Supercharging a V8

[datru]

Clipped them both out and can hear a difference.

Thanks!

[Verne Andru]

Sweet. Nice change, isn't it?

The next one is a little more complex, but not by much. Requires 2 resistors and a bit of solder. I mentioned this earlier, but it's worth repeating.

R10 & R15 control the amount of current [signal] that gets through the amp. They are both 1.5K 1/2 watt resistors. Get a couple of 1K 1/2 watters and - still on the component side of the board - solder them in parallel with the 1.5K's. This means you put the new one on top of the existing one, soldering one leg to one side and the other to the other side. Do a google on parallel resistors and I'm sure something will come up. This has the effect of changing the resistance to around 600 ohm [which is less than the stock 1.5K].

This will give the amp more low-end balls in a good way and is real easy to do and to reverse if you don't like it.

I changed C14 today from .047uF to a 1.2uF. This also opens up the bottom-end and gives it a bit more "thump." It does require removing the circuit board though - so it might not be for everyone.

[datru]

At this point I think you should list all the mods currently in place in your V8. Preferably in order of importance to the overall tone. I think it would be helpful.

Of course you've been pretty helpful so far, so I have no right to ask.

[Verne Andru]

Originally Posted by datru

At this point I think you should list all the mods currently in place in your V8. Preferably in order of importance to the overall tone. I think it would be helpful.

Of course you've been pretty helpful so far, so I have no right to ask.

Good point and one I've been considering myself.

I have a 250K stacked pot on order and I'm going to try rebuilding the tone stack to see how that goes. Once that's done I'll try doing a short summary to make it easier for people to follow.

The easiest and biggest tonal changes come from removing those 2 caps and adding those 2 resistors. If you do those you're 80% of the way there.

[datru]

Did you consider any of the other Weber speaker choices? Vintage series or even the Neo-mag? The same fit issues?

When Ted Weber said the Alnico would sound best, was that because you were aiming for a particular sound? Or is it a matter of matching the right speaker to the particular amp?

[Verne Andru]

A couple of months ago I picked up a small 60's era TAKT tube amp off CL. It has a 6" speaker that's labeled 3 watt @ 8 ohm. I plugged the V8 into it and was extremely impressed with the rounder, fuller tone and realized how harsh and brittle the stock Celestion is by comparison. I sent Ted a picture and asked if he could identify the type of speaker/magnet. He responded very quickly saying it was an Alnico. The stock Celestion is ceramic. I also have a vintage JBL K140 15" bass driver that has a wonderful, full tone to it. I've started becoming a bit of an Alnico fanboy in the process.

As I said earlier, I was considering the Eminence Lil Buddy hemp cone speaker, as that is the one Dave Carr uses in his little boutique amps, but they require a conversion to front loading as well. I looked over Weber's site and became a bit overwhelmed by the choices, which is why I asked Ted directly for a recommendation. He said he made his recommendation based on matching the speaker to the amp.

From a tone standpoint, the Weber Silver Bell Alnico is a superb choice. It actually sounds better than the 15" full range Yamaha driver [in a closed back bass cabinet] I was preferring. The Yamaha driver is "okay" for bass, but excellent for every guitar amp I've used with it.

I think it says quite a bit for a 20 watt 10" speaker in an open back combo cab to sound as good, if not better, than a 150 watt 15" speaker in a closed cabinet.

I will admit, mounting it was a pain-in-the-ass, but well worth it. A front loaded speaker is actually the preferred way to go as the sound isn't obstructed by the baffle in any way and has far better projection.

Now that Ted has some experience to draw on [he didn't do a V8 before] you might want to ask him if he has any other suggestions that will fit without modding but sound as good. He does offer a ceramic Silver Bell that looks like it should drop in directly, but I'm not sure the tone will be as nice.

[Verne Andru]

Originally Posted by dcindc

No, I think this is the way to do it:
remove C9, 10, 11, 12.
remove at least R12, but possibly R13 too.
and of course P2 the original pot.

so IN is at R11 out.
OUT is at R6 in.


I'm real interested in how that turns out. Would make for a very versatile little amp!

Done, done and done!

I ended up using the 3-knob tone stack from Ken Fischer's Trainwreck Express Version A0. I put a dual concentric 250K stacked pot where the old tone pot was and drilled a hole in the bottom of the chassis for the mid control. I still have to button it up and play with it a bit, but on firing her up and doing a few tests, she's the charm. I ended up with a 20K mid-pot [i think it's audio taper] and may try swapping a 10K linear taper just to see if there's much difference. I'll post up a wiring diagram once I get things cleaned up around here.

