To be or not to be....

[RedPlanet]

Well I'm trying to figure out which direction to go in as far as builds. What I would like to end up with is two 18 watters one for Clean and one using both channels one a little dirty and one Very dirty and Cranked.

The first thing I'd like to build is the Dirty amp and want to know the tonal differences in the TMB and the Trem. Like I said I would use an AB Box and use both channles one set to get a little dirt for dirty Rythems and the other set for extreme dirt (not high gain or anything) and set to be louder for Solos. I've done a number of things before and dont think it would be a problem building a TMB as my first amp. Although if I dont need to build the TMB for the tone I need it might be easier as Graydon has told me. I've been doing Industrial Wiring and Controls for almost 30 years. So which for what tone?

Second I would like to make one for Clean Sounds which I would only need one Channel but would like Reverb. If I play Clean I have the Reverb on and possibly a SS rectifier in it it for a little more headroom. Any suggestions on the build of that amp. I may be enuff stuff to do both and just take one at a time. Taking my sweet time so as not to screw up.

Both will go in 1x12 combo cabs of which I plan on putting a G12H30 style speaker in the amp for dirt and a Fendery type speaker in the amp I plan to use for clean. I do want both amps to be 18 watters and mostly the same with just minor differences.

This is pretty much my setup now exceot with more power. I'm using a 50 watt Plexi set into a 1x12 combo cab and a 40 watt Pro Reverb 2x12. I use two channels on the Marshall of which I have totally redone the channels on that thing and I use channel two in the Fender for clean with Verb. I really like this set up. I use Both Amps with a Stereo Chorous and back it off on the guitar vol just enuff two take out the dirt of one channel on the Marshall and use the second channel of the Marshall fulll up craked for solos. I also use an old Turbo Tube Screamer for some real gring if I need it and a Tube Screamer set low for just a little more dirt in there.

So thats what I'm looking to end up with can any of you steer me in the right direction PLEASE! I know I ask alot. Thanx so much for your help.

[RedPlanet]

Dang these pain pills are getting to me I ment this to go in the 18 watt forum. Oh well.

I had a fella kick me in the head with a Chineese Cresent Kick and it landed just right and did something to my neck. To beat it all he is a Chiropractor.

[zaphod_phil]

Looks like that guy's just trying to increase his Chiropracter business... Now I know why you don't like Chinese stuff! I would feel exactly the same after that.

OK, a regular 18W or 18W Lite will do both clean and dirty sounds real well. Being a non-MV amp you have to have cranked up to at least 5 for the dirtier sounds - in other words you have to be pretty loud. The TMB is nice because it has the higher gain Plexi channel and then one regular 18W Normal channel. So you can have your dirt on the Plexi/TMB channel (which also has an MV) and the clean/dirt stuff from the Normal channel. You can then use an A/B box to switch between them , or even blend both channels together. Maybe that just saved you building one extra amp.
18watters with reverb are pretty rare. However, here's a schem for a low-gain 18W with TMB controls and Reverb - http://www.18watt.com/storage/18watt-reverb.gif It also features fixed/cathode bias switching in the power stage, but that part's optional - you can build it with a regular power stage.

[Graydon]

Red,

If you really want a clean tone to compete with the overdrive of an 18W, you will need more power and a more efficient speaker. I would build a 1-12 18W with a Greenback and use that for dirty/crunchy tones. Then I would build a 36W head with a TMB circuit and run that through a 2-12 loaded up with Celestion Blues which are very efficient. That will give the 36W a chance to be heard cleanly at relatively high volumes. If you use a couple A/B boxes with that, you can get four distinctly different tones ranging from clean to very crunchy without using a master volume anywhere.

For reverb, simply use an old LXP-1 like I outlined in another thread. I would put this on the clean 36W only as the dirty 18W wouldn't need reverb.

[markd]

I didn't know that reverb schematic(that Phil linked to) was up in the Files. Don't build that! I did and it just doesn't sound too good. The guy that came up with that didn't put in enough work to get it right. Lazy bas**rd(OK, it was me. ha!).
Graydon's idea works well though. Go with that. I will email Gabi and have that schematic removed.
markd

[zaphod_phil]

The reverb part of it does however appear to very similar to one from another Marshall amp, the 2046 Professional - http://www.drtube.com/schematics/marshall/2046.gif

Rather than remove the schematic, why not just have Gabi place a note that it's an unfinished work, which is only there for discussion. It would be shame to remove it completely...

