As someone asked if the diodes on the plates of the power tubes affected the tone and the general answer to that question would be yes they do. All things effect tone (everything) and in the end it comes down to what we each find to be acceptable.
As many know Ken used to work at Ampeg and this was a commonly used method for Ampeg. Logic would dictate that Ken continued to employ this technique when we began building his own amps for customers.
Personally speaking I find that ultra fast recovery diodes sound and feel better than the standard 1N4007 so this may be worth A/B'ing to see what your ears prefer.
I guess that is why we have people on the internet selling wooden knobs for $100 each touting the fact that they make a difference in tone. I have never heard of people leaving the diodes out because the amp sounded better with them out. It is easy to try and second guess why someone did something but I would surmise that if Ken thought that they were detrimental to the tone of the amp (Using his golden ears) they would'nt be there in the first place.
Here is what Ken had to say about the diodes in his own words so their is no guessing what he thought
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I had used these in an amp several years back and removed them as I thought they affected the sound in a negative way. I'm hoping it wasn't psychoacoustics.
UR12 wrote:Here is a copy of the Kelly 90 schematic that I changed to match Franchesca. If your building an Express and want it to match the Franchesca pics this is what you need to use. If anyone sees any corrections needed just let me know.
I know I'm 'lete to the party', but I noticed in one of the Francesca pictures (HAMMER011.jpg) that there are two 100 ohm resistors on one of the power tube sockets which are elevating the filaments. This may be a mod, or may be stock...I don't know. But I haven't seen this documented on any schematics.
PCollen wrote:I noticed in one of the Francesca pictures (HAMMER011.jpg) that there are two 100 ohm resistors on one of the power tube sockets which are elevating the filaments. This may be a mod, or may be stock...I don't know. But I haven't seen this documented on any schematics.
They've not actually elevating the filaments in the DC elevation sense, but referencing them to ground via an artificial centre tap.
The power transformer Ken used didn't have a filament centre tap, whereas the new Pacific and Heyboer transformers are specified with one, so it's not something we've got hung up on even though using the resistors rather than the true centre tap would be historically correct.
I've tried a few different diodes to see if it made a difference. On the TW clones that I tried them on, I was able to recreate Ken's findings. 1n4007 are tonally invisible. 5408's and 5399's had adverse effect on tone.
But, if you don't use them they are invisible too!
I had added the IN4007s to an old 6G6-B Bassman years ago and wound up taking them out. It wasn't that they affected the tone per-se, but my impression was that it affected the feel and playability of the amp. Seemed to make it stiffer and less responsive although I can't really say why. I'm curious if anyone else has experienced this or if it was just my imagination.
<i> "I've suffered for my music. Now it's your turn."</i>
crbowman wrote:I had added the IN4007s to an old 6G6-B Bassman years ago and wound up taking them out. It wasn't that they affected the tone per-se, but my impression was that it affected the feel and playability of the amp. Seemed to make it stiffer and less responsive although I can't really say why. I'm curious if anyone else has experienced this or if it was just my imagination.
Yep. Not tried them in a Twreck clone, but they do effect things negatively in other amps I've tried them in. Robert Stamps pointed this out to me many years ago...and he was right.
crbowman wrote:I had added the IN4007s to an old 6G6-B Bassman years ago and wound up taking them out. It wasn't that they affected the tone per-se, but my impression was that it affected the feel and playability of the amp. Seemed to make it stiffer and less responsive although I can't really say why. I'm curious if anyone else has experienced this or if it was just my imagination.
This is a great point as many talk about how an amp sounds but the feel is equally important IMHO. Most tend to gravitate to an amp that feels easier to play verses one that is stiffer or harder to play. In the end it all comes down to what each player prefers, hence why tone is so subjective.
As a player I have found that the diodes often times make the amp feel a bit stiffer to play. You can design around it but this is easier if you already plan to implement the diodes at the beginning of the design. IE; if you already have the amp dialed in to where you like it then it you may not want to spend the time redesigning.
Whew!
I feel vindicated.
Sometimes with something this subtle, you wonder if what you are perceiving is real or if you're just off your game.
Glad somebody else has noticed this.
<i> "I've suffered for my music. Now it's your turn."</i>
crbowman wrote:Whew!
I feel vindicated.
Sometimes with something this subtle, you wonder if what you are perceiving is real or if you're just off your game.
Glad somebody else has noticed this.
The longer once plays guitar the more important the nuances become. The ideal amp is one that you plug into and loose track of time as you play.