First Tube Project - S5 Electronics Preamp - Page 2

audiowize · 22nd March 2020, 01:37 AM

A simple improvement would be to use a 6922 instead of the 5670. You'd cut the output impedance roughly in half, which is rather high in this design.

(I would absolutely use a cathode bypass cap)

vdi_nenna · 22nd March 2020, 02:27 AM

Thanks audiowse. Will try it.

Do you recommend any specific brand?

vdi_nenna · 28th March 2020, 12:50 AM

Question about the cathode resistor capacitor voltage.
I measured 1 volt across the cathode resistor.
Would a 47uF 25v electrolytic be safe or does the voltage across it change with a signal?

I picked up a 60uF MKP 300vac, but it will not fit in the case.
They are 2.25"D x 2"L.

thanks,

Vince

audiowize · 28th March 2020, 02:00 AM

There are a ton of really nice audio grade electrolytic caps that would work there that are under $2 each.

If you see 1V DC there, then pretty much any voltage rating is going to work fine.

vdi_nenna · 28th March 2020, 04:58 PM

The 6922 filament are not lighting up.
Using the Electro-harmonix gold pin 6922.
Is the 6922 really a direct drop-in replacement for the 5670?
It's ok if it's not. Will send it back.

The 5670 still works, and the bypass caps are not affecting the gain negatively.
There's a bit more midrange clarity.

I'll let this cook for a little bit.
Pretty happy with it as is.

Thanks,

Vince

audiowize · 28th March 2020, 05:00 PM

The pinout is not the same between the 5670 and 6922.

vdi_nenna · 8th April 2020, 02:59 AM

Now using the Tung-Sol 2C51 in place of the GE JAN 5670.
2C51 costs as much as the kit, but it's worth it.

JRKO · 31st May 2020, 06:40 PM

How’s the sound of the tube/F4 combo?

I’m interested in something easy to build for a newbie tuber to drive both F4 and MOFO

Cheers

vdi_nenna · 31st May 2020, 06:48 PM

It's a fantastic combo.
Replace the 5560 with a 2C51.
The tube costs as much as the kit, but it's worth it.
You might want to upgrade the caps and resistors that come with the kit but that's up to you.

You'll need to build a 200v dc supply and 6.3 heater.

Let us know what you think if you build it.

Thanks

JRKO · 1st June 2020, 03:24 PM

I’ll let you know how it goes. Might use one of these to provide he voltages required - PS-3 Power Supply Kit

What do you think?

22nd March 2020, 02:27 AM	#12
vdi_nenna diyAudio Member Join Date: Oct 2000 Location: PA, USA	Thanks audiowse. Will try it. Do you recommend any specific brand? __________________ I build, therefore I am. Do not create problems where there are none.

28th March 2020, 12:50 AM	#13
vdi_nenna diyAudio Member Join Date: Oct 2000 Location: PA, USA	Question about the cathode resistor capacitor voltage. I measured 1 volt across the cathode resistor. Would a 47uF 25v electrolytic be safe or does the voltage across it change with a signal? I picked up a 60uF MKP 300vac, but it will not fit in the case. They are 2.25"D x 2"L. thanks, Vince __________________ I build, therefore I am. Do not create problems where there are none.

28th March 2020, 04:58 PM	#15
vdi_nenna diyAudio Member Join Date: Oct 2000 Location: PA, USA	The 6922 filament are not lighting up. Using the Electro-harmonix gold pin 6922. Is the 6922 really a direct drop-in replacement for the 5670? It's ok if it's not. Will send it back. The 5670 still works, and the bypass caps are not affecting the gain negatively. There's a bit more midrange clarity. I'll let this cook for a little bit. Pretty happy with it as is. Thanks, Vince __________________ I build, therefore I am. Do not create problems where there are none.

8th April 2020, 02:59 AM	#17
vdi_nenna diyAudio Member Join Date: Oct 2000 Location: PA, USA	Now using the Tung-Sol 2C51 in place of the GE JAN 5670. 2C51 costs as much as the kit, but it's worth it. __________________ I build, therefore I am. Do not create problems where there are none.

31st May 2020, 06:40 PM	#18
JRKO diyAudio Member Join Date: Dec 2003 Location: U.K.	How’s the sound of the tube/F4 combo? I’m interested in something easy to build for a newbie tuber to drive both F4 and MOFO Cheers __________________ I collect projects - building them is another hobby altogether


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

22nd March 2020, 01:37 AM	#11
audiowize diyAudio Member Join Date: Aug 2005 Location: Seattle	A simple improvement would be to use a 6922 instead of the 5670. You'd cut the output impedance roughly in half, which is rather high in this design. (I would absolutely use a cathode bypass cap)

28th March 2020, 02:00 AM	#14
audiowize diyAudio Member Join Date: Aug 2005 Location: Seattle	There are a ton of really nice audio grade electrolytic caps that would work there that are under $2 each. If you see 1V DC there, then pretty much any voltage rating is going to work fine.

28th March 2020, 05:00 PM	#16
audiowize diyAudio Member Join Date: Aug 2005 Location: Seattle	The pinout is not the same between the 5670 and 6922.

31st May 2020, 06:48 PM	#19
vdi_nenna diyAudio Member Join Date: Oct 2000 Location: PA, USA	It's a fantastic combo. Replace the 5560 with a 2C51. The tube costs as much as the kit, but it's worth it. You might want to upgrade the caps and resistors that come with the kit but that's up to you. You'll need to build a 200v dc supply and 6.3 heater. Let us know what you think if you build it. Thanks __________________ I build, therefore I am. Do not create problems where there are none.

1st June 2020, 03:24 PM	#20
JRKO diyAudio Member Join Date: Dec 2003 Location: U.K.	I’ll let you know how it goes. Might use one of these to provide he voltages required - PS-3 Power Supply Kit What do you think? __________________ I collect projects - building them is another hobby altogether

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
FS: Audio Electronics AE-3 tube preamp (as-is)	Aercool	Swap Meet	2	22nd January 2018 04:42 PM
Help me pick my first tube kit/winter project (tube preamp)	Baronkyle	Tubes / Valves	8	9th November 2015 04:42 AM
possible project for me, tube preamp.	theChris	Tubes / Valves	20	31st October 2012 01:47 PM
Delta Electronics tube preamp. Four 7695 tubes.	nodiak	Swap Meet	9	2nd March 2012 04:58 AM
Senior Project Tube Preamp	JRiggles	Tubes / Valves	9	22nd February 2011 02:55 PM

New To Site?	Need Help?
Register to Participate Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read