Pre amp glass

[Big Jim]

I have been wanting to experiment with some different preamp tubes in my Express. My goal is to lower the level of normal expected hiss. Could this be achieved through the use of a 5751 or 12AT7 somewhere? I would imagine that the Express has enough gain that the amp would still rock pretty hard despite giving up a little preamp gain. Any suggestions?
Jim

[M Fowler]

You can try 5751, 12AY7, or 12AU7 or others to lower the gain. For the V1 or V2 tubes.

Keep a 12AT7 in the PI or EH 12AX7LPS in the PI.

You need to experiment with tubes and find the tubes that fits your needs.

[Big Jim]

+1 Mark......All of the NOS preamp tubes I have are 12AX7....I located some 5751 and 12AT7 for a pretty good price. I'll pick them up next week and do a little experimenting.
Jim

[Structo]

I was wondering if you guys have ever experimented with higher value grid stoppers on the input?

As we know, higher resistance values can filter high frequencies so I was just curious if any of you had tried higher values for your stopper?

[Big Jim]

Tom, are you talking about R1? I believe its 1meg in there right now. Any suggestions for a higher value? I've got some really good shielded cable I've been wanting to try, I'll redo the input wiring at the same time.
Thanks,
Jim

[PlinytheWelder]

IIRC, there are no grid stoppers on the input...

And a lot of other places that amps usually have them.. Gives 'wrecks their
sound in part.

[Big Jim]

My bad.... grids

[selloutrr]

Have you tried tubes tested for low noise?

Most tube depots can test for matching, microphonics, and low noise. Hiss is a common issue in hi gain amps.

once tubes tested for low noise are installed (so you now you have a solid foundation to work off) if the problem persists then you can try lead dressing to further quiet the amplifier.

[M Fowler]

Tom,

I have tried 15k and 33k grid stoppers on my Ceriatone Express.

[ampdoc1]

My Two Rock Ruby express I finished last week uses a V1-5751, V2-12AU7 and V3-7025. Almost no hiss, and the beast will feedback on just about any note played. This is the 4th express-type amp I've built, and I've always used a lower gain V1, then experimented with the other two for the best response.

ampdoc1

[geetarpicker]

I've been doing some old school country sessions lately with my Express down on "Music Row". I put a 12AU7 in V1, and a 12AY7 in V2 and leave the rest stock. At that point with a Fender Tele the amp isn't even that dirty dimed. Kept back at 1/2 it's barely breaking up at all and takes pedals well especially a Keeley compressor. Noise is a non issue even during light ballads.

Then if the next tune is a rocker and/or "modern" country I swap the tubes back, and skip the pedal board.

[Cliff Schecht]

I love the Express with a good compressor. I don't remember what circuit the Keeley is based off of but I use a homemade Orange Squeezer clone with big grins on my face. If you get the volume set right, it can be used as that perfect "channel" switch to get between spanky clean and dirty quicker. This way I get to use my awesome stock tube sets and can get all of the distortion that I'd ever want for solos and such. May not be necessary for country sessions but is great for the bar!

[Big Jim]

Have you tried tubes tested for low noise?

Most tube depots can test for matching, microphonics, and low noise. Hiss is a common issue in hi gain amps.

once tubes tested for low noise are installed (so you now you have a solid foundation to work off) if the problem persists then you can try lead dressing to further quiet the amplifier.

I actually saw the tested range tubes on the tube depot site the other day...might give those a try! Thanks,
Jim

[Big Jim]

I've been doing some old school country sessions lately with my Express down on "Music Row". I put a 12AU7 in V1, and a 12AY7 in V2 and leave the rest stock. At that point with a Fender Tele the amp isn't even that dirty dimed. Kept back at 1/2 it's barely breaking up at all and takes pedals well especially a Keeley compressor. Noise is a non issue even during light ballads.

Then if the next tune is a rocker and/or "modern" country I swap the tubes back, and skip the pedal board.

Glen,
This is the concept I had in mind..... only to a lesser degree. Maybe a 5751 in V1 and a 12AT7 in V2. To decrease the gain a little, and hopefully make the amp a little friendlier to recordings, pedals, etc.
Thanks,
Jim

[selloutrr]

Then if the next tune is a rocker and/or "modern" country I swap the tubes back, and skip the pedal board.[/quote]

tube swapping works great if you are in a studio session but swapping hot glass during a show can be hard on your playing fingers and cause restless crouds. Wait until the croud is well lubricated so the bass player's lame jokes sound funny while he buys you some time

Awesome you can make the amp fit your needs and get so much use out of you wreck!