Santana's view on his Bludotone

[wicker]

Pots positions make me feel that this amp might be kind of HRM without fenderish TS after 1st stage (drive is first then BMT).

[alvarezh]

Thanks Martin.

Interesting Wicker, you suggesting that the TS controls we see belong to the HRM, and that the amp is without a clean TS? Could be! So in essence, the amp would be on PAB all the time.

Apparently Santana uses it with his Alvarez (no relation to me!) otherwise, there would be no need for the FET input, I guess he must have some type of tone shaping on this guitar's preamp in case there is no clean TS.

Cheers.

[boldaslove6789]

Yes by the layout of the amp it appears to be an Overdrive only amp with no clean channel.... a PAB on permenantly into some kind of HRM or Ripper Overdrive?

Santana uses a WET reverb in the loop, thats whats shoehorned in the bottom of the headcase, and instead of a Ftsw jack there's a 9v supply for the WET reverb pedal.

[alvarezh]

Thanks Greg. Just curious, if the amp is OD full-time, do you have any clues on why the need for the FET?

I heard a recent recording of him played clean with his acoustic, he must be using another rig for that then? Maybe he has another Bludo with the orthodox ODS style topology? I've seen pictures where he has more than one Bludo.

All the best.

[wicker]

Since Santana got enough money to have many amp on stage, this may be his scream only machine, eventually it might get nicely clean using guitar vol only. Anyway, interesting amp.

[Structo]

Is it possible the High/ Low switch is for the local feedback on V1?

[212Mavguy]

@qtone

Great admiration for your science project. My two cents from owning and listening to nearly 600 vintage tubes in my collection dating back the the 40's in a modest stable of ten tube guitar amps including a pair of D-clones, two one of a kind turret board amps running Bendix Red Bank ICBM Nuke's tubes ...a JTM 45-ish done up better in a few ways than Jim Marshall did his. My credentials are modest, but I have something of well proven value here here and want to help in the forum spirit...

You do NOT want NOS tubes as in brand new only run in a tester old stock and this is why:

Brand new old stock tubes will be relatively bright, even brittle and harsh sounding in the top end compared to tubes that have had a few hundred hours of runtime. It's easy to look at the glass and guts of a tube with experience and know how much use it has seen, and some of those signs are unique to a particular tube brand and type. That is how I get so many screaming deals on eBay for fractions of market value...I know what to look for in the pics. One of my buddies is also one of the premier vintage and NOS tube dealers in the US, he has the best tube testing equipment lab I have ever seen or read about. His clients are Radio stations and HIFI audiophiles. So I occasionally supplement my vintage tube habit from his hoarded inventory for a fair market price.

You are already going to get some tonal drift from the amp parts during break in. Adding in tubes not broken in to the situation and the tonal drift thang worsens. You will want tubes that have already been broken in and will not drift as much tonally while the circuit breaks in, then you will have a better platform with less tube burning in variables changing/drifting in values as well as sound to the situation for any slight circuit tweaks. Stick in lightly used old glass that is relatively resistant to microphonics. However, a bit of microphony in a tube can help with a more lively bloom and sustain when playing in the dirt or even clean if placed in an appropriate socket. and a very slight tube rattle is definitely lost in the mix live, if not lost during close mic'ed recording.

I'd like to collaboratively sponsor you and Greg in this project by providing temporary loan of the kind of glass I'm talking about, to roll in your awesome creation, you take notes on the results as you go and there will be more to share with members here. When you get through with rolling the first batch, send them back to me and I will send the next batch, unlike what was in the first batch. Have 12ax's, 5751's and 12at's. PM me if you'd like to do this.

Peace.

[Structo]

That is pretty awesome of you 212Mavguy.

Can you elaborate what to look for inside tubes to see how many hours have been run on it?

Thanks!

[212Mavguy]

Umm, yes, to a point. But as far a a linear relationship to x number of hours, absolutely not.

