The complete 6SN7 preamp - Page 3

fdegrove · 21st November 2002, 12:19 PM

Hi,

Provided your xformer can handled it,it should work as a replacement.
You may have to fiddle with voltage dropping resistors to get B+
where you want it.

Ciao,

Original Burnedfingers · 3rd December 2002, 11:10 AM

Hi

Another question here...

Could a 12BH7 be used in place of a 12AY7? If so what other changes would have to be made?

Thanks
Joe

Joel · 3rd December 2002, 02:13 PM

Well, a 12BH7 is a higher current, lower mu tube. Gain of 16, I believe. If you were going to go that route, you might as well just use an additional 6SN7. It has higher gain (20), and lower current. You don't need any current in the voltage gain stage.

Original Burnedfingers · 17th December 2002, 11:45 AM

Ok

We have the perfect starter preamp circuit here. Lets assume we want to build it ti the hilt. What parts where and why would you do so. Lets assume we are going to use a 360-0-360 transformer and a 5R4GYA rect tube.

I'm going to build this one up with a slight variation .. I'm going to use 1 12ay7 tube for each side and a Red Base 6SN7 (5692) tubes. One side I will build up with cheap .50 ea resistors(metalfilm) and the other side I will use Riken at 3.50 ea. One side gets cheap caps the other gets better(remember I can't afford caps at $100.00 ea here).

I would like the suggestions that you may have to build the other side to suite your taste.

I will then listen to it and test it to see if I can hear a difference. I will then assemble a group of individuals to listen and compare without disclosure of parts used. I think this might be a fair way to test. I would even ship this to different individuals for their evaluation.

Joe

fdegrove · 17th December 2002, 01:30 PM

Hi,

Quote:

One side I will build up with cheap .50 ea resistors(metalfilm) and the other side I will use Riken at 3.50 ea.

Joe,I would advise against that.It would be a waste of time IMO.

Why not build with off the shelf components at first,get to know the sound of the preamp and later on change some components.

For example:first change the coupling caps,later on some resistors and take it from there if you like what you're hearing.

You can then build several samples with several stages of changed components if you like and have people listen to that.

Cheers,

Joel · 17th December 2002, 01:41 PM

Build the preamp, but leave the coupling capacitor out of the circuit. Then when ready to "test" use clip leads and place different caps in place.
People will complain though, "the cathode follower is 'smearing' your results", etc etc.

Original Burnedfingers · 31st December 2002, 07:34 PM

With the following changes to Joels original power supply what would my output voltage be?

Transformer changed to 360-0-360
First resistor changed to 1k (before the 100mfd cap)
Rectifier tube changed to a 5AR4

Granted the current draw for the tubes will be 20ma for each 5692 tube and 8ma for each of the two 12ay7 tubes for a total of 56ma.

Second

Transformer still 360-0-360

1ft resistor still 1k

Rectifier tube changed to 5R4GYA

Why the stupid questions?
Because I don't know what the voltage difference will be between the different tubes.

Why the 360-0-360 transformer? Because I got it cheap and that meant I could spend more money on the tubes.

Why not follow the given directions? Because I wouldn't learn from it.

Joe

Joe

Joel · 1st January 2003, 02:38 PM

Joe,

If you have a tube manual handy they have graphs of the voltage drops for each condition - ie. capacitor input, or choke input filters, etc. There's no easy way to figure the numbers, as each circuit draws different amounts of current. Why the high powered rectifiers?

ps. 5AR4's are expensive!

fdegrove · 1st January 2003, 02:57 PM

Hi Joel,

Quote:

Why the high powered rectifiers?

Didn't you once reply to the same question...because I have a shoebox full of them?

Quote:

ps. 5AR4's are expensive!

Maybe.

He's not using those anyway.

Cheers,

Original Burnedfingers · 1st January 2003, 03:42 PM

Joel

Santa never brought me a tube manual like I requested so I don't have the graphs and information in which to look the info up.
Secondly, I just happen to bring home several large boxes full of tubes and I happen to find 5Ar4's and 5R4GYA tubes. That is what I have for rectifier tubes at the moment. My first thought was to use what I happen to have. I just thought since you guys deal with tubes all the time that you might have a ballpark idea what I might expect for voltage and hince I could order the correct resistors. Never mind I will wire it up and run it up on the variac and monitor voltages as I go.

