Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: plexi50 on August 22, 2012, 10:49:10 pm
-
Can a fender tonestack be put in place of the stock YSR1 tonestack?
The more i look at the two .1 coupling caps joining the 100k resistors feeding the tonestack the more confused i get
What can i do with this diagram. Im brain freezed again. The bottom pic with a fender tonestack is what i have in mind
Im missing something that has to do with the .1 coupling caps C7 & C8
-
The plate is at 146V. You want the tone-parts nearer ground for safety and because that's where you'll dump unwanted tone. So you need a cap blocking the DC at the plate. If picked large (0.1u is pretty large against 100K and guitar) the cap serves no other purpose.
The amp surely has _two_ inputs and input tube stages (one not shown in your crop). Therefore you simply use two blocking caps. (You 'could' instead use one cap _after_ the two 100K mixing resistors. Not sure why they didn't. Perhaps they doubled-up an existing one-input layout and didn't cast-out all redundancies. Or maybe they were afraid of the small DC current flow if the two tubes were not near-matches.)
Your #2 drawing will work. The Fender stack is usually driven from _one_ plate, not two. One Fender stage, the output is 39K. The traynor two tubes and two mix resistors, the output is 70K. This will shave some of the extreme settings possible in a Fender. May not matter.
The Fender stack, uniquely, already has caps before all pots. DC is blocked. You could omit Traynor's 0.1u caps. The small cross-plates DC current does no harm.
-
Thanks PRR. Thats what i was debating last night. Loosing the 0.1 caps. I re did the schematic again to show all
-
Fender? No way. This thing is screaming for a plexi conversion! :wink:
-
Fender? No way. This thing is screaming for a plexi conversion! :wink:
NO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :wink:
I have a problem. I have the FTS in and it squeels when i turn the treble pot up and hums as well. I dont see how i can tie into the mixer resistor this way and get plate voltage on the treble 390pf cap and 47k slope resistor. Ive screwed something up in the TS voltage feed. The feed cant work this way. I haved not shorted (removed) the .01 coupling caps. Is this what i have to do? That doesnt seem right either
-
> get plate voltage on the treble 390pf cap and 47k slope resistor.
Poke the nearest Fender. That's how it is.
-
Fender? No way. This thing is screaming for a plexi conversion! :wink:
Ok im done. :l2: :laugh: Problem solved. Much more headroom and versitile channel blending. + really nice breakup half way CW
Dont tell anyone. That tonestack was killing the amp from unleashing the dogs of war
-
Look at the pic. I'm not saying that Traynor didn't put that resistor in, but I know the cap is not original. That's a 68Ω resistor and looks like a typical cathode resistor, except it's much much smaller than I would expect. Ain't no 68Ω resistor on the schematic. Which tube and pin does it connect to? Did you put that resistor in when changing the bypass cap?
-
Steve this amp is a combination of the below schematic with reverb tranny and choke and the YSR1 schematic without RT & Choke. The 68 Ohm is shown on the RT & Choke schematic. But my amp also uses the other YSR1 schematic in the preamp section where V1 does not have a shared cathode and uses two 1k split resistors for V1A & V1B. Im going call that schematic YSR1B. And i also have the 33K preamp power node resistor that is not shown in the YSR1 (A) schematic. I replaced 3 of the cathode bypass caps yesterday that were protruding from the cap can itself. It looks like both schematics show entirley different values for the reverb input. I quess who ever built the amp back then built it the way they wanted to rather than stay strictly with any one schematic. Now of course i am wondering which reverb input values sound the best. I could use a little less echo and shorter decay rate time. Here the RT & Choke schematic below
My reverb input part values are using the RT & Choke schematic and my reverb output values are using the YSR1B schematic values
-
Problem solved.
What did you do?
-
Problem solved.
What did you do?
The P word. I will show pics if you dont yell at me? I already did that. :dontknow: :w2: :laugh:
Seriously though the amp just lacked any headroom and the tonestacked sucked pretty bad. There was nothing i could do but confir with a Plexi for answers. It was the only logical solution i could think of. The verdict is GUILTY!
-
Ahhh... I feel so much better now. We all come from Plexis you know. :wink:
-
Well i tried anyway* Great amp for sure. I am really into low wattage 8 to 20 watt amps these days. Just finished all the relocation of the switches and wiring. Works. Quiet no hum. What i really like is the spacing between the last knob (Intensity) and the standby switch was dead center on so the reverb pot/knob didnt look out of place. Im dropping for today. Burnt
-
> get plate voltage on the treble 390pf cap and 47k slope resistor.
Poke the nearest Fender. That's how it is.
How come i dont take my own advice to customers? If you want a Fender then get a Fender. Cause im hard headed like an old dried out capacitor
-
Hi, I'm new to the forum but not to the Hoffman site or the tube trade. Its a labor of love for me and I'm retired. I just bought a Traynor YSR-1. It hasn't even got here yet! It's got the choke and the reverb trannie. I play a Traynor 4x10 old single channel Reverb ala Super Reverb on steriods (EL34's) with a Master vol I went through. I love that baby!
Looking at the Schemo, the tone stack on this one is a weird monkey for sure! I don't know what he was thinking? Its 59 Bassman / JTM 45 to that point. The differnce is the reverb or why change from such a proven format!
I like going to the Plexi / 59 Fender Bassman configuration and the clean way it was done moving the reverb pot into the standby hole! Ingeniuos. Ok, so to the crux of the matter, how do you best mix the reverb assuming the Cathode Follower 100k load classic tone stage, and how does it sound compared to the stocker? Thanks and many kudo's.
-
greetings waveturner; thanks for diggin' up the YSR thread....there's some good stuff in this one......I'm sure you'll hear from some techno-dudes soon....in the meantime, post some pics when you get your's unwrapped...
ps. where did you acquire said piece of Canadian lore?
hasta la vista amigo
:icon_biggrin:
-
How come i dont take my own advice to customers? If you want a Fender then get a Fender. Cause im hard headed like an old dried out capacitor
The EQ on the Traynors is what make them so unique in the first place. But the EQ values and arraingment of them cut the headroom to such a degree that the amp has this rubber band effect where it wants to open up more but cant. I tried the Fender TS and the amp doubled in volume and headroom. I wired V2 with 100k and pin 2 to 470k pair voltage divider. Amp became plexi tone. Stock the amp sounded good but some what muted in headroom. Looking back should i have left it alone and kept it stock? Yes. But that plexi platform is always sneaking in on me