Thoughts on preamp tubes in a Nomad

[Koreth]

Greetings, tone gurus.

I've been lurking here off and on for a while and have been reading various threads on use of different preamp tubes in different positions to tweak one's sound, especially the threads about NOS preamp tubes. I saw shredd6's advice of thinking of v1 v2 and v3 in a DR as highs, mids, bass and thus using tubes with strong highs, mids and bass in those positions respectively to get a good sound, and saw the positive responses of people who've tried this and figured I should go about trying different preamp tubes in my Nomad in a similar manner.

Wondering if shredd6's advice would be applicable to my Nomad, I looked up both the Nomad and 2CH recto manuals online and compared the tube task charts. The 2ch recto seems to have a nice simple design: V1A=1st stage, V1B unused, V2A=2nd stage, V2B=3rd stage, V3A=4th stage, V3B=5th stage, V4A=FX Send, V4B=FX Return, V5A&B=Phase Inverter. Looking in the manual for my Nomad, the tube setup seems to me a bit more complex: V1A&B paralell=Ch1 1st stage, V2A=Ch1 2nd stage, V2B=Ch1 3rd stage, V3A= Ch2&3 4th stage, V3B=Ch2&3 3rd stage, V4A=Ch2&3 2nd stage, V4B=FX Return V5A&B Phase Inverter.

So in the case of my Nomad, I'm guessing the best way to go about trying new tubes, be they NOS or current production, would be something like : V1=Highs all channels, V2=Ch1 Mids&Bass, V3=Ch2&3 Bass, V4=Ch2&3 Mids. Can any tube gurus chime in with some advice in this regard? Are there any particular tubes (tung sol, Mullard, RCA, etc.) I should look for that would work well in each of these positions, especially clean vs. distorted? Am I perhaps over thinking this in my efforts to understand what I'm doing before I potentially waste money in search of that magic tone in my head?

 

[212Mavguy]

Hi Koreth,

No, you are not overthinking at all, but your theory of arranging tubes could be better as far as the treble mid bass/order thang. The first tube/stage of a given channel has more effect of the basic tone for that channel than the tubes/stages following it. The following stages make copies of the first stage with some of their flavoring added.

If you have been reading Shredd's, Stokes', T-Wolf's, and my posts there are several things we agree on:

-Vintage old stock tubes tend to be more pleasing and offer more tonal variety than the current production ones,

-Tone is in the ear of the beholder, so what you like is the most important, and what sounds great when playing alone in a room might not sound the same when playing in a mix,

-Used vintage tubes, what I call VOS (vintage old stock) can be had comparatively inexpensively instead of trying to get unused, new old stock (NOS,) particularly through eBay, with the idea that some transactions will be less than wonderful. Most of the time you will be okay, and you will learn like we did from experience what to do and what to avoid. Having an experienced ebay type as a mentor is valuable.

Here are some basic recommendations for vintage tubes that are not hugely expensive...
with the idea that there are a lot more possibilities than these few, relatively surefire vintage recommendations, just keeping it underwhelmingly simple:

Clean channel: GE longplate 12ax7, tungsol 12ax7, (NOT the reissue, BTW,) RCA 12ax7a shortplate, GE or Sylvania 5751's, Raytheon 12at7, Sylvania 12at7, Since 5751's are lower gain than 12ax7's and 12at7's are lower gain yet, they work well for clean tone and are most of the time relatively inexpensive compared to their 12ax7 brothers...

Dirty Channel:

Raytheon long blackplate 12ax7a, often found on eBay with the Baldwin organ company label, RFT 12ax7, Mullard/philips/amperex 12ax7 shortplate, Matsushita 12ax7 shortplate with the 45degree angled getter halo.

Phase inverter:

search for a vintage 12ax7 from the above lists that tests out as close to perfectly balanced between sections as possible, you will get more sustain than just tossing in any old 12ax7 type. Don't believe what you read as far as the PI slot has no effect on tone, that just ain't true.

Be ready to accrue more preamp tubes than the bare minimum needed to fill your amp up, but at the same time don't be too much in a hurry.

Effects loop: a decent 12ax7 from the above lists.

roll to taste. :mrgreen:

let us know how things are going, your feedback will help others help you. Best of luck!

 

[Koreth]

What kind of sound are you looking for? What kind of music do you play?

