Gold Note HP-7 preamplifier and headphone amplifier

15.01.2014..

Today the subject of our review is an Italian product: the Gold Note HP-7 preamplifier and headphone amplifier. Gold Note is a company based in Florence, known for its turntables and cartridges of top quality and for its gigantic Diamond Line electronic devices. The HP-7 is a product of the Micro Line series, together with a DAC, a CD player, an integrated amp, monoblocks and external power supplies.

The HP-7 costs 715.00 euro and is going to be tested with the integrated power supply - as I said, it's available an optional dedicated super AC power supply unit, called PSU-7, which costs 715.00 euro and a dedicated super battery power supply, the PSU-9, for 995.00 euro - and with the following set-up: M2Tech HiFace source, DAC with IFI iUSB power supply and Denon AH D2000, Hifiman HE400 and Sennheiser HD650 headphones.

 

Manufacture and ergonomics

Aesthetically the HP-7 is very well made. Its dimensions are 20 x 8 x 26 cm and the weight is 4 kg. Like the entire Gold Note Micro Line series the style is essential. The black or silver satin-finished aluminium front panel is very tidy, without any knobs, just three grey aluminium round buttons about which we will speak later. A small display on the left shows the red digits, from 0 to 99, of the volume. There are four LEDs: the two above indicate which input is in use. Below, the blue on the left indicates if the device is on, the one on the right is red if you use the internal toroidal transformer or green if you use the external PSU. On the front panel is also the button we're interested in: the headphone output, obviously of 6,3 mm.

The three keys on the front panel oversee all the functions of the HP-7. The one in the middle has the on/off function, while the other two are for the up&down of the volume. Besides, if you push them together you can change the input, if you push them for five seconds you switch from the internal power supply to the external PSU. Everything is very functional and easy to handle. The remote control of the HP-7 is complete and well made, so to handle everything in a simple and comfortable way. The HP-7 is the only headphone amplifier with remote control available on the market and that is very appreciable.

 

On the back we find the output and input equipment:

  • IEC socket for the internal power supply
  • connector for the PSU-7
  • 1 RCA and 1 XLR line out input to connect other devices in line without pre-amplification
  • 1 pair of RCA and XLR outputs to exploit its main function as a preamplifier
  • 1 RCA and 1 XLR input

The full equipment comprises also XLR inputs and outputs which, considered the price, are a very interesting added value. All in all, besides the line and the pre-amplified outputs, it would have been perfect having another input but, unfortunately, there's no more room on the back!

The top part is a two mm aluminium plate of the same color of the amp with an air grid. The base is multi-pierced so to be used for the full Micro series, it's of top quality and CNC made. The shape of the base is shockproof with silicone and 3m anti-vibrant feet.

To look inside you have to remove the warranty seal, so "don't do it at home", and the screws. You can immediately notice a 15 VA toroidal transformer by RS Component.

The board has a SMD design. For the pre-amplification two LM833m have been used, while the volume control is handled by a PGA2320I. For the headphone output we can see an LM833m and a TPA6120A2.

 

How it performs and its driving capability

Let's start the listening test with the Denon AH-D2000. These headphones have a very low impedance – 24 ohm – and don't require powerful devices to perform at best. Instead, they suffer a lot the high output impedance of the amps which gives a bass range out of control. The HP-7 doesn't feature gain selectors, otherwise it should self-calibrate depending on the impedance of the headphone, so you just need to plug in the Denon and we are ready to start.

The bass are slightly pumped up. That means that the output impedance is not very low, although enough good to enjoy the Denon. I can deduce that the match is really good, with a great and very natural midrange coming out at the right moment, and a high range that is detailed but not tiring. The HP-7 can move the Denon easily and gives to it a convincing dynamics and rate. Also with a very high volume there's no distortion at all.

