PA50 – Compact Power Amp

(25 customer reviews)


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SKU: 180-19694 Categories: ,


Compact Power Amp Overview

Finally, the perfect power amp to compliment your Ceres, Vesta, modeler, or any other preamp! Our goal for this product was to put the excellent power section found in our amp heads into the smallest package possible. Weighing in at only 12.8 lbs (5.8 KG), it packs a huge punch in a compact, portable unit. The PA50 is probably the most compact 50 watt all tube guitar power amps on the market.

With the myriad of tone shaping controls the PA50 will be right at home with any preamp, distortion pedal, or modeling unit. The HiFi / Guitar switch is the secret weapon for running your modeler, or if your preamp is particularly dark. The extensive set of NFB (negative feedback) controls allow for near limitless tone sculpting options, garnering both the best modern and vintage tones.

The PA50 includes our first-ever built-in bias monitoring circuit, as well as individual adjustments for each power tube. This allows for the use of slightly mis-matched tubes, as well as purposeful mis-matching to generate different harmonic content.


Power Amp Specifications

Controls: Top (presence), Bottom (resonance/depth), NFB (negative feedback), Master Volume

Switches: HiFi / Guitar source select, Power, Standby

Bias: Individual tube bias monitor and adjustment, all via the front panel.
LEDs from top-bottom: Good, High, Low, Fault. It’s normal for the LEDs to blink and flash as you play, especially at loud volumes the effect is more pronounced.

Internal LED lighting color selectable via internal jumpers: Red, Green, Blue, Yellow, Purple, Cyan, White, or Off

Voltage Input: 115/230V, 50/60 Hz
Power Output: 50W RMS
Power Tubes: 6L6GC, EL34, or KT77
Preamp Tube: 12AX7 phase inverter

Dimensions: 5.75″ wide, 5.125″ tall, 10.625″ deep (not including feet or knobs/switches)
Weight: 12.8 lbs (5.8 KG)

Quick and Dirty Videos

Default specs…

Additional information

Weight 15 lbs
Dimensions 14 × 8 × 8 in

Black, Red

25 reviews for PA50 – Compact Power Amp

  1. Steven McLean (verified owner)

    Well, the KSR team done did it. And to no surprise.
    The PA50 is the perfect companion to the Ceres preamp, any other preamp or modeler. This power amp is well thought out and useful in several applications. I bought mine with the intention of using it with my band, in tandem with the Ceres preamp, so that I could leave my conventional amp heads at home. Weighing less than 13 pounds, it suits my needs to have all the power that I need, with a small footprint and lightweight design.
    The Hi-Fi switch is cool for use if you wanted to power a turntable for mono sound or even have two for stereo. I don’t currently own a modeler, but I can only imagine that the PA50 would offer all of the flexibility that one would need to get the most out of your favorite modeler. It can also be useful with darker sounding preamps.
    One can use this power amp as one may use an FX loop return on your other amps, but it offers so much more with the negative feedback control and an incredibly useful master volume. If you’re a bedroom player with PITA neighbors, this power amp can be used at super quiet volumes. Or if you’re playing a gig, it can be an integral part of your gig rig.
    One of my favorite features of the PA50 is the tube bias monitoring system and bias adjustment. One doesn’t even need a multimeter or basic understanding of electrical theory to bias your choice of tubes. Just set the dip switches to the appropriate position for EL34/KT77/6CA7 or 6L6 bias range, let your tubes warm up, and adjust the bias until it’s in the good (green) bias setting for that tube. It’s never been that simple. Leave it to Kyle Rhodes to design something with incredible features and make it serviceable by the average user. Another quality KSR product. As if you would expect anything less at this point.

    Thanks to Kyle, Mandi, Corey, Quinn and anyone else who helps make these products reality.

  2. Jason Anthony (verified owner)

    This thing…….man. It’s everything I thought it was going to be and more. It can be quiet enough to play in my bedroom, but it can also do blow my ears out brutal. It’s size is amazing. The purple finish I got is amazing. It’s not noisy at all. The NFB, the top and bottom and the guitar/hifi switch are all game changers to me. It sounds awesome and it FEELS awesome. Thanks to the KSR team and how well it was packaged up was totally appreciated.

  3. renta.1

    Moved to this from a small class D poweramp. It was great for what it was, but it was missing the punch I needed to put my Quad Cortex over the top. After A/B’ing the PA50 against the SS power amp, it was clear I made the right choice. Don’t hesitate to get one of these if you need a compact power amp for your modeler!

  4. Barry Copestake (verified owner)

    Absolute unit of a compact power amp! Perfect compliment with the Ceres. I did previously use a PS2A which is great for digital modellers with it’s transparency but if you’re using a dedicated preamp pedal like Ceres the PA50 ‘guitar’ option gives deeper tone and feel is much better.

