RV1,RV2 = 2 x 100K optional for fine adjustment U1,U2 = 2 x OPA134PA opamp Building Once you have decided the build options and output voltage, construction is straightforward given there are no high voltages. Depending upon the current draw the large power transistors on the side of the board may require heatsinking. The metal tab is live so they will need to be insulated from the heatsink/chassis. Socketing the reference and opamps is optional but it does make replacement and reuse easier. Make sure the caps are installed with the correct polarity. The line on the tantalums denotes the positive Terminal whereas the line on electrolytic caps denotes the negative terminal.... the film caps can be installed either way around as can the small ceramic caps. For the leds the longer leg is the + leg and this goes to the + mark on the pcb be careful to install the opamps and voltage reference chips the correct way around they will get very hot very quickly if installed the wrong way. make sure you don't place as ksp42 where a ksp92 should go of visa versa. Its easy to do since they look identical and its not easy to see all the markings once populating the board is finished. Testing (optional) If you have a means to control the input voltage to the board e.g. a variac, then with no load connected to the grlv the outer leds (closest to the LT voltage reference) should just start to glow at about 2.4 to 2.5VAC rms input voltage to the board and the output of the GRLV should be around 1V DC. If you cant get the outer leds to light with about 3VAC rms input, stop and disconnect, something is definitely wrong. By 3VAC rms the outer leds should be bright. Increasing the variac output further should see proportional rises in the GRLV DC output voltage until the output reaches the expected output. At this point the inner leds closest to the zener diode may not have lit and although basic regulation has been achieved, the input voltage is too low for full low noise regulation. Increase the input voltage a little more and the inner leds should light. This should happen with after about an additional 1 volt AC rms is added to the input. The output voltage should not increase. As a very rough rule of thumb, without load, the grlv needs about 2V less input AC rms than its DC output. So for example for 12v output expect regulation to just happen at about 10VAC rms input but the inner led not to light until about 11VAC rms. Note this figures depend on tolerances, the diode bridge voltage drop, led characteristics etc and are a rough guide only. Adding a load to the GRLV will mean it needs a higher input voltage in order to regulate since some of the sources of voltage drops are dependant on current draw e.g. the diode bridges. So if you adjust the variac to just get the inner led lit with no load don't be surprised if it goes out when you draw a few hundred milliamps. Another way to test is to connect the AC in of one rail to a current limited DC power supply. Set the current limit to say 0.010A (10mA) and slowly increase the voltage. Bellow about 3.3VDC input to the GRLV there should be low current draw <10mA. At about 3.4VDC the outer led will start to light and current draw should still be <10mA. Around 8.5VDC input current draw should reach about 10mA. The inner led close to the main cap should begin to light at about 2.6VDC input above the expected output e.g. 14.6VDC input for 12V output. At this point current draw should be about 20mA and you may need to increase your DC power supply current limit. Increasing the DC power supply output past this point should not result in increasing current draw or increasing GRLV output. Note when you increase the DC power supply voltage you will get an initial current draw spike as the input cap charges to the new voltage level but the current draw should quickly subside to the figures shown. If the GRLv regulates and behaves as expected with no load and has no warm components or varying output then you could continue to load testing. The reality is that if your RLV works with no load its almost certainly ok and will be fine without load testing. But if you want to be extra careful the easiest way to do this is with an electronic DC load. I setup my load so that it will abort the test if the output voltage of the GRLV exceeds 0.2V above or bellow the no load output. A properly working GRLV with enough input voltage will vary very very little with current draw - much less than a traditional 78xx/79xx voltage regulator. I then load at 50mA and check for hot components, and then in 100mA steps up to 1A. Above about 400mA the large main transistors will get hot if they are not heatsinked... this is normal as the current draw increases there is more power dissipation in the transistor. Note transformers and diode bridges etc do drop more voltage as the current draw increases so if the inner led goes out at higher current draws check the input voltage to the GRLV has not decreased too much for the GRLV to regulate. Don't load test about above 300mA for long periods without heatsinking the main transistors. Additional Checks (useful if troubleshooting) The voltage reference output voltage should be present between pins 4 and 6 of the LT reference and be stable and very close to the spec sheet voltage. Use fine tip probes and be careful not to short any pins together when probing: The opamp compares the voltage reference with the output voltage from the voltage divider (the resistors which set the output voltage) and creates a correction signal. Pin 2 of the opamp is connected to the voltage reference and pin 3 is connected to the voltage divider. When working correctly, the voltages with respect to ground to pin 2 and from ground to pin 3 should be identical and be the same as the output of the voltage reference measured above. In circuit testing and troubleshooting So its not working correctly or you want to do some more tests before powering on for the first time?. Here are some tests you can do on a fully built