Non-Traditional Express... another take (updated presence)

Express, Liverpool, Rocket, Dirty Little Monster, etc.

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Structo
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Re: Non-Traditional Express... another take (updated presence)

Post by Structo »

That really looks nice Martin!

Love the layout and board.
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martin manning
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Re: Non-Traditional Express... another take (updated presence)

Post by martin manning »

Thanks guys. I would make a couple of tiny tweaks to the graphics now that I've seen the panels on the amp in life, but I like it too.

This same arrangement could easily become a nice compact 50W Marshall 2204... now there's some food for thought!
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Re: Non-Traditional Express... another take (updated presence)

Post by amplifiednation »

Martin-I don't know if anyone commented on the backplate and faceplate but they are beautiful!!! I need to get one of those made up!!
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Re: Non-Traditional Express... another take (updated presence)

Post by surfsup »

Martin you layout on page one's OP shows the text description indicating a trimmer into stage two. I believe this should say into stage three.

BTW, i had built a liverpool-esque xitsX10 clone and have a 100k on a pushpull pot to add to the 56k to ground before the third stage, kinda similar, and find that quite useful too. Currently experimenting with some caps to alter the tone slightly when employed, though its hard because i can rarely crank the amp living in a townhome....damn housing industry...
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Re: Non-Traditional Express... another take (updated presence)

Post by martin manning »

Hi Taylor, I'm completely sold on the faceplates from BNP. They are the reason for updating the pics at the top of the thread. I also posted a few words about the great experience with BNP Lasers above. They are totally worth the cost for a one-off given the stellar result, much more durable than any DIY technique, and dead-on in their dimensions and hole locations. This amp just needs a really nice cab now, don't you think? ;^)

Surf, it says "V2 input level," so I'm ok there. Oddly enough the cut control seems to bring back some of the lost tone when the PPIMV is turned down. If you don't have one in your amp you might want to give it a try.
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Re: Non-Traditional Express... another take (updated presence)

Post by Reeltarded »

If you don't stop I am going to end up with a pretty amp. Problem? Not really, except what would I do with the ugly ones? :)

I do love the plates. Very stylish.
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Re: Non-Traditional Express... another take (updated presence)

Post by ampgeek »

I, too, have had steller results with BNP on a dozen or so projects over the last 5 years.

Always nuts-on regarding hole location and graphics quality.

The only "problem" I have had is with the metal plates on a couple of builds. There are set punch sizes for those materials so odd sized holes can be troublesome. I go with the next smallest size and carefully dremel to fit.

Any size can be cut through their standard plastic materials so no issues ever encountered with those.

Thankfully I am a long time CorelDraw user which makes the whole process all the more easy-breezy.

Cheers,
Dave O.
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martin manning
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Re: Non-Traditional Express... another take (updated presence)

Post by martin manning »

The aluminum material is very soft, and the punched holes can easily be enlarged or ovalised using a step drill. I have one with small increments that works well for that.
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Re: Non-Traditional Express... another take (updated presence)

Post by RJ Guitars »

I like step drills for chassis and faceplate holes. I have found that you need both - US and metric sizes to cover the standard variety of holes. I use a different vendor for my laser etched plates but the results are similar. I also order them marked but not drilled for the holes. This allows you to drill the faceplate and the chassis at the same time... more work but you know the holes are going to line up.

One other trick that I have added to the laser etched faceplates is to get the plate all finished up and then spray a coat of clear poly over it. This really brings out the gloss and takes it up a notch in the professional look of things.

I especially like the idea of using a rear panel... that was a great addition to this Express build. The dymo labels have their place in nostalgia but a rear plate again adds some style to the rear panel.
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Re: Non-Traditional Express... another take (updated presence)

Post by martin manning »

Here's another update- Converted to presence to see what that would sound like and see if the whistle would go away... and it did. The conversion to presence is a bit different than described in the first post in this thread. As shown below, it is now 5F6-A-style (or original Express if you like), where the presence pot doubles as the tail resistor. Mine is upside-down, though, with the presence cap connected from the wiper to the CCW lug of the pot, and the CW lug is connected to ground. This functions the same as the normal circuit. I actually left the 10kA pot from the Presonance in place, put a 10k shunt across the outer lugs to make it 5k, and paralleled the two existing 50nF Presonance caps to get back the original 100nF presence cap value. Doing that, removing the former tail resistor, and moving the presence pot's CCW connection to a different eyelet got me where I needed to go. The under-board jumpers stay as they were, so this arrangement can be configured for Presonance or two versions of presence.

