12AT7 in V1 (5153 content)

[bonedish]

Hey all,

I know I don't post here often, but I was wondering if y'all could help me out a little.

Last night I swapped out my preamp tube in V1 in my quest to lower the gain and in the 5153 50 watt. To my surprise, it really didn't alter the levels of gain very much at all. I tested it afterwards at low volume levels as well as with the volumes on each channel at 10:00 - again, no decrease in the amount of gain.

The reason I attempted this was 1) to be able to turn up the gain in the green channel to have a cleaner clean tone and to eliminate the volume jump when switching from green to blue and 2) to maybe try and get a low/bluesy/crunch tone from the the blue channel (think AC/DC, Aerosmith). My amp just seems to be be all gain all the time, IME. I don't use effects very often, so the MIDI/effects processor route is not an option at this current time.

I'm beginning to wonder if there are clipping diodes the gain stages? I've attempted preamp tube swaps in V5 as well with no change. Is a 12AT7 useless in the V1 spot? Would a 5751 be better? I'm still learning (always), so please let me know what I can do?

Thanks!

 

[mixn4him]

V1 – Channel 1, 2, 3
V2 – Channel 1, 2
V3 – Channel 1, 2
V4 – Channel 3
V5 – Channel 3
V6 – Channel 3
V7 – Effects Loop Drive/Recovery
V8 – Phase Inverter
V9, V10, V11, V12 – Output Tubes

Probably better to try in V2 or V3 position....V1 just gets the gtr level up in the preamp stage, gain ie distortion is happeneing later in the circuit...

 

[bonedish]

Thanks, bro but that's the layout for the 100 watt - mine is the 50 watt.

 

[ejecta]

I'm going to put these in V1 and V2 on my EVH 50 watt tonight. I'll post back what I find.

https://tubedepot.com/products/jj-5751-preamp-tube

 

[RockStarNick]

Bonedish -

I'm no tube expert, but I've done quite a bit of swapping. In my research, I've read that although the pin layout is the same and a 12AT7 can *function* in the same place as a 12AX7, it's not really a "tone" tube. It's more of a utility tube, for reverb circuits.

If you want to really lower the gain, try a 5751. You can get great US Military NOS versions all day long for about $20-30 bucks, and the're about 70% of the output of a 12AX7.

I got much better results using them (sweeter, more harmonically "right") than the AT7s, which sounded kinda cold to me.

 

[bonedish]

@ejecta: thanks!!! Yes please let us know the outcome!

@RockStarNick: thank you for your input. What you postd makes more sense the way you explained it!

 

[Junk Yard Dog]

I'm going to put these in V1 and V2 on my EVH 50 watt tonight. I'll post back what I find.

https://tubedepot.com/products/jj-5751-preamp-tube

Let us know!!

 

[ejecta]

The lower gain JJ 5751's were the ticket for me. Tamed the gain nicely and opened up the tone a bit more.

 

[bonedish]

Very cool, thank you ejecta! I've ordered a JJ 5751as well as some lower gain EH 12AX7s. They should be here Friday & I'll let y'all know my findings as well.

 

[nevusofota]

Let us know how the 5751 works as I'm looking to do the same in my 50w.

Per Howard Kaplan, there are no clipping diodes. What is different is the fx loop is solid state where as in the 100w the loop is tube buffered.

 

[C1-ocaster]

Very cool, thank you ejecta! I've ordered a JJ 5751as well as some lower gain EH 12AX7s. They should be here Friday & I'll let y'all know my findings as well.

I had a Peavey XXX 60 watt 1x12 and a JSX 2x12.
Very high gain amps, so much so that they could easily get fuzzy fizzy.
I had a pair or Jan Phillips 5751's, the one's that rate close to 12ax7's in gain but are on the lower side.
They really helped the overall tone in both amps.

The gain felt to be nearly the same, but the quality of the gain felt and sounded nicer and more controllable.
It's a great sounding sounding tube in my experience.
I don't know about the JJ's version as I've never tried it.
I did try a JJ's 12at7 in both amps and I still liked those tubes as well. But the Jan Phillips was harmonically and musically richer.

I find V1 to be very important in any tube amp.
It's THE Tube that sets the initial tone and gain.
The subsequent tubes will add gain as the signal moves on, but the subsequent tubes can only add gain to the signal and tone before it, and that's V1.
Get the best sounding tube you can in V1 and then work the gain on up.

Also, the phase inverter is very darn important and some people don't pay much attention to it.
It's the tube that "reassembles" the signal before it hits the power tubes and it's very important.
Some have said to NOT get a balanced PI tube contrary to conventional wisdom, citing that with an unbalanced PI it enhances tonal quality.
I think there may be something to that. I had always used a balanced PI but a couple of months ago I started swapping tube in the PI position and have settled on Sovtek LPS, and of the 3 I have not one is balanced.

