Electronics CE

[Mike B]

I have built Knight Kits and Heathkits.  Very nicely done with color glossy manuals and tech talk.  Very professional.

They are both done.  Gone.  Out of Business.  All washed up.  Tossed in the trash.  Garbage.

I don't want that to happen to Bottlehead.

OK.  The electrons want to flow to the plate.  You set up the bias to get the flow right in the middle of the window and the grid controls the flow.

How's that?

[adamct]

Perfect. Thanks, Mike. Now I know everything I could ever want to know. Scratch my comments above. I don't know what I was thinking.

[Sarcasm off.]

OK, you know more than I do and don't see the value in this. Fair enough. The Bottlehead team is busy and can't do this right now. But you can't possibly come up with a plausible scenario where making a bare bones video for one kit along the lines of what I described would bankrupt Bottlehead or force an increase in the kit prices. Disagree with me if you will, but you don't need to resort to unrealistic and ludicrous doomsday scenarios to make your point.

[Mike B]

Nah, this wasn't at you, this was a bark at the OP that thinks I have a 50 grand Harley in the garage.

The Bottlehead guys rock.  They put out kits that sound great that are unavailable elsewhere.

I love the badge.  A blue collar guy with a tube head.  Bottlehead makes the high end affordible to blue collar guys.  And you better know how to work, because it's not going to build itself.

And they make it easy with great instructions and pictures on PDF.  No manual.  Printed manuals are expensive.  I hate that. 

I have to put my kit on the keyboard shelf to see the instructions as I build it.  I guess I should whine about that.

Nah, I'll just bask in the glory of the sound.

Really, if you want to learn about electronics, start with ohms law and go from there.  If you don't know ohms law 29 books on vacuum tube theory will do you no good.

[matthewmckay]

I was really into computers when I started college... so I enrolled myself in a computer engineering program.  After finishing a few computer science classes, a EE class, and the first half of "Intro to logic circuits", I realized I would rather put a shotgun in my mouth than pursue a career in this field. 

Now that I am into the DIY audio thing, I kick myself for not paying more attention to my EE lectures, but I was exposed to enough to understand that anything I might care to learn about the subject is only a textbook away.   

The internet is flooded with free reading material, and I am sure that after a month or two of dedicated study, you would be able to elucidate the role of any component found in the bottlehead kit.

If you really want to learn, this would be a good place to start...  over 4GB of free books on this website

http://www.tubebooks.org/technical_books_online.htm

[earwaxxer]

Another thought... This is a business. They are doing what they do best. Their success, or lack of it stands on its own. You can only do so many things right. If its not broken dont fix it.... dont count your chickens before they hatch... all that glitters is not gold... all for one and one for all... dont get your knickers in a twist... yea thats it...

[adamct]

Ummmm....yeah. I'm not asking Bottlehead to change their business model by making one unpolished video.

Anyhoo...I stand by what I said above. There is a world of difference between reading some general principle in a book, vs. learning about a project you are building yourself. But I think we've probably beaten this subject to death. Some see value in the idea and would learn something. Others don't. And it's moot since the team doesn't have the time.

[corndog71]

This reminds me of a conversation I had with a friend of mine who wrote her own songs and music and performed in clubs.  One night after a few too many drinks and watching her perform I tried giving her a little advice about something.   She responded with a very curt "Let's see you get up there and do it".

Suffice to say, this stuff isn't easy.  It takes time and effort.  A lot of information is already out there.  But if you really want to know, you kinda gotta suck it up and do your own homework. 

I bought a 1962 RCA Transmitting Tube Manual from amazon for $12.  Some of it was over my head but I learned a lot of basics that were never really clear to me before.  I highly recommend it.

[2wo]

Might have a look at the Valve archives. Things like parafeed are well explained there.

There are a number of projects there that are explained in great detail, some by current Bottlehead designers. I for one always reread the "Blues Master" by Doc Himself, each time I contemplate building a new amp.

If you really want to understand this stuff, its not hard but you have to do your homework. Once you get 1 or 2 things, the other 4 or 5 are like, oh OK.

How about this, have a look at the Valve archives, Let's pick an article and break it down. I will help, I bet if we ask Granger nicely he and others would jump in...John

[adamct]

Sure, that would be awesome!

[odamone]

I just wanted to chime in with a big +1 for adam's video idea. It's a small investment for a potentially big payoff. It need not even be an official BH video. Perhaps someone on this forum who has done their homework could discuss the circuit design for 30 minutes.

[earwaxxer]

The point is, there are probably many things that Bottlehead COULD do that would, in someone else opinion, be a good move for them. Those in charge decide on all these things, such as whether to advertise, sell dildos on the side etc. I think its ridiculous to tell people how to run their business. I, personally, think it would be good to get their kit reviewed in the 'mainstream' audiophile subculture. Who cares what I think! In a way, I'm glad they dont.

[adamct]

Whoa again! Nobody is "telling" anybody to do anything. Requesting, asking, begging, groveling: maybe. Ordering, telling, demanding, threatening: no.

I'll put my money where my mouth is. If someone wants to pick a good article (or articles) for me and others to read, explains the basics of the Crack circuit, and agrees to answer some reasonable number of questions, I'll pay them $50. Maybe someone else can kick in a few bucks, too. It has to be done publicly, in a thread here for all to read and benefit from.

[earwaxxer]

sorry Adam... I'm in a "mood". Hard week. Kind of frustrated..

[Mike B]

Crack is easy.  Direct coupled triodes.  You can see from the schematic how easy it is.

The input tube is biased by the LED.  The signal goes to the grid.  The load line is determined by the resistor or the current source (speedball)

The output is direct to the grid of the 6080.  Also biased by the load resistor or the current source.

The amplified signal is coupled to the phones through the 100 uF cap.

Done.  Keep the $50.  See how easy this is?

You have a DC circuit (bias) keeping the tubes in the active region and an AC circuit through the middle isolated by the (DC blocking) caps.

[Mike B]

No questions?  Good.

Now lets look at the power supply, the heart of all things electronic.

The circuit is called CRCRC as the filter is 3 caps coupled by 2 resistors.

The transformer delivers AC to the bridge rectifier which flips the negative half cycle to positive.  Now we have DC, but it's really rough.  The first cap holds the peak voltage, the series resistor reduces it and makes it more stable, the 2nd cap increases the stability and again for the last stage where we have the output voltage of 170 VDC.

The filter has reduced the DC to just a litle over the RMS value of the transformer, so it should be nice and quiet (low ripple)

Now I have one for you guys.  Lets see if you know Ohm's Law and how to apply it.

Using the Crack manual only and a calculator, tell me how much current the power supply (B+ only) is delivering to the amplifier.