270k or 470k mixer resistors ?

[suede]

I'm sure it has been asked before. Sorry. I've gone through tons of threads and can't find what I'm looking for. Help... I have a Metro 50 watter. I've been tweaking it for quite some time now. Never really satisfied with it's tone. I've gone from one extreme to the other, lead to bass specs and everything in between. I finally believe I've found what I've been looking for. Has anyone tried this and what opinions are out there. I have a split cathode 1.5k/250uf on V1a, 2.7k/.68uf on V1b, 270k mixers with 500pf mica cap, cascade 1 wire mod, lead specs to tone stack 56k/250pf stack, .1uf coupling caps on the PI, 47k on 8ohm tap, Mercury Mag Iron Metro choke that came with the kit, dropped the B+ from 445V to 435V with a xicon 10 watt 150 ohm wire wound resistor mounted on a custom red mini turret board, just a little less clean headroom, 250pf bright cap, EL34's biased at 70%/41mA, B+ is at about 400V idle. Lar/Mar master. V1 Tungsram NOS 1970 12AX7, V2 Tung Sol reissue 12AX7, V3 JAN Phillips NOS 5751, EL34's are SED winged "C". Did this with the 470 mixers and the bass was loose as a goose but with the 270 mixers to me anyway it tightened the bass right up. Set up seems perfect. Run the head into a 412 closed back cab loaded with 2 vintage 30's and 2 G12H anniversary's. Gibson SG with Angus Young pickup in the bridge. I'm going to leave her this way unless some one talks me out of it. What do you think? Just want to thank everyone for contributions to this site. What a wealth of knowledge. George you're the man....

Suede

[xbearxau]

Thats pretty close to where I ended up with my 50 watt build.
Here are the differences.

I have a split cathode 1.5k/250uf 1uf on V1a, 2.7k/.68uf on V1b, 270k 470k mixers with 500pf mica cap No Cap, cascade 1 wire mod, lead specs to tone stack 56k/250pf 500pf stack, .1uf 0.022uf coupling caps on the PI, 47k on 8ohm tap, Mercury Mag Iron Metro choke that came with the kit, dropped the B+ from 445V 445v to 430V with a xicon 10 watt 150 ohm wire wound resistor mounted on a custom red mini turret board, just a little less clean headroom, 250pf 100pf bright cap, EL34's kt77's biased at 70%/41mA,35ma B+ is at about 400V idle. Lar/Mar master. V1 Tungsram NOS 1970 12AX7, V2 Tung Sol reissue 12AX7, V3 JAN Phillips NOS 5751, EL34's are SED winged "C". Did this with the 470 mixers and the bass was loose as a goose but with the 270 mixers to me anyway it tightened the bass right up.

I have one other main difference that I suggest you try. Change the 250pf fizz cap back to 100pf, put back the 470k mixers BUT also put a 470k between the input of V2 and ground. This forms a voltage divider and bleeds of a little of the high end harshness that you seem to be trying to get rid of with the 250pf fizz cap. Also found that when cascaded thwe 0.1uf PI caps made my build too farty no matter what. If you can be bothered try the 0.022uf's again with my other suggestions.

This is just a quick photoshop on a stolen pick of Ceriatone's site, but youll get the idea. It still looks stock on my board.


Strangely enough the values I ended up with were almost the same as what you find in the HO from AX84.com. Sounds huge, tight and never harsh. You'll also find you wont need the 5751 in the PI any more. 12ax7 will work a treat. Closest sound I can relate it to with my Eminence loaded 2x12 is Appetite GnR's.

You know you want to try it....................

[suede]

Made 1 change the fizz cap on volume pot from 250pf to 100pf. Still haven't been talked out of my set up. Sorry xbearxau, just goes to show our age difference, no offense but hate GnR.

[suede]

Ok really had a chance to nut my rig. Giving her the full dose. If ones heard AC/DC's VH1 Gone Shootin I nailed it. Best tone IMO that I've ever heard. I'll post a sound clip shortly. What makes the difference I think is #1. changing the 470k mixers to 270k, Big huge tight Bass. #2. I think I have to thank novosibir for this one. In a post here who knows where, oh I think it was the tube section, he mentioned that a 5751 in the PI helps to stablize the PA section. I think he's 100% right, thanks man. I honestly believe that for me that was the crowning jewel. For this type of tone...

Suede

[xbearxau]

Well Im 34 so you must be ancient!!!!!!!

Maybe GnR wasnt the best comparison.

[suede]

Heh xbearxau really didn't mean to offend. Thanks a ton for your reply to the post, there's always some new info to digest. Appreciate it. Oh ya 48, guess I am ancient...



Suede

[xbearxau]

No offence taken mate. Isnt it funny, ones mans Holy Grail is another mans headache.
Take EVH for instance, 99% of people get of on the VH1 tone, and I cant stand it. WACF and VHII for me!!!!! Maybe Im just tone deaf?!?!?!?!?!?! haha.

Would love to hear the clips of your current setup.

[HARLEYIII]

I swapped mine out for 220K and like the difference.

