Stereo Power Amp options

[laxu]

Building anything with some level of quality and reliability with tubes is getting expensive, especially in a rack format. What I would like to see is more SS amps that are not the same off the shelf crap Class D shit already available from 50 other vendors. Bring back an updated version of the MosValve 982 (or 962) or some semi decent class AB designs.

I'd like to see e.g Hypex modules as guitar poweramps for modelers.

BluGuitar also really needs to do a poweramp. The Amp 1 Mercury Edition is not far off from being as neutral as my Fryette PS-100.

 

[JiveTurkey]

I'd LOVE a Blug power amp \m/

 

[Jarick]

Building anything with some level of quality and reliability with tubes is getting expensive, especially in a rack format. What I would like to see is more SS amps that are not the same off the shelf crap Class D shit already available from 50 other vendors. Bring back an updated version of the MosValve 982 (or 962) or some semi decent class AB designs.

This 100%. I do not want a budget tube power amp, that screams noise and reliability issues to me. Plus given the global economy, I don't want to have to worry about finding tubes in a few years.

A clean, reliable stereo power amp for modelers would be great. Hell a stereo version of the Blackstar Amped 1 would be killer. That thing sounds really good for class D and has some tone shaping options. All that's missing is the second channel.

 

[synthpenguin]

I don't think a lot of R&D money would be needed to build a MosValve clone, or other "tube like" SS amps. The designs exist and are LONG off any type of patent protection. I don't know what the manufacturing cost would be, but mosfets are fairly inexpensive, and there just isn't that much in these things. I would think if volume was high enough, you could build them under $150 (maybe well under) and retail them at under $450. Maybe I am way off, I don't know.

I think the mosfets would be one of the cheaper parts. I just don't see these sorts of companies developing an original circuit, or adapting a MosValve 982 in a compact way, and then selling it for the same or less than what they sell the generic class D ones for, especially when they make a lot more profit on the latter, and the market for the former would be a niche of a niche (after all, even a lot of pros are seemingly fine with the cheaper class D options).

Maybe I am totally off too though idk. Or maybe we get lucky and a marketing person somewhere will misinterpret the Rockman nostalgia and some company will end up going all-in cloning a Rocktron Velocity lol

This 100%. I do not want a budget tube power amp, that screams noise and reliability issues to me. Plus given the global economy, I don't want to have to worry about finding tubes in a few years.

A clean, reliable stereo power amp for modelers would be great. Hell a stereo version of the Blackstar Amped 1 would be killer. That thing sounds really good for class D and has some tone shaping options. All that's missing is the second channel.

I was just talking about a budget product for the market who normally buys budget tube amps (home users, etc). A lot of home users are also buying cheap class D solid state options which are also noisy and unreliable too (e.g. I see people talking about using those EHX power amp pedals with modelers and preamp pedals all the time). And a lot of people are using compact bass amps with solid state class D power amps that literally light on fire lol. Def a different market from most of the active users in this forum, I think.

The good solid state (and tube) stuff already exists, it just isn't budget (in the sense of stereo 100 watt channels for 450USD) and compact. A lot of people like the current feedback / low speaker damping designs of the Amped 1 and Quilter power amps (myself included), and it would be awesome if they released a stereo version, especially a power amp only version, but it's hard to imagine it being so cheap. Maybe though?

 

[Shask]

This 100%. I do not want a budget tube power amp, that screams noise and reliability issues to me. Plus given the global economy, I don't want to have to worry about finding tubes in a few years.

A clean, reliable stereo power amp for modelers would be great. Hell a stereo version of the Blackstar Amped 1 would be killer. That thing sounds really good for class D and has some tone shaping options. All that's missing is the second channel.

It would be interesting to see Mosfet based designs with an output transformer like a tube amp. I wonder if that would mimic the dynamics better.

 

[Jarick]

It would be interesting to see Mosfet based designs with an output transformer like a tube amp. I wonder if that would mimic the dynamics better.

I'm just guessing here, but I don't know if class D automatically makes a power amp "bad". I think it's more that manufacturers are using the same mediocre class D that's readily available.

If you listen to Kyle Bull's comparison of power amps, there's some that sound great and some that sound bleh. At the end there's a comparison of the SD Powerstage and Blackstar Amped 1 which again is surprisingly really good. I've heard that several other places too where it's been more impressive than other class D amps.