Joe

21st November 2002, 12:19 PM	#21
fdegrove diyAudio Senior Member Join Date: Aug 2002 Location: Belgium	5R4 Hi, Provided your xformer can handled it,it should work as a replacement. You may have to fiddle with voltage dropping resistors to get B+ where you want it. Ciao, __________________ Frank

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3rd December 2002, 11:10 AM	#22
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Hi Another question here... Could a 12BH7 be used in place of a 12AY7? If so what other changes would have to be made? Thanks Joe

3rd December 2002, 02:13 PM	#23
Joel diyAudio Member Join Date: Oct 2002 Location: Brooklyn, NY	Well, a 12BH7 is a higher current, lower mu tube. Gain of 16, I believe. If you were going to go that route, you might as well just use an additional 6SN7. It has higher gain (20), and lower current. You don't need any current in the voltage gain stage.

17th December 2002, 11:45 AM	#24
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Ok We have the perfect starter preamp circuit here. Lets assume we want to build it ti the hilt. What parts where and why would you do so. Lets assume we are going to use a 360-0-360 transformer and a 5R4GYA rect tube. I'm going to build this one up with a slight variation .. I'm going to use 1 12ay7 tube for each side and a Red Base 6SN7 (5692) tubes. One side I will build up with cheap .50 ea resistors(metalfilm) and the other side I will use Riken at 3.50 ea. One side gets cheap caps the other gets better(remember I can't afford caps at $100.00 ea here). I would like the suggestions that you may have to build the other side to suite your taste. I will then listen to it and test it to see if I can hear a difference. I will then assemble a group of individuals to listen and compare without disclosure of parts used. I think this might be a fair way to test. I would even ship this to different individuals for their evaluation. Joe

17th December 2002, 01:41 PM	#26
Joel diyAudio Member Join Date: Oct 2002 Location: Brooklyn, NY	Build the preamp, but leave the coupling capacitor out of the circuit. Then when ready to "test" use clip leads and place different caps in place. People will complain though, "the cathode follower is 'smearing' your results", etc etc.

31st December 2002, 07:34 PM	#27
Original Burnedfingers diyAudio Member Join Date: Nov 2002	With the following changes to Joels original power supply what would my output voltage be? Transformer changed to 360-0-360 First resistor changed to 1k (before the 100mfd cap) Rectifier tube changed to a 5AR4 Granted the current draw for the tubes will be 20ma for each 5692 tube and 8ma for each of the two 12ay7 tubes for a total of 56ma. Second Transformer still 360-0-360 1ft resistor still 1k Rectifier tube changed to 5R4GYA Why the stupid questions? Because I don't know what the voltage difference will be between the different tubes. Why the 360-0-360 transformer? Because I got it cheap and that meant I could spend more money on the tubes. Why not follow the given directions? Because I wouldn't learn from it. Joe Joe

1st January 2003, 02:38 PM	#28
Joel diyAudio Member Join Date: Oct 2002 Location: Brooklyn, NY	Joe, If you have a tube manual handy they have graphs of the voltage drops for each condition - ie. capacitor input, or choke input filters, etc. There's no easy way to figure the numbers, as each circuit draws different amounts of current. Why the high powered rectifiers? ps. 5AR4's are expensive!

1st January 2003, 03:42 PM	#30
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Joel Santa never brought me a tube manual like I requested so I don't have the graphs and information in which to look the info up. Secondly, I just happen to bring home several large boxes full of tubes and I happen to find 5Ar4's and 5R4GYA tubes. That is what I have for rectifier tubes at the moment. My first thought was to use what I happen to have. I just thought since you guys deal with tubes all the time that you might have a ballpark idea what I might expect for voltage and hince I could order the correct resistors. Never mind I will wire it up and run it up on the variac and monitor voltages as I go. Joe

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