Rocket 66 update and PI values question

[Markusv]

Back again after some absence!

I think I have finally settled on the pre-amp values that complement the KT 66 rocket best given the Tranny set i used, voltages and the use of either 2x10 (combo) 1x12 (cab) speakers

Here is a summary

-PT Secondaries 320-0-320 (judybox donor amp)
-5U4 rectifier
-1K 20 Watt resistor instead of choke
-C2 is now a 2 nf cap instead of 500 PF
-C3 is a 200pf instead of stock 100pf ( I may install a small switch for switchable brite)
-I added C4. (22uF) I know people prefer the el 84 rockets without it in some cases, but with the KT 66's I feel it needs the "oomph!"
-I added a Mid pot ( great addition IMHO)

-For a while I had the 220K resistor to ground at the junction of R10 and C8 as per Twotone's posts, but I took it out. I felt it removed the amps testicles

Here are 2 final things I am considering:
-a proper Dynaco OT or I think RJ sells something really good?

-A switchable cathode and tail on the PI
Currently i have a switch that takes the stock values to about 500R and 15K respectively. (Cathode / Tail) It gives a slightly thicker, more Marshally sound perhaps. I'm not sure the values are optimal though because the difference is slight

Any suggestions? I would like a description if possible of the sonic changes that the combination could provide. For instance, what could I expect with a dropped Cathode resistor but keeping the tail stock? Or should I drop the tail even more? What could I expect?
I did a search and found nothing

Thanks in advance and thanks to all the incredible help in the past



BTW I just completed a 6SN7 Express and it blows me away!


Markus V

[Zippy]

-I added a Mid pot ( great addition IMHO)

Yes!

Any suggestions?

Is there something that it is not delivering for you?

What guitar(s) are you using?

Great to see you back, Markus.

[soma_hero]

Could someone post a pic or reference to how the tone stack should be wired with a mid pot?

I think i followed the descriptions when I put one in my KT66 rocket but I have weirdness in the tone stack. With bass full up, the bass drops out. Back it off 10% and then it jumps up and tapers off as it should. Mid control only works (barely noticeable) with the bass control all the way up where it drops out.

How have you guys wired it?

[Markusv]

-I added a Mid pot ( great addition IMHO)

Yes!

Any suggestions?

Is there something that it is not delivering for you?

What guitar(s) are you using?

Great to see you back, Markus.

Zippy
I was hoping for an answer from you

The shameful truth is that I have an extra hole in the chassis begging for a knob
So I thought to switch between a v0xy PI and something more like an express or a M*&*Shall
Perhaps as a means of accommodating different guitars, or getting more grind at lower volume settings.
Currently I am in single coil heaven with this amp. I have a Godin SD (Canadian made guitar with S/S/H pups) Much like some strats, and suprizingly nice for the price
I switch to a Yamaha SBG for les paul-like tones
The Godin through this amp is addictive though

As you see I am searching for someone who has had favourable experiences with the PI settings and who could describe what to do

Hope I'm making sense

Markus V

[Markusv]

Could someone post a pic or reference to how the tone stack should be wired with a mid pot?

I think i followed the descriptions when I put one in my KT66 rocket but I have weirdness in the tone stack. With bass full up, the bass drops out. Back it off 10% and then it jumps up and tapers off as it should. Mid control only works (barely noticeable) with the bass control all the way up where it drops out.

How have you guys wired it?

Soma

Here is how I wired it
From the Bass pot wiper, I connected to the outer lug of the mid pot and from the outer lug of the bass pot I ran it to the wiper of the mid and then to ground.
Can't remember which outer lugs but I'm sure you will figure that out depending on the effect when the pot is turned.

My experience is that the Mid and Bass are quite interactive, with similar weirdness when the bass is dimed, in the sense that it drops off.
My Bass is subtle to say the least but the amp has tons of "body" already so I don't need that much more.
The mid in my case, however, is fully functional regardless of where the bass is set
I also find that when the Bass is at a low setting, the mid tends to compensate a bit as I turn it up. Also, with the treble at very low settings, the mid compensates for that.
What I really like is that the amp really shines with all controls at noon and then it is a matter of small tweaks of the treble and bass to find the sweet spot for that given guitar.
If I play heavily overdriven chords I back the bass down to about 9 o'clock with the mids at 3 o'clock and treble at 2 0'clock. In this case, the cut control is rolled way back

Hope that helps
I have no diagram unfortunately

Markus V

[soma_hero]

Thanks Markus, yeah that's how I have it wired up I believe. Good to know I'm not the only one with the bass control weirdness.

I think I need to adjust some coupling caps as I'm not really able to get much treble bite. It's pretty bass heavy. This is with RJs Edcor OT. I was playing through a closed back 2x12 with noname speakers and I just mounted it last night in an open back 2x12 combo so we'll see what happens later today.

[Markusv]

Thanks Markus, yeah that's how I have it wired up I believe. Good to know I'm not the only one with the bass control weirdness.

I think I need to adjust some coupling caps as I'm not really able to get much treble bite. It's pretty bass heavy. This is with RJs Edcor OT. I was playing through a closed back 2x12 with noname speakers and I just mounted it last night in an open back 2x12 combo so we'll see what happens later today.

I should add
I used some generic 6L6's before I ordered the KT 66's and the amp was Bass heavy too. The different output tubes made a huge difference
The first coupling cap has a big impact in the overal tone and will help with having a certain voicing as a starting point, which can then be adjusted with the controls
If you have a Cathode bypass on the second stage cathode, consider reducing it to say 10 uF (for a while I even had a 8.6 uF poly cap in there)
It should help bring Bass under control

Also consider a larger value brite cap on the volume control such as my 200 pF. Remember this preamp was designed for 4x el84's- chimey tubes- and now we are dicking around with a completely different output section

Markus V