To date, at least 9 audio power amplifiers have passed through my hands; I still own several of them. Here’s a quick rundown. There will be detailed reviews of several of them.
- QSC Audio RMX 1850HD — The power amp that started my descent into madness. The RMX line was QSC’s entry level at the time, aimed at semi-pro musicians, and was their first venture into Chinese manufacturing. A budget version of their older MX line, it offered low-end professional features and high power output at a value price. The 1850HD model had roughly the same price and weight as the more powerful 2450, but the 1850HD’s strength was its claimed ability to drive 2 Ω loads without complaint. I put that ability to the test a few times, and the 1850HD never flinched. I might still own it if I hadn’t gotten tired of lugging it around.
Power rating: 2 channels: 8 Ω, 360 W; 4 Ω, 600 W; 2 Ω, 900 W. Bridged: 8 Ω, 600 W; 4 Ω, 1800 W.
Topology: 2-stage Class H.
Power supply: Traditional; toroidal transformer.
Other features: Switchable 30 Hz or 50 Hz high pass filter and clip limiter per channel; parallel or bridged modes.
Strengths: Inexpensive, robust, durable. Proven design. Solid technical support and authorized repair facilities everywhere. Well suited to driving low impedance loads.
Weaknesses: Heavy by modern standards. Out of production.
Would I buy another one today?: Yes, if I was setting up an installed sound system for a small club on a budget.
- QSC Audio PLX 2402 — The first-generation PLX series was a direct descendant of QSC’s professional Powerlight line. It made lightweight switchmode power supply technology available to the masses. Built in the USA and designed to professional standards, it was robust, reliable, and durable. It was a huge success. The line has long since been superseded by the PLX2, but first-gen PLX amps are everywhere on the used market today, and a tremendous value at today’s prices. The 2402 was the middle model of the line. It had more power than the RMX 1850HD it replaced at half the weight.
Power rating: 2 channels: 8 Ω, 425 W; 4 Ω, 700 W; 2 Ω, 1200 W. Bridged: 8 Ω, 1500 W; 4 Ω, 2400 W.
Topology: 2-stage Class H.
Power supply: Unregulated switchmode.
Other features: Switchable 30 or 50 Hz filter and clip limiter per channel; parallel or bridged modes.
Strengths: Lightweight for its time, robust, reliable, durable, solid technical support, and authorized repair facilities everywhere. A good value then and now.
Weaknesses: Out of production; repair parts may be getting scarce.
Would I buy another one today?: In a heartbeat, if I was setting up a portable sound system for a band on the cheap.
- QSC Audio PLX 3402 — The top of the line for the first-gen PLX series. Weighed about the same as the 2402, and was identical in all other respects, but made about half again as much power. For a while I had both the 2402 and 3402 in my arsenal.
Power rating: 2 channels: 8 Ω, 700 W; 4 Ω, 1100 W; 2 Ω, 1700 W. Bridged: 8 Ω, 2200 W; 4 Ω, 3400 W.
Topology: 2-stage Class H.
Power supply: Unregulated switchmode.
Other features: Switchable 30 or 50 Hz filter and clip limiter per channel; parallel or bridged modes.
Strengths: Same as the 2402, plus more power.
Weaknesses: Some sound professionals didn’t think the 3402 was suited to driving subwoofers hard. I never had a complaint. Out of production; repair parts may be getting scarce.
Would I buy another one today?: Yes, if I needed a portable subwoofer amp for a band on the cheap.
- Peavey IPR 3000 — The IPR series was Peavey’s first Class D offering. It promised plenty of power and even less weight than QSC’s PLX series at a bargain price, if you could look past the cheesy stamped-aluminum front panel and tacky blue LEDs. By the time the IPR series was released, Peavey had determined that their #1 virtue, “value for money,” was no longer consistent with “made in USA”; all the IPRs were made in China. As such the quality control on the first-gen IPRs was inconsistent. When they first hit the market, they were such a good value that they were hard to keep in stock. I went through several open-box units (at the advertised new price) at the local Guitar Center; all were defective in some way. I finally wound up buying a display unit at a local independent retailer (Guitar Showcase in San Jose, CA). As for support, Peavey held on tightly to its schematics, unlike previous Peavey products. Getting one repaired meant sending it to an authorized Peavey service center. Fortunately once I got a good one, it never missed a beat. It was a good solid no-frills box o’ Watts. I might still have it today if I hadn’t decided to step up to its DSP sibling.
