22 April 2014

Amps: Watford Valves, yes Sir.


This is just a short note related to my recent experience with Watford Valves.

I have a drawer full of spare tubes, that correspond to all the tubes I was purchasing trying to bring some life to my amps. Most of my purchases were made to the Tube Amp Doctor (T.A.D.) but, once I've started to be disappointed with their tubes, I went to other European tube dealers, to get even worst results.

I knew about Watford Valves and, I knew they had a strong name but, the expensive exchange rate Euro / Pound, were keeping me out of their online store. This and the fact that the five times I tried to get some guidance from them ended in nothing. Nobody seems to answer you back. This is still my main concern related to Watford Valves. Nobody seems to care about emails.

But, since Watford has some re-tubing kits, specific for some brand and model of amps and, I was in the need to re-tube a couple of amps (Vox Night Train and Fender Hot Rod III Deville) and, my spare stock contained just those tubes I had rejected, I've decided to give a try to one of those kits.

Already mentioned in a previous blog entry, I've successfully re-tubed my Fender Hot Rod III Deville with one of Watford's re-tubing kits and, as soon as those tubes were at home, I did my own tests, with the help of the Orange Divo VT-1000 tester and, I was gratefully surprised with all them being really close to specifications.

Because of that, I wanted to check again  with a couple more amps: the Vox Night Train (complete re-tubing) and the Marshall 1923C 85th Anniversary Combo (just pre-amp tubes, because power tubes are already SED Winged-C EL34s).

Retubing the Vox Night Train

As I did with the tubes for the Deville, I've tested the new tubes as soon as they came from Watford and, before installing them in both amps.

The kit I've used for the Night Train is the kit that's being sold for a Vox AC15, since they have exactly same tube topology and, very similar overall character.

Watford relabels all the tubes that are passing their exhaustive Drive Test with the Harma name.
TAD relabels also the tube that passed their own tests with the TAD name but, I have the impression that TAD tubes have a tolerance range higher than Harma tubes and, therefore, they don't bring the same life to the amp.

The kit for the Vox AC15 comes with a couple of Harma ECC83-RET (retro) pre-amp tubes and a couple of Harma EL84-RET (retro) tubes. Watford doesn't identifies which brand/model is re-labeling but, I had the impression that all them where Mullard reissue (Red Sensor).
Since I had a Mullard 12AX7 in Night Train's preamp and a couple of Mullard EL84 in power amp, comparing my tubes with tubes from Watford, gave me the impression that they were all Mullard reissue.

This is not an issue, because those were exactly the tubes I've chosen time ago for that amp. But, since I remember how they sounded after re-tubing the Night Train, this would be a fire test to see if the relabeled Harma tubes could work the same or better.

I remember that my Night Train was sounding really good (before some tube worn) but, man, now it sounds really stellar.

The Orange Divo doesn't tells me all the history. The readings for the pre-amp tubes where the same I usually get for Mullard reissue 12AX7 tubes: one triode reads 10, the other 11. The readings for both EL84 were 10, while I'm getting readings of 10 (most of times) and 11 for Mullard EL84 reissue tubes.

So, in principle, I was throwing there same tubes, with same readings. So, how that kit from Watford can sound better?.
My suspect is that the difference can be related to other variables and, very specially, to transconductance.

I made a short test, with guitar and some backing tracks and, I was fully satisfied with the sound of the Night Train. Indeed, one more score!.

Retubing the Marshall 1923C 85th Anniversary Combo

I've chosen a Classic / Hi Gain kit for this amp, because I want an early breakup, to be able to cook the tubes at lower volumes.

This time the Harma ECC83-Ret tubes seemed to me JJ ECC83S tubes but, readings where a digit over my usual readings with TAD 12AX7-Cz (JJ ECC83S) tubes. While TAD tubes usually read 8 / 9 (triode A / triode B), Harma tubes read 9 / 10 (V1 and V3), 8 / 10 (V2) and, the balanced one 10 / 11 (PI).

