REDD47 anyone?

[tablebeast]

Ok, so does anyone have any schematics and other info on the REDD47 mic pre? I looked on the net and it looks like the Ministry of Information has squashed it. I'd like to build a few of these since I just got a good score on some Amperex EF86's. Thanks in advance.

 

[funkydiplomat]

search.

http://www.groupdiy.com/index.php?topic=17847&highlight=ef86


http://www.groupdiy.com/index.php?topic=20040&highlight=ef86

:shock: :shock:

 

[tablebeast]

Yeah, those other threads didn't have any hard specifics. I need a genuine schematic for the mic pre version, not some weird copy or some unchecked schematic from 10 years ago. Anyone got the real deal here?

 

[MikeFFG]

http://www.sowter.co.uk/schematics/redd47.gif

I found this linked from the DRIP electronics website. 

 

[tablebeast]

http://www.sowter.co.uk/schematics/redd47.gif

I found this linked from the DRIP electronics website. 

Yeah, that one is 10 years old and the label says unchecked plus is has an 82k resistor with 8.2k next to it with a question mark. Sorry, but that doesn't really inspire confidence that it is genuine. There has to be another, proper schematic of this circuit somewhere.

 

[shabtek]

82k or 8.2k?
I=.0185
V=IR...

 

[MikeFFG]

why would it matter if it is ten years old?  Go check the drip forum, or download the build info pdf on their website.  I'm sure the info is there.

 

[tablebeast]

why would it matter if it is ten years old?  Go check the drip forum, or download the build info pdf on their website.  I'm sure the info is there.

What matters is that it is 10 years old and STILL says version 1.0, unchecked on it! I'd like a schematic that is at least checked and verified before I devote time and money on a project. All I am looking for is someone to say that yes it is correct at least. Is it an 8.2K plate resistor on the 6DJ8? Are there any other mistakes?

 

[pstamler]

How about this? Go build it with an 82k plate resistor. If it measures and sounds like dirt, snip the resistor and try 8.2k. You're out, what, US$0.25 and five minutes of work. And you'll have discovered something useful to the next person.

Or do it the other way round. Shabtek speaks wisely.

Peace,
Paul

 

[Kingston]

What matters is that it is 10 years old and STILL says version 1.0, unchecked on it! I'd like a schematic that is at least checked and verified before I devote time and money on a project.  All I am looking for is someone to say that yes it is correct at least. Is it an 8.2K plate resistor on the 6DJ8? Are there any other mistakes?

There are many redd 47 clone projects out there, just that not all of them shout it at your face. It's a VERY simple tube preamp and all the values are extremely non-critical. Or if they are critical, the design is basically flawed. Like pstamler says, experiment around. You aren't going to break anything

If you want just plain paint by the numbers redd47 and are not interested in experimentation (a shame really), start here: http://www.groupdiy.com/index.php?topic=33424.0

But in my opinion there are more interesting tube preamps out there. Redd47 has very low gain and boring linear sound, kind of sub optimal seeing what tubes it uses.

 

[Tubemooley]

Let's just make this simple. I confirm it. It's correct. Build it. Anything else we can do for you Mr. Beast? We wouldn't want you to have to figure something out on your own. You wanna' do this again? Bring it on. People know I am a complete piece of work. But you my friend take the cake. I have never seen so much unbridled attitude in my whole life. Why don't you leave your attitude in the basement before you come on here..... And if Drip builds it, it's right. A-hole Walcott out.

 

[Kit]

"Is it an 8.2K plate resistor on the 6DJ8?"


Not trying to sound like an A## here , but ..............if you brush up on your electronics theory and math you will find that the answer is very obvious.

 

[riggler]

Shabtek gave the formula AND the current right there. Now I will figure out how we got the current, just to learn...
Well geez there's the current on the schematic. 18.5mA = .0185A.

So how easy is this to figure out (which value is at least in the ballpark)?

I still am newbie-ish but this one is pretty easy. Do you have a hard time with the math? If you do I volunteer to help. Not trying to be offensive.

 

[Ethan]

I need a genuine schematic for the mic pre version, not some weird copy or some unchecked schematic from 10 years ago.

The people of this forum are generally polite and generous, especially with their time and knowledge.  Please don't mistake that for someone owing you something.  Just because you "need" some information does not mean anyone "needs" to bend over backwards to give it to you.

 

[tablebeast]

I need a genuine schematic for the mic pre version, not some weird copy or some unchecked schematic from 10 years ago.

The people of this forum are generally polite and generous, especially with their time and knowledge.  Please don't mistake that for someone owing you something.  Just because you "need" some information does not mean anyone "needs" to bend over backwards to give it to you.

I know this and am completely thankful for everyone's help. I was not trying to come off as anything more than just an experimenter frustrated with searching the web all over and continually finding the same 'unchecked' schematic. If there was one obvious error, maybe there were more? A lot of maybes make me just a bit frustrated. And when there are so many knowledgeable people around to help, I was just trying to tap that well. I figured if it had been fixed and checked that maybe it would be updated in the credits. I hadn't realised I was sounding so demanding and had no intention of that.

Once I build this circuit stock and can evaluate that, I'd be very interested in mods. I have already built several designs using the EF86 and it is one of my favorite tubes. I have a design of my own that I build into my modified Akai/Roberts monoblocks with an EF86 feeding a 12AU7 white cathode follower with no feedback. It is nice and colorful even without an output transformer. I also have another made out of a Ampex 601 with the EF86 setup in a totally different way feeding a 12AU7 as a bootstrapped cathode follower with an output transformer. It is a bit tamer, but still has some nice color. Now I'd like to build the lower gain, cleaner amp with the same EF86 and that is how I arrived here.

 

[lassoharp]

I need a genuine schematic for the mic pre version, not some weird copy or some unchecked schematic from 10 years ago.

The people of this forum are generally polite and generous, especially with their time and knowledge.  Please don't mistake that for someone owing you something.  Just because you "need" some information does not mean anyone "needs" to bend over backwards to give it to you.

I know this and am completely thankful for everyone's help. I was not trying to come off as anything more than just an experimenter frustrated with searching the web all over and continually finding the same 'unchecked' schematic. If there was one obvious error, maybe there were more? A lot of maybes make me just a bit frustrated. And when there are so many knowledgeable people around to help, I was just trying to tap that well. I figured if it had been fixed and checked that maybe it would be updated in the credits. I hadn't realised I was sounding so demanding and had no intention of that.

Once I build this circuit stock and can evaluate that, I'd be very interested in mods. I have already built several designs using the EF86 and it is one of my favorite tubes. I have a design of my own that I build into my modified Akai/Roberts monoblocks with an EF86 feeding a 12AU7 white cathode follower with no feedback. It is nice and colorful even without an output transformer. I also have another made out of a Ampex 601 with the EF86 setup in a totally different way feeding a 12AU7 as a bootstrapped cathode follower with an output transformer. It is a bit tamer, but still has some nice color. Now I'd like to build the lower gain, cleaner amp with the same EF86 and that is how I arrived here.

Gates used that tube in the Gatesway series preamps. There's a pay site that has many of those schematics.  I don't recall seeing any of those particulars posted at the free sites.

If you should deplete your stash of EF86s - a 5879 is easier on the wallet.