Modding a Tweed Deluxe - less bass boom required

[d. spree]

I would like to mod one of my self-built 5E3s - built from a TubeDpoet kit with a printed circuit board. Overall I like this amp. It sounds great with my strats but I would also like to get a great sound with my gretsch g5120 electromatic hollow body which has humbuckers. I know humbuckers are not ideal for this amp but that's what I want to do. I want less booming bass.

I just modded the guitar removing the stock gretschbuckers (which many players complain are too muddy sounding). I repaced the harness and installed GFS AlNiCo IIs. The tone is improved a great deal when played through the 5e# but I still get too much bass - especially in the neck position.

The tubedepot build instructions state that for less bass "replace the .002ufd coupling capacitor in position C7 with a .01 or even a .0047 capacitor." AS most folks are probably unfamiliar with the TubeDepot board, I believe this capacitor is wired to the cathodes on the V2 12AX7 - it the 5th capacitor from the right on the baord.

What other modifications might you guys suggest?

[Bruce / Mission Amps]

In the 5E3 circuit there is a .022uF cap that drives the phase inverter... on a stock layout, it would be the fifth cap as viewed from right to left and the first coupling cap as viewed from left to right.
I'll assume that is the one you are talking about when mentioning the .002uF cap.

You can reduce that .022uF down to as low as .0047uF and amazingly, still get a really good sound out the amp with humbuckers.
.01uF would be a good one too, but I'd start with reducing the cathode bypass caps on the preamp sections, down to at least 2.2uF to 4.7uF and change out the .1uF caps to something like .022uF to .047uF max.

[d. spree]

In the 5E3 circuit there is a .022uF cap that drives the phase inverter... on a stock layout, it would be the fifth cap as viewed from right to left and the first coupling cap as viewed from left to right.
I'll assume that is the one you are talking about when mentioning the .002uF cap.

You can reduce that .022uF down to as low as .0047uF and amazingly, still get a really good sound out the amp with humbuckers.
.01uF would be a good one too, but I'd start with reducing the cathode bypass caps on the preamp sections, down to at least 2.2uF to 4.7uF and change out the .1uF caps to something like .022uF to .047uF max.

Bruce once again thanks. On this Tube Depot board the caps are in the same order as the classic boards - so last night I did remove the .022uF cap that drives the phase inverter and replace it with a .01 ufd cap which made some difference but not as much as I would have thought. Working the tiny solder pads of the pcb without damaging them or the baord was tricky but I figured it out. Makes me apprecaite the classic boards with the relatively large grommet holes - mcuh better for modding. I will order replacements for the cathode bypass caps and the .1 uf caps in the preamp section. I recall that the cathode bypass caps in the preamp section are the 1st and 4th from right side of board in the stock layout?

Which brings me to another thank you - and to a wish that you would write a beginners book about how these amps work - I have read Dave Hunter's book (in which you are credited and thanked) and I have built two 5E3s - a tubedepot and a mission - but I still feel in the dark about how they work and the mods and tweaks that can be done (and why they work). A lot of stuff on the web is just already too advanced without a translator!

But my thanks to you for your generosity with your time and advice - I know you are a busy man with a business to run but I have found your posts on this forum to be a major help.

[jrfrond]

In order to reduce IM distortion down the line, I'd limit bass right at the first stage by using a 1uF (or less) cathode bypass cap, and at the same time, reduce the .1 coupling caps before the volume controls to .022. You can even put the cathode cap on a pull-switch pot to switch between the larger and smaller caps.

[d. spree]

I am excited about trying some of these tweaks - but the sites where I usually buy capacitors don't have the electrolytic caps with such low values. Finding eletrolytic caps with values like 2.2uF and 4.7uF in brands i have heard of has been impossible. Web searches lead to some dubious brands. Where do you guys recommend finding electrolytic caps and also other capacitors that are high quality. For this amp I used orange dropss, F&Ts (for the filters) and, I think, Xicon electrolytic caps for the cathode bypass. I can get the orange drops for the tweeks pretty easily. What would be recommended as the best brands for the tweeks and where can I find them?

[Bruce / Mission Amps]

Send me your address again and I'll send you a tweaking parts kit...

[d. spree]

Send me your address again and I'll send you a tweaking parts kit...

Bruce, that's generous, but this amp is NOT A MISSION KIT it is a tubedepot kit - I am about to order a second Mission Kit and will order the tweaking mod kit - I presume this is the The dual Mission Amps Switchable "Humbucker" HBI, HBII flatulence Reduction Mod Kits and Fixed Bias Phase Inverter Mod Kit you list on your website? Sounds like with this mod I can switch depending on what guitar I'm plugging in. I should note that the Mission kit I built in July is less bassy when I'm playing my humbucker guitars than is the tube depot kit.

Overall, it feels great to be able to put the amp up on the table and make these mods and tweeks - despite my complete lack of knowledge about electronics. Thanks to you guys here at music-electronics-forum. I caught up with an old friend over the weekend (a drummer) and was telling him my amp building experiences and thjis forum and he noted that the web now is an amzing reosurce for knowledge that was much harder to find years ago.

[d. spree]

Just received my order of capacitors from Mouser - and am ready to do the tweaks on this TubeDepot kit 5e3 to reduce some of the bassiness. So before I go ahead I wanted to check that I am thinking about this in the right way.

I ordered some Nichicon aluminum electolytic caps (values of 4.7uF and 2.2uF) and some orange drops (values of .022uF and .047uF). I built this board with orange drop caps in the coupling cap positions. I already replaced the .022uF cap that drives the phase inverter it with a .01 ufd cap.

I plan to switch out the 22uF 1uF cathode bypass cap for V1 (1st from right in the standard board) and install a 4.7uF cap. I understand that this is the preamp cathode bypass. Do I also switch out the cathode bypass that is 4th from right in the standard layout for a similar value? I am not sure if this position shapes tone as well as it connects to V2. I presume this is part of the output circuit rather than the preamp circuit????.

Another question is what is the impact on tone and sound shaping from the .1uF coupling caps that are 6th and 7th from the right side of the standard board layout - is anything to be gained by modding these?

I plan to replace the two .1uF caps that connect to the volume controls (2nd and 3rd from right in the standard board layout) and use .022uF here. I have caps with lower values but thought I'd start with these and see how it sounds as I want it to sound good with both my humbucker guitars as well as my strats. Am I on the right track? Thanks in advance for the feedback.

[soundmasterg]

If you want to tweak cathode bypass caps in the future, and you are going to use smaller value caps, you can use film caps instead of electrolytic caps. They are often cheap or the same price and they sound better generally too.

Greg

[d. spree]

If you want to tweak cathode bypass caps in the future, and you are going to use smaller value caps, you can use film caps instead of electrolytic caps. They are often cheap or the same price and they sound better generally too.

Greg

Thanks Greg - otherwise does my plan sound right?