Verellen Octal

[agedhorse]

Agreed, but even with class AB outputs, the fact my amps use SMPS means they are still lightweight at around 3kg. When the output sections were made class D, another half kg was saved.

The difference is usually more than half a kg, usually around 2kg for an amp that’s in the 800 watt range.

 

[baxter_x]

Yes.

That is extremely interesting.
Now, a question comes up in my mind:
Is it impossible to convert from 50 Hertz to 400 hertz? That would make class AB amps super lightweight. Like all tube amps.....

 

[Wasnex]

Now, a question comes up in my mind:
Is it impossible to convert from 50 Hertz to 400 hertz? That would make class AB amps super lightweight. Like all tube amps.....

That is basically what SMPS does, except the switching frequency is considerably higher than 400hz. So this has been answered.

The only all-tube bass amps I am aware of that used SMPS are the Peavey VB-3 and VB-MA 300W at about 37lbs. 8.1lbs per watt

In contrast, the Mesa Strategy Eight:88 was 465W at about 49lbs and used a linear power supply. 9.5lbs per watt.

AFAIK Mesa did what they could to reduce the weight of the transformers and headcase. Peavey reduced weight using SMPS, but used a traditional headcase. Perhaps it could have been 8-10lbs less with a build like the Mesa.

 

[Wasnex]

@baxter_x

From the Mesa D800+ OM

The SMPS in this amp switches the frequency from 50-60hz to about 100kHz.

 

[baxter_x]

@Wasnex ok, but then why not using only high frequency even in class AB amps? That would also result in very lightweight amps, like class D.

 

[Wasnex]

@Wasnex why not using only high frequency even in class AB amps? That would also result in very lightweight amps, like class D.

It's not quite as light as Class D but it has been done.

For examples, the Jad Freer Sisma is class G and uses SMPS. To clarify, Class G and H are just advanced forms of Class AB.

Sisma – Hybrid Tube/Class-G Bass Head | Jad Freer Audio

jadfreeraudio.com

 

[agedhorse]

@Wasnex ok, but then why not using only high frequency even in class AB amps? That would also result in very lightweight amps, like class D.

GBE-600 was line frequency power supply and class AB, which became the NeoPak 3.5 which used an SMPS and a class AB power amp.

The next evolution became the Shuttle 6.0 which was SMPS and class D.

With each evolution. The cost didn’t decrease but the weight and size did AND the performance got better and better too.

 

[Sparky Mark]

The difference is usually more than half a kg, usually around 2kg for an amp that’s in the 800 watt range.

I'm referring to 500 watt Markbass heads., I.e. class AB LM3 at 2.9kg vs class D LM3 at 2.3kg. The majority of the weight reduction was due to the class D requiring a single heatsink vs the two heatsinks in the class AB shown below.

 

[sears]

am I being impolite? does this thread have anything to do with the thread title? Mods, please give me an infraction if I'm out of line.

 

[agedhorse]

am I being impolite? does this thread have anything to do with the thread title? Mods, please give me an infraction if I'm out of line.

It may be that you just can’t appreciate how a thread’s discussions can evolve when a member either asks a question that’s partially off topic, or doesn’t understand how and why technology changes.

If you reread the thread, there’s a lot of really good and useful information, even though some deviates from the topic of the initial posts. You might be surprised at how much you can learn from these threads, even as they swerve a little.

An added challenge here specifically is that there is VERY limited information on these solid state tube replacement devices. As more information comes out on these devices, as we get more experience with them, the discussions will become more fruitful.

Once I hear more feedback from early adopters, I will likely want to get some experience with them myself so that I can then offer good technical advice for our tube amp users.

 

[baxter_x]

GBE-600 was line frequency power supply and class AB, which became the NeoPak 3.5 which used an SMPS and a class AB power amp.

The next evolution became the Shuttle 6.0 which was SMPS and class D.

With each evolution. The cost didn’t decrease but the weight and size did AND the performance got better and better too.

Would it be possible to apply the same for an all tube amp to make them way lighter? That would reduce the size of the transformers.

Could that be the reason why the Mesa strategy, prodigy and the Sadowsky SA200 are so lightweight despite being all tube?

 

[cfortner]

No, nonone of these amps has a SMPS power supply.