Great little amp. Next, I'm going to add a spring reverb to it.

[datru]

 

Originally Posted by Verne Andru

Next, I'm going to add a spring reverb to it.

 

Looking forward to that!

[Verne Andru]

Originally Posted by datru

Looking forward to that!

Adding a spring reverb is relatively "easy." I'm using Craig Anderton's Stage Center Reverb circuit [http://www.generalguitargadgets.com/...=43&Itemid=75], getting a 1/2 size tank from Accutronics [i have to upgrade my V33 anyway and the tank will fit in the bottom of the V8 cab so I'm ordering 2]. Since I'm running the FX loop through my backpack box anyway, all I have to do is mount the SCR in the backpack and tap it into the FX return. I'll probably use a wallwart for power, but could tap into the V8's AC power - still undecided on that.

And this is why the V8 is so cool - it has an FX loop! Couldn't do it without it [as easily, that is].

[Verne Andru]

Here's the details on the tone stack mod. I've attached a copy of the Trainwreck Express schematic I used as a reference. I played around with a Fender/Vox/Marshall but the Trainwreck worked out the best and I figure if I'm going to plagiarize something I might as well take from the best. I used the following Allparts parts:

Part# EP 4485-000 - 250K/250K Concentric Pot


http://www.allparts.com/store/ep4485-000,Product.asp

Part# MK 0137-002 - Gold Concentric Knob


http://www.allparts.com/store/knobs-...02,Product.asp

The shafts on the pot were too big for the knob so I had to get them drilled out.

In addition you'll need:

1 x 500pF cap
2 x .022uF caps [i used mica]
1 x 100K 1/2 watt resistor [i used a 1 watt since that's what I had]
1 x 20K linear pot for midrange control
1 x knob for midrange pot
some wire and a solder sucker for removing P2
shrink tubing to keep things from inadvertently shorting

I assembled the caps/resistor/pots beforehand and tested them between my guitar and the amp to make sure they were doing what they were supposed to and to fiddle with component values. Once it was happening, I pulled the pcb from the amp and removed the remaining components as DC indicated:

Remove: C9, 10, 11, 12, R12, R13 and P2

The pot shaft is bigger than the hole in the face of the V8, so it had to be drilled out as well as a hole in the bottom of the chassis for the midrange pot.

After that, installation was relatively easy. I soldered the IN end of the 500pF cap to the empty C11 hole that connects to R11 and the OUT wire to the empty R13 hole that connects to R6 [check the reverse side of the board and follow the traces]. DC was correct again in stating:

IN is at R11 out
OUT is at R6 in

I ran 3 wires to the midrange pot. You might be able to get away with 2 by using a different ground, but I decided to play it safe and run a ground wire back to the ground used by the center terminal on P2.

The amp sounds great. Each mod I've done has incrementally improved the tone and this is like the icing on the cake. It's nice to have midrange control and a solid bass response without loosing highs.

Sorry for the fuzzy pictures but my camera sux. The wiring diagram is "as you see it." With all the components attached, the new pot is a bit of a blob, so be careful nothing shorts out - shrink tubing on leads and solder joints helps considerably.

[Verne Andru]

The rest of the images.

A big thanks to DCinDC for your input.

[dcindc]

yer welcome!

Looks good! Like it came with it

[Verne Andru]

 

Originally Posted by dcindc

Looks good! Like it came with it

 

It shoulda come from the factory like this.

[dcindc]

Originally Posted by Verne Andru

It shoulda come from the factory like this.

I disagree. Embrace the oppurtunity to fangle. And acknowledge the bean counter.

This is why I have mostly cheap crap.

[yoyodunno]

Palomino v8 is awesome, I love to mix mine with my triple xxx for an amazing sound.

[Verne Andru]

Originally Posted by dcindc

Embrace the oppurtunity to fangle.

Originally Posted by dcindc

And acknowledge the bean counter.

If you're saying there's someone tone deaf behind these amps, then I agree wholeheartedly.

From the POV of costs, speaker aside, all I've done is swap different values of the same components. With the tone stack I removed more parts that were adversely effecting the tone than I added, so I wouldn't be surprised if it was a wash even considering the additional pot and a couple of knobs. At best, we're talking pennies in the COGS, if that.

