It includes a MM-MC phono stage, discrete solid state 1W headphone amplifier, a remote control, a OLED front panel display and the best home theater passthrough I’ve yet encountered in a stereo preamp. The American made RP-1 is probably the best value stereo preamp I’ve encountered.
Rogue Audio RP-1 Stereo Preamplifier
- The RP-1 sounds particularly, smooth, spacious and at ease.
- It’s exceptionally well built, comparable to much more expensive products.
- The tube RP-1 turned out to be an excellent match with my NewClear NC1000L switching power amplifier, keeping excellent detail and power but with the smoothness and relaxed atmosphere of the tubes.
- The completely passive home theater passthrough worked flawlessly and is the best I have encountered in a stereo preamp.
- The measured performance on the bench was without fault.
The stereo preamplifier is one of the most critical parts of a hifi system, and one that is hard to get right, especially on a budget. Distributing and amplifying the relatively low voltage line level signal from your sources is easy to get wrong and will rob the music of the detail and subtle spatial cues that are the hallmark of a system that is great, not just merely good. The Rogue RP-1, from the tube-meisters at Rogue in Brodheadsville, PA, promises excellent performance, several useful modern features, but none of the useless surround sound processor-like bells and whistles sometimes found in more budget minded preamplifiers. While I’m not typically a fan of the “tube sound”, tubes doesn’t necessarily have to mean that. I was very curious to know if Rogue has come up with an excellent value preamp, tubes or not. I was very pleasantly surprised to find out they most definitely had.
2 x 12AU7/ECC82 tubes
1Hz – 75KHz +/- 1 dB
Gain line stage:
Gain phono stage:
+/- 0.1 dB
1W (32 ohms)
Power consumption off:
Power consumption on:
3.2” H x 15.25” W X 14.5” D
115V – 50/60Hz
220/230/240V – 50/60Hz
Rogue Audio, RP-1 Preamplifier, Preamplifiers, Preamplifier Reviews 2016
Outwardly, the Rogue RP-1 looks like pretty much any other high end stereo preamplifier. Given the relatively bargain price, this is a good thing. The RP-1 uses a nicely made machined aluminum front panel, turned aluminum knobs for the balance and volume controls, and even a custom turned power pushbutton. The volume control can also be depressed to toggle between input sources, while pressing the balance toggles the OLED display on and off. The clean front panel’s only other adornments are an oval blue illuminated OLED display and a ¼” headphone jack.
The rear panel consists of an array of RCA inputs and outputs. The RP-1 is a single-ended preamp, so no XLR inputs are present. The RP-1 offers 4 line level inputs, a MM/MC phono input and the home theater bypass input. There are two variable outputs controlled by the volume knob, allowing easy connection to a subwoofer or second amplifier, and a fixed unity gain output. There’s also an unswitched IEC jack for the power cord, and a simple screw terminal for the phono ground. Annoyingly, the phono ground screw is relatively far away from the phono input RCAs. This might require you to extend the ground wire on your turntable interconnect cable. I had to.
The case itself is relatively heavy gauge sheet steel. The whole package is certainly solid and well built, particularly for the price. Internally, you’ll find a main circuit board with a cutout for the toroidal transformer, a front panel circuit board managing all the front panel controls and display, and the rear panel board containing the input and output connectors and the tube output stage with a pair of 12AU7 vacuum tubes. As I’m new to tubes, I made no attempt to mess with the tube complement. I just used what was there.
Mechanical relays on the main board switch between sources. There are also two banks of DIP switches and a couple of slide switches to set the cartridge loading and the gain. There are 8 loading settings from 30 Ohms to 47 kOhms, and two gain settings, 58 dB and 43 dB, suitable for MC and MM cartridges, respectively.
The volume control is a digital pot controlled by the front panel knob. The output stage is tube, but all other circuitry is solid state, including the phono preamp stage, the headphone amp (which uses discrete transistors) and input signal conditioning. The quality inside is every bit as good as the quality outside.
Functionally, the RP-1 is very easy to use. The power switch starts a warm-up cycle when depressed. The preamp comes online after about 30 seconds of tube warmup. Balance, source selection and volume are all digitally controlled (the actual signal path is all analog!). The headphone output is always on. Plugging in headphones does not automatically mute the preamp. You need to mute the preamp yourself or turn off the power amp.
Source selection toggle, balance, volume and mute can also be controlled with the included infrared remote. This is the only part of the RP-1 I’d like to see improved from an aesthetic point of view. It’s a very light remote made of particularly flimsy plastic. While I admit ridiculous billet machined remotes are a bit of a waste, the RP-1’s remote really feels cheap. But it works.
The most well thought out extra feature on the RP-1 is the home theater passthrough. It’s the simplest and best I’ve ever used. When the preamp is off, the relays click into place automatically such that the HT input is directly connected to the outputs, sending the signal right through passively. You don’t need to do anything other than turn the RP-1 off. You don’t waste a minute of tube life watching TV or movies and the signal doesn’t get degraded at all other than the extra connectors and wire involved. It’s fantastic. This is particularly nice for me since my system does double duty as a home theater system and a two channel audio system. Having a stereo preamp that plays well with my SSP is very nice.
