03 April 2014

Amps: Fender Hot Rod III 212 Deville - testing tubes - Part 1


After installing the re-tubing set from Watford, the amp came to good life, warmer, punchier and with rich harmonics but, I wondered if I can go further, fine tuning the sound.

Those NOS JAN/Philips 6L6WGB are great tubes, indeed. And those Harma 12AX7-STR (I bet this is a take of the JJ ECC83S Golden-pin) are delivering good sound with spades. But, I feel some crunchy mids that I am suspecting coming from the PI tube.

Even that this set works awesome, I am just curious to see the impact of changing every individual pre-amp tube.

Test: Swapping PI (V3) tube

Being the Harma 12AX7-STR a nice tube for this position, it has a short plate and, I usually prefer there long plate tubes or, the awesome JAN/Philips 5751 (with a great transconductancy and really hard to break up).

Well, I reviewed my spare depot and, didn't found a valid long plate tube, as the Sovtek 12AX7-LPS or the JJ ECC803S. Well, I had a LPS but, with very low ratings (7 / 8, triode A, triode B).
I could test a Mullard reissue there but, maybe the spiky mids and crunchy distortion can be a bad election for this amp. So, with so few options, I went to reuse my last JAN/Philips 5751.

Clearly, that blurry mids that I've hear were removed and, the overall sound was brighter and more defined.
I've tested also the hi-gain settings (Drive Channel / More Drive) and, it was awesome, with fast response to your picking technic so, fast riffs where really easy to perform, because of the immediateness of the amp.

But the 5751 works the best, the more you raise the volume of the amp, sounding a tad bonny and trebbly at low volumes. With the amp really hot, results are enough  to demolish your walls. What a beast!.

Also, the reverb was tamed down, and most of the ice picky reverb sounds were removed. JJ ECC83S tube is picking hard in mid-highs.

This little test, showed me that there is some room for improvements there, just swapping the PI tube.
I need to source some even-EQ'd tubes with large plate and good transconductancy and nice output to try there. Maybe the JJ ECC803S or the Ruby 12AX7-M or the Sovtek 12AX7-LPS (but, this one last very few in combos).

The second test was to thrown there a Mullard 12AX7 reissue, even that I knew is a bright tube, I wanted to check the effect of the change.
Well, more or less same results than with the 5751, maybe slightly more power and, overall, the tone was brighter and harsher, very specially with single coils.

Noe of those tubes has same reverb strength as the original GT but, it made the Reverb to sound really harsh.

It seems that the Harma 12AX7-STR, this time balanced, will be the best option.

Test: Sorting tubes by gain, ascending

While I prefer the V1 with higher gain to get an overall early distortion. I thought that maybe a way to remove that slightly blurred mids (due to the Phase Inverter, as demoed my previous test) could be to arrange the tubes from lower to higher gain, being the PI the tube with higher gain. Maybe, in that way I could have some headroom when cascading a tube into the other.

Wow!. Results are just Perfect. Nothing more, nothing less.
That sounds to great amp, right now.

I stop swapping tubes. Those Harma 12AX7-STR paired with those JAN/Philips 6L6WGB are awesome for this amp.
The high distortion sounds more defined, with less fizz and strange overtones.

Well, I think that Watford Valves has earn a new customer, indeed!.
Great work!.

Video Demo

to come...

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