These things don't sound "bad" stock - certainly better than most others in their class - and sales were "pretty good" as I understand it. But with a few different components they sound awesome and for the few cents extra in cost I would argue the improved tone would create such a huge demand that sales would have been significantly better. Since they're discontinued it's really a moot point, but one that falls into the "penny-wise, pound-foolish" camp.

Originally Posted by dcindc

This is why I have mostly cheap crap.

Have patience with me oh master, I'm a bit of a slow learner .

[Verne Andru]

I've made a few more changes and decided it was time to record some clips with various guitars/pickups. I really suck at clips, so apologies in advance.

I recorded from the 10" speaker [now a Weber Alnico Silver Bell] only using 2 mic's - a Blue Kickball about 2' and a SM57 about 10' back. There's some clipping on the Kickball that's likely mic placement. I'll try and fix that for next time.

Aside from a bit of flanger at the end, the only effect I used was some delay. Recorded into Cubase with a bit of compression, limiting and EQ to taste - the settings remain the same throughout all clips.

The amp starts out set with Gain @ 9 o'clock and volume almost wide open. At around 2:45 I open the gain up to a little past 12 o'clock and leave it there for the duration.

Stock, the V8 sucked at doing a clean tone no matter how hard I tried, so I'm starting this with my jazz-box - my Danedetto. It's a hollow body with a floating Kent Armstrong humbucker at the neck and strung with flatwounds.

00:49 I switch to my Hagstrom Viking [335-ish semi-hollow] with SD P-Rails. It starts with the Rail setting, neck solo, then both pups in rail, both pups in P-90, both in humbucker then the bucker bridge solo. All that changes are the pickup selections.

02:07 is my Sheena. Starts with both pups, then bridge solo, then bridge solo with gain cranked to noon.

03:06 I bust out my Les Paul with SD SH-2N Jazz in the neck and TB-4 JB in the bridge. It goes neck, both bridge than I kick on flange for the end.

http://www.verneandru.com/WebApp/Dow...-post-mods.mp3

It's been a few years now since I've heard one of these stock, but from memory they are really fizzy and farty with no clean headroom to speak of. Boxy and thin with an annoying mid-range honkiness and no balls to save its life. Basically sounded like a cheap little Crate tube amp - which is exactly what it is.

I'd like to squeeze a bit more bass response out of it, but am generally much happier with it now. It does a pretty good job of letting the character of the pickups come through. And there's plenty more gain on tap than in this clip, as the gain knob was only around 1/2 way. I'm in an apartment and can't really crank it without fear of an eviction notice, but I have no doubt it'll get really close to hi-gain metal territory.

I did another mod that I didn't record, and that is a boost switch. It disables the tone-stack allowing the full signal through to the power section. It adds from 10 to 20 db of boost [guessing here] but pushes the tone toward treble side - which is actually a good thing for lead breaks. I'm going to see about making the boost foot-switchable once I can tame the treble a bit more.

[gnoj_LL]

great stuff dude, thanks for posting this!

i have the palomino v8 myself stock.

good job! the clean tone of your modded v8 was very tasteful. wish my v8 can do that

[SciHi]

 

Originally Posted by Verne Andru

...that is a boost switch... but pushes the tone toward treble side... I'm going to see about making the boost foot-switchable once I can tame the treble a bit more.

 

We just got the newer V5 to try some of your mods and tone stack will be at the top of the list. I did the tone stack lift on the v18, it was a total screamer... I knocked it down a notch by copying some of crate's other mid boost, like on the VC20, 68K-0.001uF (no fixed boost on that model like the newer v series). You can really fine tune the boost, amount of gain and treble cut by choice of the RC curcuit. I ended up with a DT3P switch and 15K-0.001uF and 42K-0.001uF. The tone stack still has some impact with the 15K boost, by 42K pretty much defeated, still less then total lift... This was all the boost I needed for the v18.

[Verne Andru]

Originally Posted by SciHi

We just got the newer V5 to try some of your mods and tone stack will be at the top of the list. I did the tone stack lift on the v18, it was a total screamer... I knocked it down a notch by copying some of crate's other mid boost, like on the VC20, 68K-0.001uF (no fixed boost on that model like the newer v series). You can really fine tune the boost, amount of gain and treble cut by choice of the RC curcuit. I ended up with a DT3P switch and 15K-0.001uF and 42K-0.001uF. The tone stack still has some impact with the 15K boost, by 42K pretty much defeated, still less then total lift... This was all the boost I needed for the v18.

