Ground Force One 2

+rebuilt self terminating 1/4" speaker jacks

+Soldered ground right (If I haven't posted that);
&Soldering the XLR pcb ground wire directly to the ring terminal of the board will result in permanent ground hum and signal loss.  Solder to self terminating jack terminal corresponding closest to FX loop jacks.

+replaced frequency emulation compo C7 and R20 as a trial since the amp is fucking redline sherbet 8===r=e=d=l=i=n=e===D

&swapped Electro Harmonix 12AX7 preamp tubes back in.  The sticky fresh test tubes were nameless faceless asian guys.  Plan on experimenting with a combination of JJ's, EH, and generic Chinese tubes with a backpack around Europe for a while until I place an irresponsible order through the Russian Federation for a triad of AMT warm stones.

This post is mostly notes; 

Just, just setting the Avid Eleven Rack to communicate with Reason 6.5 (Also pending an irresponsible purchase regarding update to 8 something something.)

I read something about the clock rate of the 11R causing hiss over microphone input and that the default clock (44.1khz) was a contributing factor or entirely to blame or... whatever.

&You can't get reason to register by name as the external clock source via usb.

&You can still get your DAW to set the clock for whatever, 11R, with no AES cable.  If you have an USB cabe.

The 11R expects external clock to source from an aes/ebu connector. This can be shuffled in Reason if you:
1. Connected via USB
2. In Reason, under Edit > Preferences >> Audio tab  >>>Audio card driver, select ASIO Avid Eleven Rack ASIO (64 bit).
3. Sample Rate > 96khz.

In this order, I was able to have the 11R register 'Int 96khHz' in less than twelve seconds.  External clock will still register 'Invalid or None' but the clock rate is right so who fucking cares.

Ground Force One

Betwixt the flabby cheeks of time that it took me to think of writing this and the last post, I managed to conclude (by means of photographic interpretation; guitar player issue circa 2004) that I soldered the rear PCB ground DIRECTLY to the RING pin.

*The proper location for the chassis-left ground is the self terminating ring terminal.

+Fixed XLR ground location

+Reinstalled C7, R20; XLR PCB;; in discussion with the engineer who designed the amplifier about how to fornicate the bypassing of requency emulation on the DI.

*Unfortunately, my new acquaintance is unable to support the modification of this amp.  He was kind enough, however, to outline the complete list of components that handle emulation on the XLR pcb.

XLR FREQUENCY EMULATION COMPO
R20, R21, R22, and C7.

This adds two components to the prior list.

I also bent the terminating parts of the 1/4" speaker jacks in such a way that they were always shorted to ground.  Problem problem.

&I plan on creating a walkthrough for rebuilding 1/4" self terminating jacks.  Something I reasoned out do last night and completed successfully in the morning.  Makes clean removal of jack and pins an assurance rather than gamble

Still no confirmation on 50W OP mode functionality.



hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh 

Bias goes West (Bias 5 / Ground 0.5)

With the discovery of one op mode not working, I am now questioning whether or not I boggled the toggle for it.
Yes, I was touching it's joints up.
Yes, I forgot what I was doing.
Yes, whatever.

This morning in the post I received a set of 470 K / 1 Watt resistors I'll be throwing in position R26 and R2.
I may or may not have torched C11 when installing.... fucking cold solder joints which were my fault every time and I'm not patient and have bad posture and also my breath is bad sometimes.

*The center two power valves ( V4 and V5 from left to right) are the first tube pair.
*The leftmost power valve (V6) and the rightmost power valve (V7) are the second tube pair.

Just found a broken solder joint on the XLR pcb feedback connector.

+resolved and reflowed broken joint

+replaced R26, R27 (270K)

Removed the op mode switch from the amp and gator clipped the terminals several different ways.
When connecting to one point, random resistance popups spammed my dome

+alcohol toothbrushed the assholes of the op mode switch, measurements now consistent.

+moved CN wires to rightmost terminals to prevent interference via tension.