[Roe]

more important than the resistor value by itself is how it works together with the 500/560pf cap. this works as a high bypass on the bright channel. the 470k/560pf combo lets through much more low mids than the 270k/560pf combo

[Roe]

qouting chris merrem:

These two resistors which make up the "mixer" resistors is really a VOLTAGE DIVIDER.....
The sum of the two resistors is in PARALLEL with the 100K plate resistor and is also in parallel with the 1M pot....So with 270K resistors the loading the 12AX7 sees is 100K//(270K+270K)//1M = 77.8K load and a Gain of 56.4 before the mixer..than after the mixer it would be 28...

With 470K mixer resistors you get 100K//(470K+470K)//1M = 83K load and a Gain of 58 before the mixer and after the mixer it would be 29....
So the gain difference linearly is small but the harmonic content is a bit bigger with the 470K resistors...so you get a "thicker" sound with the 470K resistors since it has less loading affects on the 12AX7 gain stage..
The 500pF cap place on the 270K mixer resistors provides enhanced treble...BUT when changing to 470K resistors you would need to move the cap value down to 330pF to maintain the "same" treble boost as the older circuit..

[neikeel]

qouting chris merrem:

These two resistors which make up the "mixer" resistors is really a VOLTAGE DIVIDER.....
The sum of the two resistors is in PARALLEL with the 100K plate resistor and is also in parallel with the 1M pot....So with 270K resistors the loading the 12AX7 sees is 100K//(270K+270K)//1M = 77.8K load and a Gain of 56.4 before the mixer..than after the mixer it would be 28...

With 470K mixer resistors you get 100K//(470K+470K)//1M = 83K load and a Gain of 58 before the mixer and after the mixer it would be 29....
So the gain difference linearly is small but the harmonic content is a bit bigger with the 470K resistors...so you get a "thicker" sound with the 470K resistors since it has less loading affects on the 12AX7 gain stage..
The 500pF cap place on the 270K mixer resistors provides enhanced treble...BUT when changing to 470K resistors you would need to move the cap value down to 330pF to maintain the "same" treble boost as the older circuit..

Ah - that is why my 390pF on the mixers works so well - forgot where I read that was a better value (my have been Larry sometime )

[uiovbged332]

Nike Outlet Store Online Shopping
Ferragamo Shoes
Jordan Retro 4
Air Jordan 11
Moncler Jackets For Women
Golden Goose Shoes Men
New Jordans
Jordan 1
Nike Air Force 1 High
Nike Shoes Outlet
Pandora
Jordan Shoes
Jordan 11s
Harden vol 1
Jordans Sneakers
Jordan 4
Moncler Jacket
Air Jordan 11
Nike Shoes
Adidas Yeezy
Moncler Outlet
Red Bottom Shoes
Air Jordan Sneakers
Pandora Jewelry
Jordan 11
Jordans Sneakers
Pandora Rings
Moncler
Air Jordans
Jordan 10
Pandora Rings Official Site
Jordan Retro
Pandora Charms
New Jordans
Nike Shoes
Air Jordan Shoes
Fjallraven Kanken
Christian Louboutin
Jordan 9
Jordan 8
Air Max 90
Moncler Jackets
Pandora Jewelry Official Site
Jordan 6 Rings
Moncler Outlet
Jordan Retro 5
Jordan 11
Jordan Shoes
Golden Gooses Sneakers
Harden Shoes
Jordan 13s
Jordans 11
Jordan Retro 12
ECCO Shoes For Men
Air Jordan
Ferragamo Shoes
Yeezy
Jordans Retro
Pandora Charms
Cheap Jordans For Sale
Air Jordan 4
Air Max 2018
Golden Goose Sneakers
Retro Jordan
Nike Air Jordan 5
Mens Nike
Yeezy Shoes
Air Jordan 12 Retro
Yeezys
Pandora Jewelry Official Site
Louboutin Shoes
GGDB
Jordan 11
NMD R1
Valentino
Air Jordan 4
Jordan 6
Jordan Win Like 96
Nike Outlet
Jordan Retro 11 Mens
Pandora Charms
Jordan 12 Retro
Adidas Yeezy
Jordan 11 Red
Fitflops Clearance Outlet
New Nikes
Balenciaga Sneakers
Pandora
Jordan Retro
Fitflop Shoes
Nike For Women
Soccer Cleats
Pandora
Jordan 5s
Kyrie Irving Shoes
Cheap Air Max
Pandora Bracelet Charms
Nike Outlet Store
Moncler Outlet
Hermes Birkin
Jordan Shoes For Men
Air Jordan Shoes
Adidas NMD
GGDB Sneaker
Air Max 95
Jordan 11s
Golden Goose Outlet
Golden Goose Outlet
Nike Snkrs
Golden Goose Mid Star
Nike Factory
Nike Sale
Jordan 3
Jordans Sneakers
Nike Factory
Jordan Retro 3
Air Jordan 11
Nike Air Force One
Pandora Canada
Golden Goose Sale
Yeezy
Moncler Store
Red Bottoms Louboutin
Jordan 14
Nike Official Website
Nike Air Max 98 Cone
Golden Goose Sneakers Men
Nike Air Max 270
Golden Goose
Nike Huaraches
GGDB
Red Bottoms
Balenciaga Sneakers
Air Jordan 12
Moncler Vest
Jordan 6 Retro