This is exactly what kind of information I’ve been looking for! So stoked I found your channel.
@Francisco17Berrios3 жыл бұрын
Thank you!!! Finally someone that will explain mods in a video in a very detailed way! :)
@robertherndon5143 жыл бұрын
Thank you, Jason Tong, for your help and dedication to the craft...
@RozsaAmplificationLLC3 жыл бұрын
Great video as always Jason and explaining what the zener diodes and Volatge Clamp are doing! What you should also communicate is the 10k resistor and .22uF cap are doing. What they are in there. What compliance is and what they are doing to the signal with and without being in the circuit! All you needed to do was put a switch in between C? and Z1. Show the voltage at V2 pin 8 (CF) with full signal, then thru the 10k and 22u compliance with Zeners off....then Zeners on! This would show the effect, but also the reason for them (unless I missed it somewhere in your video (didnt watch in entirety)!!
@HeadfirstAmps3 жыл бұрын
It's a good idea this - to show the signal all the way through. I was pretty focused on just the zener breakdown effect....I'll try and remember to add this idea for a future one!
@RozsaAmplificationLLC3 жыл бұрын
@@HeadfirstAmps yep, exactly. Folks just focus on the end results...100V in...clamp at 20V (or whatever)...but there is a little more going on. If you clip a 100V signal to 5V, it's going to sound like a beehive and pretty dramatic. The compliance helps support how dramatic the clip. The threshold also needs to be considered and symmetric and asymmetric. Someone in the forum posted asymmetric, but at more wider levels....say 5V and 20V instead of say 16V/20V. In that, it looks like they are looking for a mixture of tone 180 degrees out of phase. One will be very squashed and compressed and the other half more open!!! :) All kinds of fun in tuning an amp and getting Grail Tone!! :)
@HeadfirstAmps3 жыл бұрын
Yeah man exactly. I tried a 24V/5.1V combo and was pretty impressed with the end tone!
@clintn66773 жыл бұрын
Thanks so much for these man. I'm spending my Sunday watch your vids and trying to learn something new.
@HeadfirstAmps3 жыл бұрын
Glad you like them Clint!
@perco75410 ай бұрын
Love your videos with theory. Would you consider adding a frequency analysis as well? It would be really interesting to see the difference in the overtone series.
@qddk95459 ай бұрын
That is a very interesting idea. Which application do you use yourself? You can measure on the amps speaker output, or on the speaker with a mic.
@rflessati3 жыл бұрын
Thats a really good video on Zener mods. Its clear for me now. Thanks
@mookytc3 жыл бұрын
As always great information being passed along!
@IhabIAmer4 ай бұрын
Magnificent! Keep it up.
@qddk95459 ай бұрын
Marshall often uses standard diodes in parallel reverse mode, earlier in the circuit. That will limit the signal at that point to around 1.4v P/P, and I find it sounds horrible. Recently I clipped those diodes out on a DSL60 amp, and for the first time in my life I got severe blocking distortion - the following tube stage simply locks down, until the transfer cap is discharged enough to pass sound. I should have hooked a scope up, to look at it. Often I try to mod things without removing the PCB(s), which gives me less possibilities, so right now I have lowered the incoming signal to 1/3, but if that is not enough I might try different values of zener diodes. Thank you for all your valuable videos 🙂
@azzazelo3 жыл бұрын
Such a great vid, thanks!
@RDamps3 жыл бұрын
Superb stuff!
@JosipAngeloBorovac3 жыл бұрын
Great video and explanation of different clipping schemes! Very educational! You just hit a spot with this video because just recently I acquired a Marshall 9001 tube preamp with so-called SRPP circuit and diodes used in the gain staging? Could you briefly comment on that design and if you would remove diodes from such circuit? I have wondered about doing it to possibly to get only tube clipping but was wondering if it is worth of hassle! Thanks for the vid!!!👍🏻
@HeadfirstAmps3 жыл бұрын
I'll check out that circuit and report back!
@JosipAngeloBorovac3 жыл бұрын
@@HeadfirstAmps thank you sir! :-)
@qddk95459 ай бұрын
I would be VERY surprised if Marshall have ever used a SRPP circuit. And they did certainly not on the 9001 pre amp. It has 3 standard amplification stages in series. SRPP are kind of stacked on top of each other.
@kirkgreenman13866 ай бұрын
I can’t wait to try that . Does the A-symmetric sound the same when the 5 volt clamping is on the positive half of the sign wave?
@HeadfirstAmps6 ай бұрын
Yes, for AC it doesn’t matter positive or negative
@TheSwanage2 жыл бұрын
Can I just hook two zeners to the stock MV position as an always on clipper, or is moving the MV a must?
@gbass73283 жыл бұрын
Who would watch and put a thumbs down wtf lol
@HeadfirstAmps3 жыл бұрын
The haters gotta hate!
@voxpathfinder15r2 жыл бұрын
So is it fair to say zener diodes are trying to mimic power tube clipping, but at a far lower volume?
@HeadfirstAmps2 жыл бұрын
Yes, this is a pretty good description actually.
@MAURIIIII20093 жыл бұрын
Excelent Class of mods
@chrisstevens46808 ай бұрын
Why is the JCM800 logo upside down on your amp? Is it because it is an Australian issue?! 🤣 (Comment from the UK!) PS great video’s thanks!
@patrickwilliams2530 Жыл бұрын
It is weird because compared to what some people tell the diodes are in opposite directions in your schematic look for : My Real Jose Modded 1979 Marshall 100 watt head- An in depth Look at the Build and Circuit by Ossie Ahsen. In his the diodes are inverted.
@HeadfirstAmps Жыл бұрын
Makes no difference, as long as they are in opposing directions
@patrickwilliams2530 Жыл бұрын
@@HeadfirstAmps okay thank you for the info ^^!
@errtrainer2 жыл бұрын
Wonderful series! Now i have a question. Krep in mind im a musician, noy an engineer. Ok, the zener mod can be made in other preamp stage? Not after the cathode follower of V2b but after the coupling cap in any of V1 triodes. Keep the good job!
@HeadfirstAmps2 жыл бұрын
In theory yes. Take a look at the 2205, the Jubilee, the Carvin MTS, Wizards and so on. All have diode arrangements that come straight off the plate of a triode.
@onewireman3 жыл бұрын
Thank you for all of your wonderful videos. Will this work the same if the master volume is after the tone stack?
@jasonktong13 жыл бұрын
Absolutely yes. Check out my recent mod videos for both the 1987x and the 2204 for how to wire these in properly whilst keeping a post tone stack master.
@onewireman3 жыл бұрын
Thank you so much, I will give this a try this weekend. Any tips on how to get rid of the flubby low end of a JCA20H? I've tried everything I can think of:(
@jasonktong13 жыл бұрын
@@onewireman ah yep! Have you seen my JCA50H mod video?
@onewireman3 жыл бұрын
@@jasonktong1 I will have to check it out...
@onewireman3 жыл бұрын
Thank you for the hot tip. I replaced C26 with a 2n2, and it sounds much better. Now to implement the rest of your mods!!
@kirkgreenman13866 ай бұрын
What is a good zener impedance and wattage?
@HeadfirstAmps6 ай бұрын
1N4747 is a good starting point. 20V 1W
@Brosefmcjoeseph2 жыл бұрын
What would be the difference between the diodes in series vs parallel?
@HeadfirstAmps2 жыл бұрын
Parallel is not a voltage clamping circuit, that’s more a noise gate coring circuit.