Solid state/class d vs tube amps

[BadExample]

I knew Paul Moller, his early shop was located around the corner from my old shop. He was an ME professor at the university I graduated from.

Bwahaha, he was your neighbor

He also got in a bit of trouble for ripping off investors in his flying car venture.

 

[agedhorse]

Made a fortune in the muffler business and lost a fortune in the flying car business .

 

[BadExample]

Base a fortune in the muffler business and lost a fortune in the flying car business m.

Sadly, if he had just run SuperTrapp, stuck to mufflers and spark arrestors, he could have a few helicopters and some really nice twins to fly around in, and a really nice car to get to the launch pad.

 

[Al Kraft]

Guys like Moller are all about the dream and the money part is just grease for the rails. I suspect profit and wealth would have been valuable in some ways, but I'd guess it was the adventure of inventing that he probably valued above all else.

 

[DavesnothereCA]

There are 2 nested feedback loops plus a global feedback loop in that [Garnet] amp, with high impedance phase splitter combined with grid stoppers and hefty grid to cathode capacitance, my guess is that they had some real stability problems under higher gain conditions. 220pF is about 100x the typical grid capacitance to the cathode, and the high drive impedance is going to cause some significant HF rolloff. Maybe the feedback will improve this a bit, like stealing from Peter to pay Paul.

~
220 pf does seem excessive (or overkill, or whatever caps they had handy or got for low cost), unless that was part of their desired frequency response.

In that library file, some of their other models had those same caps, but others left them out, seemingly randomly.

And if there already were stability issues as you suspect, then having the prescence boost circuit in the driver stage would aggravate them, I would think.

Nonetheless, the Fender/Marshall/Traynor/etc,etc,etc design puts it in the driver stage too.

But that group of diagrams did not include the preamp section of this particular unit, so not sure what else Garnet had going on in the earlier stages.
~

 

[DavesnothereCA]

Here's my solution to how I used to choke down SVTs and Bass 400's with big cabs at home....
View attachment 2873775

~
So what's with the tabby ?

Do cats improve the damping factor ?
~

 

[DavesnothereCA]

I've never understood putting tone and volume controls inside a global feedback loop. I've seen other designs that did this too, but it just never seemed like a good idea to me. It's going to create interesting nonlinearities when it tries to take those effects out. Maybe that's the point. Whatever works I guess.

~
The Fender/Marshall/Traynor/etc,etc,etc design puts the prescence control in the driver stage too, usually inside of a global FB loop.

But I have not before seen a volume control inside of such a loop - I overlooked this oddity when first examining that diagram.

View attachment 2873706
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[DavesnothereCA]

Here is the schematic for the Garnet B260D and L260D GUITAR amps

There should be similar models for bass but without the tremolo

http://garnetamps.com/history.htm

They nicely show the transformer phase inversion drive system, grid stopper resistors (270 Ohms) and screen resistors (470 Ohms)

The parallel connected 6SN7 is used to achieve a higher signal drive power into the transformer. Could have been a triode connected 6V6GT, 6L6GT, EL34 or similar but that would require significantly more B+ DC current, higher DC rated transformer primary and filter choke - the 6SN7 is a best fit compromise solution and most likely does the job well

The voltage divider half-wave bias supply into 64 uF and the tremolo circuit could result in a time delay in attaining bias voltage at startup. Is a low current supply - could be improved. Other brands use only 10 uF to speed up the process but that results in more ripple in the bias supply. This system is fine if the standby switch powers-on after the power tubes warm up.

The filter caps suggest the B+ is at least 600 VDC so this is a gutsy amp (maybe 130 watts rms/260Watts peak as the type number implies)

One feature common to PA amps from the 1940's on was the high frequency attenuator across the output transformer - solves a lot of problems. (A full range top end is not needed for guitar or bass amps)

View attachment 2873911

~
Plus, the main PS has a choke, so this unit was produced before the maker cheaped out.

The diagram for the P.A. version of this module (which I attached here) is easier to read, without the tremolo section, etc.

I also saw the annotation in your pic, where they increased the value of the coupling cap from the driver to the power amp by a factor of 10, to improve bass response.

The P.A. amp pic does not mention this mod though.

Also, I think that a 12AU7 has similar specs to a 6SN7, and Garnet did use those, such as in the other schematic which I posted upthread, but did not parallel the two halves in any of the diagrams which I recently examined.