 

[the grimbrewer]

A good 5751 definitely gives more of a vintage feel and sound. Got a Stephenson Stagehog, nice little 1W amp or can be used as a distortion pedal. If I wanna' know what a 12ax7 type tube sounds like I just shove it in there and you know right away whatcha' got.

 

[bonedish]

Got the tubes in the mail today! I will try and put them in tonight and mess around for a bit if I get a chance.

@ C1-ocaster: thanks for that input. Funny thing, I actually ordered a Sovtek LPS for my PI spot when I placed the order for the JJ 5751 (along with a couple of lower gain rated EH 12AX7s and a couple of Ruby AC5 HGs).

@ the grimbrewer: thanks for that - that's exactly what my aim is in popping the 5751 into the V1 spot! I'll be looking into that Stagehog as well - sounds like a cool concept!

I'll report back to y'all soon.....

 

[C1-ocaster]

Got the tubes in the mail today! I will try and put them in tonight and mess around for a bit if I get a chance.

@ C1-ocaster: thanks for that input. Funny thing, I actually ordered a Sovtek LPS for my PI spot when I placed the order for the JJ 5751 (along with a couple of lower gain rated EH 12AX7s and a couple of Ruby AC5 HGs).

@ the grimbrewer: thanks for that - that's exactly what my aim is in popping the 5751 into the V1 spot! I'll be looking into that Stagehog as well - sounds like a cool concept!

I'll report back to y'all soon.....

I'll look forward to your review.

 

[bonedish]

OK, so my initial impressions after changing the tubes and 30 minutes of playing at low volumes (I have yet to try higher volumes

Before (following the circuit path from CH1/CH2 then CH3
V1-Phillips 12AT7
V5-EH
V6-JJ (ECC83)
V2-Tungsol
V3-EH
V4-JJ
V7 (PI)-JJ

After:
V1-JJ 5751
V5-EH (slightly lower gain 110/100)
V6-Ruby AC5 HG
V2-Tungsol
V3-EH
V4-Ruby AC5 HG
V7(PI)- Sovtek LPS

With the new preamp tubes, I actually like the tone of the amp a lot better than what I had before. The tone is much clearer and a little "sweeter" to my ears - not as fizzy as it had been. I think the combo of EH, Rubys and LPS tubes make a great difference. I'm sure the 5751 is also adding that sweetness and clarity as well.

As for the gain level- it is still the same (so far at lower volumes). The clean channel is only marginally cleaner, but the tone is better as well. Not as gritty as it had been before.

Channel 2/blue still has a lot of gain. My quest for finding a lower-middle gain will not be found with this amp, I now realize. Maybe in the 100 watt? I'm not saying that the tone is bad at all - it's actually A LOT better afar the tube change out (initial impression) - but I realize if I want my lower gain tones (think JTM45/bluesy) I'll need to find it in another amp. My 5153 50 watt seems like its all high gain, all the time. Although, my work-around right now is rolling back my volume knob in channel 2 - works ok for the lower bluesy gain I'm seeking.

If I don't get called into work tomorrow I'll play it at higher volumes (9-10 o'clock).

 

[bubbastain]

I really liked the 5153 50 watter each time I have played it at GC but always felt it had way more gain than I would ever use. Blue channel I like it around 11 O'clock and the Red channel I really don't like it higher than 9 O'clock. I mainly play heavy stuff too. I also wondered about putting lower gain tubes in. Nice to hear your review.

 

[nevusofota]

I really liked the 5153 50 watter each time I have played it at GC but always felt it had way more gain than I would ever use. Blue channel I like it around 11 O'clock and the Red channel I really don't like it higher than 9 O'clock. I mainly play heavy stuff too. I also wondered about putting lower gain tubes in. Nice to hear your review.

I have both versions and have played the 100w now for 7 years. I agree, it has way more gain than I use live. However, it's nice to have it on tap for the occasional low volume bedroom playing. It's why I could never understand the need for even more gain as in the 100s.

 

[bonedish]

So I got to turn it up to 9:00 yesterday and the gain definitely smooths out on both channels very nicely, and the gain on the blue channel is slightly less. All in all a bit nicer but after doing this I feel like the head has pretty much 2 slightly different flavors of high gain and a clean channel. Turning the gain down in the blue channel helps a little, but the gain is still a little on the high side for my likes plus I lose the clean channel. I'm not a rack/effects guy, so the MIDI/fx loop trick is not going to work for me (since I don't have much more than a delay pedal - no rack unit).

I used to own a 100 watt head, but foolishly got rid of it in a phase of "downsizing" that, looking back, really didn't need to happen!!! I agree with the above posts that the 100 watt head (the original - not the 100S or the newer ones that have increased gain) was more versatile than the 50 watt. The blue channel's gain on the 100 watt was smoother and less, and a bit more versatile when dialing it in (IIRC).

The slight mistake I made was buying the 50 watt assuming that it was going to be exactly like the 100 watt. Still, the 50 watt is a GREAT amp with awesome tones, but I think I need to find/trade for a 100watt head for the added versatility.

Thanks everyone for your help and input!