[Review] A tale of three lowcost single tube headphone amps/preamps

Bravo V3, Bravo Ocean, Trends PA-10.1D

[The three amplifiers beside a mobile device]

A tale of three lowcost single tube headphone amps/preamps

Product name: Bravo V3, Bravo Ocean, Trends PA-10.1D
Manufacturer: Bravo Audio - Hong Kong, Trends Audio - Hong Kong
Cost: $US 169.00
(Currency conversion) (YMMV)

Reviewer: Richard Varey - TNT New Zealand
Reviewed: November, 2016

Introduction

This listening test project didn't start out as an amplifier comparison, but I found myself with not one but three amps to trial. As with my other reviews, I didn't want to rank these products by specifications or price, but rather by overall listening experience. I wanted to know if these lowcost products could possibly deliver the detail, dynamics, and timbre that I enjoy, and if so, which one would render the most pleasurable music experience, and which one is the best valueformoney?

It began as a tryout of headphone amps and evolved into an audition of preamps. First I describe each (in alphabetical order by name), then I put them in order of preference for their sound quality judged by listening pleasure, then homing in on dynamics, clarity, and how convincing is the tonality/timbre.

I admit that I may not be especially qualified as a connoisseur to assess these products as I haven't been an enthusiastic headphone listener for some time. Would any of these amplifiers entice me back to the private listening sensation of enclosed sound presentation? I listened with my 'modded' Sennheiser HD555s (the damping foam inserts have been removed), which I have enjoyed occasionally, although I do prefer the loudspeaker imaging in my listening room.

As each unit is a headphone amplifier and a preamplifier, I also listened with each in turn driving my 'reference' system in place of the locally handbuilt Viganoni Sachem Pure preamplifier (which doesn't have a dedicated headphone output, so I use an iFi iCan and previously a Rega Ear on the rare occasions that headphone listening is necessary). Until recently the heart of my system was a T+A Power Plant driving Philips open baffles, and now comprises Sachem Pure preamp and V2 monoblock power amplifiers and Audio Pro Avanti 100 DC floorstanding speakers.

Were these 'cheap' headphone amplifiers also up to the task of satisfactorily driving audiophile power amplifiers and loudspeakers renowned for their clean fast performance? Would I use any or all of the units for headphone or loudspeaker listening in my system? Initially, it didn't seem really sensible to substitute these units for an audiophile grade preamplifier costing 16 to 50 times more, but that made it seem much more interesting, so I did it anyway to see how well these desktop mini amplifiers would perform. This would be another intriguing project.

Bravo Audio Ocean and V3

The Bravo range of small Class A single tube headphone amplifiers/preamplifiers consists of the Ocean, B1, V2, and V3 models. China is well-known for super-cheap audio products, if also for quality issues and fraudulent traders (indeed, one of the power adaptor cables sent proved to be faulty).

I figured that I didn't know enough about such low-cost products, so when I was offered samples to try out, I asked for those models that would best represent the design, manufacturing, and marketing ethos of the vendor, in this case Bravo Audio. The very obliging Henry sent two models, suggesting that they have different operating characteristics. The Ocean is described as “like the whale moves more gracefully in the sea than the river”, this model is recommended for bass-heavy music, whilst the cheaper V3 is described as “giving great flexibility in sound”, and is recommended for vocal and pop music. Both models are designed to help high-end headphones to “prove their worth”.

The package arrived within just a few days of despatch from Hong Kong. I was surprised that the 'designer' Ocean amplifier came in a plain brown cardboard carton, while the open frame 'kit' style V3 is packaged in a nice pale blue and printed white box. I figure this one is intended for the fashion-conscious user, but it could be either depending on your taste!

The Ocean comes with a generic 12AU7 tube pre-installed, whereas the V3 requires the supplied Russian Electro-Harmonix 6922EH tube to be installed. The first obvious differences in physical format is that the Ocean has a coloured metal case (I would prefer it to have anti-slip feet), whilst the V3 is an open circuit board sandwiched between clear acrylic sheets, with rubber feet and a three-way “passive” graphic equaliser.

