5687 line stage

costa23 · 7th August 2008, 02:21 AM

I've build my 5687 line stage preamp. i attached the scheme below.
Please comment about this scheme...
And if compared with the design in this forum, which one is better...
Thanks a lot.

GMuffley · 7th August 2008, 03:34 AM

Unless money is very tight, you can do MUCH better than a Solen output cap.

Sheldon · 7th August 2008, 05:08 AM

Quote:

Originally posted by GMuffley
Unless money is very tight, you can do MUCH better than a Solen output cap.

I'd try it with AC filaments, lifted to about 25V.

Sheldon

dsavitsk · 7th August 2008, 05:39 AM

6K is probably a little low for the load in the best of circumstances, but because you have left Rk unbypassed, the rp of the tube is in the 8K range making the load way too low. I would either bypass Rk with a suitable cap, or replace it with a LED.

oldeurope · 7th August 2008, 06:38 AM

Quote:

Originally posted by costa23
I've build my 5687 line stage preamp. i attached the scheme below.
Please comment about this scheme...
...
Thanks a lot.

Hi, do you take the output from cathode, anode or grid?
http://www.diyaudio.com/forums/attac...amp=1218073742

costa23 · 7th August 2008, 10:12 AM

Oooppss sorry about the scheme.....
The output is from anode...

Does anybody know how to make this scheme better ?
thanks

oldeurope · 7th August 2008, 10:31 AM

Quote:

Originally posted by costa23
...
The output is from anode...
...

Thanks,
do you need voltage gain?
If so how much?
Note the the anode output inverts the phase.

Original Burnedfingers · 7th August 2008, 10:47 AM

check out this site

http://www.diyparadise.com/simplepreamp.html

I built this design and added gas regulators to it. Look around the site and you will find the schematic and the power supply. When built as he designed it has ZERO noise. The chokes are an important part in the design and cost very little. I would eliminate the fancy caps and led and build as shown. When you are comfortable with it then dive into a CCS and see if there are any differences to be had.

I believe if you do a search a thread should turn up here.

analog_sa · 7th August 2008, 11:03 AM

Quote:

Originally posted by costa23
Does anybody know how to make this scheme better ?

Better in what way? And to whom?

I know what i'd do. Get rid of all the nice and cosy carbon comps and Kiwame resistors. They help produce a pleasant but also very coloured sound. Put some Caddocks in place.

Replace the anode resistor with a choke and experience a really serious improvement.

Replace the diodes with mercury rectifiers or tv dampers. Obviously the entire PS will need redoing then.

costa23 · 8th August 2008, 06:10 AM

Thanks a lot....

7th August 2008, 05:39 AM	#4
dsavitsk diyAudio Member Join Date: Jan 2005 Location: Chicago	6K is probably a little low for the load in the best of circumstances, but because you have left Rk unbypassed, the rp of the tube is in the 8K range making the load way too low. I would either bypass Rk with a suitable cap, or replace it with a LED. __________________ http://www.ecpaudio.com

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7th August 2008, 03:34 AM	#2
GMuffley diyAudio Member Join Date: Apr 2007	Unless money is very tight, you can do MUCH better than a Solen output cap.

7th August 2008, 10:12 AM	#6
costa23 diyAudio Member Join Date: Aug 2008	Oooppss sorry about the scheme..... The output is from anode... Does anybody know how to make this scheme better ? thanks

7th August 2008, 10:47 AM	#8
Original Burnedfingers diyAudio Member Join Date: Nov 2002	check out this site http://www.diyparadise.com/simplepreamp.html I built this design and added gas regulators to it. Look around the site and you will find the schematic and the power supply. When built as he designed it has ZERO noise. The chokes are an important part in the design and cost very little. I would eliminate the fancy caps and led and build as shown. When you are comfortable with it then dive into a CCS and see if there are any differences to be had. I believe if you do a search a thread should turn up here.

8th August 2008, 06:10 AM	#10
costa23 diyAudio Member Join Date: Aug 2008	Thanks a lot....

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