Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on October 22, 2010, 10:43:29 am

Title: ef86 as V1 - why there aren't skematics using Tone Stack ??
Post by: kagliostro on October 22, 2010, 10:43:29 am
This days I was looking to amps using ef86 as V1

like Matchless DC30 - Vox AC15 and other new one (Weber kit 6d30 and also other projects here in our forum)

I've seen that many projects that uses ef86 as V1 haven't a tone stack

usually they have one or more condenser to be switched in order to have a different bass response

there is a particular reason for that ?

why we don't see tone stacks there ?

Thanks

Kagliostro
Title: Re: ef86 as V1 - why there aren't skematics using Tone Stack ??
Post by: jojokeo on October 22, 2010, 10:58:21 am
Hi Kagliostro! In a number of schem designs such as an 18watt, AC15/30 and other simple one or two channel amps you'll see that there really isn't a driver or recovery stage following it. Due to their high impedance their signal can be easily loaded down and there's not enough left to drive the output properly. Therefore, in keeping as much signal as possible you don't want to have an elaborate tone stack. So a simple series of caps/condensers can filter bass response accordingly for various output levels of the amp as a whole. The louder the amp is played - the less bass you want to keep your tone from becoming muddy which = using a smaller cap value.

If you follow them w/ a cathode follower stage or other recovery/gain stage then using a tone stack works perfectly fine.
Title: Re: ef86 as V1 - why there aren't skematics using Tone Stack ??
Post by: chocopower on October 22, 2010, 03:06:22 pm

Here you have one with Volumen and Tone:

http://www.flickr.com/photos/49108115@N04/4501477895/#/photos/49108115@N04/4501477895/lightbox/ (http://www.flickr.com/photos/49108115@N04/4501477895/#/photos/49108115@N04/4501477895/lightbox/)

But as said Jojokeo, keep it simple.

http://www.el34world.com/Forum/index.php?topic=8349.0 (http://www.el34world.com/Forum/index.php?topic=8349.0)
Title: Re: ef86 as V1 - why there aren't skematics using Tone Stack ??
Post by: kagliostro on October 23, 2010, 02:04:29 am
For jojokeo

Many thanks your info will be very useful

For chocopower

Many thanks also to you, one of the ef86 V1 amp schematic I've seen is your latest version of Gaņan / Green Bullet

I've intention to mod a little 15w amp (wasn't a guitar amp) and in few days I'll post the original schematic and my version as I would like to have councils from the friends here in the forum

Kagliostro