GRLV that has no power connected. With a multimeter set to diode check mode and the caps on the grlv fully discharged. you can do some sanity checks. The exact measurements will vary from multimeter to multimeter and device to device but this should give some ball park figures. My figures are based on a Brymen bm869s. Led polarity outer leds closest to the edge of the pcb and the voltage reference: red lead of multimeter to + lead of led, black on - lead of led ~ 0.8V slowly rising as a cap charges led does not light. leads reversed: 1.63V slowly rising led does not light inner leds closest to the main input filter caps: red lead of multimeter to + lead of led, black on - lead of led ~ 1.7V stable voltage led should light. leads reversed: over range / OL / open circuit, led does not light. Zener check both zeners close to the inner leds: red probe on band side black on non band side: OL / open circuit, probes reversed 0.66V Transistor Death/Incorrect Placement Checks large MJW21194 on +rail measuring looking at the front of the transistor where the markings are: red probe on left pin black on middle pin: 0.46V steady, probes reversed OL / open circuit red probe on left pin black on right pin: 0.48V steady, probes reversed OL / open circuit red probe on middle pin black on right pin: 0.5V rising rapidly, probes reversed 0.48V rising much more slowly large MJW21193 on -rail measuring looking at the front of the transistor where the markings are: red probe on left pin black on middle pin: OL / open circuit , probes reversed 0.48V steady red probe on left pin black on right pin: OL / open circuit, probes reversed 0.49V steady red probe on middle pin black on right pin: 0.48 rising slowly, probes reversed 0.5V rising much more rapidly MJW15030 on +rail next to inner led: red probe on left pin black on middle pin: 0.57V steady, probes reversed OL / open circuit red probe on left pin black on right pin: 0.57V steady, probes reversed OL / open circuit red probe on middle pin black on right pin: OL / open circuit , probes reversed 0.46 steady MJW15031 on -rail next to inner led: red probe on left pin black on middle pin: OL / open circuit, probes reversed 0.57V steady red probe on left pin black on right pin: OL / open circuit probes reversed 0.57V steady red probe on middle pin black on right pin: 0.48 steady probes reversed OL / open circuit KSP42 on +rail on edge of board: looking at flat front where the marking are red probe on left pin black on middle pin: 1.8V rising, probes reversed 0.6V steady red probe on left pin black on right pin: 1.2V rising, probes reversed OL / open circuit red probe on middle pin black on right pin: 0.6V steady probes reversed OL / open circuit KSP92 on -rail on edge of board: looking at flat front where the marking are red probe on left pin black on middle pin: 0.61V steady, probes reversed 1.7V rising red probe on left pin black on right pin: OL / open circuit. probes reversed 0.9V rising red probe on middle pin black on right pin: OL / open circuit, probes reversed 0.6V steady DN2540 on +rail between voltage reference and 220uf output cap red probe on left pin black on middle pin: 0.31V steady, probes reversed 0.32V steady red probe on left pin black on right pin: 0.004V steady. probes reversed 0.004V steady red probe on middle pin black on right pin: 0.32V steady, probes reversed 0.32V steady DN2540 on -rail between voltage reference and 220uf output cap red probe on left pin black on middle pin: 0.32V steady, probes reversed 0.32V steady red probe on left pin black on right pin: 0.004V steady. probes reversed 0.004V steady red probe on middle pin black on right pin: 0.32V steady, probes reversed 0.32V steady KSP92 on +rail near centre of board close to middle diode bridge: looking at flat front where the marking are red probe on left pin black on middle pin: 0.6V steady probes reversed OL / open circuit red probe on left pin black on right pin: 1.0V rising slowly, probes reversed OL / Open circuit red probe on middle pin black on right pin: rises to about 0.67V, probes reversed 0.56 steady KSP42 on -rail near centre of board close to middle diode bridge: looking at flat front where the marking are red probe on left pin black on middle pin: OL / Open circuit, probes reversed 1.61V steady red probe on left pin black on right pin: OL / open circuit. probes reversed 0.95V rising red probe on middle pin black on right pin: 0.59V steady, probes reversed 0.67V steady the pair of KSP92 on +rail ksp92 closest to voltage ref: looking at flat front where the marking are red probe on left pin black on middle pin: 0.62V steady probes reversed OL / open circuit red probe on left pin black on right pin: OL / open circuit, probes reversed 0.61 steady red probe on middle pin black on right pin: OL open circuit, probes reversed 0.61 steady the pair of KSP92 on +rail ksp92 closest to the inner led: looking at flat front where the marking are red probe on left pin black on middle pin: 0.59V steady probes reversed OL / open circuit red probe on left pin black on right pin: 0.59V steady, probes reversed OL / open circuit red probe on middle pin black on right pin: 0V / short, probes 0V / short the pair of KSP42 on -rail ksp42 closest to voltage ref: looking at flat front where the marking are red probe on left pin black on middle pin: OL / open circuit, probes reversed 0.59V steady red probe on left pin black on right pin: OL / open circuit , probes reversed 0.59V steady red probe on middle pin black on right pin: 0V / short, probes 0V / short the pair of KSP92 on +rail ksp92 closest to the inner led: looking at flat front where the marking are red probe on left pin black on middle pin: OL / open circuit, probes reversed 0.61 steady red probe on left pin black on right pin: 0.62V steady probes reversed OL / open circuit red probe on middle pin black on right pin: 0.61V steady, probes reversed OL open circuit Good luck with your build and thank you to everyone who contributed to the design of the GRLV and this thread.

