Preamp tube advice needed: tight and focused

[ThisBass]

Have you tried E83CC? They may be out of production, but they are still available. I was planning on eventually buying a few just out of curiosity. Guess I better not wait too long. What do they sound like (IYMO)?

The way Telefunkens ECC83 are described seems more inline with JJ ECC803S than ECC83S. However, I suspect Telefunkens have a bit more air than the JJ ECC803S.

The JJ ECC803s is a normal plate tube, the JJ ECC83s is the frame grid tube.
The naming at JJ is confusing but, that's how it is.

The JJ ECC803s was their first ECC83 in their production line, the design was aligned to the specs of the TFK ECC803s, that's why they named it ECC803s
Then later they started the production of the frame grid tube, named ECC83s.

The E83CC might have been a hand selected "frame grid" tube with more narrowed specs for systems a+b

edit:
TFK ECC83 - normal plate
TFK ECC803s - frame grid (s=selected to match systems a+b)
JJ ECC83s - frame grid
JJ E83CC - frame grid
JJ ECC803s - normal plate

If you are looking for robust and low microphonic tube you can't go wrong with a frame grid tube.

btw the frame grid tube was invented by demand of the industry, back in the day, who asked for more narrow specs between systems a+b.

 

[beans-on-toast]

If the amplifier has too much gain in the first stage, try a 12AY7/6072. The 12AY7 tube has less gain. Some tweed Fender amps use this tube in the first stage. It provides a nice smooth sound.

 

[ThisBass]

Just listened to a couple of youtube reviews of this Carl Martin bass pedal.

Here you are with some "anlytics" I do get from these vids.

Even without engaged "drive" there is already decent tubish texture audible that reminds me on a Bassman preamp.

The setting of the tone controls does effect the amount of saturation once the drive is engaged.

Rather than "tube drive" the drive does more sound like a OP-amp diode based SS-drive where some clean signal is mixed to the saturated signal.

The gain knob acts more like drive knob that controls the amount of "saturation" for the (SS-)drive circuit.

The gain knob acts very "touchy" and does add noticable saturation already at 8:00..9:00
This quite "sensitive" characeristic for the gain controil knob might be designed to obtain even balanced loudness volume levels for both sounds, "clean" and "drive" sound.

Once you swap the 12AX7 tube for something different such as 12AU7 you probably woun't effect the "drive" cause the drive is probably designed as 100% SS-circuit (OP-amp based).

Carl Martin designed many Op amp based SS overdrive circuits, even for guitar pedals. And I think he did it just the same way for this bass pedal.

The signal path may look like the following:
initial stage (tube system a)
tone stack
volume
second tube stage (tube system b)
switchable OP amp based SS drive stage with "gain" knob

A 12AU7 may lower the signal within the "tube path" but, may have little to no effect to the characteristic of the drive, except the input level at drive stage may be lowered a little bit.
And as a drawback the loudness levels between "clean" and "drive" then woun't (likely) be evenly balanced anymore.

Furthermore with a 12AU7 (that very likely woun't effect the SS-drive nothing at all) the "fenderish" tube circuits a+b woun't work at designed "specification" anymore!

edit:
personally I think this preamp provides a very nice tubish clean sound that I wouldn't try to ruin with tubes such as 12AU7 (or anything else) that woun't match properly to the tube circuits (tube system a+b).

 

[ThisBass]

@Inconnu
Try to imagine you have got a Bassman like tube preamp.
Try to imagine there was a SS drive stage with gain knob that was "back end" added to the signal path at the fenderish tube preamp.

Try to imagine you are not happy with the SS-drive due its very touchy gain knob sensitivity.

Try to imagine what might happen if you are trying to "tame" the drive sensitivity of the back end added SS-drive by swapping the tube "front ended" inside the "fenderish" tube preamp that have got nothing to do with the signal paths back end "added" SS-drive circuitry!

 

[ThisBass]

Rather than swapping/rolling tubes at the (tube-)preamp that likely have nothing to do with the drive circuitry, I think it was way more beneficial to mod the "characteristic" of the drive/(gain) potentiometer. There may be a couple of design "options" how this could be done!
(if you don't need the drives full potential of "drive" then such a mod could be done quite easily, and also was removable back to its original design if needed/wanted)

Or just sell the preamp and buy something different with less "gain sensitivity" at switchable "drive" sound.