This is the second balance tube from Watford and, both have unbalanced triodes but, both have at least one reading 10 (on specs) and, the unbalanced is just a digit more or less.

Long time ago, I did a lot of swaps to this Marshall, and my conclusion was that there is no other tube that works better in this particular amp than the JJ ECC83S. My suspect is that those ECC83-Ret are effectively JJ ECC83S tubes. If the history repeats, as with the Deville and the Night Train, my favourite amp will come back to life very soon.

I have to re-bias the EL34 to Marshall' specs (45mv). Then, I will be able to evaluate the real impact of those pre-amp tubes, which I hope to test by tomorrow.


It seems that Watford Valves do the best tests on tubes, at least in Europe.
I've wasted a lot of money before, trying to get more affordable tubes, which leaded me to unsatisfactory results and a ton of spare tubes that I will probably have to throw to the trash can.

They won a new customer, indeed. But, I would suggest to Watford to have someone taking care of the email, because not everybody can make an international call that could cost even more than a single tube.

19 April 2014

Pedals: Jetter Gear Gold 45/100 and Jetdrive


Gain pedals probably are the type of pedals that more often rotate in a guitarist's pedalboard and, I am not an exception.
From time to time, it seems that a new breed of pedals enhances the sound of your current gain pedals and, you want to check those.

I've owned / tested so many Overdrives and Distortion boxes that I can barely remember all them but, I went from the cheapest Boss and MXR units to boutique pedals from Xotic, Fulltone, Hermida Audio, MI Audio, Wampler, Weehbo, Mad Professor (hand wired), Butler Audio, etc.

But, why?.
The main issue is that I can not run my amps in their best spot. Tube amps are awesome tone machines and, sure, if you can krank your amp, the best distortion you could always find is the one coming from your amp.

So, to be able to krank your amp, you need to downsize your rig and then to go for a lower powered amp but, this has its drawbacks also. The lower the power of the amp, the less clean headroom and the more difficult to represent the whole range of frequencies and, very specially, the low end.
Also, there is a minimum of power that you will need if you need to rehearsal with a band and, if you need to play small gigs.

Also, even that your amp's distortion can be amazing, you often need a variate palette of distortions to cover different tasks. Well, there are multi-channeled multi-mode amps, with lots of switches and other goodies that make them really versatile and handy. But, usually, an amp sounds with a better singing voice the simpler its circuit design is and, the versatility of any amp can compromise the overall sound. It's difficult to have an amp that can cover everything and every style with spades. Usually the sound is being compromised to obtain useful tones in every mode but, not a killer or perfect tone in all them.

Anyway, what is every single guitarist after is his/her own business and relates to his/her individual quest for his/her tone.

I'm currently interested in an amp with good cleans that could be a great platform to sculpt my sound with my preferred pedals. I also need an amp with certain headroom, to be used with a band or for small gigs. That leaded me to the Fender Hot Rod III 212 Deville, which not being a top-notch amp is good enough for my current needs.

But, being an amp with a power of 65W and, with a couple of Celestion speakers of 12", it can go loud very soon and, at low volume level it lacks something and, that's when some particular pedals, as boosters or overdrives have a good opportunity to shine.

Re-tubing my amp

After few tests with some of my spare tubes, I've decided to try a complete re-tubing set from Watford Valves, that worked really nice, enhancing the stock voice of the amp, which was just correct (with Groove Tubes).

Watford's kit included a JAN/Philips 6L6 pair that sounds perfect in this amp. Pre-amp tubes are Harma STR and, they seemed to me relabeled JJ ECC83S Gold Pin but carefully tested and picked up, with correct specifications.

Still thinking on to swap the correct but anodyne Celestions with some Harma speakers but, tubes set the amp in a very good condition.

Re-building my pedalboard

You know, every new incoming pedal often shakes your pedalboard and, you are in the need to re-check everything again, to find the best way your pedals can inter-actuate.

I've found that my Area 51 wah wasn't working fine with my rest of pedals and, therefore, I wanted to check a Cry Baby this time. While I was weighting which want to choose, I thought... well... there is the Bonamassa's one and, that guy really rocks; if it works for him, it should work for me; reasonably affordable, why don't to try it?.

