Solid state/class d vs tube amps

[agedhorse]

That's just a standard grounded cathode amp with the grid of the first section driven by an LFO for what looks like a vibrato.

Don't know why the second grid isn't connected, but it really doesn't matter as it's "or" connected. As the grid goes positive the tube conducts which pulls the amplitude of the signal down at the LFO frequency

 

[Passinwind]

Maybe @JimmyM might stop buy.
Or @Passinwind or @johnk_10 or @agedhorse....

Nah, I don't talk religion on Talkbass...

 

[Chucky Stiletti]

As was explained by Andy, the tube conducts and goes into cutoff depending on what is applied at the grid.

Some tremolo circuits accomplish this with an optical bug, a light source (neon lamp or LED) and a photo sensor. This is less expensive than using a tube.

Since the tube is being operated at a very low voltage, sometimes you have to select a 12AU7 that will work in this circuit. If there’s a problem with the tremolo, try swapping different tubes in. But that tube should last for a very long time the way that it is being used.

Thanks.

 

[Chucky Stiletti]

That's just a standard grounded cathode amp with the grid of the first section driven by an LFO for what looks like a vibrato.

Don't know why the second grid isn't connected, but it really doesn't matter as it's "or" connected. As the grid goes positive the tube conducts which pulls the amplitude of the signal down at the LFO frequency

It's what I thought at first, but if you look, the plate of the tube to the left is connected to the cathode of the tube to the right? The plate of that tube connects to to the cathode of the one to the left and that node is grounded? the I've never seen this..

 

[seamonkey]

Back in the manual drafting age it could simply be a drawing error. The builders probably used wiring diagrams that had the grids connected.

 

[Chucky Stiletti]

Back in the manual drafting age it could simply be a drawing error. The builders probably used wiring diagrams that had the grids connected.

that would make sense..wouldn't the tube to the right act somewhat as a clamping diode though? hmmm..

 

[agedhorse]

It's what I thought at first, but if you look, the plate of the tube to the left is connected to the cathode of the tube to the right? The plate of that tube connects to to the cathode of the one to the left and that node is grounded? the I've never seen this..

I couldn't see that on my phone so I thought it was 2 tube sections in parallel. I don't know what might be going on. Possible drafting error imo as a first guess

 

[seamonkey]

IMHO - Tube lifetime is subjective. Just judging by players I know who use tubes and show happiness every time the re-tube

I suspect most the claim long lifetimes from some don't use the tube amps the same as others.

Many of the old good books are online and they all mention methods to try to increase lifetime, but the all end in the same story that tube are consumables and eventually have to be replaced. They all show the bathtub curve.

Some tube amp manufacturers today put subjective advice like a current brand that publishes:
"Replace the output tube(s) before the performance degrades or the tubes fail completely. Replace the tube(s) on a regular basis; at least once per year or as often as every 4 to 6 months if you play long and hard every day."

That's not stupid, that's survival and probably saves the manufacturer a lot of trouble from someone that doesn't try a tube change when they hear amp performance detrimentally change.

Class-D isn't going to have any kind of wear that's going to effect it over a reasonable lifetime. There's not going to be a usage difference in measurable lifetime.

 

[seamonkey]

that would make sense..wouldn't the tube to the right act somewhat as a clamping diode though? hmmm..

As drawn, it's a diode, but not a perfect one, and it shares the envelope with another triode. What does the actual amp wiring look like?

 

[mesaplayer83]

"Replace the output tube(s) before the performance degrades or the tubes fail completely. Replace the tube(s) on a regular basis; at least once per year or as often as every 4 to 6 months if you play long and hard every day."

That's not stupid,

Yeah, it is...

 

[JimmyM]

IMHO - Tube lifetime is subjective. Just judging by players I know who use tubes and show happiness every time the re-tube

I suspect most the claim long lifetimes from some don't use the tube amps the same as others.

Many of the old good books are online and they all mention methods to try to increase lifetime, but the all end in the same story that tube are consumables and eventually have to be replaced. They all show the bathtub curve.

Some tube amp manufacturers today put subjective advice like a current brand that publishes:
"Replace the output tube(s) before the performance degrades or the tubes fail completely. Replace the tube(s) on a regular basis; at least once per year or as often as every 4 to 6 months if you play long and hard every day."

That's not stupid, that's survival and probably saves the manufacturer a lot of trouble from someone that doesn't try a tube change when they hear amp performance detrimentally change.

Class-D isn't going to have any kind of wear that's going to effect it over a reasonable lifetime. There's not going to be a usage difference in measurable lifetime.

