PRS HDRX 20 Amplifier Review
Hello neighbours. As you know by know, I am a fan of Paul Reed Smith guitars. I have written reviews of the Mary Cries compressor and reviews of the Horsemeat and Wind Through the Trees pedals are coming. I own an old PRS Dallas amplifier which is a 2 x 12 50W combo that is spectacular, but have only (up until now) found another PRS amp that I would spend the money on owning. The DG Custom amp and cab are amazing sounding but out of my price range. Yesterday, I was at The Arts Music Store and noticed an instore promotion on the relatively new PRS HDRX 20 head and matching 1x12 cabinet. As I already own a couple of now discontinued PRS Stealth 2x12 cabinets, I decided to try the HDRX 20 head with one of those, instead of the 1x12.
I brought the amp home and set it on top of the 2x12 Stealth cabinet. I connected the speaker cabinet to the head, and the head to the wall. I plugged my Epiphone White Les Paul Custom into a tuner and the tuner into the amp. While there is a recommended settings top ad, I just dimed everything except the Master Volume and turned the amp on to let it warm up. I have never had a tube go in over 25 years because I allow them at least a couple of minutes to warm up before sending a signal and let them cool down at least that amount of time with no signal before cutting the power. It might be a myth, but if so the myth works for me.
Caveats
I had been warned up front that I probably would not like the amp. I was told by qualified players that it was persnickety and that it was a fair bit of work to find good tone. A number of other comments were made about design choices and “missings” given that it is 2023 as I write this. The commenters are talented players, so my expectations of the amp were rather low.
Initial Impressions
As soon as I turned the tuner off, with the volume pots at 10 on the Les Paul Custom, I could still hear guitar sound out of the cabinet with the amp master volume at zero. Hmm, odd, but whatever. As noted I had dimed every control except the master, including the treble volume and bass volume. I will talk about why these exist in a bit, but for simplicity think of a classic 4 input Marshall, where you jumper between the Lead and Rhythm channels. As I turned up the master slowly I started to hear some familiar tones. It started getting loud with the master just below nine o’clock and was a bit strident, so I backed the presence off to noon. At 9 o’clock it was louder still but the bass that had been a bit light was now coming through the cabinet. At 10 o’clock it sounded like an old Marshall head with the bass wound full on. At 11 o’clock all the critters in the house had run for cover and the volume had hit the maximum for what I could personally handle in the space where I was. Rolling off the bass a bit helped along with kicking in the mid switch and the bright switch for a really nice tone in all three pickup positions. I was impressed because I find the Epiphone Probucker 2 and Probucker 3 pickups a bit dark at ten and they are best at about 8. There are still people who see Epiphone as a lesser instrument and I am sorry for them. This Epiphone is a better Les Paul Custom than my long gone early 80s Gibson Les Paul Custom which was massively heavy and muddy sounding. But I digress.
The Epiphone does an amazing job of fighting feedback and the only way to get a bit of howl was to raise the master up past noon, and honestly that level of volume hurt. The HDRX is a tube head rated at 20 watts and as I find consistently, will take a 100 watt solid state amp out behind the school and kick the crap out of it.
Amplifier Specs
The HDRX uses three 12AX7 or ECCC83 preamp tubes and 2 5881 or short bottle 6L6 power tubes producing 20 watts output. There are five speaker outputs allowing for 4 ohm, 8 ohm and 16 ohm loads as well as monitoring ports for tube bias. The design is based on one of Jimi Hendrix’s modified Marshall heads. PRS was granted incredible access to the original in order to map out what was in this renowned head. While I am looking at the 20 watt version, there are 50 watt and 100 watt versions. There are two channels, called Treble and Bass that are jumpered together internally. Each channel has its own volume control, offering enormous flexibility in overall tone. There is a three band global EQ offering Bass, Middle and Treble selections. There is also a global presence control. There is a 2 way micro switch to invoke a Bright option, beneficial when everything is fully cranked up to bring back some high end. There is also a high-mid gain switch. In my tests, I tried the switches in all variants and in the end, just left them on all the time. The unit is covered in black Tolex and weighs in at 27.6 lbs. The amp was designed by Doug Sewell and Paul Reed Smith to get as close to Hendrix’s custom head as they could. Doing so meant building a head in the late sixties style, so no reverb, and no effects loop.
