Leaderboard

Some more good progress. The amp is up and running I've got two issues on the board, but the amp, power supplies and USB-C PD / battery management are all working great. The wires going to the pot are temporary. There'll be a board for the analog/DAC inputs. The PD chips are small with lots of pins on them. I'm surprised I could solder them Lots of 0402 chips on the right side of the board... Here's the amp running with the battery (I need to have the input board done before I can put the batteries in the chassis). This is with the amp running and USB-C charger plugged in. Below, it is sending .18A to the batteries. The battery management will stop charging once the batteries are at about 12.5V. It drops the current as it gets closer to a full charge. With the charger plugged in and batteries fully charged, it doesn't draw any power from the batteries. At the moment, it negotiated 5V from the charger (source) and is boosting it to just above the battery voltage. If we wanted, we could source power so it could charge you phone too. I'll do a drawdown test tomorrow to see how long it will run on a charge. Overall, I'm very please with this amp. Kevin's amp design is fantastic. I've been listening to it for the last several hours with my SR-007's

When I was younger I had a job in a juice factory. But I got fired, because I couldn't concentrate.

Accidental consumerism, you've upped your game, Jeff.

Thanks. I think I'll pick one up. I've had the amp playing from 9:00 this morning (did I mention it really sounds great ) and batteries were down to 9.8V at 3:20PM. They are not perfectly balanced so one battery is at 3.1V which is below the minimum 3.3V recommended. So looks like I'm getting a little over six hours with these batteries (3x2000mAH). I can look for larger batteries and also play with some optimizations. I've also been running additional 5V and 3.3V supplies for the DAC that consume extra power. They're not needed for just the analog input. The balancer should have kicked in to turn off the battery pack, but it didn't. I suppose it would have at some point, but I plugged it back in to charge. I have a different and smaller balancer that I'm going to try. Maybe that will do a better job.

Cancel/refuse the shipment. Now that I have a 16” jointer I can whole heartedly recommend nothing less that a 20” jointer.

He wasn't by any chance near a data center generator?

I dunno, is it okay with Larry if we use that? We haven’t asked permission after all.

Already planning a wood scrap, giant drawer, mobile jointer cabinet so I can have it done before the unit gets here tomorrow. I think it will be a disappointing unit, but the fancy ones you guys have would not be to be until February, months after I have moved on from woodworking.

Heh, got shipping notification today from Grizzly for the shitty bench top jointer I ordered there in December. I thought I fucking canceled it.

Bro, you just made my day. The HD800, a headphone that — when released — redefined pricing for non-exotics (i.e., not the R10, not the Orpheus, and not Stax) at a then-eyewatering 1400 USD, is now considered a beater, great for tossing in a backpack. 🤣

Got these b22 and o2 boards over at diyaudio for the price of the input jfets alone. Will have to review them and get the needed parts and case.

PM sent with offer of PCB's and help.

What The Hell Happened to Head-Case?!?!? TLDR version: The datacenter that the head-case server is located in sustained a power outage on April 4. When the backup generator kicked on it caught fire and that lead to the fire suppression system (a fucking water based one!) kicking on and causing water damage to equipment. The head-case server was in the 'more affected' area of the datacenter and as such was offline until early in the morning on April 24. For further details on the incident you can see here: https://webnx.com/outage-updates/ You may be wondering why during such a long time the site wasn't simply migrated elsewhere, this is a fair question and the answer is simple. As this is a hobby site the backup process hadn't been properly verified as working in quite a while and the latest verified backup was nearly a year old. Migrating the site and loading it from that last verified backup would have meant losing a years worth of content. This was not a valid option and until I could confirm that the drives in the server were dead I wasn't willing to restore that old of a backup. From what I can tell there has been no data loss but I don't currently have a full report as to what if any hardware needed replacing to get the server back online. Due to that lack of info, I don't trust the server and I wouldn't be surprised if there's some additional downtime due to hardware issues. The Future A fresh backup at the time of this post has been taken and moved off-site. Over the next week or so a new backup process will be put in place and verified. After that is done it's very likely that the site will be moved to a new hosting provider. Further details about any move will be provided at the proper time.

