Harma Valves / ECC83/5751-HARMA STR HIGH GAIN

ECC83/5751-HARMA STR HIGH GAIN ECC83/5751-HARMA STR HIGH GAIN Click on image(s) above to view larger
Select Test Options
  • Factory Tested
  • Balanced (Triodes)

All prices contained on this page are exclusive of VAT. This is currently charged at 20% and is payable by the UK only.

Harma valves consist of a selected range of valves that are chosen after meeting stringent standards for sound quality and reliability. These valves are sourced from current production as well as some of the finest Nos valves available. Unlike our competitors no Harma valves, past or present has been made in China. Harma valves represent the finest available items of their type available.

Harma valves are tested using a range of custom designed and built test rigs which are unique to Watford valves.These unique tests are not offered by any other valve supplier in the world.

All Harma pre amp valves undergo the drive rating system; the valve undergoes a series of through tests under full operational conditions. This involves a controlled burn in process to ensure perfect stability and correct ageing. A shock and vibration test, microphoney, hum, and a balance and symmetry test.

All Harma output valves undergo our own unique real world burst testing. No other supplier tests valves this way. The burst testing process involves a series of varying timed electrical signal bursts. This runs the valves under the same stress conditions that they will meet in your amplifier especially when overdriven. All out put valves are then dual matched by us on anode current and gain. This will ensure that you get the best selected valves available anywhere in the world.
The Harma 5751 STR High Gain is a 5751 valve with a higher gain and amplification factor when compared to an original USA made 5751.

This valve has been specially selected to offer around 20% less gain than a typical 12AX7 ECC83 Type. This is in direct response to the guitarists who wants to reduce the distortion and gain level of his amplifier by taking a slight edge off the tone.

The 5751-STR High Gain has all features of the ECC83-STR as it provides one of the most neutral and clear sounds of all the current production 5751 with the added bonus of a little more gain. The valve is very well balanced with nice even bass which has plenty of depth. The mid-range is very transparent and the treble has nice open chime.

The 5751 STR High Gain also shares the ECC83 STR construction as this design has a number of advantages such as reduced microphonics and better isolation from vibration.

This valve has a multitude of uses, firstly In the V1 position it a great choice for reducing the gain and the input position a cleaner and cleared sound. In this position it will also reduce the harshness found in some modern amplifier. In modern high gain circuits it will also reduce the fizz and hardness without comprising the gain.

If a balanced item is used in the phase splitter position this will have the effect of making the amplifier a little cleaner in the output stage when used in place of a 12AX7.

All Harma preamp valves are Dynamically Drive tested under real working condition have passed the following tests:

Gain (db) Drive Tested)
Transconductance (gm) Drive Tested
Output Drive Tested
Noise 1 (signal to noise)
Noise 2 (Aural)
Microphonics Test 1(Ambient)
Microphonic Test 2 (Shock)
Cathode Test
Grid Leakage Test



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