Express Observations

[Robert]

Hey All,

I completed my Two Rock Ruby Twreck clone last weekend and have been playing it this week. I am generally pleased but several things I think need tweaking. I have little to no electronics knowledge or experience so I can’t contribute in that manner. I’ll just share with you what I can. I could never have done it without all the help from here, 18watt, AX84, JTM45, Aiken, Paul Ruby, etc,etc,etc. The build is very similar to the A1a and Kelly schematic, however the tone control section is wired a little differently. It also has a pre-PI MV and an effects loop which you switch in or out, with no noticeable difference in sound quality between the two. I used OD 715P caps, 1/2 watt Metal film resistors, TVA Atom Electrolytics, PEC pots, solid core 18g wire, star grounding system, Garolite boards with eyelets. I use a '75 Guild Starfire IV with humbuckers and a Fender CS strat with CS Vintage pickups.

My observations are:
1. Lack of equalization control. I followed exactly the TR layout, eventhough it is slightly different from the A1a schematic and the Kelly schematic in the tone control section, but I thought they would have it tweaked to a point of improvement. I find not much variation in mid and bass levels. It really needs more bass. I will soon try the bass capacitor mod. Volume level tops out around 10-12 0'clock and no increase after that. I have to work very hard to get good depth of tone to the notes, but really don't ever get there.
2. Lower volume than expected. I also find the volume to be lower than I or others expect for a 36 watt amp. It is not to loud for home room levels. I just swapped stock Mesa tubes from my Mark IV. They are well used but only a few hours a week for a couple years. Next purchase is some good tubes. I would appreciate any recommendations.
3. Note definition really disappears when playing 2 or more strings at once. Chords are mushy. At first, I assumed this was due to the rich harmonic content the amp provides but I'm not sure. Adjustment in playing style is really necessary to compensate. The sensitivity to guitar volume adjustment is definitely there and this as well as gain adjustment cleans it up but that limits it to lower volumes.
4. Tone is abit grainy with both humbuckers and single coils. It has some glassy tones but I really have to work to dial it in and play tight, but alas still can't quite find "the tone".
5. Tone was very different between a Marshall 4x12 with G12h's and Mesa 4x12 with V30's and Mesa Thiele 1x12 with EVM12L. I preferred the G12h's, a bit glassier and definitely Marshall sounding.
6. At higher gain levels, when playing notes quickly they will play at different sound levels, almost as if they cut in and out. It is also accompanied by a slower response from the amp. Perhaps this is just compression or that "swooshy" sound I have seen posted about. It is annoying rather than a pleasant effect.


I do like some attributes of the amp. Good sustain and singing quality for lead work, much easier to achieve and better sounding than my Mesa Mark IV lead channel. Great amount of gain, very touch sensitive and a variety of tones to work with by altering guitar volume and amp gain/volume. Very quite at low and moderate gain levels,actually quieter than my Mark IV, but too noisy at highest levels. I must keep hands on the strings when not playing and really damp strings heavily when playing.

This is my second tube amp, and first build, so I really have little experience. For fun I thought I would share it with the guys at the local guitar store, to get their opinions and thinking I’m bringing them a rare, legend of an amp out of nowhere to their shop. Well, they were definitely underwhelmed. They are of course used to production Fender, Marshall, Mesa stuff which my not be as demanding of a player as the Express. They spent a minute or two each, turned all the knobs, a lot and had little to ask or comment. Of course I wanted to tell them about the mil spec pots, OD caps, Garolite eyelet boards, all point-to-point hand wired, over engineered blah, blah, blah. That was not important. What was, was ease of use, a wider variety of tones, i.e. channel switching, and low tweaking. Overall their lack of interest was a bit surprising.

Is the Express vintage Mojo-hype, the amp builder (KF), or the amp builder (Me)? I think the tone is in there, now I just need to pull it out – with some help. Any directions would be greatly appreciated.

Robert

[Robert]

Here are a couple quick pictures of the build. BTW I did use carbon film resistors not the metal film as stated above.

Robert

[Robert]

Here's a quick follow up. Dobbhill suggested in another post about a biasing issue, that I had incorrectly biased the tubes to cold, @36 mv. I have since corrected that issue and now correctly bias the tubes in the 60-80 mv range. Wow, what a difference in everything. I would now eliminate all the negative behavior and issues I reported earlier. Now this is a responsive, articulate amp and will demand some work to fully appreciate and bring out its characteristics. I would now conclude it is definitely not all hype but the real deal.

