Peavey Valveking 112 - Modded

[IUnknown]

I have had a peavey valve king 112 for a few years now, and while I absolutely love the clean channel, the 'lead' channel was ...... lacking.

There are a bunch of little annoyances in the amp - such as the following:

- Delay of 40ms or so when switching channels
- Buzzy, diode driven lead channel
- Terrible stock speaker
- External *or* internal speaker use
- No adjustable bias

I had already replaced the stock green VK speaker with a WGS veteran 30 which *really* woke the amp up. Highly recommended.

So, I found this page: http://ultimate-guitar-valveking.wikispaces.com/Amp+Mods+-+Electronics

I decided to implement a few of the 'mods' to address my concerns.

The channels switching delay was an easy fix - swap a resistor and pray. I will probably open it back up and replace it with a pot, because the delay is still (slightly) present, and I wouldn't mind having more discrete control.

Adding the adjustable bias wasn't particularly hard - finding a local source for a 25k bias trim pot was the tricky part. I actually mounted it to a 'riser board' inside the chassis that allowed for the bias control to be accessed from the back of the amp, but not 'bumpable'.

The JCM800 and 'Bright' mod were similarly simple. Adding a couple of rocker dpdt switches to the front panel was straightforward enough.

The results?

Wow - what a difference. I was able to keep the amp with the original 'stock' sound via the two aforementioned switches. The JCM800 mode *really* changed the character of the amp. The crazy saturated, noisy lead channel has been replaced by a *mostly clean* lead channel.

Playing with my les paul w/ a duncan '59 in bridge, and with a Tung-Sol in V1 and a JJ ECC83 in V2 .... I get a very mild crunch with the gain dimed and the 'gain boost' disengaged. Very plexi-like in sound. A nice chime, fully controllable via the volume pot on the guitar.

Turning on the gain boost really bumps up the crunch.... and this is NOT your JCM900 sound. It is classic 80's AC/DC lead/crunch sound... bright, chimey and with a solid midrange punch. Tossing a boost pedal in front (boss OD-3) with a fair bit of gain and a little volume results in a killer 80's hot-rodded marshall sound that keeps a lot of the presence.

The only thing I have been wanting is a little more depth/bass in the signal; The output tranny in this amp apparently has issues delivering the goods at higher volume.

Overall - VERY, VERY impressed with the mods and highly recommended for those wanting a 'less metally' sound from their amp. $20 in parts and a few hours of assembly is a small price to pay.

[jtees4]

Unless I missed it, you didn't do anything about the diode driven lead
channel? I'm not familiar with that amp, but there usually are mods
that involve simply clipping a diode out of the curcuit. Worked
wonders on a Marshall I had.




*************
Some of my music:
http://www.soundclick.com/bands/default.cfm?bandID=789610

[IUnknown]

Unless I am missing something the schematic, the jcm800 mod simply disables the 2nd half of the V2. That half includes the diodes in the circuit.

This reduces the number of gain stages from 4+diodes to 3....

[Flasherly]

On Wed, 26 Feb 2014 09:56:40 -0800 (PST), IUnknown
<stevem...@gmail.com> wrote:

I've a valveking 2x12: 46L6s and 100watts. Same, love that clean, and
hate those speakers;- Would have bought the head-only model in
retrospect, but use an external half-cab, in any event. Has some sort
of "thyristor" for both clean, or lead, thing - the A/B on the back of
my amp, aka for dialing in a brown or Peavey's class A. (Then there's
the "dwell" in the front, treble or bass tweaks, which is a nice
addition.) In a way I'm grateful, I suppose, there's no bias trim, as
maybe I'm just used to its particular lead grow, more or less, for any
brand-generic 6L6. Don't use a footswitch, so haven't noticed the
channel switch delay thing.

Good to hear of your experience with the mods, though. Should be
pretty much similar PCBs (three, with two smaller or mini-pcb sections
ribboned off the main). Though I'm happy with the amp, always good to
hear it's capable of even better when compared to known sounds.

[aaro...@gmail.com]

I want to do the JCM800 mod on my Valveking 100 head! What exactly do you do??? I can't find any exact info! Thx! Aaron

[Les Cargill]

aaro...@gmail.com wrote:
> I want to do the JCM800 mod on my Valveking 100 head! What exactly do you do??? I can't find any exact info! Thx! Aaron
>

Use Google to search for "valveking jcm800 mod".

--
Les Cargill

[jtees4]

Not trying to steal your thunder, but I just wanted to see if this
still worked....it does!
http://lmgtfy.com/?q=valveking%20jcm800%20mod

[Flasherly]

On Tue, 26 Aug 2014 21:54:36 -0700 (PDT), aaro...@gmail.com wrote:

>
I want to do the JCM800 mod on my Valveking 100 head! What exactly do
you do??? I can't find any exact info! Thx! Aaron

-
should be interesting - the new VK's will do, can be switched to 2
watts.

