A new type of tube guitar amplifier

[gonzo]

[webmaster edit] This post was reported as spam earlier, and we've cleared that up now. The OP would like to state that this is not a product of his and he has no connection with the builder. He was just attempting to point out this new product to his fellow TDPers. [/webmaster edit]




i just found this.
i thought it was fascinating, thought i would share.



A NEW TYPE OF TUBE GUITAR AMPLIFIER

(my apologies if this has been covered before)

Milbert GAGA-50


http://www.milbert.com/guitar

http://www.thegearpage.net/board/sho...1&postcount=42

[Tele-phone man]

Wow...very interesting. This is really something new! There's a lot here to read and think about.

[ThermionicScott]

That's fascinating!

[JohnnyCrash]

OT's and their "limitations and distortions" might actually be what some people like.

At the same time, this is completely fascinating to me... how does it work without transformers? Any wall voltage? 5 lbs.?!

I'll be at NAMM in a few weeks - I have to try this amp out!

[redstringuitar]

No transformers, any valve, auto biasing?? I'll be looking out for more on this baby...pretty sure it'll be way out of my budget though.

[MickM]

Figures, I'm just getting to the point where I have a slight understanding of how my Champ works.

[jefrs]

Apparently the ZOTL (sp?) system uses a RF transformer, not an audio-output transformer. It does have transformers. They must be very light. What does it do for mains?

[redstringuitar]

Originally Posted by jefrs

Apparently the ZOTL (sp?) system uses a RF transformer, not an audio-output transformer. It does have transformers. They must be very light. What does it do for mains?

Good question, it has to go high voltage DC for the power tubes to work, surely?

[ThermionicScott]

On second thought, I'm starting to wonder if the tubes do anything besides light up...

- Scott

[anacephalic]

these guys may have been the first to apply the technology to guitar amps but OTL amps have been around in high end audio for a while. It's been about 10 yrs +/_ since i first read about them. Never researched them much since i had a set of tube amps i was, and still am, in love with.

[rangercaster]

thanks, but i'll wait 'til the Chinese clones are available ...

[Zillinois]

Interesting idea, sort of sounds like the Marshall Vintage Modern, whihc uses KT-66s, or "totally lacking tube warmth".

[ruger9]

Originally Posted by Zillinois

whihc uses KT-66s, or "totally lacking tube warmth".

You obviously haven't heard a Docter Z Route 66...

[barkley]

Wow. I dont really understand how tube amps work, but I really have no idea how that one works!


Glad they work tho... :)

[Billm]

It appears to be a fresh combination of existing technologies. You can get off-the-shelf high voltage switching power supplies that are smaller and lighter than conventional power transformers. Output transformer-less (OTL) circuits have been around for decades, as Anacephalic points out. I think that many of the designs are engineering exercises--mental challenges, not necessarily a great leap forward in tone or audio fidelity.

Here's a page on OTL design for the curious:

http://www.tubecad.com/2006/12/blog0093.htm

This guy even sells a board and experimenter's kit so you can build your own OTL amp.

As Johnny Crash says, our ears are trained to the kinds of distortions produced by output transformers, however slight they might be. Audio transformers have been around for 100 years and have gotten rather good. It wouldn't surprise me if the Milbert amp had some voicing in it to tailor the frequency response to players' expectations. Compared to transformers, speakers impose far greater distortions and limitations, so I'm not all that impressed by OTL designs.

The hi-fi megasnob, however, could have a direct-coupled (no capacitors) OTL system driving planar electrostatic speakers for the ultimate in perfection. The technology is wonderful, but insanely expensive.

Today, power transformers, diodes and big electrolytic caps are still less expensive than a 400-500V switching power supply, but who knows, maybe it's time for that technology to trickle down. Ditto for OTL. A 35 lb. Twin Reverb would be pretty cool.

[Dan German]

Very interesting. I like the fact that they provide a lot of technical info (even if I don't understand half of it ) instead of the usual vague promises of "groundbreaking design" and "incomparable tone and warmth".