OTOH, they sometimes used the 6SN7 with the two halves as different stages.

EDIT : I just noticed that my diagram has a missing ground symbol at the output of the bias supply, while yours includes that symbol.

~

 

[DavesnothereCA]

....If you look at the schematic, the bias origin point is not on the secondary side of the PT.

~
I have not noticed THAT done in the past.

However, as a consequence, they also put in a fixed voltage divider before the diode.
~

 

[Drgonzonm]

Unless I missed something, the el34s are seeing a 120Hz ripple. I guess to maintain the 120 ripple, the center tapped choke had to be fed a 60Hz ripple, an elegant solution. I have think about the impact of the design.

​

 

[bucephylus]

Perhaps, one of you should just start an Amplifier Theory thread.

 

[Sparkl]

I have owned many tube amps back in the day. I've been running an Ampeg PF800, SVT 7 Pro, SVT 4 Pro, SVT 3 Pro & Fender Rumble 500 V3 head & various cabs for the past 10 years. I just picked up an Ampeg SVT 2 Pro 300 Watts all tube head (to go with my two Ampeg SVT-212AV cabs) which is basically an all tube SVT 4 Pro. All I can say is the sheer power, presence, note depth, bloom, definition, growl & 3D punch was all it took to set my 4 pro off to the side and contemplate selling it. Everything I remember loving about my old tube heads was there and then some. Yeah it weighs a ton but so does the sound! In the end my sound & my tone is my essence. I spent years trying to lighten up my rig to the point it all became anemic. The Fender Rumble 500 & Ampeg PF800 can't even ride the same wave as the SVT 2 Pro. The SVT 4 Pro has a tube preamp but still hasn't got the 3D body of sound the 2 Pro has. As far as maintenance goes. Both SVT 7 Pro's died on me as well as the PF800 which died at a show. Both of those were digital. Never had an issue with any of my tube heads or my class A/B heads except the bias going out on my SVT 3 pro which was an easy fix for my tech. I was actually about to buy the Mesa Subway D800+ but I saw the SVT 2 Pro used and remembered how amazing my SVT II Non Pro was. I made the right decision.

That's what happened to me. Got obsessed with lightweight stuff but always found that it doesn't give the same weight to the sound some of the heavier equipment gives.

Now we already had discussions about lightweight vs heavyweight and learned that it is a pointless discussion, it is all about preference. Well my preference sort of lies on the heavy side so I just accepted my own reality

 

[somebrains]

~
So what's with the tabby ?

Do cats improve the damping factor ?
~

You know your tone is on point when their whiskers get vibrated and they bolt.
The ports of my cabs are firing just right when they won't come into my office.
It's like a force field when your low mids are just under the threshold of shaking loose tools and screws.

The unfinished thoughts and projects on my desk start to get resolved bc nothing like cats bouncing off my gear and spreading parts all over the office. Either I handle it, or I have to pick it off the floor and handle it.

I still can't find all of the cover plate screws of my Spector 2A from an incident a couple weeks ago.
Just took that desk area completely apart and found fist fulls of cat hair under my PC.

Back to this whole VS thing, I'm not looking for the El Camino or Subaru Brat of bass amps.
I need variety.

 

[Drgonzonm]

Yo


Back to this whole VS thing, I'm not looking for the El Camino or Subaru Brat of bass amps.
I need variety.

rancheros it is,
Maybe a red power wagon.

 

[DavesnothereCA]

That's what happened to me. Got obsessed with lightweight stuff but always found that it doesn't give the same weight to the sound some of the heavier equipment gives.

Now we already had discussions about lightweight vs heavyweight and learned that it is a pointless discussion, it is all about preference. Well my preference sort of lies on the heavy side so I just accepted my own reality

~
Well I, as many folks are, am torn.

As I'm sure I've stated before, IF I could afford a roadie for my now part-time gigging, I would prob'ly return to an SVT like back in the day, maybe with an outboard 1/3 octave graphic or full parametric EQ.

Instead, I have been using old to middle aged s/s heads, likely class AB, with speakers which weigh much less than the old 8x10, and I just bought a lighter weight bass to try for a while instead of my trusty ol' Franken-4001.

Knowing what other folks here think of the newer s/s heads, be they Class AB or D, is valuable to me, as some time this year I plan to be buying a head, as well as likely different speaker cabs, to get the weight per cab down some more, even if it means lugging more but smaller ones to each gig.