 

[sears]

It may be that you just can’t appreciate how a thread’s discussions can evolve when a member either asks a question that’s partially off topic, or doesn’t understand how and why technology changes.

If you reread the thread, there’s a lot of really good and useful information, even though some deviates from the topic of the initial posts. You might be surprised at how much you can learn from these threads, even as they swerve a little.

An added challenge here specifically is that there is VERY limited information on these solid state tube replacement devices. As more information comes out on these devices, as we get more experience with them, the discussions will become more fruitful.

Once I hear more feedback from early adopters, I will likely want to get some experience with them myself so that I can then offer good technical advice for our tube amp users.

Dude, I have learned a lot from you. I love my Mesa. I also understand that keeping this thread "bumped" will keep the product visible. But I have fully read the thread already, and I stand by my comment.

 

[baxter_x]

No, nonone of these amps has a SMPS power supply.

Then increased frequency to reduce the size/weight of the transformers?

 

[cfortner]

No, lightweight parts

 

[cfortner]

The frequency of wall power is fix (230V 50Hz, 110V 60Hz and more). The only way to increase the frequency at home is to build a high power oscillator feeding a very small (!) transformer at frequencies f. e. 80.000Hz. The voltage on the transformers secondary Is transformed to your wanted voltage, but AC 80.000Hz instead of AC 60Hz on a normal power supply.

Then you need a rectifier, a filter stage and a low pass to remove the high frequency of 80.000Hz and convert your designed AC voltage with 80.000Hz into your wanted DC voltage.

 

[agedhorse]

Would it be possible to apply the same for an all tube amp to make them way lighter? That would reduce the size of the transformers.

Could that be the reason why the Mesa strategy, prodigy and the Sadowsky SA200 are so lightweight despite being all tube?

It is possible to use an SMPS to lighten the power supply, but the cost to design and execute at high enough quality/reliability makes it impractical for the number likely to be sold.

The Strategy/Prodigy used a high permeability grain oriented silicon steel to reduce the weight, some of the SA-200’s used a toroidal transformer. Lighter, yes but not light weight.

 

[agedhorse]

Then increased frequency to reduce the size/weight of the transformers?

Only the power transformer, the output transformer remains defined by the power and the lowest frequency being amplified.

 

[agedhorse]

Dude, I have learned a lot from you. I love my Mesa. I also understand that keeping this thread "bumped" will keep the product visible. But I have fully read the thread already, and I stand by my comment.

Sorry you feel this way, my comments have nothing to do with bumping this thread, nor does making this product visible have anything to do with me.

Now if you were to step back and look at the history of using MOSFETs as output devices in audio amps, especially as “replacements” for tubes, this is something that I have a lot of experience with because I learned from those legacy designers. I am passing on this information to those who care to learn more about it.

One of the earliest attempts was by the aerospace giant Teledyne Semiconductor, they developed a solid state small signal triode replacement for the 12AX7 family called the Fetron. There was also some design work being done on output tubes, but it wasn’t viable at the time. While it was successful in aerospace for high reliability applications, it was only occasionally used in guitar/bass amps. Randy used it for a few early high gain stages due to very low microphonics. My dad was an R&D engineer for one of the Teledyne aerospace divisions which is why I know the history of this device.

Another early developer/adopter using lateral MOSFETs was Hitachi, their devices were the gold standard, and they used them in some hi-fi products as alternatives to the “tube sound”. This was the most successful device family by far, starting with a few pro audio designers like Hafler, but also used in the MI industry. My first experience with this device was through BK Butler’s legacy TubeWorks products, but Dan van Reizen also used them in Mesa’s legacy bass amps.

There were also Sony’s vertical MOSFETs, another attempt to capture the tube sound, but Sony was a difficult company/supplier to work with so designers quickly passed.

These devices were generally used in a way that avoided high voltages and output matching transformers but not always. Eliminating the output transformer was considered a big weight savings and low frequency performance benefit which is why the efforts centered around this.

IMO, the biggest challenge is in getting these new replacement devices truly drop in because of the wide variety of circuits used in audio power amps and how different tubes are compared with MOSFETs at the micro level.

 

[cfortner]

Here they are:

I just caught a bad cold, will try it next week.