Peavey still offers a second-generation IPR2 line, with better styling, and under the Crest brand (which it acquired some time ago), a slightly upgraded Pro Lite 2 line.
Power rating: 2 channels: 8 Ω, 440 W; 4 Ω, 840W; 2 Ω, 1490 W.
Topology: Class D.
Power supply: Unregulated switchmode.
Other features: Switchable 4th order Linkwitz-Riley 100 Hz crossover.
Strengths: Ridiculously light. Powerful. Cheap. Reliable in my experience.
Weaknesses: Tacky styling. Questionable support and durability. Out of production.
Would I buy another one today?: Probably not; I’d get a first-gen QSC PLX 3402 instead.
- Peavey IPR DSP 3000 — Peavey’s IPR DSP line was a step up from the IPR. It added modest digital signal processing (DSP) capabilities to the many virtues of the original IPR series. The DSP offered input routing, adjustable low- and high-pass crossover frequencies, 4-band parametric equalization (PEQ), “horn EQ”, delay, and Peavey’s proprietary BassMaxx psychoacoustic processing. Presets for Peavey speakers were built in, and users could save and recall their own presets. I got one specifically for the ability to adjust the frequency of the high pass filter. In all other respects it was the equal of its simpler sibling. I still have this amp in my “big rig”; look for a future detailed review.
For a while Peavey offered a second-generation IPR2 DSP line and a Crest Pro Lite 2 DSP line. Both have since been discontinued. At this writing (December 2020), you may still be able to find new old stock DSP models, but probably not for long.
Power rating: 2 channels: 8 Ω, 430 W; 4 Ω, 815 W; 2 Ω, 1450 W
Topology: Class D.
Power supply: Unregulated switchmode.
Other features: Modest user-programmable DSP.
Strengths: Ridiculously light. Powerful. Cheap. DSP. Reliable in my experience.
Weaknesses: Same tacky styling as the IPR series, with a small alphanumeric display thrown in. Same questionable support and durability. No way to load or save DSP presets outside the box. Out of production.
Would I buy another one today?: Likely not. I would, however, jump at a Crest Pro Lite 2 5.0 DSP.
- Sanway DP10Q — My first foray into Chinese branded amplifiers. In spring 2018, I had learned that some home theater fanatics were using high-powered Chinese amplifiers to drive large subwoofers in high-end home theater setups. The HT crowd was most interested in Lab Gruppen clones, most of which were obvious copies of the Lab Gruppen Class TD circuitry with minor variations, and many even shamelessly duplicating the Lab Gruppen line’s styling and model numbers. The two brands most frequently mentioned were Sanway and XBS (a.k.a. Sinbosen, Aoyue).
At the time, the four-channel Sanway amps were getting the most attention. Sanway offered a few variations on the Lab clone theme, either straight up or with a couple of DSP options. The DP10Q was and still is the top of Sanway’s 10 kilowatt class, with touch screen DSP control and PC control via USB or RS-485.
I bought the DP10Q on a lark. I didn’t really need four channels for my bass rig. I might still use it as a PA amp, even though its power rating is clearly overkill for that application.
The DP10Q was a revelation. It had its flaws; the fans were rather noisy at startup, and its idle power draw was above 200 W. But it met its power specs into 8 Ω loads, with respectable distortion, noise, and bandwidth figures. It happily did full power pulse testing on all 4 channels until the circuit breaker on a 20 A dedicated circuit tripped! To really wring this amp out, you’d need a dedicated 240 V 30 A circuit, which in turn would require opening up the amp to change the voltage setting. The DSP mostly works as advertised, other than the limiter, which I found unusable because its behavior didn’t match up with the settings I gave it. The touch screen didn’t seem to like my fat fingers, but worked nicely with a stylus, such as a capped pen or a chopstick. PC control and monitoring via USB worked well.