[Les Cargill]

Oh that's cute. Snarky, but cute. :)

--
Les Cargill

[Carl Gundel]

That sounds cool. I'm always up for messing around with things, but how did you come by the amp? Did you buy it, but don't like it? Did someone give it to you?

-Carl

[Flasherly]

On Thu, 28 Aug 2014 12:32:03 -0700 (PDT), Carl Gundel
<basic...@gmail.com> wrote:

>
>That sounds cool.
I'm always up for messing around with things, but how did you come by
the amp? Did you buy it, but don't like it? Did someone give it to
you?

-

There's one in the pawn shop around corner, a 2x12 100watter, for $300
and change. Excellent shape. The one before looked like a wet dog
that had semi-dried after flood water had gotten into the cab's
fiberboard and loosened up tolex. Same price. I might have given
them $125 for it to cannibalize up another head and consider the deal
fair ($75 if you want to get really get sweet thing going on me).

Problem, I find or am semi-agreeable with others, is the VK basically
has no glaring design flaws. I've an early 212 - 46l6 100wat model.
The speakers I did find objectionable, although I did not try mounting
them in a closeback halfstack, I have, as others seem find (more)
acceptable;- they will "fart," though, in an open amp as supplied by
Peavey -- only so happens that I'm flush in various better-regarded
Eminence speakers. Praise the Lord.

Not all amps do have adjustable bias - even though Peavey's founder
did style the VK as an affordable "boutique amp," for the masses -
"frontend" user accessible bias adjustments are traditionally reserved
for amp technicians and only provided on but a few amps -exceptions-
certainly not among a $400 pricetag on a VK head, mine initially cost
(I "converted" mine, the 212, into a head, btw, with a slab of wooden
beneath;- particle board VK cabinets are constructed I found too be
altogether irritating, weighty and distracting).

Virtually any amp, practically, then, stands to benefit with the added
expensive of conveying, to an musical amp electronic technician, what
subjective tonal qualities subjectively in biasing tubes, in fact,
entail;- to couple furthermore with a rising price of various suitable
"boutique-branded" tubes, for what such qualified technical care
indeed, conceivably, might exceed over and by an initial cost of
today's tubed-powered alternatives among mass-production, value amps.
Which would include the VK.

Some, as well, manage with the distortion channel as it is, others
prefer driving the clean channel hard for their distortion;- hardly
any, I'm aware of, would forgo the clean channel's reputation and an
integral it brings to the VK's popularity. Bass, I might add, be what
it may on the distortion channel, doesn't apply to the clean. Quite
the opposite I find with a 4x12 closed cab.

One thing, though, about the mods is they're not as complex as, say,
messing with tonestack on a Peavey Windsor - Peavey, or as it was
initially received, touted out for its "Marshall Killer." (Too
"retro" for many, the Windsor, in popular reception, even if among
wider regard, "loud as hell," still, Mesa and other Peavey
design-addressable "metal amps" do garner a fair following among
serious or performing musicians, modern changing styles, et alia.)

Some consequently will say a "modded VK" sounds that - like a modded
VK and not a $2000 Marshall amp.

Gaining overall a better perspective, however, of subtleties - what
precisely is a clean valved amp, (the VK again stands well among
regards), refining an appreciation of possibilities affecting amps and
their tones - there's a hell of lot better amps, than the VK, better
musicians, yet, have risen above by performing their own mods. I'll
bet.

The VK, incidentally has a couple other mods I've noticed - a MESA
distortion mod, as well a sag-characteristic rectifier stage mod (not
a tube rectifier, that you should be so lucky). Mention might as well
include pulling the entire rear "texture" module for forgoing an
ersatz Class-A "travesty," ostensibly, against balances in the power
tranny, strictly to operate in push-pull A/B operation, as of course
the VK fundamentally is designed;- others, however, observe that the
textured design is actually well-implemented for what it's intended to
achieve.

Apart from modifying the bias circuitry for setting my own tubes'
amperage, I've really no burning desire offhand to jump into what
fires a perception about what goes crunch in the night with Ch2's
fuzzbuzz. Then again I suppose I really do like my cleans.

In my mind any rationally sane amp-lover's amp ought, per force, to
have bias adjustment. Why they all haven't is simply because the
world isn't quite so perfect as I would wish.

[boardj...@gmail.com]

On Wednesday, February 26, 2014 12:56:40 PM UTC-5, IUnknown wrote:

> I have had a peavey valve king 112 for a few years now, and while I absolutely love the clean channel, the 'lead' channel was ...... lacking.
>
>
>
> There are a bunch of little annoyances in the amp - such as the following:
>
>
>
> - Delay of 40ms or so when switching channels
>
> - Buzzy, diode driven lead channel
>
> - Terrible stock speaker
>
> - External *or* internal speaker use
>
> - No adjustable bias

The only diodes in the lead channel are the noise suppression diodes. Easy enough to jumper them out. The main difference you'll notice is a more natural decay of notes and if you like to clean up the dirt channel it will work better for that (won't sound sputtery).