I somehow thought the punch line was going to be different

This has been a handy device for me - even has pads to control it from a micro controller: https://www.amazon.com/DROK-Adjustable-Electronic-Discharge-Resistance/dp/B07KQS74C6/ref=mp_s_a_1_16?dchild=1&keywords=programmable+battery+load+tester&qid=1619718835&sr=8-16

Just send it West. I'll road test it.

I thought it was a good headphone back then, but way overpriced. I'm still of the opinion that it's price point should be around $600.

testing breakdown voltages would be a good idea. Fingers crossed you have a real ones. Here is some high resolution photos of a known good one from a reliable source- and its brothers are working my T2... Markings are printed not etched and are a greyish cream colour not white. (photo has been colour balanced). Ends of legs are fairly sharp. close up of the circular area in the middle. Lighting adjusted to make the text in the dimple more readable at the expense of the printed markings. Text in the dimple is raised. The starting angle relative to the top of the transistor for the word MALAYISA and the associated number and letters in the dimple varies between the 216s I have.

It sure has a nice finish. I wonder what kind of noises it makes. *squawk*

Test successful: user dead.

so, test successful? User dead? inquiring minds need to know!!!

Longish term modern DIY T2 reliability. I estimate its been used around 8+ hours (and more often than not 12 hours) a day almost every day since I built it. yesterday I took it apart for cleaning. I noticed all four 140K resistor strings connected to the voltage reference in the virtual batteries where somewhat discoloured.... hmmm... on further testing I found the D24 led on both channels did not light up at all not even dimly. :-(. but the amp seemed to work and sounded good. (on the left is a brand new resistor from the same pack as the 140Ks I removed from the virtual batteries.) I checked also psu voltages - good. I measured the voltage across the D24 led- about 1.4V. When the amp was originally built these leds definitely glowed as strongly as the others. All the leds where tested before soldering in and were from the same bag I even hand matched them just for overkill. The D24 leds are part of the circuit that provides base voltage and current to transistors that provide feed into the virtual batteries. I checked the virtual batteries - all were 741V on startup and the adjustment pots could adjust the output. So the batteries look good despite the slightly cooked resistors. I removed the voltage references and tested them in a glden reference LV - all good. The discoloured resistors can be explained by the fact they have about 0.423W flowing through them excluding base current draw from the 2 transistors and are on the underside of the board with little airflow - maybe1W would be better or some airflow holes in the pcb, or mount them to the topside of the pcb. So I decided to de-solder the 140K resistors for measuring and the 140K resistors have drifted slightly but all measure within 141.5K. So a little cooked but probably not the case of the problem. But why are the leds not lighting.... Looking at the circuit diagram the D24 leds should get about 0.5mA current excluding any draw from the bases of the transistors. (560V / (560K *2 resistor string to ground). I used the exact SAME leds for the other positions and it also looks like those leds get about 0.5mA excluding base transistor draw and they glow nice and bright. I de-soldered the leds and tested the D24 resistor string to ground. They spot on resistance and have not been damaged or drifted and so should provide 0.5mA current draw through the led. However the desoldered D24 leds would not glow at all with diode check on my brymen BM869s multimeter but do pass current and are not open or shorted. I tried my keithley 2015 in diode check mode (it has adjustable test current) and got absolutely no glow at 10 or 100micro amp but did get strong glow at 1mA - same situation on both D24 leds. I tested my remaining leds from the same bag and they glow on the brymen admittedly fairly dimly, and glow on the keithley at 100 micro amp again dimly but visibly. (I did test all of them on the brymen before soldering into the amp). So the leds in D24 have degraded over time . I used the same leds in the other places in the amp and they are all fine. This would explain why the batteries are working but the leds are off.... So the plan is to do some more testing on the leds and replace them with another model. But what's causing the leds to degrade in brightness on the -560V rail when the others have not? any ideas? regards and and I apologise for the long winded post James Update: I replaced the D24 leds... they now light brightly with a voltage drop across them of about 1.7V. I replaced the resistor strings with the same resistors but now placed on the top of the pcb, raised from the pcb by about 1cm. After a ten minutes with no lid on the amp the resistors reach 65C on the top and 71C on the sides. So its easy to see how on the underside of the pcb with the lid on they could reach temperatures which could cause discolouration.

DIY AVA Ultimate 70.

That Fucker!

Just be aware that Brent had several biscuits last night.

Helped a friend make it home safely: Remember kids, don’t try this at home, my first graduate student at EIU studied the atrazine and glyphosate dynamics in snapping turtles.