I've always admired this group. The hobby and community got me through some rough times, even when I didn't say I was going through them, but just coming here and laughing my ass off at the shenanigans was enough to brighten up my day. It's been a while since I've been around, and life definitely throws some unexpected curve balls. I got married a month ago. I'm moving out of my apartment to a new home, where my wife is going to help me NOT turn the place into a man cave, but make it cozy and welcoming. I'm in love. When you know, you know, as the saying goes. Things change, people, change... I think I evolved leaps and bounds the past year in so many aspects. I've been packing for my upcoming move, two weeks away. Been having fun going through a lot of my audiophile gear that at some point I stored away and forgot about because another flavor of the month came about. I was remembering the meets, the trips to Cigar City in Tampa, Hunahpuh days, etc. Good times. I guess I just wanted to drop by and give thanks to everyone. Nostalgia hit hard. Fun times! Good stuff.

Excellent writeup as always, thx James. On a side note, for the inner Phoenix 3P connector, I am using the rised version of it, just to make wiring easier. Here how it looks like.

I'm sure the good Dr doesn't mind. The offending jackass has be dealt with.

Long Time Passing: Kronos Quartet and Friends Celebrate Pete Seeger Kronos Quartet 2020 Example:

Fucking epic. Not all heroes wear capes! Wow, nice find. Heaps of places I could have historically used those, if only I realised I needed them!

Me too like schematics. I believe this goldenreference.pdf reflects goldenreference6.zip version.

All the polarized caps on the PCB are clearly marked with the polarity and voltage rating. Measure the dimensions and lead spacing of the board to decide which caps to order. Most of us used 1/2W resistors for our builds although 1/4W ones probably suffice in most if not all positions. Take a close look at the photos posted in the thread should also give you lots of information. With many parts becoming obsolete, locating an old BOM may not help you very much.

Brian Eno, Small Craft on a Milk Sea -- pacific ambient example:

Well astonishingly we won three golds today. First Adam Peaty in the 100m breaststroke. Then Tom Pidcock won in the cross country cycling; 1h 25m on an insanely difficult course in baking heat and humidity. That is the first medal of any colour we've won in that event. Then Tom Daley and Matt Lee won in the synchronised diving. So our little Island is currently fourth in the medal table. Woohoo!