It is a more complicated stage design, but not one that's too hard to figure out. I think you're on the right track. You WILL be glad you bought nos. But let's get to the bottom of what you want the amp to sound like first.

I mainly like metal and hard rock; these are the tunes I usually try to play and and the tones I try to imitate. But my taste does vary outside of that a bit. Sometimes I'll go looking for the chords to American Pie, or some other song I'll hear on the local classic rock radio station rather than the local metal station. I recall one of my former coworkers from Texas playing some sorta country-blues stuff done by a kid from his local area, and the stuff was amazing. The kid could probably hold his own against the shredders on all my metal CDs. For a brief while I considered selling my Ibanez and Nomad and getting a Strat and Lonestar and taking up blues. I'd still like to learn blues, but my heart lies with metal and hard rock.

As for tones, lets start with cleans, as that would be the easiest; I'm still discovering things I do and don't like about distorted tones. The best clean tones I've heard, be it from myself or another, regardless of what guitar was being used, have come from silverface Fender reverbs, the Lonestar, and the series II Recto Road King. I know I'm not going to get an exact Fender clean out of my Nomad, but I'd like to get something very similar. The clean channel also has a second mode, called "Pushed", which ups the gain so the channel sits on the edge between clean and dirty, depending on where you set the gain control. Here I'd like the transition between clean and breakup to be as smooth as it can.

No, you are not overthinking at all, but your theory of arranging tubes could be better as far as the treble mid bass/order thang. The first tube/stage of a given channel has more effect of the basic tone for that channel than the tubes/stages following it. The following stages make copies of the first stage with some of their flavoring added.

So, since V1A&B are the 1st stage for all channels, I should look for a tube that will help me get the cleans I want, but will still play nice with other tubes better suited for distorted tones further down the chain in the other channels? Does having a good clean tone in the beginning of the chain actually help with getting better distorted tones when more gain is piled on, or do the two tend to be mutually exclusive?

 

[cscotto]

Hi,

I have a Nomad 100, and I have been tube rolling for about a week. I finally decided on a selection that I like. First, I agree with 212Mavguy, about rethinking the V1 treble, etc. I have the Nomad schematic in front of me, and if I knew how to attach or add pictures to the post, I would. Again, 212Mavguy is correct on the importance of V1, it feeds all the other stages. V2a and V2b are the second and third stages of channel 1. The gain pot for channel 1 is before V2 and after V1. Also, the tone stack is before V2. V4a is the second stage for channels 2 and 3 and the gain pot is before V4a. V4b is after the FX loop. Interestingly, V3a and b are the third and fourth stages for channels 2 and 3, and the tone stack is after V3.

I am not using any NOS tube, all modern production. I have had plenty of NOS tubes, but it just gets too expensive rolling with the NOS. I probably could have bought a nice amp with the money I have spent.

I am using the Tung-Sol 12AX7 reissue in V1. I really like the way it sounds. Lots of gain, but very clear and articulate. In V2, I am using a high gain JJ. In V4, I have a new Chinese 12Ax7. I choose the Chinese tube, because it is bright and it works well for the effects loop. In V3, I have a Sovtek 12AX7 LPS. This tube has gobs of bass, and really makes my chugga chuggs sound great. I also the same tube in V5, the phase inverter, because long plate phase inverters add a lot of power.

I tried four different tubes in V4, and EH, the chinese, a JJ, and an LPS.
The LPS was too dark, I think in combination with the other LPSs in V5 and V4 it added too much bass.
The JJ was nice, but it dropped the gain, but by so little it might not be noticeable. It also made higher notes a little harsher.
The EH had plenty of gain, but I lost definition.
The Chinese, seemed to have the right combination of gain and brightness.

HTH

cscotto

 

[Koreth]

So, if I'm understanding you correctly, Channel 1 goes Stage1->Gain Control->Tone Control->Stage2->Stage3->Poweramp, and Channels 2 and 3 go Stage1->Gain Control->Stage2->Stage3->Stage4->Tone Control-> Poweramp? Do the switches that select the higher or lower gain modes of each channel add or remove the last stage or two of each channel to switch it between the higher and lower gain modes?

 

[cscotto]

]

So, if I'm understanding you correctly, Channel 1 goes Stage1->Gain Control->Tone Control->Stage2->Stage3->Poweramp, and Channels 2 and 3 go Stage1->Gain Control->Stage2->Stage3->Stage4->Tone Control-> Poweramp?