*Photos of stock switch/pcb setup show that a tech more than likely discovered an issue with the switch, as I did, but didn't attempt to clean the terminal contacts.  Instead, the terminals were switched.  Poor form.  Always try to clean your switches before you toss or utilize different positions as a workaround.  This will prevent future problems with your equipment, fucking duh.

Rebooting system
.
..
...

.
..
...

New tubes inserted sensually, bias points engage, master volume down, 100w op mode, helmsman go go go go.

bias reads .8 but I get that.  Was using a combo of JJ's and EH, of which I have no designation for bad or ugly.  Chopped it with the bias trim pot and, blammo, proper voltage across a matched quad of JJ's.

IN THE HEADPHONES
Ground hum.  Significant loss of input signal.
Which suggests a grounding issue to me duhhhhhh
which is kinda back to square one
which I was dreading before the bias voltage scrapeskied.

Unplugging CN-IN and CN-1, still getting ground and chassis noise, eliminating the input pcb as suspect uno.

&Here, I've disengaged the PAD switch on the 11R and turned the gain all the way up.  This amplifies the noise created when I tap on the chassis, in turn chasing geese, but it's a good way to approximate the problem area.  I'm frenetic and bounce the house, corner to corner, and shit the whole way.   The noise is full bass and slight pinging, around the first tube pair (V5, V6)

Notice bad GND pin joint on XLR pcb.

Late.
so tired
Work tmrrw. 

Bias 3 : Voltage Forever

updated power amp work list :
Replaced 14DEC2015:
R11, R12, R13, R14 (10 OHM)
C9, C10, C13, C14 (whatever)

In the mail I have received a number of components.  A number of projection televisions gave their guts.  In front of me, they are.  And so, with newly fashioned tip I bear to deign them upon Devil, most dainty and malfunctioning.

*When replacing resistors, I increase the wattage of the component as far as the PCB will allow.  This is because internet.  Most of what I have used to replace compo are 1 watt metal film, across the board, for 1/4 - 1 watt resistors indicated in the schematic.

After consulting with the tech that raised me, we decided that upon reassembly I will :
1) test both valve groups individually, recording bias voltages
2) disconnect speaker load simulator and substitute with actual cabinet.

The latter is due to the schematic.  It says that disconnected speaker jacks are shorted to ground to prevent 'excessive flyback voltages from damaging XF3.'  So perhaps I have baddened a ground, overtensioned speaker jacks (my own theory), blown my load sim soak, or some other space wizardry.

I aim to test fire this evening.  Which means ending this


-girls in space be wary-


R23, R24 replaced (220K)
BD 3 replaced (bridge diode)
R2 REPLACED (50K)
R4 REPLACED (100K)
C11 REPLACED

reboot...

... with speaker cable attached to speaker cabinet.

Bias reads 9V

WHOOP fuckin'
getting closer.
Attached to power soak, same reading.  Not blown.
WHOOP FUCKIN'

Pull V4 (or power tube 1) - voltage reads 0.1V
pull V5 (or power tube 2) - voltage reads 6V
pull V6 (or power tube 3) - voltage reads 6V
Pull V7 (or power tube 4) - voltage reads 0.2V

power down
switch to 100W op mode, for literally no reason
enegage and the bias voltage is .45....
and I'm guessing this is becuase I have the trim pot turned all the way down
and it isn't drifting
and I turn it up to 0.6
and it isn't drifting
with old tubes.
what in the loving fuck
it's working



Which I suppose would point the dickfinger at me?
or the switch

Early start tomorrow, though, not necessarily on the amplifier; eventuality of testing tomorrow will be to wrangle new tubes in, bias, power down, bias, test run via emulation-minused balanced DI (-30) to 11R MIC in (PAD engaged.)

During this process, I plan on testing each of the preamp tubes I have lying around.  To this end I will be using a lightly modified Marshall AVT20, which requires but one 12ax7 tube and a dummy plug.

