EL 33 replacement - UK Vintage Radio Repair and Restoration Discussion Forum

Dick Glennon · 13th Dec 2021, 8:37 pm

Hi again, Is it possible to replace an EL 33 valve with either a 6P 25 or a 6V6.Thanks again Dick.

G6Tanuki · 13th Dec 2021, 8:41 pm

The EL33 has a relatively high Gm [around 8] whereas that for the 6V6 is somewhere more like 4 - so depending on the circuit you may find that a 6V6 will not give the same maximum loudness as an EL33.

paulsherwin · 13th Dec 2021, 9:09 pm

This will indeed usually work, though the valve characteristics are different. There is usually enough gain in a standard superhet to hide the changes. You should check the substituted valve's operating characteristics and increase the cathode resistor if necessary.

Craig Sawyers · 14th Dec 2021, 9:52 am

I've looked through my various go-to valve suppliers, and the only one showing stock of NOS EL33 is Langrex. For £60!!

The identical equivalent, the 6P25 (NOS) is here https://www.vintage-electronics.co.u...25-valve-tube/ for a mere £40.

I can see why you are interested in the 6V6 because it can be had for £15 from Watford Valves.

Craig

Craig Sawyers · 14th Dec 2021, 9:59 am

There is quite a long discussion about the various options for substitution here

https://www.diyaudio.com/community/t...eborne.173625/

Craig

Gabe001 · 14th Dec 2021, 10:34 am

I've just finished a set with a el33 to 6f6 replacement that could have been factory/very old. The cathode resistor value had been appropriately adjusted. I asked the same question as yourself here:
https://www.vintage-radio.net/forum/....php?p=1415945

Output was decent. The el33 would have been louder, but the volume and sound quality were good enough for me to keep the 6f6. A 6v6 will be fine with the appropriate cathode resistor adjustment as others have said.

Skywave · 14th Dec 2021, 6:14 pm

Dick - You haven't stated why you wish to replace the EL33. Could it be that your existing EL 33 is defective and that a replacement EL33 is actually preferred, but that you do not have one? In that case, a member here might be able to help.

Al.

13th Dec 2021, 8:37 pm	#1
Dick Glennon Hexode Join Date: Oct 2006 Location: Edenderry, Republic of Ireland. Posts: 428	EL 33 replacement Hi again, Is it possible to replace an EL 33 valve with either a 6P 25 or a 6V6.Thanks again Dick.

13th Dec 2021, 8:41 pm	#2
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: EL 33 replacement The EL33 has a relatively high Gm [around 8] whereas that for the 6V6 is somewhere more like 4 - so depending on the circuit you may find that a 6V6 will not give the same maximum loudness as an EL33. __________________ I'm the Operator of my Pocket Calculator. -Kraftwerk.

13th Dec 2021, 9:09 pm	#3
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: EL 33 replacement This will indeed usually work, though the valve characteristics are different. There is usually enough gain in a standard superhet to hide the changes. You should check the substituted valve's operating characteristics and increase the cathode resistor if necessary.

14th Dec 2021, 9:52 am	#4
Craig Sawyers Dekatron Join Date: Nov 2010 Location: Oxford, UK. Posts: 4,984	Re: EL 33 replacement I've looked through my various go-to valve suppliers, and the only one showing stock of NOS EL33 is Langrex. For £60!! The identical equivalent, the 6P25 (NOS) is here https://www.vintage-electronics.co.u...25-valve-tube/ for a mere £40. I can see why you are interested in the 6V6 because it can be had for £15 from Watford Valves. Craig __________________ Doomed for a certain term to walk the night

14th Dec 2021, 9:59 am	#5
Craig Sawyers Dekatron Join Date: Nov 2010 Location: Oxford, UK. Posts: 4,984	Re: EL 33 replacement There is quite a long discussion about the various options for substitution here https://www.diyaudio.com/community/t...eborne.173625/ Craig __________________ Doomed for a certain term to walk the night

14th Dec 2021, 10:34 am	#6
Gabe001 Octode Join Date: Oct 2019 Location: Stockport, Greater Manchester, UK. Posts: 1,641	Re: EL 33 replacement I've just finished a set with a el33 to 6f6 replacement that could have been factory/very old. The cathode resistor value had been appropriately adjusted. I asked the same question as yourself here: https://www.vintage-radio.net/forum/....php?p=1415945 Output was decent. The el33 would have been louder, but the volume and sound quality were good enough for me to keep the 6f6. A 6v6 will be fine with the appropriate cathode resistor adjustment as others have said.

14th Dec 2021, 6:14 pm	#7
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: EL 33 replacement Dick - You haven't stated why you wish to replace the EL33. Could it be that your existing EL 33 is defective and that a replacement EL33 is actually preferred, but that you do not have one? In that case, a member here might be able to help. Al.