[markd]

Hey Phil,
I can't remember where I stole(er, came up with) that idea. ha! But it sucked when I fired it up. So instead of putting the work in to get it right, I just tucked it into file 13 and moved on to my next disaster(er, genius idea, I mean).
Do you know if anyone here has mated a Trainwreck preamp to the 18watt power section? That preamp is almost exactly like the 80's VOX V15 preamp, without all the cap suppression and with the second and third gain stages switched around.
markd

[zaphod_phil]

OK, so the design just needs some tweaking. I'm still in favour of leaving it there, but with a note to say that the design isn't fully cooked. The preamp looks very low gain the way it's shown at the moment. Possibly, you would want to either make the preamp more like your Vajra with TMB tone stack and cascaded gain stages, or a regular 18W preamp with a simple tone control.

[RedPlanet]

Thanx guys now you really got my wheels turning.

Graydon you really dont think the 18 watter would be loud enuff for clean tones? I did read what you wrote about hooking up an external Reverb unit maybe I should just do that. If I did that I would want to find a Pedal that maybe I could set a couple of jacks in the bottom of the amp chasis to just leave it in the back of the amp. That wouldnt be to hard would it? Maybe hardwire a wall wart and strap it and the pedal down. I would never turn it off for my clean sounds.

The reason I think a 36 watter would be to much is I'm allready using a 40 watt Fender Pro Reverb for practise and barley have it on. I set it on 2 to 2 1/2 and still get complaints about being to loud and we play Rock. My Fender dosnt have a master volume but it being a 68 I dont want to fool with it. I do have a Post Phase Inverter Master Volume in my Plexi reissue but opted for the version that dosnt work well when turned down really low. I'm at my limit with it as well. Wrather than mess with my current rig I'm real happy with it but everyone else isnt. I cannot get any lower in volume without switching the power off.

That would be the main reason for building the two rigs I'm talking about is to be able to get the Tone I want at an even lower volume ( for Band Practise).I dont mind turning down but when the the tone starts suffering I get testy. I also am excited about building I can play with that while making my bandmates happy at the same time.

Zaphod I do want two amps one set up for Clean only with Verb. The other with one channel a little dirty and the other channel full up.

How I do it is I come out of my AB Box B out to an Ibanez Stereo Chorous. Out of the stereo outs from the Chorous to the Clean amp and to the mildly dirty channel of the Dirty amp. Then I go out of the A out on the AB Box to the full up channel on the Dirty amp. This gives me a number of options which are as follows -- While in B on the AB Box I have signal to a slighly dirty channel and a clean amp which gives me a dirty Rythem sound at lower volumes so as not to drown out the vocals and if I so choose I step on a Cheapo Tube Screamer with the level set low - it just gives me more dirt. When I want to clean it up I roll back my volume a little and step on the Stereo Chorous for a very pretty shimmering clean sound with Reverb. Now by doing this my low volume dirty sound isnt really that good but its generally while all the vocals are going on so its not like anyone notices it.

Anyway out of the A out on the AB Box goes to the really dirty channel of which I can use alone or use A and B and step on one of two Tube Screamers one set low and one (Turbo Tube Screamer) set almost full up and set in the 2nd gain position.

As you can tell by now it gives me a wide variety of tonal options and loudness options. I would want to do the same thing just with two smaller amps and if they worked well enuff I might even try em on some gigs.

The options are too many for me to list all right now less my Brain get Scrambled but I can do a number of different things. One of which I like is using A and B with the Stereo Chorous on it isnt hooked up to my really dirty channel so I get this killer dirty sound with some stereo Chorous going at the same time. Thats my version of one of the EVH sounds although me no play any of that stuff just use that sound. lets just say with just a few pedals I've got a wide array of combinations to choose from. I could go on but my two typing fingers are fixin ta fall off.