I'll be interested in hearing how things work out. I would pick up one of those if they drop to $50 and there are some effective mods.

There is an error on my tone stack drawing. I have the bass control wired as a pot - it should be wired as a rheostat. It's corrected by connecting the end term with the cap to the center terminal. Thanks to DC for pointing this out.

I mucked with the tone stack values as well. I ended up with:

R1 - 33k
C1 - 390 pF
C2 - .047 uF
C3 - .022 uF

The tone stack now has nice range and all controls work well. I find in daily usage the bass is always maxed and I use the mid control to tweak the tone and the treble to add or cut brightness depending on the guitar/pickups. The mid control is really key to getting a nice tone happening.

On the V8 the key to taming the treble going into the tone stack is the value of C5. It's 56pF stock. I tried a number of values and am currently at 390pF. I'm liking the overall tone of the amp but might up it to 500 or even 860 to see if that will allow me to pull back on the bass control. It's a trade-off though, as the boost switch has a nice bite to it at the moment and too much bass might kill its effectiveness. I have not been compelled to pull the amp apart in the past couple of weeks, so it's pretty safe to say I'm content with the tones I'm getting out of it now.

[SciHi]

Originally Posted by Verne Andru

I would pick up one of those if they drop to $50 and there are some effective mods.

I just read that GC has them for $79 plus 10% off coupon, getting close...

We have been watching Jim P's mods for the new v5 here: http://www.thefret.net/showpost.php?...9&postcount=32
The new v5's seems to have similarities to older models, plus a few more issues. Between my brother and cousin, we have three of these now in various stages of mods.

I like your dual pot tone stack, these amps don't have much room for any more pots, the new model v5 only has a gain on the opamp and no volume, so most move the gain to a volume position, fixing the opamp gain pretty low.

[Verne Andru]

Originally Posted by SciHi

I knocked it down a notch by copying some of crate's other mid boost, like on the VC20, 68K-0.001uF (no fixed boost on that model like the newer v series). You can really fine tune the boost, amount of gain and treble cut by choice of the RC curcuit. I ended up with a DT3P switch and 15K-0.001uF and 42K-0.001uF. The tone stack still has some impact with the 15K boost, by 42K pretty much defeated, still less then total lift... This was all the boost I needed for the v18.

Are you putting the resistor/cap in series or parallel?

Originally Posted by SciHi

I like your dual pot tone stack, these amps don't have much room for any more pots, the new model v5 only has a gain on the opamp and no volume, so most move the gain to a volume position, fixing the opamp gain pretty low.

Allparts also has a stacked/concentric 500K/500K. Not sure of the values on the V5 but you could put a stacked pot for gain/vol and another for bass/treble. Still will need to mount the mid control somewhere.

Take a look at the V8/VC508 schematic. The gain for that is also on the opamp. The volume control is between the 2 sides of the 12AX7, which works for an FX send level control but since the V5 doesn't have an FX loop you could easily put one in after the 12AX7 and before the EL84 and put both gain and volume on the same stacked pot if the values work out. On the V8 the gain is 250K and the volume is 10K.

[SciHi]

Originally Posted by Verne Andru

Are you putting the resistor/cap in series or parallel?

Yes. I put the resistors in series so I could add the 27K to the 15K to get 42K, in parallel to the 0.001uF cap. My first setup had a 47K-0.001uF boost, and tone stack lift. The lift was just too much for the v18. I have a simple drawing, if that helps. Yea, it says corrected because like most things, took me three tries to get it right! EDIT: Maybe this second picture will help, mid boost shown on the tail of v18 tone stack.

I like the dual 500K pot, Rock Mumbles has pointed out that a 500K resistor across 1-3 legs makes that a 250K treble pot leaving the 500K for bass. I will definitely check them out, $12 from allparts isn't too bad a price for a easy way of adding more control!!!

[Verne Andru]

Thanks.

If real-estate is at a premium be aware the 250K stacked pot is pretty small [in a good way] while the 500K looks like 2 of the big pots stacked.

[SciHi]

 

Originally Posted by Verne Andru

If real-estate is at a premium be aware ...

 

Thanks, and it is. Rock Mumbles thought he had enough room for a 24mm pot but too much stuff on the board in the way, so he just reused the 16mm gain pot for the volume.