30+ watt amp the size of a pedal!

[olddawg]

Quilter Performance Amplification
Quilter Microblock 45... $149
I just wonder if you can get a clean and overdrive sound out of it in a live performance with no channel switching...
Your amp is now on your pedal board. The 24v external power supply is almost as big as it is!

[d95err]

Clean and overdrive - I guess you'll just have to use the volume control on your guitar. Probably works best with pedals before it for distortion and overdrive.

As far as small amps go, have you seen this? Palm-sized 50W (hybrid) tube amp:
http://www.voxamps.com/MV50

[eschertron]

Clean and overdrive - I guess you'll just have to use the volume control on your guitar. Probably works best with pedals before it for distortion and overdrive.

As far as small amps go, have you seen this? Palm-sized 50W (hybrid) tube amp:
http://www.voxamps.com/MV50

"Equipped with Nutube" We've talked about that before.

Future of Tubes is TODAY
Nutube ? English | korgnutube.com ? English

[olddawg]

Clean and overdrive - I guess you'll just have to use the volume control on your guitar.

If it reacts like an old school tube amp. I can see adding a jack to vary the gain or Tone Q control
With a volume pedal...

[nickb]

The irony is that us oldies who know and love the classic tube amps are also the one buying these lil' guys as we find the others too big to carry

I wonder when there will be a equivalent revolution leading to a significant weight reduction in speaker technology?

[g1]

Traynor had a mini 25W amp called the quarterhorse which had more controls and reverb, was a little bigger, but cost more.
I'd imagine you could find them used for cheap, but you'd need a bit more room on your pedal board.
Traynor Amps

[olddawg]

The irony is that us oldies who know and love the classic tube amps are also the one buying these lil' guys as we find the others too big to carry

I wonder when there will be a equivalent revolution leading to a significant weight reduction in speaker technology?

I often reflect on the irony of the situation. When I was young I had huge amps, roadies, and was too loaded to load anything anyway. Now I use a small amp, am on prescription drugs, have one of those "Rockstar" carts, and have to tell any band I'm in that they have to help me load and unload my gear. Lol! I don't see any way around speaker physics except QUIT USING MDF!

[olddawg]

Traynor had a mini 25W amp called the quarterhorse which had more controls and reverb, was a little bigger, but cost more.
I'd imagine you could find them used for cheap, but you'd need a bit more room on your pedal board.
Traynor Amps

That actually looks pretty good. I would have set up the controls better. The question is.... does it suck?

[R.G.]

Here's a thinking process.

Is it possible for clean solid state amplification to **re**produce good guitar sound? Sure - PA systems and hifis do it all the time. So the magic is not in what amplifier actually drives the speaker. It's in the signal fed to the amplifiers that drive speakers.

It >>may<< be necessary to feed guitar through some tubes and maybe even a specially voiced guitar speaker to make the right signal for power amplification. Miking small amps on stage is all about that. And many people think it's OK.

So maybe. Maybe pedals can make a decent signal to feed to a PA amp. Maybe the nutube, or micro "peanut" tubes from the old golden age.

Suckingness is increasingly going to be what you get from a signal source, not a quality of an amplifier. Probably it won't be easy. But then nothing about the last 50 years has been, has it?

[olddawg]

Here's a thinking process.

Is it possible for clean solid state amplification to **re**produce good guitar sound? Sure - PA systems and hifis do it all the time. So the magic is not in what amplifier actually drives the speaker. It's in the signal fed to the amplifiers that drive speakers.

It >>may<< be necessary to feed guitar through some tubes and maybe even a specially voiced guitar speaker to make the right signal for power amplification. Miking small amps on stage is all about that. And many people think it's OK.

So maybe. Maybe pedals can make a decent signal to feed to a PA amp. Maybe the nutube, or micro "peanut" tubes from the old golden age.

Suckingness is increasingly going to be what you get from a signal source, not a quality of an amplifier. Probably it won't be easy. But then nothing about the last 50 years has been, has it?

True that! Nowadays I play through 20 watt El84 two channel open back combo amp with one 12" through a speaker attenuator with a pedal board. The guy on the other side of the stage uses a very expensive and complex pro processor and rack preamp set up into the main amp input of a JCM 2000 then into an oversized 4x12" cab. I can't convince him that ALL of his trashy tone is in the damn processor. The power amp is never driven to saturation so any power amp would work and he doesn't need that mountain of gear for small venues. But he tells me the preamp "has a tube" in it and he can only hear that monsterous pile of amp, preamp, and speakers. It's also DIed into the PA. A couple of times he's accidentally blown us off the stage after a couple of shots because the overhead is still there even though the preamp output is on 1. Go figure. He has to have it! And at the end of the day he can still lift it!

