Dear Headfellows,
A Chinese amp, made in Germany, and a PCB produced in Slovakia? Seems a little bit strange indeed!
According to the German distributor the KHV has originally been designed by the THORENS Company. When this company went broke, the production of the amp was continued under the name of Vincent. (KHV is short for Kopfhörerverstärker = headphone amplifier).
Vincent is a Chinese company but the world-distribution is done by a German company that also owns the rights on the name THORENS. (Thorens was recently resurrected). I guess (but it's just a guess) that it's this company in Germany that produces the amp.
Anyway, let's start with my impressions.
Upon receipt of the amp, first impressions were a little bit mixed. The amp has substantial weight and looks very decently build. However, separate volume knobs for left and right channel seems a little bit odd for a headphone amplifier and no user manual was added to the box. Of course, there isn't much to explain, but nonetheless.
Technical information on the internet is also rather sparse:
Frequency range: 10Hz - 40 kHz
S/N Ratio > 90 dB
Weight 4 kg.
Moreover, this information wasn't found to be completely correct. After a decent break-in I did some additional measurements:
Frequency Range (-3dB): 6Hz - 60 kHz
Weight 3.4 kg.
THD (4 Vpp, 400 Hz) 1.5%
THD (4 Vpp, 1 kHz) 0.7%
THD (8 Vpp, 1 kHz) 0.9%
Maximum Output Voltage (peak value): 6.4 Volts
Maximum Gain: 9dB
All measurements at a load of 110 Ohm
Nothing special. Harmonic Distortion is rather high but that's usual for a tube amp. Output voltage is a little bit low and gain factor is moderate. With a 2V source (most CD-players) the maximum output voltage is barely reached. Fortunately both volume controls are non-linear. To achieve a proper balance of both channels is not a big problem, even with sensitive headphones.
The amp looks simple but nice, especially with power on. Not only do we see the glowing tube (there's only one inside the amp!) but a red LED behind the tube gives appearance a little extra. A bright blue LED on the front indicates that the amp is working.
For the inside of the amp take a look at the pictures. Components are neatly arranged but their quality isn't very special. Nice toroidal transformer though, which seems to be custom made. This transformer is made for 220V. Different voltage-versions are not available right now (but can be made if a larger series of amps is ordered).
I have to admit that I have no experience with real tube amplifiers. Therefore be aware that my impressions might not carry much weight. (Sure, I know the RKV, but by its design this amp has very low distortion factors and sound is (almost) independent on the tubes that are used. As such it's not very tuby!)
Test Equipment:
SONY SCD-XB770 (modified)
Sennheiser HD600
Beyerdynamic DT931 (modified)
AKG K1000
Meier-Audio interconnects
CORDA PREHEAD (for comparison).
One thing is immediately made clear at first listening. This is a very nonagressive amp. Sound has a somewhat syrup-like quality that removes any edginess. Actually, the K1000, which itself has a slight metallic touch, sounds very nicely out of this amp. Warm and full-bodied (although no very high sound levels can be reached).
Listening to the DT931 and HD600 however, showed that the amp lacks some speed and that the bass lacks some definition. It's not bad, but not very good either (compared to the PREHEAD that is!).
The amp makes for a relaxed listening, but some of the micro details are lost in the process. While listening I find myself continuously looking for more definition (cymbals, percussion, guitars). However, for what it's worth, be aware that I've always been a solid-state man and that, from an engineering point, I have a slight aversion against tubes (that's why I'll never build them myself).
As I have so little experience with tubes I feel that I'm not competent enough to make a true judgement on this amp. If any of you find he might be the right person to do so, just let me know and I'll be happy to send you the amp. Be aware that the amp is a 220V-version and that you have to pay for return-shipping.
Cheers,
Jan