I also added an 0.002uF ceramic across the 0.002uF V1-to-V2 coupling cap C8, ala Trudy and Ingrid. The first thing I noticed is that there is a lot of hiss coming from V2. Pulling V2 silences it completely, pulling V1 or turning down the volume doesn't, but turning down the master does. The expected filling-out of the mids and a little more bass is there, and the amp now seems to want to feed-back more readily.

Edit: The increased noise turned out to be a bad ceramic cap (a new Vishay 1kV part!), so I'll have to get another one. Also, using a log pot on the upside-down presence does not spread the effect over the rotation as I first thought it would. Something about that didn't seem quite right, and it turns out that there is an issue with the pot model I'm using in SPICE. It works for now, but I'll have to replace the log pot pot with a 5kB if I keep the presence.
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Re: Non-Traditional Express... another take (updated presence)

Post by rock_mumbles »

Interesting PI values, they are about half way between Express and Liverpool values ...

So what do the PI resistor value changes do to the character of the amp?
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Re: Non-Traditional Express... another take (updated presence)

Post by martin manning »

r-m, I got those those PI tail values from Colossal, who said that they gave him a tighter bottom-end with more clarity when he was tweaking his pcb Express. I had meant to play with those, but since the amp is sounding pretty good I'd forgotten about it. Thanks for reminding me! In theory the larger resistance should balance the PI a little better, and the bias point will be more centered, possibly recovering some of the lost headroom from using a larger tail resistance.
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Re: Non-Traditional Express... another take (updated presence)

Post by M Fowler »

I order my panels with pilot holes then tape to chassis and drill away, that's why I always want the faceplate before I start a build.

The step drill works great for enlarging my faceplate holes.

Mark
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Re: Non-Traditional Express... another take (updated presence)

Post by Colossal »

martin manning wrote:r-m, I got those those PI tail values from Colossal, who said that they gave him a tighter bottom-end with more clarity when he was tweaking his pcb Express. I had meant to play with those, but since the amp is sounding pretty good I'd forgotten about it. Thanks for reminding me! In theory the larger resistance should balance the PI a little better, and the bias point will be more centered, possibly recovering some of the lost headroom from using a larger tail resistance.
Those values were picked for use in conjunction with a PPIMV which I have in the amp. The slightly colder bias adds a bit of warmth. So I was aiming for a little fatter and tighter sound while keeping the clarity. Little more crunch too but that might not be what some are after.
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Re: Non-Traditional Express... another take (updated presence)

Post by rock_mumbles »

Colossal wrote:
martin manning wrote:r-m, I got those those PI tail values from Colossal, who said that they gave him a tighter bottom-end with more clarity when he was tweaking his pcb Express. I had meant to play with those, but since the amp is sounding pretty good I'd forgotten about it. Thanks for reminding me! In theory the larger resistance should balance the PI a little better, and the bias point will be more centered, possibly recovering some of the lost headroom from using a larger tail resistance.
Those values were picked for use in conjunction with a PPIMV which I have in the amp. The slightly colder bias adds a bit of warmth. So I was aiming for a little fatter and tighter sound while keeping the clarity. Little more crunch too but that might not be what some are after.
Thanks,
I've been working on a 10w Exp like amp with 6P1P (Russian 6AQ5) output, the amp has the stock Exp PI values with split load plates so the 6P1P's don't get driven too hard (sets the PI/output balance), overall the amp operates really well, the clean to mean with very little volume change is amazing. The amp sounds killer with a friends Epi LP with SD Antiquity PU's ... this is the first amp we've played with where the backed off neck position cleans are really nice ...

But ... the highs aren't as smooth as I'd like, the high end is too edgy for me ... so I've been thinking about tweaks.
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