I've tested the Bonamassa's wah alone and delivered good tones but, I had still not opportunity to check the pedal together with the rest of pedals of my pedalboard. This will come later.
One of the questions I need to clarify is if I need to run such a pedal in Buffered or True Bypass mode.

I've started to build the pedalboard from scratch.
Firstly, tweaking the amp with the guitar direct to amp then, being increasing the pedalboard chain, pedal by pedal.

I've started with the tuner, the TC Polytune, which is theoretically true bypass but, I really suspect it's sucking the tone a bit, thinning it and making it brigther. But, until I can throw there a best pedal, as a Peterson's one, this is the best place for this pedal, since switching it off, the whole rig mutes.

After the tuner (that should be true bypass), the Wah is the natural election to lead the chain and, therefore, I've thrown there the Bonamassa's wah, in their stock setting (which I guess is buffered but, the internal dip switch has no sign that can help you, neither the user's manual. I've decided that once the rest of the pedalboard is ok, I will go back to the wah to check both modes and see how it impacts to the rest of the chain.

Next pedal, the compressor. The Wampler EGO compressor is the one I'm using for a long while.

Next pedal, just before my overdrives is where I like vintage vibes so, my Dry Bell Machine Vibe was placed there.

Then, I've tried the two Jetter pedals I love, the Gold 45/100 and the Jetdrive. While I had these pedals sorted with the Jetdrive stacked into the Gold, results weren't satisfactory at all.
This time, I've decided to swap the order of both pedals, stacking the Gold before the Jetdrive and... that was a great idea.

But, what I've noticed is that there was a drop in tone as soon as I've inserted the Jetdrive.
It seemed that the chain was safe with the five first pedals (tuner, wah, compressor, vibe and first overdrive) but, as soon as I've added the sixth, the tone started to suffer.
I've decided to insert the Wampler Decibel+ before those two overdrives, just to recover the signal level and guitar tone.

I've also discovered that the Vibe had a lot of impact over the overdrives, depending on its mode.
The Original mode (unbuffered output) worked better than the Bright mode (buffered output), as soon as I was able to recover the tone sucking with the Decibel placed just between the Vibe and the two overdrives.

Following those two Jetter's overdrives, I've checked several boxes that I wanted to cover the hi-gain distortion but, liked none. They all sounded or weak or undefined (compared to the Jetters).
None of the Jetter's distortions liked me: Red Square, Dharma; both seemed to me having less gain range than the Jetdrive itself.
Searching for a more liquid and bold distortion, I've checked also the Suhr Riot Reloaded and the Weehbo Bastard. None delivered what I am after.
I am thinking on to test the new Mesa Boogie's boxes, which sound as good candidates.
I've already tried Bogner's boxes and, probably the Red is a good candidate but, too big for my pedalboard room.

Anyway, I've decided to don't stack a higher distortion pedal after the two Jetter's overdrives until I have a firm candidate. So, my chain was ended with the all-in-one modulation effect, the Strymon Möbius and, my echo tape emulation, the Strymon El Capistan.

Jetter Gear Gold 45/100 and Jetdrive

These two are the two best overdrive pedals that I've tested up today and, the only two Jetter Gear's pedals I can highly recommend to anyone.

The Gold 45/100 is after nailing the tone of the early Marshall JTM45 and, I don't care how close it is to the real thing but, I really care (as always) is how useful it's for my needs.

There are several overdrive boxes that bring you that "Plexi" tone, somewhat close to the original Bassman tone (which the JTM was originally based on), which usually translates into a clean but warm sound, with a delicious break-up when picking hard.
Lots of good pedals are covering this soft-warm overdrive tone, as the Mad Professor Sweet Honey (delicious), the Wampler Tweed 57 or Plexi Drive or the Weehbo Plexdrive or Plexface.

None of the Wampler's had a really "clean warm" tone. They had a clear break-up that was there from the very beginning, as if the volume of the amp was always kranked, with more or less gain.