Hi,

Yes, on channel 1, but Stage 1 consists of V1a + b. After Stage 2 and 3, at the end of FX loop circuit (and it does not matter whether you use the loop or not) the signal passes through V4b, then goes to the phase inverter, V5a + b.

Yes, on Channels 2 and 3 as well, except the second gain stage is handled by V4a and the third and fourth gain stages by V3a + b, which means the tubes are out of order from the way one might expect them to be.

Another schematic I have shows the tone stack and the switches. The Modern/Vintage switches simply add or subtract different resistors, which increase or decrease the the voltage passing through them.

 

[212Mavguy]

Hi again Koreth,

Some tube positions are for the clean channel, other ones are for the other channels/effects/reverb, etc. So beginning with the clean channel, you might start with a GE longplate and RCA 12ax7a shortplate for your clean channel. V1 and V2 are your spots to try these, in the order that best suits your ears. The sounds these tubes provide can get pretty close to your big bass/sparkly top fender clean tone. Again, I'm NOT talking NOS, used VOS is the best way to start. Look for ones that test as new or close to it and you will find them for a similar price or within close price of a new production tube. As far as the Chinese tubes go, the reason why many think they sound appropriate is because when the amps are being designed they are designed around what current production tube is available at the time production for a given model. That does NOT mean that the sound can not be improved to personal taste by vintage tube rolling, experience will show for trained ears that the opposite is true more often than not. Lots of posts in the Tubes section here will verify that. The oldest Boogies used to occasionally have Sylvania and Siemens 12ax7's in them. Again that was what was available at the time. I have seen vintage Sylvania short grayplate 12ax7's and Siemens shortplate 12ax7's with Mesa labeling on ebay. A comparison of vintage Siemens shortplate vs. ANY modern production 12ax7 will most likely favor the Siemens to well trained ears. A new production Tungsol reissue is NOT anything like the build of the vintage Tung Sol, try the REAL one first. They are still going fairly cheap. Careful, unhurried shopping will get you some nearly new ones at a very decent price. The real one will give a gorgeous clean tone and is right up there with the two tubes recommended earlier in this post if not actually superior. A given tube can sound slightly different in different amp circuits to the same set of ears.

Shop for a vintage preamp tube with both systems very well balanced to each other for your phase inverter. Again, you can find vintage stuff, used, for very reasonable prices on eBay. You can start from the PI position before doing the clean channel revoicing if you want.

Cscotto has provided a helpful post as the result of personal experience doing the science experiments... Kudos. The one thing I would say is that while NOS seems expensive, and believe him it can be, the tube life gotten from them is greater than most of the new production stuff. That means that if you were to purchase lightly used VOS instead of unused NOS you will still in most cases gain the increased tube life as a result and over time the vintage way will cost you less while sounding better. The more one knows from experience the more that is the case. For the cost of a Mesa amp going the increased up front expense of nice vintage tubes is very much well worth it. Mesa amps give back well when their preamps are pimped out. 8)

I occasionally revoice amps for friends out of my collection, and I charge a reasonable price that covers both my actual item costs plus a bit extra to cover the cost of not so wonderful used tubes that sometimes arrive through ebay auctions. I factor in a third, but actually it's more like a tenth, others may not enjoy that kind of fortunate success, especially at first, hence the reason for seeking an "ebay tube mentor." Enjoy!

 

[Old BF Shred]

+1 to Mavguy on this.

I have found that my stash of used, but good Telefunken, Amperex and Sonotone 12ax7's make my amps more of a joy to play.

Just something about the sensitivity to touch and lack of shrillness that breaths life in to my amps.

Most new production tubes don't have these quality's...or the longer life.

I do see some promise with the JJ and new Tung Sol. The JJ's do sound pretty smooth to my ears and the TS's seem to have a lot of gain but with less shrillness than most Russian or Chinese tubes today.

But if you have the means to go with some of these older tubes, do it; you will appreciate the difference.

Good luck & take care!

 

[Koreth]

So, on the acquisition of used but still good vintage tubes, is something like this eBay auction a good deal? Those are shortplate RCA's with halo getters, right? Is there a website which lists the various nuances and details between different brands and variations of tube types so as to make identification of tubes in places like eBay, craigslist and flea markets easier?

