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Quote by Cathbard
I love 317's. Awesome chip. I always have a few laying around. They simplify power supplies so much.
A great little tool you may want to bookmark:
http://www.electronics-lab.com/articles/LM317/

Saves having to think.


Already got it bookmarked.

I use them for constant current drains as well. Very good for an SRPP output stage.
Quote by Cathbard
^ self biasing setup?
Have you ever seen this:


I've always meant to try it on something. That's probably overkill though. This would probably do for the sort of shit we play with:
or even without the zeners.


I've got the LM317 in a very simple stereo amplifier that I designed. It uses 6 tubes, 4 signal caps, and a handful of resistors.
For kits and a pretty good starting amp head over to www.ax84.com. They offer an amp called the P1 and an amp called the High Octane. Both are fairly easy amps, but the P1 is usually the suggested starting point. Download the P1 Theory Document to get a start on learning amps. You don't have to build the P1 first, but the theory document is a good first start into amps.

From there http://www.freewebs.com/valvewizard/ is a good place to learn. If you want you can even buy his two books. They are very theory heavy, but very useful.

After all of that you can start looking into older books about vacuum tubes and studying schematics.
Quote by mmolteratx
Question: What was ghetto ****** doing in Hong Kong?


That one I wasn't sure of, and he wasn't even in Wan Chai where the ghetto stuff is anyway. He may very well be a very good professional employee but like that on the streets. I can't count the number of guys I know who can party their ass off but still be great at what they do.

On another note I did see two prostitutes while on LKF street in Central. They actually looked extremely clean and not at all like prostitutes you see here in SC.
So I'm back in the US after my interesting trip to PRC and HK. From the sounds of it I might be back in HK as soon as May, or PRC by October.

Interesting highlights of the trip:
Random Chinese people asking to take pictures with me
Being on top of the highest point of the Great Wall at Badaling
Freezing while on top of the Great Wall
Having a woman wrap a belt around me to get me to buy stuff.
Running into a lady in Yangshuo who graduated from Clemson
Getting highly intoxicated in Hong Kong and eating McDonalds at 2 AM
Eating food that I had no clue what it was in PRC
Eating food in HK and finally knowing what I was eating
Paying $5 for a can of A&W Root beer.
Finding APC Film caps for less than $1 each
"Copy Watch? Copy Handback? Copy Rolex? Copy Gucci?"
"Tailor sir?" "Nah sorry... I'm a fat ass and want to get a suit when I lose weight" "Oh... okay I was thinking the same thing so hurry up and come back when you weigh less"

The best even of the whole trip though occured between two black guys in HK

Black Guy 1 w/ Gangsta Accent: "Hey my brotha what up?"
Black Guy 2 w/ South African Accent: "Who are you? You do not know me? You are not my brother? Why are you talking to me? Do you know me?"
Black Guy 1 : "Man I knew you was a punk. Tryin to act all white like. You should get back to your roots"
Black Guy 2: "I'm from South African sir. Are you telling me that talking ignorantly is going back to my African roots? You must be American."
Quote by gregs1020
but they can use rosewood and ebony.

they are choosing not to.


You mean Gibson right? They haven't gotten either giant lot of wood that the government took from them back, even though charges have never been filed. So if I were them I wouldn't start using it again either until everything is cleared up. They know for a fact they can laminate the boards though.

I'd love to see some more of the carbon fiber composite fretboard and reinforced neck. Parker does some really nice things with their necks. I think its basswood they use for the neck core?
Quote by DeathByDestroyr
China just wants to sell more Bugera. Once they realised we all know about the plastic clips, they bant our forums


Isn't Bugera built in Malaysia though?
So the Chinese government blocks TAG, TGP, and the weber amps site. I don't think China likes cork sniffers.
Quote by targetdude
I know this technically the wrong forum for this, however I know that most of the really knowledgeable guys are here.

I am in the process of breaking in a new set of WGS Rebel 30's, and am wondering if the wattage on an Amplifier (or a PA) is actually the amount of wattage it pulls from the Walls. I am asking because I want to set it up and run for a long period of time, but don't want destroy my electric bill.


Your amp's wattage rating (for power output) is less than the total wattage it pulls from the wall. You should be able to check near where the AC cord goes into the amp.
So does anyone here have any suggestions for what to ask for as far as in a new contract when moving overseas.

