Reduce gain on express
Moderators: pompeiisneaks, Colossal
-
- Posts: 35
- Joined: Wed Oct 04, 2006 5:48 pm
- Location: UK
Reduce gain on express
Whats the best way to reduce the gain down a bit. I don't want to lose too much just a bit to make it more usable.
Cheers Karl
Cheers Karl
Re: Reduce gain on express
12AT7 in the V3 phase inverter and or 5751 in V1 or V2.
-
- Posts: 485
- Joined: Mon Mar 13, 2006 4:17 am
- Location: akron, ohio
Re: Reduce gain on express
you could add a"fast/gradual" switch
anything worth doing, is worth doing right
Re: Reduce gain on express
I have Changed dropper/decoupler string resistor (R26) from 18K to 10K
to raise the voltage of preamp tubes. I noticed this difference between a JTM45 and a 5F6-A circuit and tryed it on my express.
to raise the voltage of preamp tubes. I noticed this difference between a JTM45 and a 5F6-A circuit and tryed it on my express.
- PlinytheWelder
- Posts: 205
- Joined: Sun Jun 29, 2008 6:48 am
- Location: North Jersey
Re: Reduce gain on express
+1 on 5751 in V1 or V2 or even a 12AU7...
I like the AT7 in the PI socket, but I don't think it reduces gain there due
to it's low plate resistance interacting with the circuit. It just sounds better, IMO....
I like the AT7 in the PI socket, but I don't think it reduces gain there due
to it's low plate resistance interacting with the circuit. It just sounds better, IMO....
Gary
Re: Reduce gain on express
Mine has the 12AT7 in th PI position, and a split plate load resistor, and for me, the gain is just right.
Re: Reduce gain on express
And this reduced the gain ?crocket wrote:I have Changed dropper/decoupler string resistor (R26) from 18K to 10K
to raise the voltage of preamp tubes. I noticed this difference between a JTM45 and a 5F6-A circuit and tryed it on my express.
Re: Reduce gain on express
You can cut signal level between stages, or reduce stage gain. The former is easier and much more noticeable than the latter.populartsl wrote:Whats the best way to reduce the gain down a bit. I don't want to lose too much just a bit to make it more usable.
Cheers Karl
Cut signal level :
Turn down the volume control
Put 220K between the Treble Control center tap output and the top of the 1M Volume control.
Put 22K between the .0022 uF 2nd stage coupling cap and the top of the 150K 3rd stage grid ref resistor.
Re: Reduce gain on express
drop the feedback resistor from 100k to 47k
Re: Reduce gain on express
I simply deleted the bypass cap of the second
stage cathode resistor,that did it for me,
now I can turn the volume to 11...
stage cathode resistor,that did it for me,
now I can turn the volume to 11...
-
- Posts: 35
- Joined: Wed Oct 04, 2006 5:48 pm
- Location: UK
Re: Reduce gain on express
Thanks guys, i'll try a few things mentioned.
Thanks again
Karl
Thanks again
Karl
-
- Posts: 35
- Joined: Wed Oct 04, 2006 5:48 pm
- Location: UK
Re: Reduce gain on express
Is the feedback resistor is the one connected to presence to 8ohm tap. Just want to make sure i correct.
Cheers Karl
Cheers Karl
Re: Reduce gain on express
Yes the feedback resistor is normal 100K you can change it to the 47K as Richie suggested.
Re: Reduce gain on express
That would certainly do it. Was a change in tone/feel of the amp noticeable ?two tone wrote:I simply deleted the bypass cap of the second
stage cathode resistor,that did it for me,
now I can turn the volume to 11...
I wonder how a 5751 or even a 12AY7 in V1 would work in an Express.
It seems to me that this amp just has too much gain/distortion , or said another way too little headroom, for most people who build it.
Re: Reduce gain on express
less gain,smoother tone,PCollen wrote:That would certainly do it. Was a change in tone/feel of the amp noticeable ?two tone wrote:I simply deleted the bypass cap of the second
stage cathode resistor,that did it for me,
now I can turn the volume to 11...
I wonder how a 5751 or even a 12AY7 in V1 would work in an Express.
It seems to me that this amp just has too much gain/distortion , or said another way too little headroom, for most people who build it.
no more need to worry which bright cap to use..
turn up this volume control