Loss of volume and gain after modification

[Stevem]

The amp mod rule of Thumb is to make one change at a time and then audition the amp, especially when your new to making mod's and electronics and can't prejudge what the out come will be before lifting up the hot soldering iron!

Yes, at times it can be a PIA and time consuming to put the amp back together enough to play it, but with what you have gone thru so far with this amp you would have saved yourself a bunch of aggravating hours I bet?

Note, clip leads are your friend in terms of not having to fully reassemble a amp to audition it!

[Mikante]

Jumpering the NFB resistor will give you a TON of NFB. Lifting/disconnecting the NFB resistor is what will give you more grit as you're breaking the connection between the OT and the cathode of the preamp stage, completely, eliminating the NFB network. Jumpering the NFB resistor will eliminate all resistance between the OT and cathode of the preamp stage, giving the maximum amount of NFB possible.

That is it.
Before touching r7 the amp was sounding just fine. Too much preamp distortion in my opinion, but the sound was fine.
Instead of just removing the resistor i put a jumper, what was i thinking?
I just wanted to listen the sound without any resistor and see if it was worth to put a switch.

The amp mod rule of Thumb is to make one change at a time and then audition the amp, especially when your new to making mod's and electronics and can't prejudge what the out come will be before lifting up the hot soldering iron!

Yes, at times it can be a PIA and time consuming to put the amp back together enough to play it, but with what you have gone thru so far with this amp you would have saved yourself a bunch of aggravating hours I bet?

Note, clip leads are your friend in terms of not having to fully reassemble a amp to audition it!

You re right and i was just too quick to put my hands on a amp for the first time.

[Phil_S]

The youtuber who made the video in the first post needs to pull it down. It's an accident looking for a place to happen. You could more easily and for not very much money build a 5F1 board to swap for the factory board. The 5F1 small parts count is about 20 items, and that includes 3 filter caps. <Sigh!>

[Mikante]

I could build it my self,
is that the only thing you would need to swap, the board?
The amp doesn t sound bad, the eq is very mid scooped though, plus it is not responsive and it feels too tight when you play through. For tight i mean clean or dirty, not much sound in between.
So i decided to do this mod.
It sounds better after, sure, it can be improved but i have not enough experience to do it my self or understand where the improvements can be made.
Anyway, i will put all the parts back to place and just leave the eq bypassed along with the negative feedback. I will also leave c10 out.

[thetragichero]

Before touching r7 the amp was sounding just fine. Too much preamp distortion in my opinion, but the sound was fine.

too much preamp distortion is due to drastically increasing the power supply dropping resistors (as has been mentioned). get those back to what they were and it should be a lot cleaner

[Phil_S]

Mikante: My comment about building a board wasn't meant as a suggestion for you, as you've already come this far with the mod. It was a more general comment that I can't see putting that much effort into modifying that PCB. While the video is only about 18 minutes, my guess is that's been edited from something that took him about an hour, maybe more. I know I could populate a board for a 5F1 very quickly because of the low parts count. If I were you, I think I'd do my best to finish what I started with the PCB.

If you wanted to swap out the board, you'd need to make sure that you've included everything you are removing. I see fuses, various spade lug connections, etc. A swap probably isn't as simple as I might have implied.

[Firestorm]

Mikante: My comment about building a board wasn't meant as a suggestion for you, as you've already come this far with the mod. It was a more general comment that I can't see putting that much effort into modifying that PCB. While the video is only about 18 minutes, my guess is that's been edited from something that took him about an hour, maybe more. I know I could populate a board for a 5F1 very quickly because of the low parts count. If I were you, I think I'd do my best to finish what I started with the PCB.

If you wanted to swap out the board, you'd need to make sure that you've included everything you are removing. I see fuses, various spade lug connections, etc. A swap probably isn't as simple as I might have implied.

Most of the changes in that video are pointless. You could accomplish the same thing by lifting the ground end of R19 and the ground end of C10. Put them on a DPST switch ang toggle between stock and tweed. I should make a 2 minute video.

[Phil_S]

Most of the changes in that video are pointless. You could accomplish the same thing by lifting the ground end of R19 and the ground end of C10. Put them on a DPST switch ang toggle between stock and tweed. I should make a 2 minute video.

I admit that I never looked at schematics. It's clear that a board swap is overkill.

[Mikante]

Mikante: My comment about building a board wasn't meant as a suggestion for you, as you've already come this far with the mod. It was a more general comment that I can't see putting that much effort into modifying that PCB. While the video is only about 18 minutes, my guess is that's been edited from something that took him about an hour, maybe more. I know I could populate a board for a 5F1 very quickly because of the low parts count. If I were you, I think I'd do my best to finish what I started with the PCB.

If you wanted to swap out the board, you'd need to make sure that you've included everything you are removing. I see fuses, various spade lug connections, etc. A swap probably isn't as simple as I might have implied.

Hey, i got what you were trying to say but now the thought is in my head
Im kidding.
It is definitely something worth trying in the future.
Right now I have removed the jumper on r7, put back stock values on r11 r12 and r23.
I like the voice now, with the eq gone.
It feels more responsive but I'm getting to much preamp overdrive, the amp goes wild with the volume on 3

[Mikante]

Mikante: My comment about building a board wasn't meant as a suggestion for you, as you've already come this far with the mod. It was a more general comment that I can't see putting that much effort into modifying that PCB. While the video is only about 18 minutes, my guess is that's been edited from something that took him about an hour, maybe more. I know I could populate a board for a 5F1 very quickly because of the low parts count. If I were you, I think I'd do my best to finish what I started with the PCB.

If you wanted to swap out the board, you'd need to make sure that you've included everything you are removing. I see fuses, various spade lug connections, etc. A swap probably isn't as simple as I might have implied.

Most of the changes in that video are pointless. You could accomplish the same thing by lifting the ground end of R19 and the ground end of C10. Put them on a DPST switch ang toggle between stock and tweed. I should make a 2 minute video.

In hindsight, those are probably the modifications that will make some difference.
Putting back r11 r12 and r23 didn’t do anything to the sound or at least, something that anybody could tell. I will probably put the rest of the components back where they were.

[Mikante]

Hello everyone,
Yesterday i had a bit of spare time to work on the amp.
As you suggested i have put everything back to stock and just removed the eq.
Some of the stock components didn t survive through the process so had to replace them with what i had available.
R10 is now 530 ohm instead of 470, i really don t know what would be the difference.
Also c3 and c10 are now 25uf instead of 22uf. I have put them both back because i like to have more distortion.
Would this make any important difference? I mean, changing the value from 22 to 25uf?
I had these two sprague atom caps that are much better quality then the stock ones.
Thank you guys and by the way, the amp sound perfectly fine now, a little to compressing when cranked, blackface kind of compressing, if you know what i mean. I remember now, sag is what they call it.

[thetragichero]

quality difference between the stock caps and sprague atoms negligible at best, and no difference between 22uf and 25uf is within likely 20% tolerance, parts could likely measure the same