<3  

Pre-amp PCB Resistors

Pre-amp section resistors:
*1/4 watt unless otherwise specified

01: 1 M
02: 68 K
03: 10 K
04: 100 K / 1 Watt
05: 2.2 M
06: 1.5 K
07: 10 K
08: 470 K
09: 10 K
10: 1 M
11: 470 K
12: 10 K
13: 10 K
14: 330 K
15: 10 K
16: 100 K / 1 Watt
17: 1.5 K
18: 10 K
19: 330 K
20: 180 K
21: 10 K
22: 180 K
23: 4.7 K
24: 47 K / 1 Watt
25: 1.5 K
26: 100 K / 1 Watt
27: 10 K
28: 100 K / 1 Watt
29: !NOT PRESENT!
30: 1.5 K
31: 100 K
32: 270 K
33: 1 M
34: 10 K
35: 33 K
36: 10 K
37: 4.7 K
38: 5.6 K
39: 10 K
40: 10 K
41: 68 K
42: 68 K
43: 1 K
44: 560 OHM
45: 470 K
46: 33 K
47: 150 K
48: 1.5 M
49: 22 K
50: 560 K
51: 12 K
52: 68 K
53: 1 M
54: 10 K
55: 33 K
56: 10 K
57: 4.7 K
58: 5.6 K
59: 10 K
60: 10 K
61: 68 K
62: 68 K
63: 1 K
64: 100 K
65: 2.2 K
66: 22 K
67: 47 K
68: 220 K
69: 100 OHM
70: 4.7 K
71: 47 K
72: 1 K
73: 22 K
74: 1 K
75: 1 K
76: 100 K
77: 2.2 K
78: 22 K
79: 100 K
80: 1 M
81: 82 K
82: 47 K
83: [FSW] 220 K
84: [FSW] 470 OHM
85: [FSW] 470 OHM
86: [FSW] 150 K
87: [FSW] 10 K
88: [FSW] 3.3 K
89: [FSW] 10 K
90: [FSW] 3.3 K
91: [FSW]10 K
92: [FSW] 3.3K
93: [FSW] 10 K
94: [FSW] 3.3 K
95: [FSW] 10 K
96: 7.5 K / 5 Watt
97: 7.5 K / 5 Watt
98: 10 K
99: 10 OHM
100: 1.5 M

Power amp PCB Capacitors

Power section capacitors:
*35 volts unless otherwise specified

01: .1 UF
02: 47 PF
03: .001UF
04: 47 UF (electrolytic, radial)
05: 10 UF / 50 Volt
06: 10 UF / 50 Volt
07: .22 UF
08: .01 UF / 1 K Volt
09: [SCREEN] 100 UF / 400 Volt (electrolytic, radial) *Schematic states 1000 UF******
10: [SCREEN] 100 UF / 400 Volt (electrolytic, radial) *BOM states 100 UF***********
11: [SCREEN] 100 UF / 400 Volt (electrolytic, radial) *Components on PCB are 100 UF*
12: [SCREEN] 100 UF / 400 Volt (electrolytic, radial) *Schematic is in error**********
13: 47 UF / 450 Volt
14: 47 UF / 450 Volt
15: .1 UF
16: .1 UF
17: 4700 UF / 35 Volt
18: 4700 UF / 35 Volt
19: 47 UF / 63 Volt
20: 47 UF / 63 Volt
21: 4700 UF / 25 Volt (electrolytic, radial)
22: 47 PF
23: 47 PF
24: 10 UF (electrolytic, radial)
25: 10 UF (electrolytic, radial)

56: 47 UF / 450 V

201: .1 UF
202: 100 UF

-Schematic instructs no stuff for 100 H
101: 10 UF
102: 10 UF
103: 100 PF
104: 100 PF
105: .1 UF