[potatofarmer]

I wonder when there will be a equivalent revolution leading to a significant weight reduction in speaker technology?

Neodymium-based speakers are hitting the bass world pretty well. Some manufacturers are taking advantage of the increased flux density to get performance that ceramic magnets can't match. The Eminence 3015 comes to mind.

There are some neo-based guitar speakers, but maybe they're taking longer to catch on?

[loudthud]

I have often considered building a non tube amp with an external power supply. Common AC transformers are limited to 24VAC and 40VA in the US, not sure what the limit is in other countries. That's enough for something like a solid state 5E3 or slightly more power. A SMPS can go to 48VDC and 200VA or more. That will get you to 45-50W @ 4ohms. The advantage of the SMPS is the universal 100-250VAC input.

Quilter must be using a digital power amp, I wouldn't go that way so I would need a heat sink or at least a bigger box. Still it might make a cool kit or DIY project.

[J M Fahey]

Common AC transformers are limited to 24VAC and 40VA in the US, not sure what the limit is in other countries.

Where does that come from?
I feared something similar but this standards page, although focused on efficiency and idle consumption, mentions all sizes of "external supplies" from less than 1 Watt to Larger than 250W which is more than enough for any loud amplifier and could easily imply up to a couple kW , although they actually do not state any limit.
Efficiency Standards for External Power Supplies | DigiKey
I´d *love* to be able to build different 100W (or more) amplifiers all sharing the same plug-in power supply module or worst case, glorified wall wart,to drastically simplify certification.

[R.G.]

External power supplies are not limited in power in the USA that I know of. I can certainly be wrong about this, because I am NOT a standards/certification guy by any means, just have scars from dealing with folks like that.

But I think you may be talking about the standards for hazardous secondary voltages. There are limits on how much power you can pipe through wires to a second unit before having to protect users from contact with the connections on either end of the cable carrying the power between external power supply and the powered unit. The limits on that are something like 24Vac, 42Vdc, and 40VA, maybe. Above that, you're obligated to insulate and protect the external wiring and connectors just as you would AC mains cords. That is, if you want to get certification, which is not mandatory in the USA at all. In the USA, we have a steadily decreasing number of freedoms, but we still have the freedom to create electrical equipment with no safety review at all, and get sued for our pains.

Yes, Quilter is using a Class D amp. The revolution in Class D amps is that we now have MOSFETs that can switch high power fast enough to get audio-speed signals out and not run into either sudden smoke pouring from the outputs or horrible band limiting to prevent aliasing. Class D will probably eat up the entire high-power audio market as a result. It's just too tempting to have high audio power in a tiny, cool package. In fact, until the last election, I kind of expected the DOE and EPA to >>>require<<< Class D power amps on all new audio equipment to save the electrical heating. Maybe we won't have to do that for a few years, anyway.

There is a lot to commend Class D, so long as it can turn out similar audio quality.

[uneumann]

I have often considered building a non tube amp with an external power supply. Common AC transformers are limited to 24VAC and 40VA in the US, not sure what the limit is in other countries. That's enough for something like a solid state 5E3 or slightly more power. A SMPS can go to 48VDC and 200VA or more. That will get you to 45-50W @ 4ohms. The advantage of the SMPS is the universal 100-250VAC input.

Quilter must be using a digital power amp, I wouldn't go that way so I would need a heat sink or at least a bigger box. Still it might make a cool kit or DIY project.

My recent build is based on LT's line of thinking. It is a drop in replacement for a tweed bassman chassis. The whole chassis weighs in at under 6 Lbs which includes a 3 tube preamp and PI and a SS power amp and its 24v SMPS (150w). Also includes tremolo and spring reverb. Lots of EQ features and puts out a solid 50w sine wave at 4 ohms.

This link has a project history. https://sites.google.com/site/string...m-lite-project

[SoulFetish]

Quilter's been making quality solid state power amps for a long time. I respect the dude. He's not the first to take advantage of class D output stages for guitar amps, but he's creatively packing some decent power in small enclosures.
David Bering has some really interesting techniques using switching in tube output stages. He calls it Zero-Hysterysis Output Transformerless... wait, was he trying to get cute with that name? I just realized that it kind of rhymes and it just became bit more lame. Ugh. I'm gonna' let it slide this time, because it otherwise is pretty interesting.
Tube amplifiers for high-end audio by The David Berning Company
http://davidberning.com/images/paten...ent5612646.pdf

I wonder if they drive the speaker directly with a PWM signal counting on the speaker to be an LPF?