They have identical performance specifications and both run from supplied external 24V power adaptors. Each can be used as a headphone amplifier, and as a preamplifier, although this is accomplished through the ¼ inch jack output on the V3 rather than the line output phono sockets as on the Ocean. These units are similar in size and weight, with the Ocean 'end-facing', and the V3 'landscape' orientation.

Both are intended for desktop use and are not portable since they need a mains power supply. Documentation for both units is minimalist, comprising just a small six page leaflet with scant connection and operation information and specification details. The company web site is a little more forthcoming.

The Ocean is the flagship product of the range intended to appeal to the serious listener. It is a budget hybrid pure Class A amplifier with IRF510 MOSFET and 12AU7 Shu Guang valve (equivalent to ECC82/ECC802) for low noise and medium gain (there is no op amp IC), and has an RCA line level output, making it easy to use as a preamplifier. Line inputs cater for RCA and 3.5 mm jack plugs. At just 94 x 80 x 42 mm and 320g this unit delivers unreasonably extensive musicality, with a claimed 10Hz60kHz +/0.25dB.

I fitted a No-Ring Ring (supplied by Design Build Listen) to dampen glass envelope vibration in the supplied tube, although I didn't notice improved performance, and I can't really claim to have heard a huge difference to the other Bravo model or the Trends Audio unit. I did note that one section of the power cable was faulty.

The V3 design, according to the manufacturer, focuses on sound quality and so has a (somewhat crude) adjustable equaliser, that is effective, and can be 'flattened' thus removing emphasis by putting the sliders at the 'bottom' of their scale as viewed from the front in normal use. Headphone listening is straightforward, but to use the unit as a pre-amp requires using a cable with &frac; inch jack plug and suitable connectors for power amplifier input. For me, at least, this is unusual and not readily to hand.

The unit is 79 x 150 x 35 mm and weighs only 225g. First impression, before any 'running in' is that the amplifier is a little light on bass and fullness, and with perhaps a hint of harshness. This unit is supplied with an Electro Harmonix 6922EH triode (from Russia). This is an improved equivalent of the ECC88/E88CC/6DJ8, with gold-plated pins. The unit also features high-grade parts, including an ALPS potentiometer and Chem-Con capacitors. After a few hours of 'hot running', both units performed very well indeed as headphone amplifier and as pre-amplifier.

Trends Audio PA-10.1D

This product is different in that it is a dual output tube headphone amplifier and pre-amplifier, intended for use in the Trends Audio BA-10 Biamp system. It's packaging is obviously following the established Trends form to match the amplifier and DAC. In its Aluminium case just 115 x 78 x 46 mm and 360g, it has a more utilitarian 'engineered' (and durable) feel than does the Bravo Ocean and V3, which seem in comparison more 'lifestyle' in design, and less serious audiophile quality.

I understand that this amplifier can be run on batteries, and is offered to audiophiles who like to try diferent valves. One of the PA-10 family, this is a pure Class A amplifier with audiophile-grade components and using a single bi-triode 6N11 valve from China (6DJ8/6922 series) for voltage amplification and twin MOSFETs as output driver.

This is a new version of the PA-10 reviewed by TNT-Audio in February 2009, the differences being the dual output, the valve, and the facility to change settings for alternative valves. Also available in SE and GE editions with Russian 6H23n and USmade GE 12AU7 valve respectively. Trends suggest differing sound quality from these options, to suit musical tastes. As do Bravo, Trends suggest the 12AU7 is especially good for warmer midrange and particularly with female vocals, and I did prefer this.

On paper, the performance specifications suggest that this unit is notably superior to the Bravo products (15Hz-100kHz - 1 bD, 0.05% at 10k Ohm). Eager to hear music through this unit, I originally connected it to the preamp output of the T+A Power Plant. Taking the pre-amp output from my amplifier allowed me to listen to any source through this unit by muting the speakers. I had to crank the volume control well beyond my normal range of settings to get any reasonable sound level on my 'phones. Connected this way, the unit lacks both gain and punch.