 

[Chocol8]

It would be interesting to see Mosfet based designs with an output transformer like a tube amp. I wonder if that would mimic the dynamics better.

It doesn't need to be mosfets but it definitely helps if it is a lower damping factor design to somewhat mimic how a tube power section interacts with the cab impedance curve. You also don't want the harsh distortion you get with class D as you approach the power limits.

The transformers I think would be technically called autoformers (sp?), and they were used in a lot of the classic MacIntosh designs. The benefit there is you get full power into 4, 8, or 16 ohms. The downsides are weight and cost. The average guitarist doesn't want to haul around something like an MC2100 which is close to 60lbs and puts out 105 watts per channel! The MosValve 982 is a 1u rack mount at more like 12-13 lbs and the 962 is the same power in a 2u and maybe a couple pounds heavier. I think you could do cheaper and lighter with a modern power supply feeding a similar circuit, but perhaps adding Asian wound autoformers/transformers wouldn't be too bad. I don't really know.

 

[Shask]

I'm just guessing here, but I don't know if class D automatically makes a power amp "bad". I think it's more that manufacturers are using the same mediocre class D that's readily available.

If you listen to Kyle Bull's comparison of power amps, there's some that sound great and some that sound bleh. At the end there's a comparison of the SD Powerstage and Blackstar Amped 1 which again is surprisingly really good. I've heard that several other places too where it's been more impressive than other class D amps.

I find a lot of times it isn't something you hear, it is what you feel. The dynamic punchiness to your playing, and you really can't hear that on YouTube videos.

 

[Shask]

It doesn't need to be mosfets but it definitely helps if it is a lower damping factor design to somewhat mimic how a tube power section interacts with the cab impedance curve. You also don't want the harsh distortion you get with class D as you approach the power limits.

The transformers I think would be technically called autoformers (sp?), and they were used in a lot of the classic MacIntosh designs. The benefit there is you get full power into 4, 8, or 16 ohms. The downsides are weight and cost. The average guitarist doesn't want to haul around something like an MC2100 which is close to 60lbs and puts out 105 watts per channel! The MosValve 982 is a 1u rack mount at more like 12-13 lbs and the 962 is the same power in a 2u and maybe a couple pounds heavier. I think you could do cheaper and lighter with a modern power supply feeding a similar circuit, but perhaps adding Asian wound autoformers/transformers wouldn't be too bad. I don't really know.

I know some of the old huge solid state power amps like H&H had output transformers, and they are still considered some of the best ever.

 

[Chocol8]

I know some of the old huge solid state power amps like H&H had output transformers, and they are still considered some of the best ever.

Yeah, whatever you call them, the transformer is a plus, especially in a guitar world where we often want to power 16 ohm cabs (or even 2 ohm). I just don't know if there would be demand to pay for that from the average Joe guitarist. The other thing about those old amps were the big power supplies which I think makes the difference in the transients. I think you can do that better these days with modern power supplies but you still probably need substantial caps. Smaller than they were in the 70's but not small, cheap, and light like the class D junk.

 

[JiveTurkey]

I would trust Quilter and Blug. I would not trust Blackturd. Some coloration can be good but honestly; flat and the capability to be INSANELY LOUD would be greatly preferred for an SS power amp for this purpose.

 

[Chocol8]

I would trust Quilter

They could probably leverage the QSC power amp designs and optimize it for guitar use with minimal R&D.

 

[Shask]

Yeah, whatever you call them, the transformer is a plus, especially in a guitar world where we often want to power 16 ohm cabs (or even 2 ohm). I just don't know if there would be demand to pay for that from the average Joe guitarist. The other thing about those old amps were the big power supplies which I think makes the difference in the transients. I think you can do that better these days with modern power supplies but you still probably need substantial caps. Smaller than they were in the 70's but not small, cheap, and light like the class D junk.

Actually, I think the power supply is the other big issue. They try to be all energy efficient and small these days, but that means the power supply dont have the capacitance power reserve to handle the big bassy chugs. The bass just kind of thuds out as the power supply runs out of headroom for the big spikes in energy.

Yeah, I dont think it would be a big seller, but if someone built big solid state power amps with big power supplies and output transformers, they would probably be able to compete with the big tube amps.