Of the Chinese manufacturers I’ve dealt with to date, Sanway has the best tech support, with downloadable software and product manuals easily accessible on their web site. Current scuttlebutt from the home theater crowd is that XBS makes a more reliable and robust product at the extreme high power end of the market, but Sanway has better initial quality control and support.
Power rating: 4 channels: 8 Ω, 1300 W; 4 Ω, 2200 W; 2 Ω, 2500 W. 2 channels bridged: 8 Ω, 4400 W; 4 Ω, 5000 W.
Topology: Class TD (confirmed by inspection).
Power supply: Regulated switchmode.
Other features: DSP, 96 kHz sample rate, 24-bit converters, touch screen control, PC remote control via USB (standard A-B cable provided) or RS-485.
Strengths: Massive power, modest weight for the power produced, decent if slightly flawed DSP, remote control and monitoring via PC, good value.
Weaknesses: Fan noise, questionable support, only available through Alibaba or direct contact with the manufacturer, DSP limiter not really usable, intake air filter requires disassembling front panel to access, high idle power draw, too much power for a standard US 120 V wall outlet.
Would I buy another one today?: Probably not, but mostly because I don’t have a use for that much power, or a way to feed it enough power.
- Tulun Play TIP-1500 — Around the time I ordered the Sanway, Tulun Play caught my eye. The TIP-1500 is a lightweight, compact, 2-rack-space Class D stereo amp with a claimed 1500 W per channel at 8 Ω, and a very good price. So I bit. I figured even without DSP, I figured it would be a good candidate for the bass rig.
The reality didn’t live up to the promises. If I could sum up the TIP-1500 in a word, it would be cheap, as in poor quality.
Some examples: The fans made clicking noises. The sensitivity switch settings were inconsistent between channels, as were the meter displays. Continuous full power testing was impossible, because a limiter kicked in after 2 seconds at any power level above 400 W. (When I complained to Tulun Play, to their credit, they responded quickly, but their answer was “Test it with actual music.”) The level controls were detented, as is common in pro amps; but there was significant play in the detents, so setting consistent levels between channels was also impossible. In pulsed power testing, it came close to its 8 Ω rating, but didn’t quite reach it.
This is an amp that will probably suffice in a pinch, but will frustrate you in the process. Tulun Play has a presence on AliExpress, Alibaba, and eBay. I mention this as a warning, in case someone might be tempted as I was. I can’t recommend this amp to anyone.
Power rating: 2 channels: 8 Ω, 1500 W; 4 Ω, 2500 W.
Topology: Class D.
Power supply: Unregulated switchmode.
Other features: Switchable sensitivity per channel, bridge mode, front panel meters.
Strengths: Approaches rated power. Didn’t blow up. Lightweight. Cheap.
Weaknesses: Cheap. Mismatched channel gains. Meters don’t track between channels. Non-defeatable limiter. Noisy fans. Detented gain controls have slop. Did I mention cheap?
Would I buy another one today?: Hell no. You couldn’t pay me to take another one. Anybody want this one? Free??
- XBS (Sinbosen) K4-1400 — XBS has been selling to the public on AliExpress and Alibaba for years, at first under the Aoyue brand, later under their actual company name, Xinbaosheng (hence XBS), and the Anglicised Sinbosen. While it was their Lab Gruppen clones that originally piqued my interest, they also produce a family of high-powered one-rack-space Class D amps. I got the bug again a few months ago and found the K4-1400 attractive. This is a no-frills, high-power-density power amp built with modern technology. Its pricing of around $500 before shipping (and California sales tax, more about this below) makes it a particularly attractive deal in XBS’s line. Despite a minor bait and switch on the price and shipping, I purchased one to see if it was as good as XBS claimed.
