5751's?

[lingering_lead]

I just ordered some JAN Philips 5751's to replace the 12AX7's in my MKIIb. Has anyone had any experience running these in their MK Boogie's?

I should point out that I do not use the gain channel on my boogie and use pedals for gain.

-rob

 

[stokes]

They are great for smoothing out and reducing the gain/distortion.Most effective in the first stage.I have them in the V1 position in all my amps but one,which has an even lower gain 12AY7.

 

[lingering_lead]

They are great for smoothing out and reducing the gain/distortion.Most effective in the first stage.I have them in the V1 position in all my amps but one,which has an even lower gain 12AY7.

Thanks for the info. So, do you still use 12AX7's in the other stages of your boogies?

I also have a NOS Mullard 12AT7. I found it too mellow for another el-84 based amp. I should try it in the MKII at V1.

Interestingly, I have put other (new) 12Ax7's in the V1 position of the MKII and found them to be much harsher than the old stock boogie 12ax7's I have.

 

[stokes]

In my IIC+ I use it in V1 and the input of the lead channel,which I believe is V3.All the others are AX7's.I find the AT7 is too flat anywhere but the PI or the reverb drive.To me all new production AX7's sound harsh,prefer various NOS.In all my other amps I have 5751's in V1 with AX7's in the other positions except for a couple of AT7's in the PI of a couple of amps.I have a SOB that has the 5751 in V1,At7 in the PI,but I havent seen that amp in a few years,loaned it to a friend.

 

[dodger916]

In my IIC+ I use it in V1 and the input of the lead channel,which I believe is V3.All the others are AX7's.I find the AT7 is too flat anywhere but the PI or the reverb drive.To me all new production AX7's sound harsh,prefer various NOS.In all my other amps I have 5751's in V1 with AX7's in the other positions except for a couple of AT7's in the PI of a couple of amps.I have a SOB that has the 5751 in V1,At7 in the PI,but I havent seen that amp in a few years,loaned it to a friend.

+1. I love the way the 5751 in V1 smooths out my C+ without neutering it.

 

[Monsta-Tone]

I've always been curious about them.
I'm with Stokes, I've had very little luck with AT7's anywhere but the PI or the Reverb. They just seem to suck the sparkle right out of an amp!

 

[lingering_lead]

I put a 5751 in V1 and it sounds good.

 

[Monsta-Tone]

How did it affect your distortion channel?
What kind of noticable differences do you hear and feel in the clean channel?

 

[CoG]

I started doing the 5751 thing in the V1s of my Mark IIIs. Personally, I don't think it makes any difference in the "tone" of the amp, it sounds exactly the same to me, the difference is that it makes the lead channel more manageable when I have the EQ set for volume balance across all three channels. When I have Volume at about 7.5, Master at about 3, Lead Drive juuuust short of 7, and Lead Master at about 5.5, I have balanced volumes but with a normal 12Ax7 the lead channel has just a little more distortion than I want. With the 5751 the volumes still balance but the lead channel smooths out a little bit. Note that this isn't a really high-gain sound, though. The clean channel stays a little bit cleaner unless I use fairly hot pickups.

 

[lyman]

I have a JAN Phillips 5751 running first in my Maverick's lead channel. I wanted something to make that channel a little less nasty and I am happy with the result. It's still nasty, but in a good way! 8)

 

[Gruffnutz]

I ahve a JAN Philips 5751 in V1 in my Caliber .50+. V1 is used only for the lead channel in this amp and it mellows it out a bit and improves the balance with the clean channel. The balance bit is important in the .50 Cal as the gain control is shared between the channels.

I agree with the abovr comments on 12AT7s, they're not really appropriate for pre-amp gain stages. Good as PI and reverb drivers.

12AU7s and 12AY7s are the really low gain alternatives for pre-amp gain stages.

 

[RedEyeJedi]

12AU7s and 12AY7s are the really low gain alternatives for pre-amp gain stages.

do u know, if so, in what way would they affect your tone??

I use a studio .22+ and would really like a little more clean headroom so im thinking of switching the tubes to lower gain ones like the above mentioned~

 

[edward]

I run a NOS RCA 5751 in my V4 spot (the clean channel and right after the V1) on my DC5 it smooths out the highs (seems to attenuate the upper highs) and more solid/tighter bottom ...just "rounder" and smoother overall, especially with edge of clip tones. Beautiful!

FWIW, I also ran 12AT7 on the PI and V1, V2 on my MkIII simul greenie. Really made the R1 channel clean and lush, again, "rounding" the tone which was, IMHO, too "hard" a clean with ax7s in there. Not to mention it made the R2 truly usuable as I deplored the R2's tone with the ax7s initially. For my tastes, "softening" the gain structure with good at7s really made my MKIII sing!! BTW, Mullard NOS cv4024s are much cheaper than their NOS ax7s.

Edward

 

[MesaDCLP]

Myles Rose provided me with this about the 5751's.

If you want to use an AT7 in the phase inverter position for more clean headroom that is fine but I prefer an NOS 5751 which has the same gain but is less "sudden" in the attack.... a much smoother tube.

Still have yet to try it, but smooth always sounds good to me.

 

[Tacoiardul]

here s a nice article about these preamp tubes
http://thetubestore.com/gainfactor.html