First off I almost always know what the color of the getter flashing is on the new tube of the type in question. I know what the glass looks like new what can be seen from the inside and outside of the bottle. I can tell by shading/silvering on the glass between closely spaced micas, such as Shuguang 12ax7's or Philips/Siemens e83cc/6681. The change in clarity from clear to light gray to silvery shading between the topmost getter splash guard and the top mica beneath it on a Siemens e83cc is a dead giveaway to new, moderaste, or lots hours of use. In that tube I have auditioned several samples with well shaded glass that still resisted microphony and sounded full, strong and glorious, if slightly more compressed than a less used one. They are my PI tube of choice for the Marshally tones, and they will carry through the Fendery ones if the preamp is circduited and tubed up to do so. Nothing like a Vintage RCA shortplate 7025 or second choice for me, 12ax7a shortplate that looks almost identical inside the bottle, have different tone palettes, both Fendery, in V1 for Fender tones, using the original Fender tube brand/type for that... They get a lot of gray shading throughout the entire inside, and erosion/darkening of the getter. awesome sounding tubes even when really dark in color, if not too microphonic they will sound as warm, smooth, sweetly musical, woody, and fat. Lots of fundamentals in the OD tones.

There is a place on the bottom between the pins where the place that flashes on startup in Philips family shortplate tubes like Mullard, Amperex, Philips, Mniwatt, over time and repeated cycles starting from clear glass over repeated on/off cycles leaves a what starts as a lightly shaded bar shaped deposit that gradually becomes more like a lightbulb in shape increases in opacity, and starts to go up the side of the bottle in cases of many, many on/off cycles. On I have observed silvery color deposits for Amperex, grayish brown for mullards except the 10m's, Philips labeled blackburn batches and Amperex labeled Mullard shortplate units, their deposit is colored purple-ish. I look for the purp as a good thing in the Blackburn batches. I got the same tones from the big Philips white print blackburn 12ax7's as ai do with by blackburn 10m's. I would not be surprised of the god ont he pins was the only difference! On Philips family 12ax7's, I look at the inside color of the getter flashing as a reliable indicator of how much things are used up as well the darker the outside is, can in certain tubes indicate usage. The bottom of the flashing area tends to erode away first, often the old original getter deposit line can be faintly seen as a slight leftover artifact of the edge that once was there, now having retreated to slightly higher on the bottle. Also, if looked through toward a ceiling lamp, the geter might exhibit many small pinholes that are visible in this thpe of view where a new tube would exhibit little to no pinholing. Dark brown where mercury bright silver was is a good indication. RFT 12ax7's in different batches flash or not at startup, and in some of the fat bottle units made with the Amoerex Globe Label (GOD tubes for high gain settings/resistance to microphony/long life) go black looking from the part of the flash you see from looking at the side or top of the bottle...Raytheon long blackplate partial third mica 12ax7's get a 1/8 inch or so shading on the bottle above the plates and below the getter halo, it gets black with time of use. There is some correlation with what I see on the bottle and microphony in circuit, but it is by no means a direct relationship.

Clouding on the sides of the bottle often occurs in certain places after a preamp tube has seen a lot of use. The signs of aging are unique to a maker's tube type. so it's inexact and arbitrary at best, but results in my Hickok as well as in circuit correlate well with my visual observations in the great majority of the cases. Darkening of the glass is an idications of use in many but not all 12ax7's, I have seen the same Raytheons spoken of earlier well used up and clear as can be between the pins, you do have to know from some experience. I hope this helps to explain.

Peace.

[Structo]

Thanks!
A lot to digest.

As for the flashing at start up, isn't that due to the filament doing something when energized?

[212Mavguy]

Exactly. Tubes of that type having had many on/off cycles will flash less for a given amount of use than the same tube turned on and off less times.

Lot to digest? My post? Hah!