 

[OrganicZed]

Actually, I think the power supply is the other big issue. They try to be all energy efficient and small these days, but that means the power supply dont have the capacitance power reserve to handle the big bassy chugs. The bass just kind of thuds out as the power supply runs out of headroom for the big spikes in energy.

Yeah, I dont think it would be a big seller, but if someone built big solid state power amps with big power supplies and output transformers, they would probably be able to compete with the big tube amps.

I just use an amp meant for PA applications. You can get them pretty cheaply on the used market and they have the power reserves to reproduce the tube amp dynamics. The downside is the weight.

 

[synthpenguin]

Power supply is definitely the issue for stage volume. I don't think you need a big transformer, that just depends on the design. There are plenty of class D options with large enough energy reserves out there; they're just not small and cheap enough for what a lot of guitarists who want to avoid rackmounted gear are looking for. Approaches like Quilter has taken and their guitar-oriented design choices are nice because of the speaker interaction aspect, and just overall quality compared to most of the competitors in that niche, though I doubt they'd step on QSC's toes by making something more like those designs.

If someone wants something affordable, stereo, and not class D, why not just get a QSC GX3? It's class B (a good form of it), stereo, 425w across both channels, recommended by Cliff of Fractal ( https://forum.fractalaudio.com/thre...-vs-the-real-thing.191689/page-3#post-2383327 ), and 600USD. Yes, it's 27lb and rackmounted, but idk it's hard to get this sort of performance, have it not be class D, AND make it super light and small.

 

[Shask]

I just use an amp meat for PA applications. You can get them pretty cheaply on the used market and they have the power reserves to reproduce the tube amp dynamics. The downside is the weight.

I was reading a quote from Cliff at Fractal not too long ago which made me think about all of this. Having a 1000w amp like a GT1000fx doesn't matter if it doesn't have the power to handle the huge power spikes for things like bassy palm mutes.



FractalAudio said:

A lot of it is about transient energy storage. A tube amp stores a LOT of energy. Take a typical 100W tube amp like a Diezel. It will typically have 220uF of reservoir capacitance and a B+ of 450V. The energy stored is 22.3 Joules!!!

Now take a typical consumer Class-D "500W" power amp (actual continuous power about 100W). They usually have voltage rails around 50V and 680uF or so of capacitance. The energy stored (assuming bipolar supplies) is 1.7 Joules.

The tube amp has over 13 times the energy storage. So those palm mute transients are reproduced accurately. The Class-D amp runs out of gas.

For example, if your transient duration is, say, 100ms, and you're pushing a full 100W then the energy required is 10 Joules. The Class-D amp simply can't do it.

It's one of my pet peeves. People use cheap, low-end, consumer grade Class-D power amps and then make bold proclamations that the models don't sound as good as the real amp without understanding even a lick of the physics involved.

I put an Axe-Fx through a Crown X2 once and it Marty McFly'd me.

 

[GLiDE-BPM]

You should hear this thing like I do into a Laney LFR-412, Laney LFR-212, and a V3 preamp modded Fender FR-12 all at once!!!
Wall of Sound!!!!!!!!!!!!! My neighbors love me....

 

[mavrick102000]

I still have the Carvin 600W class AB power amp from when I had my standard and ultra. I also used a 2/50/2.

The Carvin was a bit lighter to carry but they both sounded and felt great.

I've thought about picking up a couple of 1x12 or 2x12 cabs to run in the Helix in stereo during the early evening.

 

[Shask]

I still have the Carvin 600W class AB power amp from when I had my standard and ultra. I also used a 2/50/2.

The Carvin was a bit lighter to carry but they both sounded and felt great.

I've thought about picking up a couple of 1x12 or 2x12 cabs to run in the Helix in stereo during the early evening.

Speaking of old Fractal favorites, I recently did the same thing after thinking about the power supply stuff. I pulled out my old ART SLA-2 instead of using the GT1000fx I have used for years. I was really listening for the dynamic differences since the SLA is much bigger, heavier, and has a huge transformer inside for power.

 

[laxu]

I'm just guessing here, but I don't know if class D automatically makes a power amp "bad". I think it's more that manufacturers are using the same mediocre class D that's readily available.

Exactly. So many products are literally the same ICEPower modules. They are also very common in bass amps.

Meanwhile both of my BluGuitar Amp 1s work great all the way up to ridiculously loud volumes, and sound great like that.