Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Leevi on April 21, 2018, 11:16:30 am

Title: 5E1 vs. 5F1
Post by: Leevi on April 21, 2018, 11:16:30 am

How do you describe the difference of the sound of these two circuits.
Since 5E1 has a cap on the 1st stage cathode and the screen voltage is higher
it is probably louder than 5F1?



http://el34world.com/charts/Schematics/files/fender/Fender_champ_5e1_schem.pdf (http://el34world.com/charts/Schematics/files/fender/Fender_champ_5e1_schem.pdf)

http://el34world.com/charts/Schematics/files/fender/Fender_champ_5f1_schem.pdf (http://el34world.com/charts/Schematics/files/fender/Fender_champ_5f1_schem.pdf)


/Leevi

Title: Re: 5E1 vs. 5F1
Post by: sluckey on April 21, 2018, 11:36:04 am

I've never heard either amp but on paper I'd say they both sound like a cheap low end practice amp. The 5E1 is probably a bit louder due to the cathode cap  and screen voltage, and it probably has less hum due to the filter choke. I would chose the 5E1.

Title: Re: 5E1 vs. 5F1
Post by: PRR on April 21, 2018, 02:01:03 pm

.

Title: Re: 5E1 vs. 5F1
Post by: Leevi on April 21, 2018, 02:26:20 pm

Choke is not an option in my case since the power supply is implemented by using a VVR.
I have already done the implementation based on 5F1 and I'm thinking now if I change it to 5E1.
The circuit is extreme silent i.e. no hum at all.


/Leevi

Title: Re: 5E1 vs. 5F1
Post by: shooter on April 21, 2018, 02:40:46 pm

Quote

I'm thinking now

put a switch on the cap and you have both!
what' your objective?

Title: Re: 5E1 vs. 5F1
Post by: Leevi on April 21, 2018, 03:07:57 pm

Quote

what' your objective?

As clean as possible, I think the screen should be changed according to 5E1.


/Leevi

Title: Re: 5E1 vs. 5F1
Post by: sluckey on April 21, 2018, 03:48:23 pm

Why don't you do it and tell us what the results are? Might just be on to something different. Maybe a 5EF1. Call it itty bitty tornado.   :icon_biggrin:

Title: Re: 5E1 vs. 5F1
Post by: Leevi on April 21, 2018, 04:11:29 pm

Quote

Why don't you do it and tell us what the results are?

I'll do that but tomorrow, it's midnight here now;)


/Leevi

Title: Re: 5E1 vs. 5F1
Post by: Willabe on April 21, 2018, 05:32:33 pm

Quote from: Leevi on April 21, 2018, 02:26:20 pm

Choke is not an option in my case since the power supply is implemented by using a VVR.

I don't see why you can't use a choke with a VVR. 

Title: Re: 5E1 vs. 5F1
Post by: Leevi on April 21, 2018, 11:54:44 pm

Quote

I don't see why you can't use a choke with a VVR.

Of course I can but I don't see it necessary at least from hum point of view.


/Leevi

Title: Re: 5E1 vs. 5F1
Post by: Leevi on April 22, 2018, 07:56:26 am

I made some measurements with different combinations like
5E1, 5F1, 5E1 without cathode cap, 5F1 with cathode cap.


The cathode cap on the first stage increases loudness and early distortion but doesn't increase the headroom
so I didn't add the cap to the circuit. The 10K resistor drops the screen voltage which decreases the power.
Since my objective was to maximize headroom my choice is to keep the circuit like in 5F1 but remove the 10K resistor.


See the measurement protocol:


/Leevi

Title: Re: 5E1 vs. 5F1
Post by: Tomahawk on July 08, 2021, 02:33:34 pm

I know this is an older thread, but I have a question regarding the 6V6. So is the 10K resistor after the input cap there to simply filter ripple before it hits the screen and in the schematic with the choke doesn't do this because the choke filters more ripple to the point where it does not need any further filtering in the power stage?