In every respect but one, I was impressed with its performance. The K4-1400 is efficient, powerful, quiet at idle, robust, and easy to use. Power factor correction lets it extract maximum power from a wall socket. I accidentally triggered the overload protection while looking for the continuous power limit, and the channel simply shut itself down without drama.
The one flaw I observed, and it’s minor but annoying: Unlike every other amp on this list, the frequency response is not a straight line, and worse, it’s not consistent across all four channels. There is a slight hump around 40-50 Hz on every channel. On the worst two channels, it’s about +1.1 dB, but even on the best channel, it’s +0.35 dB. In actual use, the speakers it would drive are far less consistent, and the hump would be trivial to tame with a DSP speaker management processor like the ubiquitous DriveRack series. One might even find it desirable for driving subwoofers. But it makes testing maximum power across the audio band tricky. And how it got there is puzzling, because the K4-1400 has zero built-in signal processing. I informed the sales rep about this roughly a week ago, attaching the test charts, and have yet to hear back.
Despite this quirk, I can recommend the K4-1400 without hesitation. It’s ideal, if somewhat overpowered, for driving main and monitor speakers for a small rock band. And I can’t wait to do just that with mine.
As for dealing with XBS, I recommend caution. I don’t think they’re out to rip anyone off; but (1) they offer the identical product at different prices and different shipping terms across their 3 brands’ stores, and even within the same store(!); (2) the particular page I’d bookmarked with an extremely good price and free shipping to the US had different numbers once I started the transaction. Also of note is that XBS maintains a US warehouse now, in the Los Angeles area, thanks to the home theater fanatics and DJs buying their gear. This means quicker shipping for the items stocked there, but they have to charge California residents state sales tax on every sale.
Power rating: 4 channels: 8 Ω, 1400 W; 4 Ω, 2200 W. 2 channels bridged: 8 Ω, 4500 W.
Topology: Class D.
Power supply: Universal regulated switchmode, with power factor correction (PFC).
Other features: Detented gain controls; stereo/parallel/bridge switch per channel pair; common sensitivity switch; easily serviceable air intake filters.
Strengths: Lots of power in a compact package. Fans are quiet at idle. Modest idle power draw. Efficient under load. PFC works as advertised.
Weaknesses: Funky frequency response. Detents on gain knobs are subtle; knobs are small and hard for this fat-fingered user to adjust precisely. Uncertain post-sales support. Curious pricing discrepancies.
Would I buy it again today?: Despite my reservations, yes.
- Powavesound TD13 — Currently in testing. I have high hopes for this candidate for a bass rig update. The TD13 is a two-rack-space, stereo Class D power amp with DSP. Initial impressions on opening the box are very positive. No-signal power-on testing reveals quiet fans and remarkably low idle power consumption. The DSP control software for PC shows a surprising amount of control. Initial testing under load shows flat response but more distortion than I’d prefer; still under 0.5% up to 1000 W per channel. Watch this space for updates.
Power rating: 2 channels: 8 Ω, 1300 W; 4 Ω, 2200 W. Bridged: 8 Ω, 4000 W.
Topology: Class D.
Power supply: Universal regulated switchmode,with PFCclaims PFC but the Kill-A-Watt says otherwise.
Other features: Extremely capable DSP with 41 (!!) PEQ bands per channel, low- and high-pass crossovers, noise gate, compressor, and limiter; PC control via RS-485 (dongle included, requires additional Ethernet cable); XLR “through” outputs for daisy-chaining; power input via Powercon (clone?) connector; easily serviceable air intake filter.
Strengths: Quiet fans; low idle power draw; highly capable DSP; Powercon connector and universal power supply allow hooking up to a variety of power sources; RS-485 dongle included in the package.
Weaknesses: Minimalist front panel; volume knobs are tiny and lack detents; lack of 2+/2- wiring on the output Speakon jack makes bridged operation awkward.
Would I buy it again today? To be determined.