The RP-1 lived in between my NewClear NC1000L IcePower based power amp and my Oppo BD-105 Blu-Ray player used as a USB DAC. I broke in the RP-1 by leaving it on playing music over the weekend with the power amp turned off. Since the HT bypass is active when the RP-1 is off, I couldn’t use my normal trick of just watching TV and movies casually to break in the preamp.
When I started listening, I got the immediate first impression of space, air and relaxation. It actually reminded me very much of listening to Sennheiser headphones. The RP-1 presented an enormous sense of space, with a relatively distant and wide soundstage with plenty of spatial cues to fill up all that space. On well recorded classical and jazz, the room sounded huge. Even on my favorite obscure electronica, the laid back soundstage presented a lot of space. My favorite of late, Daft Punk’s Random Access Memories had a wide and deep soundstage and managed to sound both relaxed and exciting at the same time. I think the key to this result is that the RP-1 does an exceptional job of extracting detail, operating with low noise and avoiding any sort of tube like coloration while still giving you the smoothness and lack of harshness that tubes are known for.
While some listeners and engineers rag on tubes as old fashioned, they have one property that turns out to be excellent for audio. Like Nelson Pass’ discrete no feedback transistor designs, most all tube electronics keep all their distortion in low order harmonics (2nd and 3rd). This is a guarantee of a sound that’s easy to listen to and never harsh. If that distortion level gets too high, then you start to get that tube coloration. But if the product is well engineered you can get the best of both worlds.
It’s a particularly good match to my NC1000L, which is super clean, powerful and detailed, but will easily pass on any sort of upstream harshness. I particularly like big soundstages, so the extra space of the RP-1 was very welcome. Some might find the presentation a little too laid back if they like lots of added excitement, kind of like with headphones. Some people love the open, airy, spacious sound of Sennhesiers, some find them a bit boring. I am definitely in the former camp. I love my HD600s and I also am very attached to the RP-1.
The Rogue preamp managed to simultaneously increase the amount of detail I heard directly and indirectly (like spatial cues that make a soundstage wide, tall and deep), and made the sound more relaxed, smooth and easy to listen to. It reminded me very much of the difference between Redbook CD format at 16 bit 44.1 kHz sampling rate and a 24 bit, 96 kHz high resolution format recording. A little more detail, but mainly the removal of the harshness and glare that’s present with the lower sampling rate file.
In operation, I found no hiccups with the RP-1. No technical problems or weirdnesses I had to deal with. Unfortunately, I was not able to test the phono stage of the preamp. I was about to, and found that my turntable’s cartridge had the stylus cover missing and the stylus had been damaged. I didn’t manage to get it fixed in time to do the test. Given the performance of the line level section of the RP-1, I would expect good things from the phono stage as well.
Really, the only criticism I could come up with is the lack of balanced inputs and outputs. My amplifier is balanced, so real balanced outs would be nice, but that would really jack the cost of the RP-1 up if done right. For the price point Rogue was trying to hit, single ended only was the right choice.
Measurements were performed with a M-Audio Profire 610 Firewire sound interface and Spectra Plus FFT analysis software. No fancy loads were necessary here, just the soundcard as the input and output. Measurements were done at 192 kHz sampling rate and 24 bit depth.
Distortion spectra were measured at 50 Hz, 1 kHz and 10 kHz. The measured values of THD and THD+N was less than 0.01% at the lower two frequencies and a bit higher at 10 kHz. The THD numbers are lower because of the 60 Hz pickup I get between my sound card and pretty much everything I measure, due to a ground loop I can’t get rid of. Most distortion is concentrated in the second and third order, which is a clear indicator of a good sounding piece of electronics.
The THD+N versus frequency plot shows levels below 0.01% until about 4 kHz, then rises gently to about 0.04% at 20 kHz. Still, very low numbers.
Intermodulation distortion, measured with 60 Hz + 1 kHz tones was a super low 0.002%. Again, you can see the 60 Hz pickup in the spectrum, but that doesn’t affect the calculation of the IMD.
Frequency response is flat as a board as expected all the way to the limit of the sound interface. I also measured the noise floor of the preamp. The 60 Hz pickup is 90 dB down, and the broadband noise floor not including the 60 Hz pickup was about 120 dB down. This is almost at the dynamic range limit of the sound interface. It’s a very quiet preamp
THE ROGUE RP-1 Might Be The Best Value Stereo Preamp You Can Get. It’s Certainly The Lowest Price Preamp I’ve Listened To Where I Couldn’t Find A Thing Wrong With It That Really Mattered. It Sounds Fantastic, Has All The Features You Could Need (As Long As Single Ended Is Ok), And Nothing You Don’t Need. I’m Buying One Myself.
- Excellent build quality.
- Excellent value.
- Exceptional smoothness, spaciousness and air.
- Fantastic home theater passthrough design.
- A better quality remote control.
- A balanced version.
The Rogue RP-1 is a great preamplifier. For only $1695, it’s a benchmark for value-priced high end preamps. You’ll have to work pretty hard and spend a lot more money to do significantly better. Unless you really demand balanced inputs and outputs, I’m not sure it’s worth it to try. Especially if you have a solid state power amp, the RP-1 might just be the perfect preamp for you. I know I loved it and am planning to keep it. I’ve had my previous preamp for almost a decade, so this upgrade is not taken lightly. If the worst thing I can say about it is the remote control is a bit cheesy, that’s a really good thing.