The cabs will get more attention in another thread.
~

 

[somebrains]

~
Well I, as many folks are, am torn.

As I'm sure I've stated before, IF I could afford a roadie for my now part-time gigging, I would prob'ly return to an SVT like back in the day, maybe with an outboard 1/3 octave graphic or full parametric EQ.

Instead, I have been using old to middle aged s/s heads, likely class AB, with speakers which weigh much less than the old 8x10, and I just bought a lighter weight bass to try for a while instead of my trusty ol' Franken-4001.

Knowing what other folks here think of the newer s/s heads, be they Class AB or D, is valuable to me, as some time this year I plan to be buying a head, as well as likely different speaker cabs, to get the weight per cab down some more, even if it means lugging more but smaller ones to each gig.

The cabs will get more attention in another thread.
~

Aguilar GS and Markbass cabs are cheap used in California, dunno about your area.
Couple of 112's get the job done.
700/1001RB II, Markbass F1/LM2/LM3, Mesa Walkabout/Carbine, later Genz, SVT 4 Pro, all of that does the trick.

I got off the nostalgia of the 15l in the Buster combo last night and plugged my epifani T310 into it.
That was fun.

I do get why people start collecting pedals/preamps/DI boxes and go IEM.
Eventually you Sanford and Son your way into piles of gear.

 

[otp57]

ok guys. As generic of a topic as this is I have a big dilemma.

If you check my sig, you will see that I am a (proud) owner of Aguilar amps.

They sound great and all but yesterday I tried to hook up a fender bassman tube clone.

Wow! I couldn't believe the sound I was getting. Barefaced big twin 2 has a renown of being a cab that is able to pump monstrous lows, that are sometimes even hard to control. But with the clone, every low note has a clear and round, veery warm low end that doesn't extend over the limits. What surprised me even more is that every note I played, even on higher registers is still meaty and has a great low mid presence and just keeps on going and seamlessly blends with the low notes with zero volume difference.

My aguilar amps work great as well but there was an obvious and immediate difference in the sound the moment I plugged in.

I immediately felt groovier and a better bass player.

Should I go after an all tube amp? I never played a solidstate with a similar warmth and meat to the sound and I am starting to think I never will.

The bassman clone was 40w and I couldn't believe how loud it actually was.

The size of these amps is bugging me though.

I use Tube and ss amps but I must say I do like the way a tube amp SOUNDs
My home system was Mcintosh SS and now I am using Mcintosh mc275 tube amps.
My old Mac amp was 200w rms but my mc275 is 75w rms and sounds more real like to me.
I also have a HA5500 SS bass amp I also love.
My Tube bass amps sound very warm and deep.
Tube amps can last as long as SS amps (remember tubes are like light bulbs you can't drop amps)
It sounds like you will go for the tube amp and it will not let you down.
I can use a 5lbs SS amp but my ears want the Tube sound
You must go with the amp that sounds good to you SS or tube

 

[somebrains]

Eating only oranges for a couple days makes bananas taste amazing.
Save some dough, get yourself a couple of options.
It's like giving your eyes a rest turning on night mode on your phone.

 

[BadExample]

Eating only oranges for a couple days makes bananas taste amazing.

Damn man, eat some meat. No civilization has survived a meatless diet, but a meat only diet has survived. It's the amino acids. Eat the dambid cat if you have to

 

[somebrains]

Damn man, eat some meat. No civilization has survived a meatless diet, but a meat only diet has survived. It's the amino acids. Eat the dambid cat if you have to

I ate a Honeybaked Ham practically by myself for a week after Christmas 3 meals a day.
I go thru this every year where Xmas dinner everyone wants a couple slices, then they're over it.

I was also playing a Spector thru an Ampeg SVP-CL thru 10's btw Thanksgiving to Xmas.
Before that it was a long stretch of a $$4 with Bigmans thru an Electric Blue and 12's.
Now I'm about the Jazz 5 and Buster 200.
Blackline SVT is sitting in a garage in Burbank on my last LA work trip bc, well I'm over it for a while.

At some point I'll either get bored and deal will roll by and I will need to start thinking about mounting my PC on the wall in a chassis.

For now I'm using a Genzler 800 basically as a power amp.
I literally don't like that amp on it's own unless I'm playing only a $$5 with SD Alnico MMs.

It's been a long time since I played a 15L, I missed it.