I'm already asking tax equalization, housing allowance, transportation. Anyone have any ideas as far as what else to ask for?
My last week here in PRC is starting today. After this week I get a weekend in Hong Kong and head back to the US. Its about time to see my dog again.

Then when I get back to the US, I get to start negotiating the terms of my move here around July... Three AC Units will be a requirement will be required. Its already 78F here with 100% humidity.
So I ordered one of those raspberry pi boards. My shipping time is estimated in the next few days, so I should have it when I get back to the US.

From the sounds of it I might be moving back to China sometime in the next 6 months as long as everyone agrees. It might be for 2-3 years. Obviously more money etc. It is actually pretty exciting, the area I will be in is quite nice. Not the best, but coming from a shit town it is actually an upgrade
So I just got back from Beijing. Now back in the other area of China that I'm working in.

Cats speak Chinese... I saw some older Chinese guy talk to a Cat and get it to do whatever he wanted.
Quote by AcousticMirror
waaaaah?



Yeah I thought that was it, but they kept telling me it was closed for some reason. Zhongshan Park was really pretty though. You can't see anything like this stuff in the US. Apparently to have awesome historical things you have to have intelligent people and money.
Min... how the hell do you actually get into the Forbidden City. I swear I spent two hours going through various parks and couldn't figure it out. Is it Forbidden because you can't actually find a damn gate?
Quote by AcousticMirror
Well yes. But oversizing isn't the entire story. Give the exact same winding a m4 will be half the size and X percent more efficient with -Y degrees of heat loss compared to m19.

where x and y are numbers from wikipedia.

not really important really though. Just doing some reading. There's effectively quite a bit more weight reduction possible though without ditching transformers.


But M4 will also cost about three times as much as M19. Unless your building something that has to have small transformers then M19 is "power transformer" steel. Either way, I want a certain overhead for my electrical limits, so if I need 3A for heaters my string is 4.5A or so. So M19 might be $50 where as M4 could be $150. I'll take a $50 heavy transformer, especially when most people think "heavier" is better.
Quote by AcousticMirror
ya that's the gist of what I got as well.

edcor only uses m6. I seem to remember an onetics spec sheet saying he used m4 for his stuff but I can't find it.

however, if i'm understanding this stuff right...there doesn't appear to be any sort of mojo in terms of power transformer building. An m4 will always be more efficient then an m27.


There is some "mojo" to power transformers. Depending on how much power you are going to pump through the transformer you can possibly wind up saturating the transformer core, which can cause some really wired things to happen as far as your output waveforms. I usually just oversize the power transformer a good bit to keep it from happening, but some various amps have thrived off of this. Early fender tweed amps had undersized output and power transformers.
Quote by AcousticMirror
ya I was wondering because I was reading Aiken's notes on transformers and how core steel grade corresponds to size and therefore bigger isn't always better.

heyboer apparently uses like m27 on their "vintage" lines and m19 on their other stuff.

The heyboer I'm using in Dom's amp is like 2.5 times the size of my onetics transformer. and now I know why.


Assuming that I remember this right, M27 and M19 are the two types of steels used a lot in guitar amplifier transformers. They offer "desirable" characteristics as far as how they saturate,etc. M6 is usually more often found in "hi-fi" stuff and M4 is even better for "hi-fi". M4 is about three times as expensive as M6 right now.

The old trainwreck transformers used a mixtureof M19/M27.

I'm in Beijing right now... just got back from visiting the Temple of Heaven. Quite a magnificent sight.
I just had a draft Guinness here in China. The Guinness was brewed at the Ireland factory... it was amazing.

Essentially I just spend $20 on a Guinness and Cappuccino... **** poor people. I'm rich I guess.

Best way to end my week in China ever.
The only area where you really will see much of a difference in caps is if you have caps with crappy ESR. They can somewhat affect the charge/discharge times of the caps. This can cause the cap to heat up a lot more and drift more, which can give you an interesting "dynamic" to your playing. It will usually cause your bass frequencies to drop out. Now... that doesn't mean that it is a bad thing though... if you take a Vox AC30 and filter the crap out of the power supply you have an entirely different feeling/sounding amp. If you take a Dizel and don't filter it a lot, you also get an entirely different amp.