Longer Play Time
For my second session, I wanted to see how the amp would fair in its less distorted configurations, wanting to see how clean that I could get it, and where I would be able to get the preamp just at the edge of breakup where a volume setting on a guitar at 8 was still mostly clean and at 10 was starting to have the edge of grit. Again, others had said that the shift was abrupt. I could not duplicate that, as I found I could leverage the combination of the guitar and the amp that would give me both. For this session, I used a PRS CE24 in both full humbucking and different split coil scenarios. I had read that the HDRX did not like single coils, especially low wind single coils so I wanted to run the gamut of single coils as well.
The PRS sounded even better than the Epiphone. I put this down to the pickups because the Epiphone has a full CTS control stack. I have it on my list to upgrade the factory pickups on that Les Paul to Bare Knuckle Mules with gold covers. I have done that on Gibson Les Pauls, including one of my own with a substantial improvement in tone from my point of view. That said, the Epiphone sounds as good as my R8 as it stands. Again, I have digressed.
The HDRX with the PRS in both hum and split coil modes delivered the ability to go from clean to edgy, with the volume pots at 10 with the amp treble and bass volume knobs at noon. All I had to do was vary my pick attack to move between them. As some of you will know, I prefer heavy picks between 2mm and 3mm with no flex and I was using a V-Picks Dimension in all my tests, both with and without the ghost edge variations. So far I find that I am very impressed with the PRS HDRX 20.
Next up were single coils. I have an older Strat that I modified with a VegaTrem and with a Bare Knuckle Pickups PAT Pend ‘63 Veneer Board pickup set. All the controls and related electronics were also updated to BKP kit. It’s a really wonderful Strat and sounds terrific, but can be picky about the amplifier preferring Fender Twins and Deluxe Reverbs. I plugged it straight into the HDRX 20, same as with the PRS. In all dime mode, I had to disable the bright switch in pickup position 1. The Bare Knuckle pickups are not wound particularly hot, running 6.3 Kohms in the bridge and 5.8 Kohms in middle and neck. Rolling the channel volumes off to noon, and bringing the master up gave me a very flexible tone based on pick attack, clean generally and starting to bite a bit when digging in. Moving the pickup selector to positions 2 and 4, where I use the Strat most often and rolling the volume and both tone controls up to ten delivered that perfect Strat tone, albeit without the reverb that I think is required. Rolling off the channel volumes to ten and the presence to just below noon, while raising the Master gave a beautiful clean tone, still without the bright or mid-high switches engaged. My guitar is wired as Tim Mills recommended, the first tone control is neck and the second is middle. The bridge pickup has no tone control at all and can get a bit spiky. For position 1 I rolled the treble off to about 1 and that solved that.
From these play tests, my conclusions are that the amp works well with scatter wound, average single coils, split coil humbuckers and full humbuckers and has plenty of room to achieve the tones desired. I briefly plugged in my Gretsch Electromatic G5210T with P90s and it too sounded really good. These P90s are a really good representation of a normal wind P90 not overly hot and again delivered a great tonal range through the HDRX.
For the PRS, the Strat and the Gretsch, I also briefly engaged a PRS Horsemeat Overdrive to push the front end of the amp a bit when it was set to be just on the edge of breakup. The two pair nicely for certain, but I don’t need the OD with the HDRX if I am prepared to turn a few knobs on the amp.
What I Miss
The PRS HDRX is a traditional design. It has a preamp section and a power amp section. There is no built in reverb, and I can live without it because many of my older amps and even some newer tube amps do not have reverb, While I can put a reverb pedal in front of the amp, I prefer to put reverbs, delays and modulations between the preamp and power amp sections and wish that the HDRX had an effects loop. I can function without it, but would really prefer a loop if one was built in. Worst case, I will move my Strymon Cloudburst to this amp.
