[SteveM732]

I've tested the plate voltage on both and averaged about 8.2 V on one coaster and 8.5V on the other. Next I'm going to see what I can do with 9.1Kohms (RR1220P-912-D0)at R101 and R201 to get closer to 7.5V on the plates.

I could try one of these but unfortunately it is not precise enough....

https://www.elenco.com/product/resistor-substitution-box/

unless I went off the rails and subbed in my own resistors of 1/2W .1% tolerance. Say Kohms of 8.56, 8.87, 9, 9.09, 9.2, 9.31, 9.76, 10, 10.4, 10.7, 11.7, 12.1. Then I'd have dedicated Schiit Coaster Plate Loader box. Of course I'm not likely to build more than three Coasters so I might build/use the box and ship it on to other Coaster makers for identifying the correct R101/201 plate loads.

or just buy one of these which would be more flexible but less accurate. 1W and 1% accuracy with 1 ohm steps.

https://www.elenco.com/product/1-watt-resistor-substitution-box/

So for those who don't know there are size and tolerance and wattage trade offs with resistors, that in my deep dive into mouser made quite plain. 1/2 watt allows .1% tolerance. If you increase from there you the next step with the required steps of 8.5-12Kohms in resistance lands you at 1W with 1% tolerance. At least with the filters of Vishay and axial leads on Mouser.

I'd like to hear ya'll's thoughts on the DIY (pick your D) Coaster Plate Loader Box idea. The kit is like $22 with shipping and another 22 for parts at Mouser.

You could get a 10K Potentiometer and add it in place of the resistor using some wires. Start out with the Pot set to 10K and slowly drop it till you see 7.5V on the output. Take the pot out of the circuit and measure its resistance and order the nearest resistor value. You could even buy a bunch of 1% or 5% precision resistors and sort them yourself to within 0.5% tolerance if you can't find what you need in 0.5%. Their absolute value isn't nearly as important as having the same value.

I'd hadn't got around to testing my first coaster till now and found it to be 8.35V and 8.49V so I'll be going through this exercise as well. This is also the coaster where at very low volumes (near my threshold of hearing) I hear the left channel before the right, so I was assuming a tube matching session would be needed.

Since I lack a signal generator in my home collection I used my computer and a "free" tone generator program to generate the 1KHz 250mV RMS input signal. Thankfully the program refused to continue working and demanded money before I had finished as that caused me to abandon it and learn that a free audio sample on youtube was more frequency accurate and had a much cleaner signal. Any how, on my Tek 2236 scope I can't see but a few mV difference between the channels at any volume setting. I don't notice a difference between the channels at normal listening levels and I can't measure a difference so I'm calling them matched.

 

[RCBinTN]

I confess that upon hearing of research where reduced risk of alzheimers was observed when scientists induced gamma waves in mice brains through optical pulsing (https://en.wikipedia.org/wiki/Gamma_wave), I ran off an made a bunch of flac files of 40Hz tones, and tone sweeps with a 40Hz offset between the L and R channel to make a virtual beat frequency of 40Hz in the brain, and then listened to them hoping to induce gamma waves and hopefully reduce my chances of alzheimer's.

This is probably the only place someone could admit this in public and not seem weird.

OK, it's still weird.

But either it prevents Alzheimer's and I won't care, or it doesn't work and I won't remember all y'all laughing at me

Just to let you know...I posted this on our friend @Currawong thread "Funny comments from the forums."
And at age 61, I can relate and will likely experiment...

 

[bclark8923]

@Jason Stoddard I think you've just been going to the wrong concerts Glad you liked the David Byrne one it sounds epic! Moments like that are what concerts are really for, you should go see a Jam band some time!

 

[garbulky]

What are the most advanced DIY audio projects out there? I'd prefer to hear about stuff that's not class D.

 

[CAPT Deadpool]

You could get a 10K Potentiometer and add it in place of the resistor using some wires. Start out with the Pot set to 10K and slowly drop it till you see 7.5V on the output. Take the pot out of the circuit and measure its resistance and order the nearest resistor value. You could even buy a bunch of 1% or 5% precision resistors and sort them yourself to within 0.5% tolerance if you can't find what you need in 0.5%. Their absolute value isn't nearly as important as having the same value.

I'd hadn't got around to testing my first coaster till now and found it to be 8.35V and 8.49V so I'll be going through this exercise as well. This is also the coaster where at very low volumes (near my threshold of hearing) I hear the left channel before the right, so I was assuming a tube matching session would be needed.

Since I lack a signal generator in my home collection I used my computer and a "free" tone generator program to generate the 1KHz 250mV RMS input signal. Thankfully the program refused to continue working and demanded money before I had finished as that caused me to abandon it and learn that a free audio sample on youtube was more frequency accurate and had a much cleaner signal. Any how, on my Tek 2236 scope I can't see but a few mV difference between the channels at any volume setting. I don't notice a difference between the channels at normal listening levels and I can't measure a difference so I'm calling them matched.