This never would've happened on postjack's forum.

Definitely not feeling up to a show tonight. Here's two previous week's:

Incredible work on both of those pieces Jeff! Does Kasia love her most expensive evar bedside table? Or does she get one?

I missed all of you mucho, and Brent a little bit, but he's down here ATM anyway.

Easter Deck Brunch

The pcb files are in zips with the contents in a format called gerber which can be uploaded to a pcb manufacturer like jlcpcb. The gebers contain all the necessary information for the creating the copper tracks, drilling of holes, silkscreen printing etc. Often there are minimum order sizes of around 5 of each type of board so often people have spares... There are no step by step instructions. There is an assumption that you can read a schematic, are prepared to read through some very lengthy forum threads and do basic drilling for mounting boards to heatsinks etc. the information is a bit spread-out. In general you need: BOM - bill of materials to get the right value and size components. Downloads from the appropriate forum thread for your build (and possibly two threads - the second thread being for the power supply) schematics - for troubleshooting etc in the forum threads and or download from https://drive.google.com/drive/folders/0B7egryukiT7_TFlEQlBRejdVdDQ the gerber files for getting the pcbs made in the forum threads or download from https://drive.google.com/drive/folders/0B_iJFfZStuVhSE5nOHBVdTByR1k the specifications for the transformers. in the forum threads. advice. in the forum threads and ask in the threads. in general the markings on the pcbs takes precedence over the schematic or bill of materials (unless the pcb has a silkscreen error). Some amps have more information than others - the threads grow organically over time depending upon popularity, etc. In general support is available for everything on a voluntary basis. You post questions on the appropriate thread hope for someone to answer. There are some very knowledgeable and helpful people active in the forum for example Kevin Gilmore, Kerry, JoaMat. Often the people who created the design will answer questions in the forum posts or people who have actually built one or even modified one. Unless you have lots of money/luck/ or existing stocks of obsolete components obtained from known good sources, I would stay away from any design which requires no longer manufactured transistors. There are many fakes floating around which can and will fail catastrophically on first switch on and non fakes are rare and there are few trusted sources willing to sell to non friends. I would advise reading the forum threads from start to finish and making notes, that way you can see the different versions/modifications emerge, see issues with certain components for example in the DIY T2 thread the voltages are high enough that some makes of resistor sparked and the insulation broke down.... Look at what people did that worked or did not work and learn from their experience. Finally if you can, give as well as receive. Post what works for you, post pictures, post updated bills of materials etc.

I don't think it's a question of 'proper' sound stage, of course no headphones can do that. It's fair however within the context of headphones to critique the Utopia's (really any Focal for that matter) for having a smallish sound stage. It's just not a focus of the sound they are going for and that's perfectly fine. They excel in detail and dynamics and are fantastic headphones in those regards.

i will be disgustingly intoxicated and indulgent the next time i find myself at Marshall Store with our crew.

Beef rib meat teriyaki stir fry for Lance.

You nailed it 🤣 Here's my modest Estats collection (thus far) - STAX 009BK, L700 Mk1/MKII, L500 Mk II, 404 LE, L300 LE, L207, Jade II, Kaldas Research RR1, Pollinator (by Nectar Sound). Yes, I do have both KGSShv and 353X. For L700 main improvement would be tigher/faster bass. KGSShv quite a powerful amp than 353X so might be a big step up, mainly I found it to be very revealing so it's a must that you have good source & music recording. Benefits - I would say overall helps realize the full potential of inefficient cans (007/RR1/VOCE) if you hear your music loud then KGSShv could be a good choice. I heard good things about Perun as well, you might also check out ES Labs offerings ES Labs ES-Sigma Electrostatic Headphone https://www.eslabhk.com/product-page/stock-es-sigma-electrostatic-headphone ES-1 alpha (es1a) https://www.eslabhk.com/product-page/es-1-alpha-electrostatic-headphone I think music/hearing preferences is very personal in nature and would say audition the headphones/amps before pulling a trigger the good luck with your hunt. Thank you!

A bagel with tomato, cucumber, sprouts, red onion, cream cheese and avocado, from the Fairfax Roastery.

RIP Michael Collins. The man who orbited the moon but never walked there. That just leaves Buzz Aldrin from the first landing.

R.I.P. astronaut Michael Collins...

BLTA