 

[cscotto]

So, on the acquisition of used but still good vintage tubes, is something like this eBay auction a good deal? Those are shortplate RCA's with halo getters, right? Is there a website which lists the various nuances and details between different brands and variations of tube types so as to make identification of tubes in places like eBay, craigslist and flea markets easier?

Those are RCA tubes. I have a bunch of those tubes. My problem with auctions like this is you really never know what you are getting. Here is a web site that sells RCA: http://www.tubedepot.com/nos-12ax7a-rca.html
They are $99.00 each, but you get a guarantee.
Here is another site: http://www.audiotubes.com/12ax7.htm#12ax7%20list
I know he is reputable, because I have sold him tubes. He wants about $60.00 a piece for RCAs.
I might take a chance for $49.00. I have spent more than that on new tubes that I never wound up using.

 

[212Mavguy]

Looked at your five RCA shortplate 12ax7, that's great, but thought that the lot of ten various 12ax7's that the same seller is offering is a better way to go for someone starting out tube rolling. If a couple or even three don't make the grade for Microphonics it's still a screaming deal at 79 bucks BIN + shipping. Hard to get that many new production tubes for that money. At time of this posting they will close in something like 19 hours though. There will be others. Stratbasturd is a competent seller that takes pride in his tube offerings. Have done biz with him.

I would almost NEVER pay tube dealer high prices for guaranteed tubes personally, I have had too much success going the lower price route and taking the occasional bad deals in stride, still come out WAY better in the price/performance thang. With that said, I did buy a perfectly matched pair of vintage Emitron KT66's from a serious HIFI weenie tube dealer, but he is a personal friend of mine, lives a half hour away, and I can count the number of those kind of transactions on the fingers of one hand. But if you want to pay too much money, then that's fine with me. More lowball buzzard bait for me to swoop on at sniping time. :wink:

 

[Koreth]

I went ahead and pulled the trigger on the latter auction posted with the 10 tube asortement of RCA, Matsushita and GE 12AX7s. I also read a couple guides I found on Stratbasturd's eBay profile page, talking about tube buying, covering the difference NOS and vintage used tubes, as well as the numerical scores for tubes and how to tell the ones from cheap testers and serious testers apart -- all very good info to know. I also found this eBay auction for what are supposedly some Mullard and Amperex branded Matsushita tubes. Regardless of which they actually are, the numbers posted look strong for new tubes, and a couple of them have identically testing sections, so if I pick up that set, I should have a couple candidates for a phase inverter tube in V5. When looking for a candidate for a phase inverter, should I look only for tubes with identical sections (which I assume is ideal) or is a tube with sections that are +/- 25, 50 or even 100 acceptable?

Edit: Something just occurred to me. I realize this is probably more a question for the speakers section, but since the speakers and cabinet are what's actually *producing* the physical sound you hear, speaker choice probably has a major influence on the sound heard as well, I'm guessing. If that's the case, wouldn't a more transparent speaker/cab selection be better for evaluating the difference in sound between various preamp tubes than a speaker/cab selection that tends to color the sound? Are there speakers I should avoid when trying to evaluate the sounds of different tubes, and speakers that would aid in tube rolling? Or is the influence of preamp tubes on the tone great enough that so long as the speaker remains constant, one can tell the difference between the tubes being rolled. Finally, since I know I have a tendency to do so, am I overthinking things in this regard?

 

[212Mavguy]

Hi again Koreth,

Please let us know what you think after your tube rolling. I bet you will really enjoy it!

+1 on Shredd's comment on overspending 98 bucks for relabeled Matsushitas. Regarding speakers, if you stick with the same cabinet through your current round of experiments, that is a good idea.

 

[Koreth]

So the tubes arrived today. Merry Christmas to me! I might get pics up later.

I've been opening the various boxes and comparing the tubes to each other, to try to get an idea what the various tubes are supposed to look like in absence of identifying markings painted on to the bottle.

The RCA looks to have long medium grey plates with ribs that run vertical along the edge of the boxy section, as well three horizontal ones, marking two squares formed by these ribs, as well as a square-ish getter. Two of the GE long plates lack these vertical ribs and also have a halo getter. Three of the GEs have the vertical ribs on the plate and have some different getter shape, but I'm not sure how to describe it. A "D", "C", "U" shape, maybe? It curves around, then straightens out on both sides, then both ends connect to the thingy that connects the getter to the plate. There's also 1 GE short plate with a halo getter. I might be imagining things, but the GEs look to have thicker micas than the the RCA does. There's also one Sylvania with short plates and a halo getter. The ribbing on the plates is similar to that of the RCA in that it makes a couple squares, but smaller. Finally there's two Matsushitas. The ribbing on their plates makes for a rectangle instead of a square, and the getters are halos, but angled.