[loudthud]

I wonder if they drive the speaker directly with a PWM signal counting on the speaker to be an LPF?

Like R.G. says, there are no regs in the US about how dangerous your product can be, but there are regs about how much noise your product can radiate and inject into the mains. An unfiltered PWM signal on a speaker wire would be a huge radiator.

Where does that come from?

I was speaking of the "wall wart" type AC transformers that hang off of wall outlets or sometimes have a line cord much like laptop power supplies, but are not inside a product. Back in the early 90's I was looking at product offerings and 24VAC 40VA seemed to be the limit of what was available. The vast majority do not have the third wire safety ground (unless you pay extra). The safety ground helps keep the hum down when you try to make a high gain guitar amp using a wall wart type transformer. AC Voltage regulation is poor but I think it makes the amp sound and feel more like a tube amp. For a SMPS I'm tempted to install a resistor inline with the DC to deregulate the supply.

[SoulFetish]

Like R.G. says, there are no regs in the US about how dangerous your product can be, but there are regs about how much noise your product can radiate and inject into the mains. An unfiltered PWM signal on a speaker wire would be a huge radiator.

Also, wouldn't the PWM magnetic field generate high voltage spikes on the speaker coil?

[nickb]

Quilter's been making quality solid state power amps for a long time. I respect the dude. He's not the first to take advantage of class D output stages for guitar amps, but he's creatively packing some decent power in small enclosures.
David Bering has some really interesting techniques using switching in tube output stages. He calls it Zero-Hysterysis Output Transformerless... wait, was he trying to get cute with that name? I just realized that it kind of rhymes and it just became bit more lame. Ugh. I'm gonna' let it slide this time, because it otherwise is pretty interesting.
Tube amplifiers for high-end audio by The David Berning Company
http://davidberning.com/images/paten...ent5612646.pdf

I really don't know how he can justify calling it "transformerless" when it uses two where one used to work. The audio frequency one has been replaced by a ferrite one so it will be smaller and lighter with better HF performance, all good attributes, but at the expense of complexity.

I wonder if they drive the speaker directly with a PWM signal counting on the speaker to be an LPF?

The switching frequency in Class D is going up, now over 2MHz meaning the inductor is tiny.

[nickb]

Also, wouldn't the PWM magnetic field generate high voltage spikes on the speaker coil?

Most (all?) of these FETs have a built-in source-drain diode which will clamp any spikes during the off-time from destroying the FETS to the power rails. Sometimes they add external diodes across the output FETs too.

[printer2]

I want to play with Fets yet but for now I plan on running a Marshall preamp into a switching amp, TPA3118 BTL.



The tubes run off a boost converter, the PA and the tubes run off a 28V laptop brick.



Picked out the lightest piece of pine board I could find, cab the size of a 5E3. Speaker fairly light weight Yamaha.



I have a Yamaha that is more efficient and I like the sound a little better but it has a cast frame and a heftier magnet.

[Zozobra]

I want to play with Fets yet but for now I plan on running a Marshall preamp into a switching amp, TPA3118 BTL.



The tubes run off a boost converter, the PA and the tubes run off a 28V laptop brick.



Picked out the lightest piece of pine board I could find, cab the size of a 5E3. Speaker fairly light weight Yamaha.



I have a Yamaha that is more efficient and I like the sound a little better but it has a cast frame and a heftier magnet.

I'll be following this with interest

[printer2]

I'm curious as to what it will sound like. Probably won't be doing it for another month or so as I am building a Tele and I have a couple of people waiting for their acoustic guitars at the moment.

[Zozobra]

I have my ZVS board and a DC-DC converter for the heaters on order so I may get to start fiddling fairly soon. The laptop PSU I was planning on using doesn't have an earth bond to the plug though so I need to think about how to proceed with that from a safety POV. Would connecting the chassis to the DC negative be sufficient? Seems a little flaky.

[loudthud]

The laptop PSU I was planning on using doesn't have an earth bond to the plug though so I need to think about how to proceed with that from a safety POV. Would connecting the chassis to the DC negative be sufficient? Seems a little flaky.

There will likely be a small current that wants to flow between the output (either side) and Earth ground. It may simply be stray capacitance to one side of the Mains or possibly noise from the switching inverter. Without a safety ground, this current wants to flow from the guitar strings through you to that damp floor you are standing on or a properly grounded microphone. A DVM (set to AC Volts) or oscilloscope will usually show a substantial Voltage between Earth ground and either side of the DC output.

Not a good situation. This noise will probably find it's way into the audio path, another thing to avoid. There is also the possibility that a component failure inside the PSU could allow Mains current to find it's way to the output posing a lethal hazard. To be safe, you need a ground.