All I currently use is the Ibanez Stereo Chorous, an Ibanez Anolog Delay, an Ibanez Turbo Tube Screamer , an Ibanez Soundtank Tube Screamer, the AB Box, and a Boss Foot pedal Tuner. All tucked in my Pedal board I made and covered with NOS 74 Dodge Dart Seat Cover Material.

Any more thought on this would be mostly appreciated. Thanx. RP

[idiotwithasolderingiron]

Do you know if anyone here has mated a Trainwreck preamp to the 18watt power section? That preamp is almost exactly like the 80's VOX V15 preamp, without all the cap suppression and with the second and third gain stages switched around.
markd

Hey Mark - the guys at Two Rock have a 2xel84 version of their "Ruby" amp, which is essentially a modified Trainwreck Express. I'm contemplating building something similar... But I'm looking at the schematics for both the Vox V15 and the A1a Express and I dont see the similarity you describe... Values are all different, tonestack is after the second stage, etc... What are you seeing that I'm not?

[zaphod_phil]

BTW, Richie says he's working on the idea of a 36W with one Trainwreck channel, and one Normal (IIRC)....

[markd]

>But I'm looking at the schematics for both the Vox V15 and the A1a Express and I dont see the similarity you describe... Values are all different, tonestack is after the second stage, etc... What are you seeing that I'm not?<

I should have mentioned the placement of the tone stack,sorry. But what I'm seeing is the three gain stages(Rp,Rk values are the same).
In particular the operating points. Try and think of another guitar amp, that predates the Trainwreck, that has a 10K cathode resistor on any preamp gain stage. A 10K cathode resistor will bias any 12**7 gain stage way over towards cutoff. The preamp signal will be assymetrically distorted before the amp is turned up past 3, maybe even 2.

The designers at VOX knew this of course. So,like Mr. Fisher, they must have been looking to create a unique kind of preamp distortion. The V15 was designed around 1980 so distortion had become a design goal for some guitar amps. But an EL84 power amp(like the V15 and our 18watt) doesn't allow for too much voltage gain in the preamp. So perhaps offsetting the operating point of one gain stage was a way to address that. You can also see the small(470k verses 1M) grid resistors on the imputs of the V15 as well as the small value volume(220k pot acts as a grid resistor for the 2nd stage) and master volume(100k) pots. That's another way to limit the total voltage gain of a preamp.

To a lesser degree is having all three gain stages on a single power supply node. It is considered a minor no no because of the interaction between the first and third gain stages where the signal has the same polarity. I have only read that some Trainwrecks were set up this way. I have seen two later day Trainwreck designs, and they both had the third gain stage on a different power supply node. So maybe there is no mojo there.

So that's what I'm seeing. hth. I have never heard a V15, but with those insane values for the cathode bypass capacitors it must have been a strange sounding beast(bright for sure). All the caps to ground on the plates of the preamp gain stages makes me think they must have had some serious squealing without them.
markd

ps. If anyone hasn't read the loadlines pt.2 article at the AX84 site, it is an interesting read: http://www.ax84.com/resources.html

[zaphod_phil]

Mark you make some good points.

I should have mentioned the placement of the tone stack

Well...., that is quite a major feature of the TW preamp, and generally not considered the optimum place to put a tone stack in a high gain preamp.

Try and think of another guitar amp, that predates the Trainwreck, that has a 10K cathode resistor on any preamp gain stage. A 10K cathode resistor will bias any 12**7 gain stage way over towards cutoff. The preamp signal will be assymetrically distorted before the amp is turned up past 3, maybe even 2.

Yes, I think we're talking of the Marshall JCM800, which was probably the first to do that. I had never looked that closely at the V15 schem, until you mentioned this interesting feature. Biasing the stage that cold, as I'm sure you know, produces a very squared-off hard-clipped distortion, which is ideal for metal. You then need warmer biased preamp stages after the clipping stage, so it doesn't sound like a buzzy, overdriven transistor amp. Mike Soldano then took it further with the 39k cathode resistor in the SLO 100, PV5150 and Meza DR, which basically causes the preamp stage to slice most of the the top half of the signal right off.