I happen to have an extra 10kohm pot. From tye coaster BOM. I think it should work but mouser specs say its only rated for 50mw???? Can someone explain how it is so low? Is it placed before the amplification?

Edit: After further review of the schematic the ruling on the board stands. The Pot is first thing in the circuit from the input jack so it doesn’t need a high power rating. Now I’ve go got to do a little math with my multimeter to see if 50 mw is a winner or a fire.

Edit to the edit so a quick visit to rapidtables tells me that if 30v goes into 10kohms it equals 90mw. I May have to find more pots. I have others in my parts collection time to dig. I’ll double check by measureing the amps as well just for triangulation.

Moose Edit: So I used a B50K Pot I had in my parts collection and soldered it into a board with 8.2 volts on that particular resistor. It was a cheap 50K so when I hit 7.4Vs I called it good. When I measure the resistance of the pot setting I got 8.4 Kohms. I figured out that the best match in the resistor series for the R101/201s if your getting plate volts in the 8.2-8.5V range is 754-RR1220P-822D a 8.2Kohm resistor.

For the less tech savvy (over simplified): Make sure you remove the resistor R101 or R201 that you are going to replace or your voltages get cut roughly in half (bc the resistors will be roughly 8k to 10k aka mostly equal) and you'll order the wrong part. The actual formula for total resistance which affects the voltage is 1/Rtotal = 1/R1 + 1/R2 + 1/R3 +... I did it wrong (R101 in place) first just to see if I could be lazy and proved my suspicion that parallel resistors had this feature then googled. I don't really learn these principles until I do something practical with them.

@SteveM732 and @Paladin79 if you could all check my math and resistor selection I'd appreciate it. I'm sure you guys are getting similar plate voltages.

Well I learned something and didn't spend $40 making a custom Schitt Coaster Variable Plate Resistance device.

Thank you Steve for the assistance and the money saving idea.

 

[jimmers]

What are the most advanced DIY audio projects out there? I'd prefer to hear about stuff that's not class D.

Browse
http://www.diyaudio.com/
then you can pick which you think is the most advanced

Spoiler: Only look if you are interested

Not wishing to leave it too terse and not wishing to pollute the page too much, what sort of thing are you looking for?

"advanced"
as in only for the advanced constructor due for the need for dexterity, care, technique or support equipment (test gear, tools ...)
or advanced as in close to or beyond the current state of the art?

"audio project"
Passive:
equipment stands, speaker box/baffle, amplifier chassis, turntable, tonearm, transformers for passive preamp/valve gear etc.
Active:
linear preamps, non-linear preamps - RIAA equalisers, electronic crossovers, tone controls etc.;
power amps of the various classes and topologies. Any of the preceding using thermionic valves, BJT, FET, SIT, IC or any mix thereof.
+ many things I haven't thought of.

Digital electronics ...

Give the guys a bit of a clue and I am sure they will give you plenty of suggestions.

 

[SteveM732]

I happen to have an extra 10kohm pot. From tye coaster BOM. I think it should work but mouser specs say its only rated for 50mw???? Can someone explain how it is so low? Is it placed before the amplification?

Edit: After further review of the schematic the ruling on the board stands. The Pot is first thing in the circuit from the input jack so it doesn’t need a high power rating. Now I’ve go got to do a little math with my multimeter to see if 50 mw is a winner or a fire.

Edit to the edit so a quick visit to rapidtables tells me that if 30v goes into 10kohms it equals 90mw. I May have to find more pots. I have others in my parts collection time to dig. I’ll double check by measureing the amps as well just for triangulation.

Moose Edit: So I used a B50K Pot I had in my parts collection and soldered it into a board with 8.2 volts on that particular resistor. It was a cheap 50K so when I hit 7.4Vs I called it good. When I measure the resistance of the pot setting I got 8.4 Kohms. I figured out that the best match in the resistor series for the R101/201s if your getting plate volts in the 8.2-8.5V range is 754-RR1220P-822D a 8.2Kohm resistor.

For the less tech savvy (over simplified): Make sure you remove the resistor R101 or R201 that you are going to replace or your voltages get cut roughly in half (bc the resistors will be roughly 8k to 10k aka mostly equal) and you'll order the wrong part. The actual formula for total resistance which affects the voltage is 1/Rtotal = 1/R1 + 1/R2 + 1/R3 +... I did it wrong (R101 in place) first just to see if I could be lazy and proved my suspicion that parallel resistors had this feature then googled. I don't really learn these principles until I do something practical with them.

@SteveM732 and @Paladin79 if you could all check my math and resistor selection I'd appreciate it. I'm sure you guys are getting similar plate voltages.

Well I learned something and didn't spend $40 making a custom Schitt Coaster Variable Plate Resistance device.

Thank you Steve for the assistance and the money saving idea.

I want to say that I measured around 8V across R101 at one point, P= V^2/R = 64/10k = 6.4mW.