I dunno if any of this matters or not, I just thought It'd be interesting to see if there were any noticeable physical differences in the tubes that could be used to possibly ID them. I'm gonna start rolling them here shortly. I'll let you know how it goes.

Edit: Is is safe to swap the tubes with the amp in Standby? Standby just powers the heaters, and not parts of the amp circuit that could be damaged by the tubes being removed, right?

Also, is there an easy way to get to the preamp tubes without burning myself on the power tubes or output transformer? I tried unscrewing the faceplate of the head shell, but it was just a facade. I'm afraid to try to remove the chassis from the head shell for fear I might damage it or the thin wires to the reverb tank.

 

[Tommy_G]

I have a Nomad 100, and swapped around a bunch of different new production tubes. Best way on mine was to remove the back bar, then pull one of the power tubes, then you can get access with one hand/wrist or another. Getting the pins lined up right is the real trick. It takes some practice, especially on V1, which is tucked away behind a transformer if I recall. I'd be turning off the power if I were you, especially since you'll need to pull a power tube to get access.

Seeing as were on the topic of vintage tubes, I've been thinking about buying some, but the knowledge one needs to pick the 'right' tubes is incredible.

Lets start with Mullard:
What plate length? getter style? production era?
What are the relabelled Mullards? How do I know if a relabeled tube is really a Mullard?

I could use some help before I blow a couple of hundred on bad experiences.

 

[212Mavguy]

Hi Tommy_G,

When most guitarists say Mullard, they mean the later production shortplate version. If you look carefully near the bottom of the bottle on the side you will see an acid etch on most of them. The most common ones have two lines, the first looks like I61, I62, most commonly I63, and the second one has a capital B followed by a few digits. The B stands for the Blackburn, England plant.

Mullard shortplate tubes have plates approximately 15mm long, gray on the outside, with an inner layer that is bright in color if you look really close where the plate tabs protrude through the mica spacers, there is a round vent hole approximately 1/16 inch in diameter each side of the box-ish looking part of the plates, through the outside half of the plate only. The getter halo has a single support and is round.

Philips is the company that owned Mullard at the time, and that means Amperex, including Bugle boy, Philips, Philips Miniwatt, and my personal favorite, Siemens. The Amperex code is similar in the first line and the second line begins with a right triangle, which denotes the Heerlen, Holland plant. You will see Amperex, some Philips, and Philips Miniwatt with the right triangle. Some Philips and Amperex tubes were made in the Blackburn plant and were relabeled, so you will see the B code on those. All except Siemens have one getter halo support, Siemens have two. The Siemens code second line begins with an equal sign with a vertical or diagonal slash through it. Kinda cocky, no equal, get it? :wink: My ears agree, but you will spend more per tube for that wonderful tone.

Siemens made a special grade of 12ax7, the e83cc. Some look identical to their ecc83 brothers,and most have a third mica positioned on two supports above the second one, with another pair of supports holding the halo. Those commonly go for 80-100 bucks each on ebay, and considerably more from vendors. They are a 10,000 hour rated tube. Mullard made a premium shortplate 12ax7 with a 10M yellow label, they go for stupid money, and have gold plated pins. Mine sound a bit fatter than their already fat sounding shortplate brothers. The Philips family of shortplate tubes produce a flash in the bottom when first turned on. There are other family characteristics of Philips shortplate 12ax7's, but these are easily recognizeable ones.

 

[Koreth]

Okay, I've only rolled three of the 10 tubes I bought so far and already, wow.

Sylvania 12AX7A (short plate): I started plinking various scales on the guitars and didn't notice anything immediately, but once I got futher up the neck and onto the high strings I noticed there was something different and perhaps a bit sweeter about the higher notes that I liked. It also seems quieter than the JJ ECC83 that was in there previously. I may go back to this one again. I kinda like those sweeter highs.