Robert

BTW, am I just having this conversation with myself or is anybody out there?

[v00d00blues79]

I was wondering where i could get the two-rock ruby kit you guys are talking about?


Thanks,

Andy

[doctord02]

It's doubtful that there are any left; contact the guys at Two Rock and ask. They were discontinuing the Ruby and were selling off the chassis and transformers and bits as a "kit".

[loverocker]

Robert - re the underwhelmed reaction of the music store guys - now that the amp's properly fettled, perhaps it might be better to leave the amp there for them to try over time?

Amp looks good. Get a discount on red wire?

Just kidding

[Moose]

BTW, am I just having this conversation with myself or is anybody out there?

Yeah, you might have been. If I'd been checking in I would definitely have refuted your "hype" comment. The amp is different, and you might not like things like the voicing or how it is so touch sensetive and articulate that it shows mistakes, but nobody calls it "Grainy" or "Mushy" or anything like that!

I'm glad you got it biased up and can join the religion. Great fun to play now, isn't it?

[dms]

Hi Robert - nice work! I have one of these kits, and am slowly amassing stuff to do the build - since you've done the legwork, would you mind sharing your shopping list for the panel switches and tube bases? By the way, I remember 2 comments from the K&M guys: one was that their personal Rubys don't include the effects loop, and they don't recommend polypropylene Orange Drops i.e. 715/716..... I tried to start a thread on the "recommended" Orange Drop 418p polyester capacitors, but no one seems to know them. No wonder: after weeks of calls and research to SBE, I could not find any small number supplies or suppliers with stock; I purchased the 225p orange drop polyesters instead.... we'll see. I have Sozos and Mullards to try, as they are also polyester caps. Sounds like the bias adjustment was the missing piece for your build, and you are now up and rockin'. Davids

[Bear]

Only source of I know for 418's in small quantities is Torres, and just thinking about that shop makes me feel the need to shower.

Bear

[Robert]

Hi All,

Davids I'll be glad to share my parts list. I found the tube sockets at Angela Instruments, www.angela.com. I paid a couple extra bucks for the gold finish, just thought it would look nice against the black. I used brass hardware on the top. I used solid core 18 gauge wire throught in one color, since I'd never seen one done that way. Since this amp has some fire to it, I decided the inside should look like it. I got the hook up wire and the mil-spec PEC pots from DIGIKEY. I debated alot about the caps. I had read your post about the 418s, but I'm not going to buy from Torres. That left Sozo, OD 225, 715,716s and Mallorys. I read KF used 715's on some of his, so I just made a decision. Omar stated he replaced his caps with mallorys for ~$8, so a cheap experiment and a bit of fun some afternoon and I may try that or Sozo's. I frankly hear know tonal difference between the MV/effects loop, but prefer the MV engaged to better control the gain and volume of the amp. In the future I would prefer to remove the effects loop and use the extra side of tube 2 for a Dumbleish OD if I can. Everything else I got from Mouser. They have a great tool that lets you build a project list over time. It took a couple days to assemble everything. I'm very pleased with the switches I used. Carling SPST On-Off #691-110-73 & Carling DPDT On-Off-On #691-2GM51-73 I have wired as the power switch now, but will use it to switch between the 2 HV tap sets in the future, the miniature switches are ITT Cannon C&K Toggle SPST On-On #660-CF1/2L226J. I need to order the same thing but a DPDT On-On for the MV/effects loop, I forget this and ran to Rat Shack, but a real piece of crap I can't wait to upgrade so I don't have that part #. Electroswitch 02-04POS/3P/1Section #690-C5P0304N-A for the impedance selector. I just figured out the tabs I wanted to use and clipped the rest. You will have to fiddle abit to adjust it correctly to select 3 Positions. Mouser's 1K 25 watt Xicon resistors were back ordered so I used 2 500's but it took up some real estate. It is a tight fit as you can see, not at all ideal but I didn't want to wait.

Last week, Thursday the TR's had 11 kits left vOOdOOblues79.

Thanks for all the electrical expertise. It's a damn fine amp now!

Robert