02 April 2014

Amps: Fender Hot Rod III 212 Deville


I was in the market for an amp with a great clean channel that could take every pedal with ease and, that could be used at studio and gig levels. For dorm levels, or you end with a good solid state amp or, some amp modeler (digital) or with some kind of dummy load to reduce the overall loudness.

But, I haven't really planed to get one, right now.

What happened is that I went with my fellow friend to a big store, to help him to select his new brand Strato. I wanted to have the opportunity to test some amps, just to discard some models and narrowing the search but, I hadn't any real willing of buying an amp that time.

Well, I've plugged my guitar to several, including some unaffordable or unpractical ones (as the Bassman 4x10 or some Victoria amps). Suddenly, I've remembered to watch some videos about Fender's Hot Rod series and, was really curious to test one.
Between the Deluxe and the Deville, my election was to test the Deville, because of its higher power (60W), which should give me more clean headroom.

Hell!. As soon as I plugged my guitar and pedalboard to that amp, I loved it.
Well, we were 4 friends in the room. Everybody liked it and, pushed me to buy it!.
I had the credit available so... what the heck... I did it!.

The amp

It seems to be the most selled amp in the world and a total score for Fender but, is that good?.

The amp works with three pre-amp tubes (12AX7 / ECC83 types) and a couple of power tubes (6L6).
Rectifier is solid state.

It has two channels (well, just one more stacked triode in the second tube), two inputs (higher and lower impedance), a mode switch (normal, bright) and a gain switch (gain, more gain).

Controls are: Volume (for clean channel), Treble, Middle, Bass, Reverb and Presence.
For the gain channel, the Volume is being deactivated and the Gain pot takes its place. The overall volume of this channel is handled later with the Master control.

Channel and gain levels are switchable with an external pedal switch (two switches).

It has a post-preamp output and a pre-power input so, you can even chain several of those  or, you can use those as the FX loop (whitout level control).

This is one of the few Fenders I see having a Bypass switch, what is very well welcome. Also, one of the few Fenders that comes with a trim pot for cathode-method biasing and a clear testing pin for your probes.

On the dark side, the amp has the jacks for plug alternative cabs inside, instead of on top or back. The power cord is directly soldered to the PCB and its white, while the whole amp is black!!!. So, you cannot unplug that hanging white cord from the amp.
The tube sockets are floating, just supported by the solders to the PCB, which makes me feel that I am gonna break the PCB if pushing the tubes really hard. As in most Fender's combos, the tubes hang down so, you will probably have to tilt the amp to see the sockets, when replacing tubes.

Well, I know price is a compromise but, can those important things be part of price compromise, really?. Even VHT, with unbeatable prices, gets rid of this things!.

Overall, the amp has a typical Fender look and, seem well built (except for those mentioned design details).

The sound

Stock, the amp sounds really good but, as soon as you drive it a bit more, with the help of a clean booster or alike, you quickly see that the sound can be enhanced.

Without any pushing pedal, it sounds nice but, like lacking some mojo. Too much defined, even aseptic. More hi-fi than musical.

The drive channel farts a bit and, sounds like a IC / transistor / diodes are doing the dirty work, instead of cooked tubes. But, well, I wasn't interested on the drive channel anyway. For that, I have my good pedals.

As usual, I've removed the tubes and, tested them with the Orange Divo VT-1000 tube tester, to check which tubes came stock and which values were used.

All tubes were Groove-Tubes. Not surprise, since GT belongs to Fender, as well.

The three pre-amp tubes were SV-12AX7-R, so Sovtek 12AX7 tubes, which are very EQ even and silky but, lack tridimensionality and character.

The power tubes were, at the end, a couple of EH 5881 tubes.

Measured their matching values, I've found following figures:

V1: 7 / 8
V2: 8 / 8
V3: 7 / 8
Power: 9 / 10

Being each value the corresponding to each triode (for pre-amp tubes) or the value of each tube (for power tubes). The degree that each tube (or triode) satisfies standard specifications is being give by such a number, being 10 the reference value.

That means that, if a 12AX7 tube should have a gain of 100 (10 for each triode), V1 had a gain of 7  for triode 1 and 8 for triode 2 therefore, under specifications. Power tubes were right well on specs values.

Speakers are Celestion G12P-80. Not great speakers but, very even EQ'd and, often used for modeling-amps, which need a very broad frequential representation, to mime several amps with very different EQ characteristics. Not being specialized speakers, they can serve as a good clean platform to build your sound with the help of pedals so, I am not in the need of swap them, by now.

Tube Swapping

I was understanding that I should get more tone from this amp, just swapping stock tubes.
This is my first 6L6 amp so, I had to investigate a while about 6L6 tubes and, recommendations.
As always, NOS tubes seem to be the reference but, the Winged-C 6L6 (of the real Svetlana factory, in St. Petersburg) seemed to be the natural election, followed by some TAD 6L6WGB.

So, I did my research and, this time, I wanted to try Watford Valves, for this set of tubes.
Watford Valves had a re-tube kit ready for this amp, with NOS 6L6 tubes and, three of their re-branded tubes (Harma ECC83-STR).
Watford Valves is, probably, the tube dealer with the best name but, I had never ordered to them, because of the Pound / Euro ratio, VAT, etc. But, there is always a first time.

