Marshall 1987x Plexi Head New PreAmp Tubes???

[jasonmaska]

Greetings

It's about that time where I need to replace my preamp tubes, I'm noticing some crackling during my playing and I was told at at amp shop where I replaced my Power Tubes that when that happens I will need to replace my PreAmps.

I bridge my two channels together and have the volume very low on the high treble channel but near 4 on the normal channel. I notice if I bring the high treble volume up anymore, it almost breaks up immediately.

I'm looking to replace the preamp tubes to have a smoother clean tone and less easy to break up. I want to preserve the clean tone so that I can use an overdrive pedal over it (Route 66 overdrive and compression) to get my overdrive.

Currently I use Winged C's as my power tubes, I'm looking to get something that will go easily with those.

Thanks!

Jason

 

[Rodney]

I have the 100 watt version and tried the reissue mullard tubes and they were ok but ended going back to the stock tubes as I think they sounded better. All I can tell you is the stock tubes have a gold coloured marshall logo on then but not sure brand they are as Marshall don't make tubes. Everybody will have their own opinion on tubes.

 

[Tim Semeryuk]

I have the 100 watt version and tried the reissue mullard tubes and they were ok but ended going back to the stock tubes as I think they sounded better. All I can tell you is the stock tubes have a gold coloured marshall logo on then but not sure brand they are as Marshall don't make tubes. Everybody will have their own opinion on tubes.

i think marshall gets there tubes from svetlana but im not sure. please correct me if im wrong. try a pair of svetlanas. they should fit perfectly

 

[jasonmaska]

i think marshall gets there tubes from svetlana but im not sure. please correct me if im wrong. try a pair of svetlanas. they should fit perfectly

I have heard this before, I don't mind tweaking the tone a little bit, I'm looking for something that won't break up as easily. Like I said when I bridge the two channels, the normal channel is perfectly fine, but once i get past 1 on the high treble it breaks up which I'm assuming is fairly normal for that channel but I'd like to see if I could change out the tubes to have the clean last longer at higher volume.

 

[Tom99SS]

Do a searchon "Bright Cap". This may answer some of your questions.

 

[Lucifuge]

Marty's the tube man... He's the one to get in touch with here...

 

[David Corrales]

The early breakup might be because of the bright cap on the amp.

If you need less gain, try replacing V1 with a 12AT7 or 12AU7 as they provide less gain. Do a search for gain characteristics of the 12A_7 family of tubes.

 

[MartyStrat54]

In the same vein as what David was saying, I would say a 5751 or a 12AY7 as these are a more toneful sounding tube over the 12AT7 or 12AU7.

Sticking with 12AX7's, there is the Preferred Series 7025 that you could try in V1.

Based on what you want, the NOS tube would be a smooth plate Telefunken.

 

[jasonmaska]

In the same vein as what David was saying, I would say a 5751 or a 12AY7 as these are a more toneful sounding tube over the 12AT7 or 12AU7.

Sticking with 12AX7's, there is the Preferred Series 7025 that you could try in V1.

Based on what you want, the NOS tube would be a smooth plate Telefunken.

So looking at the back of the amp, V1 is the first slot for a tube? Say I use 12AY7 in V1 and then for the other two I would use 12AX7's? I plan on replacing the whole set.

Also, is this a job I can do myself? I've heard about re-biasing tube amps and all that is recommended by taking the amp into a shop. Then I watched some youtube videos saying that biasing is not needed when preamp tubes are changed out.

Thanks again for your help guys.

 

[BluesRocker]

You do not need to rebias an amp for preamp tubes. You will, however, for power tubes.

 

[David Corrales]

So looking at the back of the amp, V1 is the first slot for a tube? Say I use 12AY7 in V1 and then for the other two I would use 12AX7's? I plan on replacing the whole set.

Also, is this a job I can do myself? I've heard about re-biasing tube amps and all that is recommended by taking the amp into a shop. Then I watched some youtube videos saying that biasing is not needed when preamp tubes are changed out.

Thanks again for your help guys.

As BluesRocker said, there's no biasing for preamp tubes.

Just grab then using a soft cloth and remove them using a circular motion. Make sure to line up the pins properly when putting the new ones in. That's about it... Nothing to worry about

 

[jasonmaska]

Alright, thanks for the info. I just wanna be sure that I understand which slot is V1 though and which tubes to use for V2 and V3.

 

[Dogs of Doom]

usually, it follows the path from your guitar input to the power section.

V1 will be where you plug in your guitar.

 

[jasonmaska]

So for V1 I would use a 12ay7 and then v2 and v3 would get 12ax7's?