The internal jumper design that provides only one input jack instead of four has received some criticism. My oldest Marshall head has a high and a low input only so no jumping available My Laney head has four inputs, and yes I have tried different inputs and jumper cable configs but I go into the high treble and then jump from low treble to high bass and just leave it like that. Myself, I cannot tell the difference, and the more I use the HDRX, the more I like having a separate treble volume and bass volume, so what I thought I would miss, I don’t miss at all.
I do however miss an output that I could run direct to an input on a recording interface. While I can, and do, mike the cabinet, there is a nice bonus in being to record direct to the interface and otherwise keep things silent. That’s one of the best parts of the Laney LA-Studio head. Oh well, back to miking the cabinet. Since I will be miking the cabinet to record anyway, I will apply reverb during the recording process using my favourite EMT-140 plate reverb from Universal Audio, or a Lexicon 480L digital reverb, also from Universal Audio.
About the Cabinet
The PRS HDRX 2x12 and 4x12 cabinets use Celestion G12H-75 cream back speakers. The HDRX 1x12 uses a Celestion V-Type. My PRS Stealth cabinets have a pair of Celestion G12T-75 speakers. These have a slightly lighter magnet and a 3db less efficient than the HDRX 2x12 cab versions. Less efficiency means pushing more power is required to achieve unity volume in a comparison. I love Creambacks in general, although the G12T-75s are really the classic rock speaker, from the maker’s perspective, and the pairing of the HDRX 20 with a PRS 2x12 Stealth is a real winner in my opinion.
Quick Samples
I’ve recorded four quick samples for your reference. All were recorded with guitar direct into the HDRX, which was connected to the PRS Stealth 2x12. Mic was a Shure SM57, vaguely off axis and about 3 inches off the grille cloth. The mic went into a UA Apollo Twin X with a Neve 1084 channel strip in the Unison slot.
The amp was set with the bright switch on, the high-mid gain switch on and the rest as follows;
All amp controls at 10 except Presence at 6 and Master Volume at 3 - The Amp pretty much dimed
All amp tone controls at 10, Presence at 6, Bass Volume and Treble Volume at 10 and Master Volume at 3 -The Amp dimed for single coil
All amp tone controls at 10, Presence at 6, Bass Volume and Treble Volume at 5 and Master Volume at 4 - The Amp at the edge of breakup
All amp tone controls at 10, Presence at 6, Bass Volume and Treble Volume at 3 and Master Volume at 5 - The Amp set for clean tones
All samples were in the mastering phase put through a Lexicon 480L reverb set to the Jazz Hall preset with the wet level at 20%. The final step was to use a Shadow Hills Mastering Compressor using it’s VOX Optical Nickel preset. While this ostensibly a voice preset, I find it excellent for electric guitar because it uses an optical compressor that is fairly light and produces unity gain on the output.
My Conclusions
While I was warned up front that the amp would be hard to get a decent tone from, I did not find that at all. Mind you, the only cabinet I used was the PRS Stealth 2x12 and I found the two went together beautifully. It’s Marshall-y as expected, and in my personal opinion, I like it better than the Marshall Origin 20 which is a fine amplifier and will cost you less money. I would have liked to compare it against the Marshall SV20H Studio which is their power scalable 1959 Plexi unit that uses a pair of EL34 power tubes instead of the 6L6 tubes in the PRS. The PRS is assembled in China, like the Marshall Origin series. The Marshall Studio series are assembled in the UK and MAP is $2149 CAD. MAP on the PRS HDRX 20 is $1073 so pretty much half the price. The world changes. I remember when Made in Japan was used as a denigrating claim and how things have changed. I’m not convinced that all workers and assemblers in China get up every day trying to make a poor product, and given my experiences with Fender USA/Squier and Gibson/Epiphone, I don’t believe that the assembled in China label is an automatic indicator of poor quality. Do not let the Made in China designation get in the way of an amp or guitar that you like.
I like the HDRX 20 very much and I think that the price point for a 20 watt all tube head is not unreasonable if the amp delivers what you want. In my opinion, the amp is much more versatile than expected delivering really nice clean tones and easy to set edge of breakup depending of course on the guitar. However pushed into overdrive, it is, again in my opinion, glories. It delivers what I would hope to hear at I think a fair price if you use a good cabinet with great speakers. Some bank manipulation is required so I do not have to send it back.