As far as all of the "phase angle" and other talk going on, it is mostly bull for anything we are doing. All of the signals are at such low frequencies that we aren't going to get any interesting modulation affects of phase angle differences. UHF transmitters care more about their power supply than a guitar amp ever will and it was good enough for them.

EDIT: By the definition of an amplifier, a guitar amp does suck though Thankfully we don't care about that with our amps.

In case it isn't obvious, I made it to Hong Kong alive.
I'll chime in before I leave about the EL84s. I've seen them handle as much as 800V on the plates in class B. These tubes are vastly underrated... they typically have almost 400V on their plates in most modern amps as it is. Keep their dissipation under their maximum at 400V and make sure the screens don't over dissipate.
Okay guys... Flight to HK attempt number 2 happens tomorrow. I'm busting out my suit and charm to try to get an upgrade... probably won't happen but it never hurts to try.

If I mention that I'm going to be doing circuit board layouts while on the way maybe I can get that... don't need the little people to see me working on electrical things... I might spook them.
Quote by Cathbard
http://cathbard.com/files/cathbard-marshall-18W.pdf.
R19 should read 390R


Well, as I said it's been running fine with the current cathode resistor - but I'm running JJ's. I don't have any shit EL84's to try.


I would think it should be fine even with Sovteks in there. EL84s all seem to be a bit tougher than they are rated for. I think that the 12W rating is conservative and that Phillips wanted to have two tubes EL34 at 25W and the EL84 at half the power of an EL34 when they introduced them in '53.
Quote by Cathbard
100 ohm screen resistors. What plate resistors? You didn't mean to say that did you?
The screen current is like 0.5 mA so we can just ignore that

It's an 18W Marshall. So A/B EL84 amp.


Damn it, I meant input grid resistors. I've not usually had problems with them, but I had an amp one time with some crazy high frequency oscillation that was causing the tubes to go crazy and kill themselves.

I would bump the screen grid resistors up to 1k if you have them. I've never noticed a difference in the sound, but it fixed a Vox AC30 I worked on one time that killed tube after tube. If I recall correctly the EL84 has the suppressor grid tied to the cathode and your cathode biasing it so that will extend the tube operating life. In either the EL84 (already to the cathode I think) or EL34 it is best to tie the suppressor grid to the bias supply rather than ground.

Quote by AcousticMirror
rawrwuh? it's an 18 watter. it's not class A.

can't tell if joking?!


Derps Its EL84 and cathode biased... its class A n00b.
Quote by AcousticMirror
bias has very little to do with the output wattage.


Dude... its EL84 and cathode biased... it is obviously class A so the output wattage is 8W if each tube is dissipating 8W.

EDIT: The whole 75% of maximum dissipation thing is a bunch of bull. If it sounds good and the tubes don't die fast run it at whatever you want.
Quote by Cathbard
Thought I'd better recheck the biasing on the JD amp before I pack it.
I am using a 390 ohm cathode resistor.
plate voltage = 390V
voltage across the cathode resistor = 16V So 41mA for both tubes.

That becomes 8W per tube. Seems a tad high for EL84's wouldn't you think? Looks like I may have to go for a drive and pick up some bigger 5W resistors. It sounds good though and there's no redplating.


What are your plate and screen grid resistors? What kind of amp is this? What are the screen voltages?

I run 8W per tube all the time and don't run into issues. In fact, I've run them as high as 15W a tube and don't have many problems.

Max plate dissipation for an EL84 should be about 12W.
Quote by AcousticMirror
i think pregnancy should be controlled by lottery.

sterilize everyone unless they win the lottery.

also in this reality I get to sex gattaca era uma thurman.


No lottery... we need test that will determine who will be the best parents and who will produce a child that won't be a little bitch. The Wal-Mart test Min... I need people to pass it more often... with a child lottery only the idiots will win because God hates me.
Quote by tubetime86
Last time I flew I got upgraded to first class when I missed a flight due to a delay. Best flight ever. Its amazing how big a difference it makes when they start serving drinks on the runway.


I'm gonna see if I can get anything out of it when I go back tomorrow. I'd love to get an upgrade to business if I can... we'll see. I know that Tuesday flights aren't usually crowded.
So..... Just kidding about leaving for Hong Kong today. I got to the airport and found out my plane was experiencing mechanical delays. We wouldn't get to Chicago until 12:30 and the plane to Hong Kong would leave at 1:05... not enough time to get through everything. So I'll be flying out tomorrow morning at 6:30 instead of 9:00 to ensure that I get there on time.