RCA 12AX7 long plate: This one was a disappointment. It seemed a little duller than the Sylvania. There was nothing special about it's tone that really stood out for me. It was also noisy. Once I got into channels 2 and 3, there was a definite hum present. At first I thought it might be because I'd forgotten to replace the cap that sheilds the tube, but the hum was still there. Playing with distortion, there was also an unpleasant crackle/popping noise that was breifly present in the background as the notes fadeded. I dunno if that was the RCA's fault, or if it was revealing qualities to the tubes later in the preamp chain that weren't audible before with a JJ in V1. Either way, I didn't like it.

GE short plate: Wow. Immediately I noticed a certain clarity across all the strings. Bass doesn't seem as strong as the Sylvania and the highs were perhaps not as sweet, but things seem so much clearer. Or something. There's something about the way this tube sounds that just makes me all smiles and giggles. This same quality is heard across channels 2 and 3 as well. There's just something more delicious about the amp now. Even without a lot of bass (which is on purpose, as before bass could get muddy and overwhelming) my palm mutes were more to my liking. I always thought it was a lack of competence with the technique on my part, but now palm mutes seem crisper, with more definition. It makes me want to be playing my guitar rather than typing up my thoughts here or rolling more tubes.

Some additonal thoughts: Per the manual, both sides of V1 are used in parallel for the 1st gain stage. Since both sides of the tube are being used, I can't help but wonder if an imbalance would have an effect on how things sound. Thus far, the GE short plate has has the best match between sections (1100/1175) of all the tubes. The Sylvania was 1175/1075, and the RCA long plate was 925/1425. Maybe the major imbalance between sections of the RCA contributed to the noise and hum?

Okay, back to rolling tubes.

 

[Koreth]

V1 is now a short plate GE 12AX7/ECC83, V2 is is a long plate GE 12AX7 that's missing the vertical ribs from the ribs on the plate that make up the 'ladder' pattern. The amp seems brighter now. The High knob on the tone control seems so much more powerful and useful now. Cranking it up, the bass tones from the low stings on the guitar get a nice tight, and bright, and the high strings become big and loud. I'm still wondering if I want more bass in my clean channel, I like the brightness, but I can't help but wonder if maybe it's a little too much, perhaps as a result of having two GEs in there. Do GEs tend to be bright tubes? IMO, the Sylvania short plate isn't as bright and has more bass, but the highs are sweeter.

Since I don't have any Mullards, I was going to use one of the Matsushitas for V4. but I'm hesitant. If I'm correctly understanding what I've read here and elsewhere on the Internets, Matsushitas are a Japanese Mullard, with more top end. If the GEs are bright tubes, having a GE short plate, a GE long plate and a Matsushita making up the gain stages of channels 2 and 3, plus a Matsushita in V5 for the phase inverter, I can't help but wonder if the things would get too bright.

Finally, since my RCA turned out to be a dud, how do RCAs compare to GEs and Sylvanias? If an RCA long plate or short plate were in between the Sylvania short plate and GE short plate in terms of both bass and brightness, I think that would be ideal. Any other tubes I should look at picking up to try in V1? Original Tung Sol? Ratheon?

 

[Tommy_G]

One of the most noticable things I found with tube rolling was how it effects the Ch1 "old time rocknroll" break up tones. If it breaks up politely retaining balance and clarity , it gets shortlisted. Out of newpro tubes, only the Tungsol RI did that for me. I run my Nomad clean channel at about 2:00 gain (depends on pickup output), and 2:00 treble to get some "hair". I run the mids and bass about 10:30.

Koreth - I'd be interested in what you found with forcing Ch1 into breakup with these settings. Also, which Nomad do you have?

 

[212Mavguy]

Hi Koreth,

Could be that the RCA longplate had seen a ton of hours of use and was near toasted. One symptom of a tube with a lot of use is a rolled off top end. Don't set your mind about RCA longplate based on a sample size of one...that would be poor science. Nice to hear about the GE shortplate and how you like it. Above all, your impressions from being new to tube rolling are important. Don't worry about what anybody says about the Matsushita, run any tube you like in any position you are curious about and let your ears decide, after all it's your tone...

So glad to hear you're having fun, and above all don't be surprised if the tones you really like three months later become different than when you started, or become different three months after that, your ears are getting trained on an ongoing basis. After a while you will know your tubes well enough to voice your amp for a particular guitar or speaker cab. I do think that finding a preamp home for the sylvania shortplate would be a good idea, it really is a sweet tube. Also try to get your hands on at least one Siemens shortplate. Great for the dirty channel(s) or clean.