Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: newguitarsmell on December 01, 2020, 08:43:38 pm

Title: Better bass response
Post by: newguitarsmell on December 01, 2020, 08:43:38 pm
Hey all
I modified a 5f2a to use with keys - put in a huge OT - - a nice big speaker but the bass response is a bit flat. Maybe I'm asking too much of a single ended 5Watter?
The tone control helps kick out the top end but it needs more.
https://el34world.com/Hoffman/files/Hoffman_5F2A.pdf

Nice and quiet though - sounds great overall I am happy with it. Just wondering. Haven't checked in for awhile.
Title: Re: Better bass response
Post by: sluckey on December 01, 2020, 10:07:45 pm
Maybe I'm asking too much of a single ended 5Watter?
Most likely.
Title: Re: Better bass response
Post by: newguitarsmell on December 01, 2020, 11:18:07 pm
Sluckey - you would know!

Title: Re: Better bass response
Post by: Leevi on December 02, 2020, 03:38:13 am
Add a cathode bypass cap to the second stage.
Cut the NFB.


/Leevi
Title: Re: Better bass response
Post by: pdf64 on December 02, 2020, 06:39:08 am
Add a cathode bypass cap to the second stage.
Cut the NFB.
A fully bypassed 2nd stage cathode would disable the NFB loop (which would tend to result in a brighter sound due to the amp’s output then tracking the load impedance).
Whereas a partial bypass would actively boost higher frequencies (eg same as a presence control on max) :w2:
Title: Re: Better bass response
Post by: Leevi on December 02, 2020, 07:48:05 am
Quote
A fully bypassed 2nd stage cathode would disable the NFB loop (which would tend to result in a brighter sound due to the amp’s output then tracking the load impedance).Whereas a partial bypass would actively boost higher frequencies (eg same as a presence control on max)


This is true but I think the cap value affects the frequency? A small cap gains high frequencies and a big cap low frequencies?
Furthermore the overall loudness will increase which highlights the bass as well.


/Leevi