You are correct about parallel resistors, a shorthand for two resistors in parallel is (R1*R2)/(R1+R2). So even at the maximum resistance of 50k, that pot in parallel with the 10k is only 8.33k. If you have a 100k pot and don't want to pull a resistor then you start out at 9k which is probably high enough, then when you get to 7.5V you can remove the pot from the circuit, measure its resistance and do that math to figure out what the parallel resistance was.

We've got scads of 0603 and 0805 resistors at work (and a few 0402 for the hardy) so I may try a pair of 8.2k and see where that puts me.

 

[Rowethren]

I had a moment of stupidity in one of my undergrad chemistry labs. It was a transition metal experiment, so pretty much one of the main reasons people first get interested in chemistry (bright color changes in test tubes, then you take organic chem and it is mixing white solids in a clear liquid, boil for an hour, then add another white powder to collect a white precipitate).

Anyways, I want to say it was vanadium we were working with, but my first attempt flopped with the first transition. I am setting it up again while talking to a classmate who is down the bench from me. I mix the reagents, cork the test tube and start the one minute of manual shaking. It looks different which is good because the first time did not work. I finish shaking it, set the test tube down in the rack, let go of the cork stopper and it instantly shoots up, bounces off the ceiling and lands fifteen feet down the bench. Like a genius, I tilt my head down to look at the test tube from the top. A puff of air hits my face (I was wearing safety glasses), and I realize that was not smart, but continue on. About ten minutes later my face starts to itch and I realize the effects of my mistake. I go wash it off and am fine.

What happened is that the experiment called for 4-5 drops of 30% perchloric acid added to 5 ml of water. In my distracted state, I used 5 ml of 30% perchloric acid, and that is the vapor that popped the cork and got on my face. It took me a third attempt, but I did finally get the lab done that day.

Reminds me of a story my A-Level Chemistry teacher told me about ammonia... Long story short make sure you waft not sniff or you might never sniff again lol!

 

[Zojokkeli]

That reminds me of this comic from Scandinavia and the World, where Denmark, Norway, and Sweden try to teach the US Danish (then Norwegian and Swedish).

(Edit: It is a long comic, so put it in a spoiler so that it does not annoy people)

Spoiler: Long comic about Scandinavian languages

The part about Danish is pretty much spot on, though. I've been watching The Bridge with my girlfriend and the Danish language parts never fail to amuse us.
For your Norwegian language fix, Lilyhammer is pretty entertaining series. (Or just drink an obscene amount of alcohol and it'll come next morning, with the associated dose of shame.)

 

[JamminVMI]

What I never do with people is to belittle them if they are happy with BT, or MP3's or an 8 track player. If they enjoy it who am I to say they should not?

Exactly. I will happily confess to having a BT speaker that I take on road trips - for convenience... An you are SO right, zealotry is seldom (if ever) appreciated - or warranted...

 

[jimmers]

What are the most advanced DIY audio projects out there? ...

Browse
http://www.diyaudio.com/
then you can pick which you think is the most advanced

I edited a spoiler into the above reply in case you thought I was being off-hand, unhelpful or rude.

 

[Derrick Swart]

"Un homme vaut autant d'hommes qu'il connaît de langues." (A [wo]man is worth as many [wo]men as the number of languages s/he knows.)

Pietro, by this logic, you have 9 lives - just like Constanza.

Also, I want to be born in the Netherlands or Flanders in my next life. I visited Bruges once and commented to my wife that one has to know at least 4 languages to work in any kind of tourist business. Sure, you can pour a Duvel with a perfect head every time - but can you serve it in English, French, Dutch and German?

Best beer in the world is indeed Duvel. My favorite by far after LaChouffe blonde. After a couple I can serve it in any language you like

 

[CAPT Deadpool]

Exactly. I will happily confess to having a BT speaker that I take on road trips - for convenience... An you are SO right, zealotry is seldom (if ever) appreciated - or warranted...

I have a pair of BT headphones I bought for exercising or mowing the grass. Both use cases are low-fidelity situations where it can be hazardous to my headphone cables. I mean who doesn't hate when the cable snags ripping the earphones out of your ears or bending the jack (I've destroyed several sets of earphones this way over the years by breaking the jack or loosening the wires at the ear buds). Luckily Etymotic has a recycling program for old phones. Now I have a pair of ER-4s that I can safely use and if the detachable cable breaks I can just replace it.

 

[CAPT Deadpool]

@Jason Stoddard I'm listening to "Winning Mars." First impression it is a good book. Reminds me of aspects of the Formic Wars, the Martian, 2001 (Hilton Hotel), and Seven Eves which are all near current Sci-fi vice far future Sci-fi and have political or business conflicts. I especially liked the part about the Russian's with their space epoxy for leaks given this mornings news:

https://arstechnica.com/science/201...-full-name-of-technician-who-caused-iss-leak/

The hole in the Soyuz had been covered up by epoxy before launch, the epoxy obviously got sucked out into space causing the leak, and the fix for the missing epoxy was more Russian epoxy. Nice!

 

[riffrafff]

make sure you waft not sniff or you might never sniff again

Yeah, tell me about it. I sniffed some 10 molar hydrochloric acid before a lab class in college. My sniffer has never been the same.