The designers at VOX knew this of course. So, like Mr. Fisher, they must have been looking to create a unique kind of preamp distortion. The V15 was designed around 1980 so distortion had become a design goal for some guitar amps.

So I suspect this was an ill-conceived attempt by Vox to grab some of the '80s wannabe metal player market. Still an interesting idea, which maybe could be re-visited.

But an EL84 power amp(like the V15 and our 18watt) doesn't allow for too much voltage gain in the preamp. So perhaps offsetting the operating point of one gain stage was a way to address that. You can also see the small(470k verses 1M) grid resistors on the imputs of the V15 as well as the small value volume(220k pot acts as a grid resistor for the 2nd stage) and master volume(100k) pots. That's another way to limit the total voltage gain of a preamp.

Yes, that's a good point.

I have never heard a V15, but with those insane values for the cathode bypass capacitors it must have been a strange sounding beast (bright for sure).

You mean the two 270 ohm resistors unbypassed, but with a 4uF cap between them? I wonder if that's an attempt to tighten up the low end response for those metal guys. The whole idea of Vox doing metal does seem pretty unusual. But who knows, maybe it sounds OK. Sometimes I see these V15 amps going on FleaBay.

All the caps to ground on the plates of the preamp gain stages makes me think they must have had some serious squealing without them.

Yes, as they were sharing the same PSU node. But I bet they're also there to tame some of the harshness caused by the hard clipping stage.

[idiotwithasolderingiron]

according to the vox showroom site, the V15 was marketed in '79 as a studio amp, a kinda compact AC30...

http://www.voxshowroom.com/uk/amp/v15.html

I can accept that Ken Fisher might have been influenced by these amp since he did a lot of Vox and Marshall repairs and mods, but the tonestack placement, swapped 2nd and 3rd stage and value differences make it difficult for me to make any direct connection. Most folks I know that dissect Trainwreck topology give more of a nod to Fender Blackfaces than to Vox wrt the Express.

[markd]

Phil,
I can't believe I have never been in a JCM800. But being a vintage snob has it's rewards. ha! I'm sure Ritchie has seen a lot of those and can make them sound great. Notice how I just assume they sound bad.

doctord,
I'm sure you are right about Mr. Fishers influences. I can't remember if any BF fenders had three gain stages in the preamp though. One interesting point about the V15 is the schematic of it that is in Aspen Pittman's Tube Amp Book. He may have gotten it from Ken Fisher because the schematic is stamped with the Trainwreck circuits address and phone#.

Here's some 18watt content. I got the new Deluxe edition of The Tube Amp Book at Claptons Crossroads guitar show in Dallas recently. Marshall was there and had a display of six or so of their new handwired 18 and 20 watt amps. They were quite beautiful. I talked to them about the grillecloth and they repeated the story that the original grillecloth was flammable so they couldn't use it. This makes me think Gabi is on the right track with his linoleum theory. Linoleum is made from linseed oil(also used in paint and putty) and would be flammable for sure. Also looking at the original grillecloth under magnification it is clear it was somewhat liquid when it was deposited on the backing and then hardened. The new grillcloth Marshall is using is a woven cloth but looks amazingly similar to the original from just over a few feet away.
markd

[zaphod_phil]

Well, I think it was probably a case of Ken Fischer adding a JCM800-style clipping stage to a Blackface preamp and Vox doing something similar in their V15 preamp. See http://www1.korksoft.com/~schem/marshal ... 03_pre.pdf for a JCM800 preamp.

Mark, you might actually like the JCM800 amps, as they have one of THE definative Marshall sounds - much in the same way that the JTM45 and various Plexi amps also do, athough with a slightly different tone. Whereas the latter were blues/classic rock amps, the JCM 800s are mainly heavy rock amps. The lack of any bypass cap across the 10k cathode resistor however reduces their preamp gain quite a lot, so that you can get very nice shimmering clean sounds out of the JCM800s. When you drive them hard (often with the help of a boost pedal), you get that familiar Marshall grind.