  5. rbasaria

    I wasn’t totally sure what to expect with this thing because of my past experience with KSR gear, but I have been floored with how good it sounds. Recently got a syn-1 and uber module, and after running it through various FX loops and a small AB power amp, it became clear that I needed a tube power amp for it. I didn’t want something rack, and I don’t need stereo, so the 290, 2902 stuff that is standard these days was sort of out. That left the power station and this thing. Ultimately, I think the fact that it weighs 13 lbs was what sold me haha. After about 5 seconds of playing, I knew this is exactly what I needed for this preamp system. Small, light, portable, and that all tube sound we all know and love so much. No noise problems like I was having through all these FX loops, sounds better, I don’t totally know what the NFB control does, but the other controls all make perfect sense, and are exactly what you’d want in a modern power amp. I can see the hifi setting being great for modelers.

    Anyway, this power amp makes so much sense. I think most guitar players looking for something like this are running some kind of standalone preamp/pedal thing. Most of us don’t need the size, weight, and cost that come with stereo power amps these days, and there aren’t a lot of affordable, compact options for mono tube power amps for guitar out there. All these little solid state amps just don’t do the same thing, no matter how hard they try to.

    Sounds great, you get the RIGHT controls, and you get something that can easily hang in any band setting. It can be as loud as you need, but also as quiet as you need. I’ve never heard a power amp be as transparent as you increase the volume as this thing. Really, just perfect for this type of setup.

  6. JOHN DIGIOIA (verified owner)

    Very good power amp and very nice people at KSR AMPLIFICATION

  7. Marvin Whitmore (verified owner)

    Exactly what I was looking for. The possibilities are endless with the PA/50.

  8. Paul R. (verified owner)

    The whole process has made me a KSR fan for life! The amp sounds as amazing as it looks. It has brought my quad cortex to life.
    Also, not many owners personally respond to customer emails the way Kyle does.
    My hats off to the whole KSR team.

  9. Sunwook Ha (verified owner)

    Loverly amp it was, i preferred el34 so i requested a new one with this tube and it was perfect. Communication between me and ksr amp was good also. I recommend you allo

  10. Matthew Crocco (verified owner)

    Love it!!

  11. Kyle Brown (verified owner)

    Wow! This unit is beyond words! It’s so power and so small, the tone….. brought my quad cortex to life! The warmth and bite is unreal. Now as far as build quality you can tell it’s built to last the metal is very thick and the paint job…. The slime green glows under black light its so freaking cool. I’m definitely getting another and ditching the matrix for my axe fx3 this thing rules

  12. Japheth Boivin (verified owner)

    KSR is the best! The quality of their products and customer service is second to none! This is hands down the most versatile and best sounding power amp I’ve ever used. Paired with my KSR Vesta, I have the most amazing compact, lightweight setup. You would never know it’s not a full size, traditional rig by the sounds that come out of it. Kyle and his staff are truly amazing and their products are unrivaled, in my opinion!

  13. Mark Sifuentes (verified owner)

  14. john gronski (verified owner)

    PA50 sounds great with my axe fx! KSR gets an A+ for quick replies to my tech questions.

  15. Josh Carlson (verified owner)

    Easy ordering, fast shipping, totally high-quality workmanship. Already eyeballing an Orion 45 for my next purchase!

  16. John P. (verified owner)

    The PA50 is awesome and works excellent with my Fractal FM3 and Mesa 2×12!!! Amazing tone! Very happy customer! Highly recommend!!

  17. Mike Spears (verified owner)

  18. Clint N. (verified owner)

    Got a PA50 to run with a Fractal FM3 recently. I’m blown away by the results.

  19. Robert Siriani (verified owner)

    Amazing !!

  20. sibalence18 (verified owner)

    If you are reading this then you are already pondering whether or not you should buy this…Let me give you the answer, BUY IT NOW ! ! ! This is exactly what I needed. I run preamp pedals and a Quad Cortex and the PA50 just gobbles everything up and spits out the tastiest of tones thru whatever cab/speaker/ir you are running it into. It is very very easy to dial in the exact poweramp tone I need for the application be it a standalone preamp pedal or the more complex Quad Cortex. I cannot say enough good things about this, it is absolutely perfection!

  21. JONATHAN (verified owner)

    From placing the order all the way to playing this beast, I’m very impressed with Kyle and team, and their products. The Amp I ended up with is better than I had hoped for, too!

  22. Jared W. (verified owner)

    Kyle and co are the best!

  23. Steve Embry (verified owner)

    Super compact. Plenty of volume and headroom on tap. The negative feedback control is awesome for tone tweaking and this thing sounds great! I run it with my KSR Vesta into a 1×12 and it rips.

  24. David Valenzuela (verified owner)

    Incredible design, loud, and gig/travel worthy.

  25. Kamal Nuaimi (verified owner)

    I love it. Easy to handle. Beautiful voice. Only thing I would like to be there is if there are recommended settings for the knobs for different styles or a tutorial of what exactly these do to the sound.

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