The copy, however, shows that letting engineers write their own copy is almost as bad as letting copy writers design amps. "Harshless alacrity" indeed...

I'm perfectly happy with the overweight, old school amps I have now, but I'd like to get the chance to play around with on of these, once they actually exist.

[klasaine]

That's definitely something I'll check out at NAMM.
The sound samples didn't impress me too much - sounded like 'modeling' cleans and dirtys - but I never rely on sound samples via dig recording and through a computer to really tell me anything.
We'll see - would be great if it's for reals.

[Billm]

Ready, fire, aim!

I just read their patents and tech descriptions and it's nothing like previous OTL designs... and my previous comments have limited applicability. This really is fresh. It strikes me as an audio-modulated switching power supply that incorporates the transfer characteristics of tubes in order to warm up the tone.

I'm looking forward to members' reactions when they get to play it.

[jhundt]

darn, will I have to sell my '55 Deluxe to buy one of these now?

[keithcc]

This basic design was done by David Berning almost 20 years ago and was discussed in the audio buff magazines, particularly <i> Audio Amateur/ Glass Audio</i> quite a bit. Using it for a guitar amp seems ridiculous since it will not generate any of the characteristic sonic modifications of an overloaded, undersized-transformer, undersized power supply conventional tube audio amplifier of the late 1940s.

But yeah, it works.

[muchxs]

Originally Posted by anacephalic

these guys may have been the first to apply the technology to guitar amps

They're not. They're infringing on several existing patents.

[woodman]

I'll wait til you guys test 'em out in the real world and give a full report!

[BigDaddyLH]

When it's that light, you can go for some heavy cabinets:



(1,200 lbs. per speaker and $275K per pair!) Heh...

[krauser2]

its about freaking time.......I mean comon....we can clone, cure disease, fly to other F'n planets for crying out loud. We have robots that can do things better than people

It took us this long to update 60+ year old technology. I blame you stubborn old guys for holding this back for so long ;)

But yeah, really cool, if anyone gets to demo it let us know what its all about

[therecordfable]

WoW! If it sounds good what an ease of mind factor this would give you. I find this truly fascinating. It does seem strange no sound samples or demo vids to showcase the sound. The ability to change tubes on the fly and any combo of tube without a worry blows my mind. I will be very interested in this if the sound indeed is worthy of the hype.

[Tim Armstrong]

Originally Posted by krauser2

It took us this long to update 60+ year old technology. I blame you stubborn old guys for holding this back for so long ;)

I'm sure all the modeling amp manufacturers would politely suggest that there has been SOME new work done in amp design...



Tim

[kludge]

If it's a Benning-style Class B OTL, it's going to be HYPERSENSITIVE to speakers, even more than tubes. And a transformerless power supply operating at sufficient voltage to operate tubes? That's a quadrupling step-up from 120v line voltage. That's also kind of a shock hazard, especially when dealing with the working conditions of a guitar amp.

I can see how this is possible, but when someone offers something too good to be true, it probably is.

[PennyCentury]

Milbert GAGA-50

Lady GaGa already has signature gear????

[jjkrause84]

"recovers instantly without hangover"

Can milbert do this mod to my body?

[therecordfable]

Originally Posted by kludge

If it's a Benning-style Class B OTL, it's going to be HYPERSENSITIVE to speakers, even more than tubes. And a transformerless power supply operating at sufficient voltage to operate tubes? That's a quadrupling step-up from 120v line voltage. That's also kind of a shock hazard, especially when dealing with the working conditions of a guitar amp.

I can see how this is possible, but when someone offers something too good to be true, it probably is.

True I will have to play and hear this for myself to get on board but it's intriguing.

[guitarzan13]

Wow! And ONLY a little less that 2 Grand!