[Plexi]

"""Phil,
I can't believe I have never been in a JCM800. But being a vintage snob has it's rewards. ha! I'm sure Ritchie has seen a lot of those and can make them sound great. Notice how I just assume they sound bad. """

You know how opinions go. I own a 2203 bought it new from 77,still have the box it was shipped in. But anyway they are great amps. Some do have issiues,that can be corrected with shielded cable. When they first came out people talked bad about them,being buzzy..well mostly because they had a 100 watt amp,turned at a whisper,with the preamp cranked.
But when its opened up,it sounds great.Now they are one of the most sought after amps,and used by many players.

Yes i have my TW-18-36 on the bench. And hopefully can get time this weekend to finish it. It will have some things to make both type circuts work.So a switch on the back for which channel i might use. This amp will have the trem channel tone circut,and values. The 10k cathode has been a little gain mod thing for quite a while..some change it to 6.8k or in between 4.7k and 10k It can be a bit much. Sometimes a cathode resistor that is high,can make a metalic sound with pick attack..hard to explain,but sounds like a blow speaker.

Mark, yes amps that have those snubber caps,can dull the true tone of the amp,but i guess some need them to keep the high oscilations out. But sometimes too,can take a bit of harsh treble out of the amp. Just depends on the amp..
Richie

[idiotwithasolderingiron]

Phil - your description of a Blackface Fender preamp with a Marshall style gain/clipping stage is just about exactly what I heard elsewhere.

Mark - I also think you might be pleasantly supprised with the JCM800 series. For all intents and purposes, they amount to the old style 4 prongers with the conservative kinds of mods that folks of the day were doing, just repackaged by Marshall themselves. Of course the same cannot be said of the 900's tho.

Ick. That was a bad idea... I owned one - briefly. Traded it away within six months.

[s2]

I think I'm doing something like your query. I don't gig much anymore since getting custody of my 6 year-old, so I do mostly studio stuff now. I used to use a home brew Black Face Princeton and an attenuated 18 TMB in stereo quite a bit. I miced both of them when we played larger clubs, which always makes the sound guy happy. The same setup works very well in the studio as well :)

The Princeton doesn't break up much unless you overload its preamp (I use a Seymour Duncan Pickup Booster (just wish I had a Rangemaster)). On its own with single coils, it will only begin to break up when it is cranked to 10. With vintage style humbuckers, it will begin to break up at 8. Be warned, though. The Princeton is not very loud at all--I think it is something like 12 watts, so you will need efficient speakers to get much volume out of it.

With 2 A/B/Y boxes, I can use the Princeton and 2 channels of the 18 together for a bunch of combinations, etc., etc., etc. I got away with this setup playing a very wide variety of covers (from jazz to disco, to pop, to rock). Before going back to being a tube snob, I used a Line 6 to do the cover thing, which worked pretty well, but it never satisfied this tone hound.

You could accomplish the same thing with 1 trem 18 watt (or lite) and 1 TMB 18 watt, or you could look into builing a lower wattage Fender clone like I did. The Princeton is the easiest of the black face family to build, and it is quite versatile.

The trem 18 watt will let you go up to around 5 before it begins to break up, but it is a pretty loud 5. The TMB will let you do the same on the normal channel. The TMB's other channel is higher gain and gives you the fabulous Marshall crunch. The 2 of them jumped give you more distortion (keep in mind these are vintage type amps, so they won't ever act like a JCM800). The jumped TMB sounds a lot like the VH brown sound of the late 70's to my ears.

Anyway, there are my useless 2 cents. FTR, I use the trem and TMB for different things. It certainly doesn't hurt to have one of each in your personal arsenal.

[RedPlanet]

Thanx Dude. You put that very to the point and sweet. That Brown Distortion sound is the sound I'm looking for. I think that is the best thing for me to do. Get those two amps build the Trem first and then build the TMB and do the Reverb on the Trem like Graydon says.

He had suggested I use 2x12 for the clean amp with a Couple Celestion Blues but I only want 1x12 for the compactness of it. Is he saying use two speakers to add to the Clean Headroom and would using a Solid State Rectifier give more Clean Headroom? I might consider 2x10's for the Clean Amp if two speakers would be much better for the Clean Amp. Would that be a Good Choice? That way I could maintane the sise of the amp to be as small as the other.