Says the guy who hates tube amps just for existing and never played one in his life

 

[agedhorse]

For players that claim that new tubes are necessary, innsome experimentation, I have replaced tube sets with sets that have several thousand hours on them, or never even changed the tubes, and in every case the player felt that the re-tube was a big improvement.

NEVER ignore the placebo effect, it's a very real phenomenon and is the basis for many tube sales and marketing company business model.

 

[JimmyM]

For players that claim that new tubes are necessary, innsome experimentation, I have replaced tube sets with sets that have several thousand hours on them, or never even changed the tubes, and in every case the player felt that the re-tube was a big improvement.

NEVER ignore the placebo effect, it's a very real phenomenon and is the basis for many tube sales and marketing company business model.

My dad taught me that when I was younger, but I didn't listen and insisted on a full retube for my V4B because of Aspen Pittman's articles in Guitar Player mag. So I get the tubes (back in the day when it wasn't hard to buy tubes at an electronics store), put them in, and zero difference in sound. They all went back the next day. I listened very closely after that, and that amp burned up in a bar fire 9 years later with all the same tubes except one.

 

[Son of Wobble]

For players that claim that new tubes are necessary, innsome experimentation, I have replaced tube sets with sets that have several thousand hours on them, or never even changed the tubes, and in every case the player felt that the re-tube was a big improvement.

NEVER ignore the placebo effect, it's a very real phenomenon and is the basis for many tube sales and marketing company business model.

"Fittingly, Agedhorse's last earthly words pertained to tubes."

 

[Wasnex]

For players that claim that new tubes are necessary, innsome experimentation, I have replaced tube sets with sets that have several thousand hours on them, or never even changed the tubes, and in every case the player felt that the re-tube was a big improvement.

NEVER ignore the placebo effect, it's a very real phenomenon and is the basis for many tube sales and marketing company business model.

Is it placebo effect, or does reseating the tubes reestablish good conductivity in the tube sockets?

 

[agedhorse]

Mrs. Horse got a good laugh from that!

 

[seamonkey]

Placebo, Change blindness, Music related memory, all real and scientific.

People just can't detect slow degradation. A good example are LED light bulbs, like those used in stage lighting today. Energy star rates lifetime at 75% of initial lumen. If you buy 1000 Lumens it's lifetime is over when it hits 75%. It's still going to light up and most people aren't going to even know there's a change. LEDs dim very slow compared to average filament bulbs.

Class-D doesn't have anywhere near this kind of degradation. Measure them.

 

[nomaj]

My main thing about Class-D amps is you can get some of the tube goodness with the hybrid setup in sometimes a smaller and lighter package.

I've never really experienced "tube goodness" with a hybrid bass head (in the sense that it sounded like an all tube head) although I've liked the sound. My experience is that a hybrid bass amp sounds like a smooth (in the good sense) first rate SS amp, but I've only used a tube pre/bipolar output Class AB design, not tube pre/Class D output ones, although I can't imagine a Class D output sounding better/tubier than an AB, although the power to weight benefit with Class D is such a plus.

The only really tubey sound I've experienced from a hybrid amp was from when I plugged into a friend's old MusicMan HD-130 head, (which was the other sort of hybrid, not really seen in bass amps, that I know of - it had a SS pre/EL-34 tube output). Now, THAT amp had "tube goodness," especially when cranked and when using a pick.

 

[Old Garage-Bander]

My dad taught me that when I was younger, but I didn't listen and insisted on a full retube for my V4B because of Aspen Pittman's articles in Guitar Player mag. So I get the tubes (back in the day when it wasn't hard to buy tubes at an electronics store), put them in, and zero difference in sound. They all went back the next day. I listened very closely after that, and that amp burned up in a bar fire 9 years later with all the same tubes except one.

Was the amp the cause of the fire?

 

[JimmyM]

Placebo, Change blindness, Music related memory, all real and scientific.

People just can't detect slow degradation. A good example are LED light bulbs, like those used in stage lighting today. Energy star rates lifetime at 75% of initial lumen. If you buy 1000 Lumens it's lifetime is over when it hits 75%. It's still going to light up and most people aren't going to even know there's a change. LEDs dim very slow compared to average filament bulbs.

Class-D doesn't have anywhere near this kind of degradation. Measure them.

So because of LED's, we should throw out perfectly good tubes after a year? Yeah, no. Your anti-tube agenda is clear, apparent, and has been for a long time. I'll take the word of people who have actual experience with tube amps instead.