The Plexdrive had a lot of "clean warm" range and very few of "broke up" range, except if you switched on the boost section, which added a lot of floor noise (as the boost in Wampler's pedals).

Probably, the more balanced one was the Sweet Honey but, the kranked tone was a tad undefined to my taste.

I would say that the Gold 45/100 is closer to the good tone of the Weehbo, with an enhanced gain range closer to the Sweet Honey. As it happens with Weehbo pedals, one thing that defines Jetter Gear pedals is that they stand very defined even when at full gain but, differently from Weehbo pedals, the gain range seems greater in Jetter Gear overdrives (while their distortions lack gain!).

What I love of the Gold 45/100 is that, placed as the first gain stage in my pedalboard, it converts my amp into an old-school tube rectified amp so, my Hot Rod III Deville goes closer to an old Bassman, with that nice warm but sparkling clean. Rest of distortions stacked after, get an old-school tone that instantaneously remember the great bands of the '70s, when the Hard Rock was founded.

The Jetdrive is an awesome dual overdrive, with tons of gain on hands.
Playing with the Volume and Gain controls of each individual overdrive channel you can get lots of overdrive nuances, until you get the ones that better suit your needs. Tone control is highly responsive and, small touches have a direct impact in the sound.

The Green channel sounds to me with a crunchy attitude and, with an EQ probably bumped in mid-highs frequencies. The sound isn't compressed but, very open and in your face. Maybe, a British crunchy low to middle gain overdrive, more modern than vintage.

The Blue channel sounds to me more silky but slightly compressed, the EQ seems more even or with recessed mids. It has more gain available than the green channel but, surprisingly stays clean. Maybe a more American low to middle gain overdrive and, probably more vintage than modern (compared to the Green channel).

Stacking both pedals, you achieve tons of gain, enough to get the singing but liquid solos of a Peavey 5150 and, that remain so defined as in that amp. Sure, you cannot cover high gain metal distortion tones and, the pedal doesn't goes that hard in low end but, the tone is closer to the "brown sound" or the liquid tones that were available in the '80s - '90s.

The Gold stacked before any of the two channels of the Jetdrive or, before both channels stacked, adds warm and definition to the sound, taming down some high end.
Those two pedals together, give you 6 different nuances of overdrive/distortion, always very dynamic, responsive and organic. They sound more like an amp than like a pedal (as in the case of Weehbo's).

I wouldn't say that my pedalboard is already finish but, those two Jetter's are two clear keepers, right now. And, very interesting, I'm running those at standard 9V, since they are clear enough.

One Video

I made some video, while tweaking the pedals and, while testing them with some backing tracks to see how they help me with real performances.

First part of the video includes two improvisations over two free downloadable backing tracks. The first one was named "Blues in G" (If memory doesn't fail) and, the second one is based in "Old Love" by Eric Clapton. Pure improvisation, while testing the pedals, switched by hand.

The second part includes the building-on process of the foundational tone to which I add the the two Jetter's pedals. The foundational tone is built with the Wampler Decibel+ buffer/booster (to recover the signal level and tone lost after the Vibe) and the Strymon El Capistan (to add the Delay and better fit the guitar into the mix of the backing tracks).

Since my #1 guitar is on hands of my fellow friend Luthier (Alex Tirado, search that man if you are in Mataro or Barcelona areas!), I've used my PRS 513 Rosewood, since it can covers single coil, vintage and modern humbucker sounds so, I could get some compromised settings to be useful with the three types of pickups.

But, I've ended just checking singles and mid output humbuckers, in the building-on part. For the two improvisations, single coil modes were used, only.

Room' sound (and video) was recorded directly with a Zoom Q3HD device.
Sound wasn't processed in Pro Tools or any other kind of DAW.
In the Video Editor, I've just used IK Multimedia Classic Compressor (to bring back the sound level, dimmed by the low-sensitivity setting of the Q3HD) and the Brickwall Limiter (to avoid clipping). Nothing else used, no effect added.

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...

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.