EVH 5150 III - preamp tubes

[Lucky Angus]

Hi there !


I'm using the EVH 5150 III since 6 months and I'm really happy about it ! :AOK


Now ... I want to experiment a little bit changing the factory tubes in the preamp with something different. Here is the preamp tubes description:

- V1: channel 1/2/3 ... now 12AX7WC
- V2: channel 1/2 ... now 12AX7EH
- V3: channel 1/2 ... now 12AX7EH
- V4: channel 3 ... now 12AX7WC
- V5: channel 3 ... now 12AX7EH
- V6: channel 3 ... now 12AX7EH
- V7: effects loop ... now 12AX7LPS
- V8: phase inverter ... now 12AX7LPS


Do you have some "combination" to suggest me ? I alredy have some TAD, Sovtek, EH tubes to try ... :stir


Thanks for the help ! :dude

[Lucky Angus]

No suggestions ??? :hide

[RedMan]

All those tubes are made in the same factory by new sensor. You may want to try some NOS tubes. Some lower gain tubes might be a good choice for that amp.

[HipKitty]

NOS is a great start. If that's too far out of the pocket, try some of the Chinese offerings (i.e. GT-12AX7C, TAD 12AX7-C), the Mullard 12AX7, the Tung Sol 12AX7.

Though the Mullard and Tung Sols are made by the same folks (New Sensor) that make the EH's and Sovteks, each are soncially different as there are differences in materials and, sometimes, contruction.

Also, have you considered getting the amp properly biased to the output tubes?

[Lucky Angus]

Just a little "update" ...


yesterday I removed the metallic caps on the tubes and I discovered that all the 12AX7 tubes are JJ's ECC83.


I changed the first tube (#1 for chan. 1/2/3) with a TAD 12AX7 and the amps starts to sound "better" (in my hears) ...


In your opinion wich is the right "mix" ... put same tubes in all the sockets or change different types (ex.: a tube with more gain in first position and one with less gain after) ?


Thanks !

[HipKitty]

In your opinion wich is the right "mix" ... put same tubes in all the sockets or change different types (ex.: a tube with more gain in first position and one with less gain after) ?
Thanks !


That all depends on your style and the tone/response you want. Setting NOS aside, I like the Tung Sol in the first position with the TAD 12AX7-c in the other positions of our production amps.

[Lucky Angus]

So, if I understood weel, you suggest to put a more "evil" tube in the first position (where se "signal chain" starts) and than "softer" tubes in the other positions ? :hiP

[HipKitty]

So, if I understood weel, you suggest to put a more "evil" tube in the first position (where se "signal chain" starts) and than "softer" tubes in the other positions ? :hiP


Again, it depends on what type of sound and response you want from your preamp.

To me, the Tung Sol offers a little more clarity at the first stage, but has the same gain characteristics as the TAD 12AX7-C. In many amp designs, it's that 1st tube that gets amplified by other tubes (stages), so clarity there can keep some of the "mud" out of the signal. Again, the Tung Sol seems to offer better clarity (IMHO) and keeps the gain, which, in turn, works great with the Chinese tubes down the line.

Also, low microphonics are critical to me. For a while, Tung Sol was having a problem with noise and microphonics. They increased their glass (envelope) size and thickness (from what I've been told by New Sensor) to eliminate the problems...which seems to be true as I've had very good luck with them for the last several months.

Again, if you are wanting to open that amp up for better tone, get it biased to the output tubes.

[Igneous]

this is going to take a LONG time. have fun!

[beavis1]

I had a tube failure problem and Fender was excellent they replaced my Pre tubes but when I got it back it sounded very solid state not like tubes. I found they went to 8 JJ tubes. I purchased some sovtek WB tubes for V1 2 and 3 and it was better but not great. I moved a sovtek to the phase and a huge improvement.

I just got 2 LPS sovtek for the phase and loop spots.

So I have a Wc Wc Wc on ch3 a WC Wb Wb and a JJ on the loop and Wb on the phase.

It sounds realy good but could use a little somthing to get it back. Like I said I have the LPS to put in yet and then I will try a tung sol in 1 and 4 backed with all WC sovtek. and try a WC in 1 and 4 and back that with EH tubes like stock

Old stock that is

Not sure why the JJ's sounded poorly the new amps I have tried sound good with them. I do have sovtek in the power section as they were stock. That should not be why ?

[Rosewood]

I've stopped trying to use just one tube for everything, you just have to choose tubes that adds or subtracts what's needed, kinnda pi$$e$ me off but that's life.

[HipKitty]

I've stopped trying to use just one tube for everything, you just have to choose tubes that adds or subtracts what's needed, kinnda pi$$e$ me off but that's life.


This has been a trend for some time now...and with good reason. Each preamp tube serves a specific function within the amp. With the variable for each (manufacturer's) tube design, material content and manufacture, they do allow tailoring of the preamp. The same applies to the output tubes as well.

Though it can be a costly "adventure", there's a lot of fun in trying different tubes (and rewarding to most)....just beware of your amp's biasing needs when changing out output tubes.