Next time I will be flying Delta again. Last time I went to China we were running late to Detroit. Delta made the plane wait on us.
Hey everyone, I'm headed out for the long trip tomorrow morning. Just wanted to drop by and wish everyone well while I'm gone. I'm going to try to get inside of the tube factory nearby while I'm in PRC... who knows... maybe pictures?
Quote by Cathbard
This looks promising. I wonder what shipping would be worth. It'd be light so probably not a lot.

http://www.mcmaster.com/#plastics/=g7wo9n


Depending on how you buy it you can get it down to about 5 cents per square inch and then you just have to cut it yourself. I ordered a few sheets a couple years back and shipping was pretty low, but I got the 48"x36" sheets. Cutting it to shape is a pain in the ass as the board is quite stout and the dust is pretty harsh.
Quote by Cathbard
I may just have to stick with the guy I have been using. His sheets of fibreglass are 12" x 7" for $10. Starting to sound not so bad afterall.


That isn't a bad cost for a board that has been trimmed to size. FR4 can be a pretty expensive material.
I doubt that McMaster Carr will work for Cath. If I remember correctly they no longer ship anything outside of the US to small "private" industries. I couldn't even get them to ship a huge batch of materials out to us when I was in Hong Kong.

EDIT: Obviously someone in this thread could send it to Cath.

In other news, got my passports... and my flight leaves in less than 24 hours for Hong Kong. Tomorrow will be tons of fun...
Anyone have any experience with getting a new passport the week before you leave...

My dog got into my packed bags.... pulled everything out including some snack bars, and ripped my passport to pieces. Didn't even touch the snack bars or candy in there... just the passports.

So now I get to spend all of the next two days in Atlanta trying to get a passport, and then I get to spend all of my first day in Asia trying to get a new Visa in HK. Yay spending shit tons of money because of a stupid animal...
Quote by forsaknazrael
xgamer:


I'm going to PM you my email address so that you can send me some information about what your doing and I'll see if I can get some of my reference materials together. I'm leaving for China very soon, so after I go to bed tonight I likely won't be on UG again for about two weeks. I will have access to email though.

Anyone else that thinks they might need to reach me while I'm in China can ask for it as well.
So essentially... Israel has the iPad 2 and is the cool kid on the block in the Middle East, but Iran is close to having saved up enough allowance to get an iPad 2 so Israel is planning on attacking Iran and stealing their money to keep Iran from getting a iPad 2 since Iran is better at Words With Friends than Israel. If only we could just give Israel the iPad 3 now while we let Iran play with the iPad 2... and give Israel a cheating app for Words With Friends.

Any questions?
Quote by Roc8995
No, see, you forget that we have the most guns. If we pull a Zimbabwe the whole system falls apart and we take over. Hitting the reset button on the world economy is a way of circumventing NATO and the UN. It's a bold move but we'd probably come out on top if push came to shove. China has a bigger army but we've got more nukes.

This is the equivalent of kicking the monopoly board over and punching people until they agree you've won. I feel like that's a policy America could really embrace and excel at.


I'm totally up for that. It will just lead to me being able to implement the McDonalds/Wal-Mart test earlier. China has lots of people, but the majority of them have never fired a gun and aren't even able to control recoil from one... meanwhile we have the South where you are born with an innate ability to bust a cap into any living thing that you want.
Quote by Cathbard
That idiot is still arguing. Some people just don't know when to quit.

You say he's not just a troll al? He's like this in EG too?


I'm going to laugh my ass off when his 2x12 and 4x12 don't have the same speakers...
Quote by danvwman
Thats total bull.
My 2x12 sounds good. My 4x12 sounds way better. Same amp. So my 4x12 is not needed ???cant get the same sound from the 2x12.


What speakers are in the 4x12 and what speakers are in the 2x12? Are they the same type of construction? Both open or closed back?
Quote by coolstoryangus
i once got kicked out of the club but i'm so cool and rebellious they let me back in


I just barged in and no one ever told me to leave Kinda like how I got my job. I just kept working since no one told me to stop coming to work.