HAHA. Dracula! https://www.nytimes.com/2021/07/25/sports/olympics/mbc-broadcaster-apology-olympics-opening-ceremony.html

@ShortBtwnHdset: Don't let Pars scare you away. No build guides doesn't mean you won't get answers. The Dynalo is easy. That kit you bought looks pretty good, assuming the MPSW parts really are genuine and matched as advertised. Look at BOMs, but above all follow the silkscreen on the boards. Stuff the boards. Check the GRLV board you have for the type of transformer secondary windings you'll need, whether center-tapped or not (there are a couple of different GRLV versions floating around). I used an Antek 50VA 22V for a Dynalo, it worked great, but might not be right for your GRLV board. This thread will have more info. Do you know how to safely wire up mains? That'll be the next challenge. It's also not difficult, but needs to be done carefully and correctly. While the wiring is pretty self-explanatory, you'll also need to ground the amp correctly to avoid noise. Again, there's info in various threads (including the KGSSHV thread), and feel free to ask when you get that far.

Uhhh, I have to downsize. I don't need 20 headphones. That said, I have six or seven HP1Ks and intend to only keep one of them. I'm also going to sell the BHSE, but keeping the balancing Act. Going to sell all my stat gear, actually. Way too much stuff. I rather it gets put to use by someone who will enjoy them. I'll be posting stuff at the other place but if any of you all want dibs, just say the word. Thanks for all the good wishes! Forgot to mention that, of all things, what I surely believed beyond a shadow of a doubt would receive a big "HELL NO" from her were the massive obelisks that are the Cain & Cain Abby & Bailey speakers... with matching subwoofer. Turns out she absolutely loves the way they look and says they go well with what she had in mind for the living room. So they get to stay.

I guess this is just telling me what I already knew: depending on grind I’m getting a 4-4:30 total on a 15:1 20 gram dose V60 (I forgot to adjust from the Chemex the other day, so this was long) with the method I use, which isn’t quite James Hoffman’s, but I came up with my method long before I learned his and they aren’t terribly different (some days I stir, some days I swirl). I guess that isn’t super useful. Having said that, I like the Acaia Pearl 2021 a lot. My hands don’t work very well until my Gabapentin kicks in, which I take in the morning before I have coffee, and not having to juggle starting timers while pouring is a luxury I’ll have a hard time going without.

James, all: Nice writeup BTW. Correct me if I'm wrong, but I believe you can use a dual secondary transformer as a CT simply by tieing the two secondaries together? http://engineering.electrical-equipment.org/wp-content/uploads/2013/07/Dual-Voltage-Transformers-1.jpg All of the GRLVs that I have built use dual secondary transformers and dual bridges, and I don't foresee a reason to use the single bridge for one.

congrat!

Hope Amid Tears - Beethoven: Cello Sonatas Yo-Yo Ma, Emanuel Ax 2021 15 TRACKS (2:32:07) -- takes a little while Example:

Well as long as Alex keeps his audio gear packed in boxes and not scattered around the living room, marital bliss will prevail.

Meanwhile ... https://www.theguardian.com/sport/2021/jul/26/australian-swimming-coach-dean-boxalls-wild-celebration-goes-viral-after-ariarne-titmus-wins-gold

Woohoo! Lance's former coaches helped their fencers win gold and bronze in Men's foil. Both of the fencers, Alex and Cheung have trained with Lance at the club and been over to the house for BBQ dinners prior to Covid happening. I firmly believe my tritip had a play in those results.

Leon Bridges – Gold-Diggers Sound

Interstellar (Original Motion Picture Soundtrack) Hans Zimmer 2014 Example:

[Checks calendar]

Nancy 10 Nancy Ajram 2021 Example:

Kevin retired from Northwestern Univ. (the .edu links) a few years ago, so those links are no longer valid. The Stax thread will provide google drive links to the board files and other documents. For a Dynalo, you will want +/-20V for the GRLV. There are BOMs for the GRLV posted in the thread. Sorry, but we don't provide build guides, etc. here. Going thru both the Dynalo and the Golden Reference LV threads should provide you with all you need to know. Build the GRLV first, and test it unloaded to make sure it is performing properly. Pretty easy build. And I would stay out of the and now for something completely different part 3" thread for now. The Dynalo is a very good amp. Not sure what phones you are intending this for, but the CFP 2/3 is a very good amp.