[kludge]

It'll be interesting to see how it really works. Supposedly, they've been granted a patent on it, and it's not just a recycling of established OTL techniques. And supposedly, it operates in Class AB1 (which is really what you want for octal power tubes like 6L6 and EL34). Now, the reason the transformer is there in traditional designs is impedance matching. Plate-loaded tubes (especially pentodes in Class AB1) are high impedance devices... on the order of 5k ohms. And speakers are inherently low impedance devices, 8 ohms. You can't transfer power from a high impedance device to a low impedance device, basically. The output transformer provides the tubes with the high-impedance load they want to see, and speakers with the low-impedance source they want to see, while safely decoupling the speaker from the dangerous voltages of the tubes.

Apparently, they're using switching mosfets to create an impedance load for the tubes (which despite their claims of "This is not Class D", it's a kissin' cousin). What I don't get is how they're also getting the low-impedance load out to the speakers, without a separate amp stage. If the tubes are in Class AB, the voltage swing is very high - speakers would arc in a second. The way I see to do it is to just take the voltage swing off the tubes, run it into a high-impedance voltage divider (basically a volume pot), and then use the scaled-down voltage to drive a low-impedance mosfet buffer that drives the speakers. But this makes their claims of "all tube" completely specious... they can claim that tubes aren't used for voltage gain (true), but then the tubes wouldn't be driving the speakers directly. They'd just be a glorified preamp, and solid-state devices would be driving the speakers.

Of course, I haven't read the patent, and I'm very much an electrical engineering amateur. Maybe they're doing something with those mosfets that I just don't understand. But common sense says they're not driving low-impedance, low-voltage speakers directly off of high-impedance, high-voltage power tubes, using just switching mosfets to fake low impedance. Doesn't solve the voltage swing problem.

[SURF]

It will not stand the time. Who will pay $2k for "tube amp" with a computer type power supply and without output transformer? It's lightweighted, but the most weight is the cabinet and the speakers.

To drive 8 Ohm speaker for 50W you need 20V and 2,5 A output. No way to get 2,5 A directly from the output tubes unless there are a lot of them (more than 10). They simply will not have enough emission to do the task.

So all that sounds to me like a big BS they try to implant in our brains. Thank you - I have enough.

[krauser2]

Originally Posted by Tim Armstrong

I'm sure all the modeling amp manufacturers would politely suggest that there has been SOME new work done in amp design...



Tim

Sorry I should have added this *Good Design*

[krauser2]

Originally Posted by jjkrause84

"recovers instantly without hangover"

Can milbert do this mod to my body?

YES......ME TOO

[mlove3]

why are there no audio samples or video on their site or youtube?
if they wanna spring this on the amp buying world the fact that it's 5 lbs is nice but aaahh...i wanna hear it.

[therecordfable]

Originally Posted by therecordfable

WoW! If it sounds good what an ease of mind factor this would give you. I find this truly fascinating. It does seem strange no sound samples or demo vids to showcase the sound. The ability to change tubes on the fly and any combo of tube without a worry blows my mind. I will be very interested in this if the sound indeed is worthy of the hype.

My sentiments exactly.

[ThermionicScott]

Just because there is no output transformer, doesn't mean it's OTL in the hi-fi sense. These guys are probably using solid-state components to actively match the impedance. (I dunno much about SS electronics, but you could theoretically take a signal off the speaker wire to "read" how the speaker impedance is reacting to the output signal, right?) Perhaps they've come up with an analog version of Class D...

We're at the point where you can just about simulate everything, but not perfectly yet.

- Scott

[F6_FullMelt]

Originally Posted by jjkrause84

"recovers instantly without hangover"

Can milbert do this mod to my body?

Originally Posted by krauser2

YES......ME TOO

me three!
says I as I pour a drink down my throat as I am too embarrassed to go sing without one, or six.

[WickedGTR]

It appears they showed it at summer NAMM 2009 as well.

And no sound samples, anywhere.

Must be very... transparent.

Anyway, no reverb or tremolo? I'll pass.