I'm fond of using a pair of resistors to simulate a heater center tap. I'm also a fan of biasing the "center tap" at a DC voltage that's more positive than the cathodes in the preamp stages.
Thanks for the vid Lyle. When you say lav mic clipping I assume you actually mean the lav mic clipping the input of your sound-card. You may be able to put a Y cable from the mic to two inputs of the sound-card and run one at lower gain, then pick the appropriate track in editing.
I just run the lav into the phone for on the bench recordings and adjust as needed. For real playing videos the amp gets a separate mic and I mute/unmute the lav in post.
Always been curious about the yellow and white Mallory (M150?) caps (not the old electrolytics Fender used in the 70s). I always seem to see a mixture of those and rarely all one or the other. Do they have different characteristics or is it just that the yellows pre-date the whites?
@PisionicAudio You’ve answered a question I’ve been thinking about a while. I recently built a 5e3 and Mojotone called for a twisted pair for the heater. Then I noticed my original tweed deluxe only had one and also my vibro champ. This explains it. Do you normally add the other wire when you do a service or only when it really needs it ?
Lyle, you know so much about these tweed amps. I have a 1957 5E3 and I want to do some what I call upgrades. Would putting in a choke where the 5K dropping resistor is for the screen grids make the amp more quite or is that too much voltage on the 6V6s screens? Also the 5F11 has a neg. feedback 56K resistor. Would that give any benefit to the headroom or overall volume output of the amp? The heater supply change like you describe one could do like it this 5F11 would also be an upgrade. You really know your your stuff on tube amps so any input from you on these subjects would very helpful! ❤️🌨 Colorado. Thanxz
Thanks man. I wouldn’t mod a ‘57. Choke won’t give much/any benefit. NFB changes the character but again, it’s a ‘57. If you want to see some subtle effective changes look for the ‘58 5E3 on here.
Coffee helps with EMBS . Well the 50ohm RCA connector are at best they are cheap . Used by most so changing to a far better connector not in the cards for most people. Cost control is a major factor in that amp . Not using a center taped heater is more lazy than cheap given you can make a pseudo center tap with 2 resistors .
Yeah, you expect to find an unbalanced heater supply in a single-ended, student-level amp such as a Champ, but not in a mid-level unit like a Vibrolux. Actually, you could argue that the single-ended amp needs a balanced heater supply more than the mid-level push-pull amp, because the push-pull amp has better common-mode rejection and would cancel some heater-circuit hum in a way that the S-E amp would not.
@@goodun2974 With S-E amps I prefer a dc heater regulated to 97% rated voltage and elevated about 45 volts above ground reference . Found that the h-k internal capacitance need that bias to be quieter. This is a bit in the weeds for most people .
@@johnwilliamson467 there's more than the internal capacitance in play here. If the cathode is more positive than the heater in any part of the ac cycle, it will draw a small amount of current and introduce noise. DC supply for heaters isn't uncommon in the hifi world but adds more complexity (and cost) than we usually see in a guitar amp. A pair of resistors to emulate a center tap and biasing that well above the cathodes in the preamp section is a dirt-cheap and effective improvement even though it's not as effective as a DC heater supply.
@@retread1083 interesting does give a fine reason for the need for bias of at least 45 volts. Have seen bias tap on power trans work as an ac bias 70 volts . Works very well .
If the owner wants you to re wire the heaters, it might be fun to hear the difference (if possible with a recording) in a future video.
First cup of coffee at 8:30 and working on cool vintage amps.....your living the good life Lyle!
Good vid. Really enjoyed listening and learning.
I'm fond of using a pair of resistors to simulate a heater center tap. I'm also a fan of biasing the "center tap" at a DC voltage that's more positive than the cathodes in the preamp stages.
Does the Selenium Rectifier Add more SAG compression? any reasons why they used selenium rectifiers
Thanks for the vid Lyle. When you say lav mic clipping I assume you actually mean the lav mic clipping the input of your sound-card. You may be able to put a Y cable from the mic to two inputs of the sound-card and run one at lower gain, then pick the appropriate track in editing.