The recommended connection is a source to a line input on the amplifier, with a PC/iPod or CD/DAC connected, so the unit is a passthrough pre-amp and headphone amplifier! My confusion stemmed largely from the User Guide supplied which did not correspond it's for the PA-10 single output version, so inputs and outputs are different. I received the updated manual promptly on request and this clarifies the connection options. Now correctly connected between source and power amplifier, the unit certainly delivers on the promise of high quality audio, and easily was my second preference after the Bravo Ocean.

Following the instructions in the Trends Audio User Guide for retuning the DC bias voltage, I swapped out the supplied valve for a Mullard ECC88/01 fitted with a NoRing Ring from Design Build Listen to dampen glass envelope vibration. The result of this change was to instantly elevate this to the position of preferred performer. It truly is surprising just how lush and present the music sounds through this amplifier.

I ended up driving my Sachem monoblocks and Audio Pro Avanti 100 DC towers for a couple of weeks with this preamp, and most satisfying it was, too. A small gripe is that the power lead is short possibly for a good reason, but it made it harder to locate in my system, and I resolved this issue with a longer-than-usual audio interconnect. And it is only a small thing to connect my headphones, and that's the problem. The 3.5mm headphone output socket is recessed on the front plate, and in order to use my headphones I needed a ¼ inch to 3.5 mm adaptor (which has a 13 mm diameter) and also a 3.5 mm inline socket-to-plug lead that would physically fit into the 1112 mm diameter machined recess on the fascia.

Conclusion

So, would I use any or all of these units for headphone and/or loudspeaker listening in my system? Are they serious hifi products, and is one clearly the best performer? I have ranked them by listening and operating preference with the retail price shown for interest.

As in my other listening tests, I listen for overall impression in terms of detail, tonal accuracy (clarity, dynamics, timbre), and musical satisfaction. In third place, I put the Bravo V3 (US$99), but this is mostly because it doesn't really allow easy use as a preamp and the equalisation seems like a compromise on the purity of sound. Looking at the stock valve configurations, I do seem to prefer the sound emanating from the 12AU7 valve circuit of the Bravo Ocean (US$140), although differences were not great. The sonic star is the Trends PA-10.1D amplifier (US$299) with the Mullard special version fitted. For valueformoney, the Ocean is the winner, unless you want to biamp and valveroll.

I feel sure that dedicated 'head-fi' listeners might come to a different conclusion, but for me as an occasional headphone listener, the experience has been really enjoyable and somewhat surprising. Actually, I would be more inclined to use either unit as a preamplifier rather than as a desktop headphone amplifier. They perform that well in delivering pleasurable music in terms of threedimensional soundstage, clarity, and dynamics. As technical innovations diversify, price is no longer a direct signal of quality, if it ever was, and you don't always get what you pay for in this overhyped field.

Yet, highend performance nowadays doesn't have to come with high price, and there are bargains to be found (see my recent review of the Collybia media box, for example). For the first 25 years of my audio hobbying, the hifi market was local shops, regional shows, and national magazines. Now it's whatever your search terms show up on the web, and there are way more viable options available and accessible. Thinking about how I reacted and felt when I listened to my music with these products, in terms of involvement and awareness of 'tonal character', I am very surprised how similar the sound was through these units (until I fitted the Mullard tube to the Trends), and how pleasing was their music rendition. There are some sonic differences in clarity, dynamics, and timbre, but they were quite subtle. All are recommended, with a slight reservation on the Bravo V3. Oh, and yes, I did happily go back to my regular solid state preamp at the end of this project, with a newfound appreciation of the auditory virtues of valve.

You might be interested in reading another comparison test of headphone amps: Cavalli Audio Liquid Spark vs JDS Labs Objective 2 vs Schiit Magni 3+