In the US some products have a two wire polarized line cord. This allows you to only insert the Mains cord one way into the wall outlet. Since one side of the Mains (called neutral) is grounded at the breaker panel (again, in the USA) it can sometimes be used to minimize the current, but not totally eliminate it in all situations. I don't know if this is the case in your country.

This can not be over emphasized: TO BE SAFE YOU MUST HAVE A GROUND !

[printer2]

I have nothing against having a ground, I am just curious about the concern about the safety aspect. Every PSU that I took apart (hey, I have to figure out how things work) the circuit attached to the mains and the secondary side is isolated from each other and only is connected through the magnetic circuit. One side resides on its area of the circuit board and the other on its. I guess you can conceive of a component failure and the board or the transformer melts down and a path to the mains is produced, no different than a regular transformer in our amps frying and shorting out between the primary and secondary.

[nickb]

I have nothing against having a ground, I am just curious about the concern about the safety aspect. Every PSU that I took apart (hey, I have to figure out how things work) the circuit attached to the mains and the secondary side is isolated from each other and only is connected through the magnetic circuit. One side resides on its area of the circuit board and the other on its. I guess you can conceive of a component failure and the board or the transformer melts down and a path to the mains is produced, no different than a regular transformer in our amps frying and shorting out between the primary and secondary.

The design of the transformers differs between grounded (Class I) systems and double insulated (i.e no grounded case class II). The basic idea as I understand it is to have two levels of protection. In a class I system the transformer will have basic insulation plus a metal screen between the primary and secondary. The screen is connected to safety earth and so protects against insulation failure. For a class II system the insulation is reinforced to provide the second level of protection. This is rather simplified but hopefully you get the general idea.

[Zozobra]

Yeah, I figured it was a no-go from a safety POV. The AC inlet to the brick is 2 pin and no ground passthrough so I'll not be using it to drive my ZVS. Maybe I'll use it for a class D poweramp or something similar...

[uneumann]

Yeah, I figured it was a no-go from a safety POV. The AC inlet to the brick is 2 pin and no ground passthrough so I'll not be using it to drive my ZVS. Maybe I'll use it for a class D poweramp or something similar...

There are two issues here that seem to be mixed in the discussion. One is whether your chassis has an earth ground and the other is whether your PS brick has an earth ground. IMO - disclosure: I'm not a code/UL safety expert - having an earth ground and a 2pin PS are not incompatible.

Use a 3 prong cord to the chassis and make an earth ground to the chassis. Then - after the switches and fuse - wire the 2 pin PS brick as you would wire any 2-wire transformer primary. The output of the brick will need a connection to signal and chassis ground - as any DC supply does. The idea is to treat the brick as you would any transformer/rectifier/filter DC supply.

[printer2]

Use a 3 prong cord to the chassis and make an earth ground to the chassis. Then - after the switches and fuse - wire the 2 pin PS brick as you would wire any 2-wire transformer primary. The output of the brick will need a connection to signal and chassis ground - as any DC supply does. The idea is to treat the brick as you would any transformer/rectifier/filter DC supply.

Was thinking about it and came up with the above as a possible solution, glad to see I am not the only one.

[printer2]

I'll be following this with interest

Been thinking of this project and thought some changes would be in order for the tube section. I did a paraphase inverter once and thought it sounded good in the just to the edge of breakup range fattening up the signal. Figured adding a switch to go from a Bassman to a sort of Tweed is worth the added complexity of a four pole switch. The input may have its own switch to go to one channel or the other or both. I might start this sooner than latter, it isn't that big of a project and I could be building guitars till who knows when.

[olddawg]

I had a bass player show up at audition yesterday. SHE was using a Quilter Power Brick into a GK 1x15" cab. Sounded great. $249 amp.

[R.G.]

I think we may see designs soon that are either switching amps designed to go under popular pedalboards or pedalboards that ARE the amplifier.

Just to be clear, I'm not currently designing such a thing at my day job, it just popped into my head.

[eschertron]

...or pedalboards that ARE the amplifier.

And you put this idea out for just anyone to grab and run with? Reading your posts I feel as though I am in the presence of a bodhisattva

[printer2]

A step closer. Threw together a cabinet for a 12" speaker. Still need to round off the corners and not sure how I want to finish it. Weighs in a 10.2 lbs and Yamaha speaker that is 5 lbs or if I want to go light weight an old Jensen C12R at 3 lbs will be easy to carry around once I put the handle on it. I went to Home Depot and picked out the lightest piece of pine they had. Just a break from my Telecaster project, need to carve the neck next. Might start the amp once I start finishing the neck.