 

Now let's test a hard headphone like the Sennheiser HD650 which, with its 300 ohms that shoot up in the mid range, it's a tough nut for many amps. The adapting to the impedance works, so I keep the same volume notwithstanding an impedance ten times higher than the impedance used with the Denon. Surprisingly the amp has no problem in driving the Sennheiser HD650 and the mid range of the headphone is really pleasant. The bass is precise and natural, never overflowing or cumbersome and the HD650 keeps its quite dark sound, with the high range that is never too annoying or sharp, even if less detailed. The dynamics is of good level with a scene of wide dimensions.

 

The last headphone is the HE400, the magneto-planar by Hifiman. The magneto-planar headphones are notoriously very hard to drive and we have to consider the low impedance that requires a huge quantity of current to perform at best. The match with this headphone, unfortunately, is below my expectations. Most probably the amp has not been thought to be paired with this kind of headphones. The HP-7 cannot provide the necessary power to take out at best the mid range, which isn't very natural and seems forwarded. Also the low range is less controlled and invasive and the high range becomes annoying and quite distorted. Obviously the dynamics drops and the headphone is bothersome and weary at the listening.


Since the HP-7 is also a preamplifier, I've tested it with the following components: Transport Bit4Sound HRT01 as a source, McIntosh MC252 and Jeff Rowland Model One power amps, Kef LS50, Thiel CS 0.5 and Monitor JBL 4320 loudspeakers.

The preamp has a sound-print that tends to the clear and a well balanced frequency response. The bass is slightly dry and the harmonic richness is not at the top, but exceptional for the category of the device. The focalization is good, as well as the detail. The soundstage is correct.

 

Conclusions
If you are looking for a good amp for dynamic headphones and you strongly need a remote control, the HP-7 can be the right deal. Nice on view and with a convincing sound, it has been uncomfortable only with one of the most demanding magneto-planar headphones, while with the dynamic headphones it hasn't had any problem both with high and low impedances.

Besides, the HP-7 is also a good preamplifier to drive your power amp thanks to its balanced and unbalanced outputs. Or it can be connected to an integrated amplifier, thanks to the line out that bypasses the pre-amplification.


In brief
Vote: 8,5 out of 10


Pro
Good output both with high and low impedances

Balanced and unbalanced outputs and inputs

Pre-amplified and line out outputs

A headphone amp with a full optional remote control!

 

Cons
Not suitable to magnet-planar headphones

The output impedance is not very low


Official technical specifications:

Headphone power output: 1500mW at 32ohm – 80mW at 600ohm

Preamplifier and headphone amplifier: All Matching Impedance Stability

Frequency response: 10Hz-50kHz at +/-3dB

Dynamic range: >120dB

THD – Total Harmonic Distortion: <0.001% at 20Hz-20kHz

Signal to Noise ratio: -105dB

Volume control: Double Mono Active Volume Control

 

Audio inputs
Analogue inputs: stereo RCA and XLR balanced
Input sensitivity: 450mV
Input impedance: 47kOhm
Headphone input impedance: Proprietary Variable Design
Power amplifier input: stereo RCA and XLR balanced

 

Audio outputs
Pre out: one stereo RCA and XLR balanced
Fixed out: one stereo RCA and XLR balanced
Line output impedance: 100ohm
Headphone output impedance: 10ohm

 

Connectivity
Infrared remote: RC5 proprietary code

 

Power
Mains supply: 100/115/230V, 50/60Hz, depending on market destination and not convertible
Power supply: hybrid with temperature automatic stabilizer
Power consumption: 15W max

 

Upgrades
External PSU: PSU-7 AC or PSU-9 Dual Battery, both Plug and Play power supply units
Other: Gold note Lucca power chord

 

Physical
Dimensions: 200mm L x 85mm H x 260mm D
Total weight: 3.5 kg

 

Finishes
Front panel: brushed black or silver anodized aluminium
Case: black powder coated

 

Official Italian dealer: to Gold Note website

Official current price in Italy: 715.00 EUR

Associated equipment: to Matteo Turotti's system




 
by Matteo Turotti
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