I just run the lav into the phone for on the bench recordings and adjust as needed.
For real playing videos the amp gets a separate mic and I mute/unmute the lav in post.
Thanks for the info.
Always been curious about the yellow and white Mallory (M150?) caps (not the old electrolytics Fender used in the 70s). I always seem to see a mixture of those and rarely all one or the other. Do they have different characteristics or is it just that the yellows pre-date the whites?
Deep dive into the secret sauce. Thank you Sir.
@PisionicAudio You’ve answered a question I’ve been thinking about a while. I recently built a 5e3 and Mojotone called for a twisted pair for the heater. Then I noticed my original tweed deluxe only had one and also my vibro champ. This explains it. Do you normally add the other wire when you do a service or only when it really needs it ?
Just wondering what the yellow caps are in the middle of the board? Great vids thank u
The yellow and white caps are all Mallory 150Ms. They went through a period of making white and yellow ones, now all back to yellow.
@@PsionicAudio Awesome! Thank you
Lyle, you know so much about these tweed amps. I have a 1957 5E3 and I want to do some what I call upgrades. Would putting in a choke where the 5K dropping resistor is for the screen grids make the amp more quite or is that too much voltage on the 6V6s screens? Also the 5F11 has a neg. feedback 56K resistor. Would that give any benefit to the headroom or overall volume output of the amp? The heater supply change like you describe one could do like it this 5F11 would also be an upgrade. You really know your your stuff on tube amps so any input from you on these subjects would very helpful! ❤️🌨 Colorado. Thanxz
Thanks man. I wouldn’t mod a ‘57. Choke won’t give much/any benefit. NFB changes the character but again, it’s a ‘57.
If you want to see some subtle effective changes look for the ‘58 5E3 on here.
Put a footswitch in one of the open jacks and you can switch between two different gains.
Ahh the lower octave morning voice. Sounds like a radio show.
Is the volume pot linear or audio? Schematic says linear
Hi Lyle, busy as ever I see. Don’t work too hard.
So...this clients amp is bi-polar...?🤔
Cool amp...really looks like a cool design 😎👍
Coffee helps with EMBS . Well the 50ohm RCA connector are at best they are cheap . Used by most so changing to a far better connector not in the cards for most people. Cost control is a major factor in that amp . Not using a center taped heater is more lazy than cheap given you can make a pseudo center tap with 2 resistors .
Yeah, you expect to find an unbalanced heater supply in a single-ended, student-level amp such as a Champ, but not in a mid-level unit like a Vibrolux. Actually, you could argue that the single-ended amp needs a balanced heater supply more than the mid-level push-pull amp, because the push-pull amp has better common-mode rejection and would cancel some heater-circuit hum in a way that the S-E amp would not.
@@goodun2974 With S-E amps I prefer a dc heater regulated to 97% rated voltage and elevated about 45 volts above ground reference . Found that the h-k internal capacitance need that bias to be quieter. This is a bit in the weeds for most people .
@@johnwilliamson467 there's more than the internal capacitance in play here. If the cathode is more positive than the heater in any part of the ac cycle, it will draw a small amount of current and introduce noise. DC supply for heaters isn't uncommon in the hifi world but adds more complexity (and cost) than we usually see in a guitar amp. A pair of resistors to emulate a center tap and biasing that well above the cathodes in the preamp section is a dirt-cheap and effective improvement even though it's not as effective as a DC heater supply.
@@retread1083 interesting does give a fine reason for the need for bias of at least 45 volts. Have seen bias tap on power trans work as an ac bias 70 volts . Works very well .
A coffee before play keeps EMBS away!
"Bipolar Heater Supply" ... new tech term, yay!
It’s not quite accurate. I should have said balanced. Insufficient coffee tech speak.
So,, to simplify,,, input one is P A, input two is kind of P A and input three is kind of P A but best for guitar.
Maybe a Monster Cable jumper would be better.
😮🤭