While I was waiting for such a set, I wanted to try some pre-amp tubes and, thrown there a Mullard Reissue in V1, a Svetlana (Red Sensor) 12AX7 in V2 and a Tung-Sol in the PI (since I had no better option).
Results were awful. What a way to destroy the sound of that amp!.

Overall loudness did fall about 2 numbers in the volume dial and, the sound was bonny, hollow and excessively crunchy. Not a good set of tubes to be paired with those 6L6 tubes.
So, since I had that re-tubing set on the way, I've decided to wait for it and, to continue my tests later.

As soon as the Watford tubes came, I prepared the Orange Divo VT-1000 tube tester and, checked every tube. That was a very great surprise. While most of tubes coming from TAD are rated around 8/9, the set from Watford was very consistent and, very close to specifications. These were the values:

Harma ECC83-STR - tube 1 - 9 / 10
Harma ECC83-STR - tube 2 - 10 / 11
Harma ECC84-STR - tube 3 - 10 / 10

NOS JAN/Philips 6L6WGB - 9 / 10

I've decided to put tube 2 in V1, because it had the two triodes with more gain, to push the input stage.
I've decided to put tube 3 in PI, because it had the more balanced triodes.
And, tube 1 was placed in V2.

Next decision was how to BIAS the amp. Fortunately, the Hot Rod III Deville has a (big blue) trim pot to bias the power tubes, this and my TAD Bias Master system, made it very comfortable.

The factory biasing sounded a tad cool and, I wanted to get a little more harmonic content so, I've searched everywhere and, found (as always) highly contradictory information.
Fender recommends 30 mV by tube but, if you use Weber Bias Calculator, it seems that 6L6 tubes can go up to 40 mV at 70% of max. disipation power.
Eurotubes was biasing to 40 mV by tube.
A mate was really happy with his amp biased to 32.5 mV by tube and, added that his tubes last years and years because of it.

I made my own calculations, taking into account the highly variable voltage ratio read in my mains, and decided to go with 38 mV by tube.

Switched on the amp and plugged the guitar. Overall, the sound was warmer and darker than with original Sovtek tubes but, in a good way. But, the sound seemed to me a bit cooked and, breaking really early. The power delivered was brutal and, most of the objects on the bins around started to fall down.
Tested the guitar direct to amp, both channels, every mode.
I've ended taking the decision to move down the biasing value and, I wanted to try those 32.5 mV that seemed to satisfy that guy.

Next day, I re-biased the tubes to 32.5 mV and, tried again.
Wow. The overall loudness was reduced but, the sound was less crunchy or cooked and, allowed me to set up the amp in a good sweet spot, to play clean and break the tubes by picking hard.
There is a warm pad bellow the sound, rich in harmonics and really tasteful.
I've enjoyed the test session a lot. It was like being plugged to a good old-school amp, a la Bassman or alike.

The Normal mode of the Clean channel sounded a bit dull and lifeless with factory tubes but, with this re-tubing, it sounded warm but beautiful. Really nice.
The Bright mode of the Clean channel sounded too much bright (even piercing) with factory tubes but, now it was easier to tame down the excessive high end.

The Gain channel sounded too dirty with Factory tubes. Now, it sounded more like a tube-distortion.

I can try to rotate those three tubes in the different positions. Maybe a higher output tube with a later break in PI will bring more clean headroom to the amp. And maybe, a lower output tube with a later break can help the pre-amp to stay cleaner. But, it's clear that British sounding tubes, as the Mullard reissue, the EH or the Svetlana aren't the best option for this amp, since they have a classic British crunch.

I have no clue which tubes are those Harma 12AX7-STR because, STR (Special Tube Request) means that the maker introduces some variations to make the tube to buyer' specifications (that is, Watford Valves' specifications) and, this usually mean you are ordering a Chinese tube. But, tube pins don't have that dull aspect that Chinese tubes usually have and, it's overall aspect resembles me to a JJ ECC83S (maybe with golden pins). The sound is also closer to a JJ, specially in the middle-high frequencies but, surprisingly darker than the Sovtek. I have to investigate it a bit more.

Maybe, now that I have the tubes biased and controls set up to my taste, I will try some tubes, in individual positions, to see what changes. Maybe, the TAD 7025-S highgrade in V1 could do something good. Will see. I would like to tame a bit the spike on mid-highs and, a cleaner Reverb recovery sound.

Will come back with my tests in a further entry in this blog.

Notes on Biasing this amp

Biasing this amp, don't forget to:

  • Roll down every control, including the tone stack, presence, master and drive. Everything down.
  • Switch the mode to Normal (not Bright).
  • Set your biasing probes between the socked and the tube (safer than just a multimeter).
  • Switch off the amp and, wait 5 mins.
  • Switch off the bypass
  • Bias to your target value
  • Leave the amp like this for about 20 mins, to help the whole circuit to stabilize.
  • Re-check your bias setting and, do latest adjustment.
To avoid to remove the amp's framework out of the combo, I've flipped the amp down, over its speakers' grill to better access tubes and that blue trim-pot for biasing.
By careful, there are a lot of components that can be accidentally touched and, have lethal voltages.

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