Hellzero

There are no stupid questions. Your Peavey TNT 150 equipped with a Black Widow (BW) 15 inches speaker is already a really good combo (a head with a cabinet). I'm not sure the Behringer BDI21 adds something, on the opposite, as the 9 bands EQ + plus Bass and Treble and the Punch button of this combo are already excellent and it has a very good integrated chorus too. I would use the Behringer BDI21 for what it's intended when it's needed : a D.I. box. Here's the manual for you great (but really heavy) combo : https://peavey.com/manuals/80300755.pdf Check the proposed settings as a good start up for your sound.

Hush, hush, or everybody will take my place when going to a concert ! 😇

Middle one !

Next time, don't forget to put Fender strings on your Fender bass, use a Fender pick, plug it to your Fender amp using a Fender lead and wearing a Fender T-Shirt, otherwise it won't work. 🤪 Come one, this is utter nonsense ! Show this to any amp maker or repairer and he will laugh for hours : Beware Mesa Boogie amps only work with Mesa Boogie valves !

Always use the one finger per case technique, you'll thank yourself later.

And so is the magnetic battery backplate...

Looks like a push-pull issue. Check the knobs first, yes the knobs, as they might have moved and are blocking the correct contact of the down position.

Becoming lazy ? 🤣

🤣 🤣 🤣 Mesa Boogie valves are rebadgeg Chinese or Russian valves... Valves are valves and as long as they are quality ones, they are the almost the same with minor sounding differences, but sometimes microphonic (a 12AX7 is a 12AX7 and they all are interchangeable). The only big difference is the way and where they are made. The military grade 7025 for instance is a ultra high quality long tested with very low tolerances and measurements 12AX7. Do a simple trick if you don't believe me : take some acetone and remove the rebadgeg Mesa Boogie logo and you'll see the acid engraved original Sovtek logo or Electro Harmonix or another brand, or simply a superb Made in China ! At some time, there were only 3 places left in the world making valves : Russia, China and old communist block. The rest is pure bullsh*t marketing. The totally fixed power valves bias à la Mesa Boogie is not a good idea at all, but again a marketing trick as power valves must be biased when changed (or getting old) to become perfectly matched, especially if you're using a push-pull designed amp, but a fixed bias is, in fact, a variable bias that becomes fixed when the bias is correctly adjusted. It bears the name fixed bias by opposition to the automatic cathode bias. The preamp valves are cathode biased, but could also be "fixed" biased for a "perfect" sound if you wanted too, but (again) you would need to change the bias system to a fixed bias one which would be useless as the cathode bias in itself is perfect. Check this : https://www.ampvalves.co.uk/cathode-bias/

I'm still using the 60/40 0.8 and 1.6 mm wire that my father gave me some 35 years ago. I finished my first kilo of wire a few years ago (I was making loads of repairs) and I don't think I'll see the end of the remaining kilo I still have (500 grams of 0.8 mm wire and 500 grams of 1.6 mm). My soldering iron is still the same JBC SL 2300 I bought at the same time, some 35 years ago... And it still has the same soldering pin ! I've tried lead free, but it's simply awful. Here is the wire I still use :

There's only one person saying the NS Design are not good sounding. I found them very good sounding and very close to a real double bass if you know how to dial an EQ...

Check this, maybe it's what you're after. Don't bother the stupidest haircut ever...

Are you Jacob Collier ?

And still can't play with other musicians the correct way today...

For that "orchestral" sound, you can try a shimmering effect, that will surely sound big. Not that easy to use, but worth giving it a try. And don't forget a good reverb too. Strange that nobody mentioned this.

I've been a touring guitar tech, and I can tell you that Mesa Boogie's do have their shares of issues. And dry solders are some of them... An old valve will compress your sound more and more and more, but they rarely really die, except if there's a break in the glass (or crystal for some). But you can have a loose connection in the socket which happens sometimes If that's the case, don't try to fix it yourself as there's a potential risk of death if the capacitors are still fully charged. That said simply taking the valves out and back in will remove oxydation that can also cause some similar issues.

Now, with your new explanations, it sounds even more like a dry solder. 😉

Very old dead nickel round wound strings can really sound like flat wound strings. For glissandi, nickel is way smoother than stainless steel that are real cheese grates.

Dave, To check the issue, just change things one by one, not all and everything at the same time. 😉 To me, it sounds like a dry solder in your amp which is a nightmare to isolate, so the best thing to do is redo all solders. That said, just checking around the voltage lowering resistors might be a very good start as it often starts there.

Wow !

Truer than the original. 🤣

Calling @Beedster...

@Niksonbass is apparently not in the U.K. 😉

I would go for a second hand NS Design as they invented the correctly sounding EUB (Electric Upright Bass). Eminence are great too. Check the Gollihur American guide to give you an idea of what's available : https://gollihurmusic.com/electric-upright-basses-which-one-is-best-for-me/