I'm the rookie FNG here and looking at the gutshot porn is eye candy, but looking at a schematic and translating that to layout, which directions the electrons move and what they are doing and what effects those behaviors have on volumeand tone is staggering, even the most rudimentary construcion is challenging to my little tiny pinhead brain. Electronics is my worst science subject, and I'm slowly teaching myself.

Got Merlin's book but even Merlin is a bit tough for me, I dat ignant, read Torres' book, I liked it, was written at 9th grade level.

I truly guitarded, have built only one circuit, stuffed a fiberglass turret board with components of my own choosing, PIO signal caps, 30-50%-ish oversized filtering capacity, Tantalum, or carbon film 1% resistors, Black Gate bypass caps, all new iron, different 8 incher, a 70's silverplate Frank-en-Champ with almost no Fender parts left but the cab, pots, fuse holder and light socket.

The build and dead dress is f-ing horrible especially after I saw how you guys do it here, it sounds much louder and better than it should. A month ago I replaced the original 12ax7 socket with a salvaged mil spec ceramic one, I redid my lead dress for that socket, and noticed an improvement in tone. But now I have to do the other two sockets and completely redo the ground bus.

Guys like you are my heroes. This is just my teensy tiny piece of the product that the real workhorses of this forum provide. Thanks to you!

[brentm]

Yeah, this is definitely some great information! Probably deserves its own thread somewhere.... I was just checking the tube I have sitting on my desk that I pulled and deemed unworthy. Been here for months... I used the info in your post and it's pretty accurate. It happens to be a 80's Chinese tube found in the Two Rocks... The base is defintely cloudy all around and the getter flash has eroded, and is particularly uneven. Other than that, hard to tell...

I do agree on the Orange Globe Amperex... I have some labeled made in holland, but are really Matsushita. The only way I can tell is the holes in the plates go through and the getter is at a pretty extreme angle as is the getter flash. Anyway, these are sleepers for sure. I really like them in V2.

Here's an example I'm waiting for in the mail. You never know what you'll get, but I sniped this one for cheap.

http://www.ebay.com/itm/221014558466?ss ... 1439.l2649

[212Mavguy]

Yup, the "Japanese Mullard" is what you have there. They have a brighter top end than any philips family shortplate tube, fat mullard-y mids and a big bottom. Euro Philips family 12ax7's have plate vents on the outside only or none. The Japanese Matsu-not-so-shitty have vents on the inside as well as the outside half of the plates, the 45 degree getter flash version has the brighter top end. I also have some in a level getter halo/flash, they are darker, very close to Mullards in tone, sometimes these are found in Raytheon yellow rectangular block label with the word "Registered" underneath, They are particularly resistant to microphonics and last practically forever, the getter will blacken around the edges and the whole getter will eventually turn black, but that will be with a few thousand hours of use. The more used they get, the better, more organic they sound to my ears. New they can be used in a very agressive amp circuit for some serious rip yer face off tones. This tube should outlive three new production tubes.

BTW, very nice snag. Hover like a buzzard, then FWOOOSH!

[brentm]

I think I have some of the level getters from Japan labeled Baldwin. They have a "12AX7" with octagon line around it, but slightly larger than the RCA label.

So with respect to the tube pins. Are there any key indicators on those? Seems like some NOS tubes have pins that look like the tube has been plugged in for a length of time with uneven corrosion.

[Structo]

I have noticed that vintage tubes have dark pins that can sometimes be mistaken for oxidation or corrosion.

I think they get darkened by heat treatment perhaps with the idea that it will temper the pins.
Because the discoloration doesn't really come off with cleaning.

I could be all wrong, but for the most part, all vintage tubes have darker pins than current production tubes.

@212Mavguy,

Have you read Dave Hunter's book, "Guitar Amplifier Handbook - Understanding Tube Amplifiers and Getting Great Sounds"

He explains each stage of a tube amp in easy to understand language.
It was one of the first books I read when I got back into tube amps.

$16.49 at Amazon

http://www.amazon.com/Guitar-Amplifier- ... 768&sr=1-1