If you've been keeping up with the posts here at Jeff's Place, you know I've been thoroughly enjoying listening to music with the combination of the Audio Note (UK) CD 2.1x/II Level Two Red Book CD player combined with the Audio Note (UK) Oto Phono SE Signature integrated amplifier.

The combination of the Audio Note (UK) CD 2.1x/II Level Two Red Book CD player with the Audio Note (UK) Oto Phono SE Signature integrated amplifier does it all for both vinyl and CD, and I have been extremely impressed with its performance on my Duelund-ized "Stokowski" Altec loudspeakers.

Not only has the Audio Note (UK) CD 2.1x/II Level Two Red Book CD player allowed me to enjoy Red Book CDs on a level comparable to my enjoyment of listening to vinyl on my CTC Garrard 301, I've actually bought Red Book CDs to listen to again, which is something I haven't done for about a decade, if memory serves me correct.

I've said this before, but vintage Altec's with good crossovers seem to get the best out of digital, and the combination of an excellent digital source like the Audio Note (UK) CD 2.1x/II Level Two Red Book CD player combined with my "Stokowski" Altec's, and their Duelund-Altec Project's CAST tinned-copper crossovers, really make listening to Red Book CDs an inspiring experience, one akin to the pleasure I get from listening to LPs. 

However, my music listening bliss was interrupted over the last few days when the normally ultra-quiet Oto Phono SE Signature integrated amplifier started doing the "snap, crackle, and pop" thing out of the right channel.

Often that means a power tube is about to give up the ghost, so I rummaged through my vacuum tube stash and found a quad of premium "Harma Cryo EL84L Burst Tested" tubes to swap out the stock Sovtek EL84's with. 

The "Harma Cryo E84L Burst Tested" vacuum tubes are offered by Watford Valves in the UK - an audio and guitar focused tube supplier - and they were developed specifically for Queen lead guitarist Brian May.

I buy all my EL84 vacuum tubes from Watford Valves and highly recommend them, and they are open for shipping orders during the Covid-19 pandemic.

As you might expect, Brian May, being the lead Queen guitarist, as well as a singer, songwriter, record producer, and an astrophysicist (!), wanted the best EL84s for his guitar amp, and this is what Watford Valves came up with for him.

Here's what Watford Valves says about their "Harma Cryo E84L Burst Tested" vacuum tubes (HERE):

"This valve is the specially treated cryogenic version of our E84L. The Cryo version offers more clarity and treble detail than the standard item. The bass response is also clearer and has greater depth and punch. The Real Benefit of this valve is that it remains warm and smooth even under the heaviest saturation providing the maximum clean headroom out of any current EL84.

This valve is our recommendation for high end audio amplifiers due its musical transparency.

The Harma E84L Bust Tested Cryo is a high quality special application military valve which has a number of unique features. The valve is electrically rated at having a plate dissipation of 14 watts, which is higher than any other EL84, all others being rated at 12 watts.

The valve has a mechanical rugged construction and thick glass as they were originally designed to be immune to shock and vibration as they were designed for military applications.

These features reduce microphonics and rattle in all guitar combos. The valves also use high grade filament isolation so even after long periods of use the filament will not degrade and a triple supported getter and thick grade mica. The valve has a coated anode which makes it stable and able to stand high voltages.

No previous or current EL84 was made to this specification.

This will explain why over the years this valve has given exceptional performance in the most demanding circumstances.

The valve produces the maximum clean headroom out of any current EL84 providing the best clean sound by far in guitar applications. The bass is really deep and solid with excellent balance and no hardness. In guitar applications it offers late breakup and displays a rich warm overdrive sound when distorted which is not matched by any current made EL84.

In Audio applications this valve is very difficult to beat without spending vast sums of money on new old Stock items. The valve has a clarity and musical performance which is enjoyable and engaging and will upgrade the modern and Vintage High end audio amplifiers such as Beard, Audio Note and Leak.

This is the specially burst tested and Cryo treated version of the Harma E84L which is tested on the rig built for Brian May for the ultimate reliability. They undergo our own unique real world burst testing. 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. This gives you the most through tested valve available anywhere in the world.

This valve is a specially treated cryogenic version offers more clarity and treble detail than the standard item. The bass response is also clearer and has greater depth. This valve is our recommendation for high end audio amplifiers due its musical transparency."

As I found with the Leben HiFi Company CS-600X that I just reviewed for Positive Feedback, premium vacuum tubes can make a huge difference in performance, so I was really interested to hear what the quad of Harma E84L Burst Tested Cryo vacuum tubes could do in the Oto Phono SE Signature integrated amplifier.

After I installed the quad of Harma E84L Bust Tested Cryo vacuum tubes into the Oto Phono SE Signature integrated amplifier, I powered it up to make sure I had correctly diagnosed the issue with right channel "snap, crackle, and pop" that had developed. 

The Oto Phono SE Signature integrated amplifier's right channel was now dead quiet, and not only that, but the Harma E84L Burst Tested Cryo vacuum tubes in the Oto were even quieter than the stock Sovtek EL84's. 

Next up was a little music listening with the Oto and its new quad of Harma E84L Burst Tested Cryo vacuum tubes, and it didn't disappoint. 

The Harma E84L Burst Tested Cryo vacuum tubes elevated the Oto's performance to another level, providing a naturally warm and liquid presentation that was full of clarity, resolution, beautifully rendered treble, and deep, nuanced, and punchy bass response. 

The Oto Phono SE Signature integrated amplifier that had impressed me so much with its overall musical & sonic performance, now impresses me even more.

If you happen to be one of the lucky listeners who owns an Audio Note (UK) Oto Phono SE Signature integrated amplifier, I recommend you give the Watford Valves Harma Cryo E84L Burst Tested vacuum tubes a try. I suspect you'll like the combination as much as I do.

For EL84 valves, the Watford Valves Harma Cryo E84L Burst Tested vacuum tubes are a bit spendy at    £26.00 each ($33 USD each), but I don't know of anything you could do that would improve your hifi's performance for the $132 USD that a quad of Watford Valves Harma Cryo E84L Burst Tested vacuum tubes cost. Highly recommended.

As always, thanks for stopping by, and may the tone be with you!