Power amp PCB Resistors

Power section resistors:
*1/4 watt unless otherwise specified

01: 1 K
02: 50 K
03: 470 K
04: 100 K
05: 100 K
06: 470 OHM
07: 1 K / 1/2 Watt
08: 1 K / 1/2 Watt
09: 1 K / 1/2 Watt
10: 1 K / 1/2 Watt
{BIAS TP2}
11: 10 OHM / 1 Watt
12: 10 OHM / 1 Watt
13: 10 OHM / 1 Watt
[SW9 100/50W OP MODE]
14: 10 OHM / 1 Watt
15: 1 K / 3 Watt
16: 1 K / 3 Watt
17: 1 K / 3 Watt
18: 1 K / 3 Watt
19: [XLR PCB] 470 OHM
20: [XLR PCB] 470 OHM
21: [XLR PCB] 47 K
22: [XLR PCB] 4.7 K
23: {SCREEN} 220 K / 1/2 Watt
24: {SCREEN} 220 K / 1/2 Watt
25: {SCREEN}150 OHM / 5 Watt
26: {SCREEN} 470 K / 1 Watt
27: {PREAMP B+} 470 K / 1 Watt
28: [BIAS PCB] 220K
29: 4.7 K
30: 10 K {BIAS TP1}
31: 10 K {BIAS TP1}
32: 10 K {BIAS TP1}
33: 10 K {BIAS TP1}

201: 220 K

LED PCB resistors have no designation but are 47 OHM.

-Schematic instructs no stuff for 100 H
101: 22 K *NOSTUFF*
102: 22 K *NOSTUFF*

103: 22 K *JUMPER* 

104: 22 K *JUMPER*

Infinite Everest 2 : Rise of New Vaccuum Tubes (Bias voltage cont'd.)

Last time on Infinite Everest

-I approached the singularity when replacing the cathode coupling resistors with old ones from the original power PCB to my amplifier, dropping the bias voltage from 24v to 14v.  This leads me to believe that I have one or more faulty resistors, still.  Waiting on compo.  

Having received a new matched quad of JJ EL34's from www.tubesandmore.com and el-cheapo Chinese 12AX7 pre's, reattaching the reverb tank leads and panel (just in case) and slapping in the multimeter; 14v on the bias.  

SONOFABITCH.

But we haven't faltered yet.  After further investigation in to similar issues across a broader spectrum of amplifiers, I will be checking the screen section that is most closely illustrated to the transformer it pulls from.

4:37PM. Sunset redemption. 

It becomes apparent that wildly checking values and pointing fingers in all directions is perverted inefficiency. 

Guys, Tom Hardy totally steals Peaky Blinders season 2.  Fucking nails it.

Productive free time at work translates to a checklist for me to follow whence I return home, running through all power pcb resistors and capacitors before I'm sodomized by the preamp board. 

Checklist and eagle-eye suggest replacing a dying star of components.  I happened to have some 10K metal-film resistors on hand, so

+replaced R30, R31, R32, R33.  (10K)

Looks like all but two of the screen resistors are on my naughty list : 25 and 25-1 seem to be decent christian folk.  Also, R23 and R24 are incorrect as far as wattage is concerned; obviously replaced before.  That means replacing replacing R23 (220K), R24 (220K), R26 (470K) , R27 (470K), all of which I believe are 1/2 watt or they will be when I'm done.  Compo will be arriving in waves.  Maybe the traces will stay on the board.  Who knows.
R2 tests badish, replacing (50K); R4 tests badish, replacing (100K)
R11, R12, R13, R14: (10ohm / 1watt), replacing due to age.

&Found out the Fluke 117 I use to test components has a diode test mode.

+All power pcb diodes test OK

C4 dissipates to quickly for my inadequate taste; replace it.
Capacitor 14 tests bad by my indifference.
This means I'm to replace both C13 and C14 as I prefer not worrying about one blowing up moments after I finish installing el otro.  Also 4 to please the lad.
C10 and C11 reside on the screen; C11 doesn't act right.  C10 was marked; replacing the pair.  I believe I have these on hand.

Other compo check and clear :
Resistor
3, 5, 6, 7, 8, 9, 10, 15, 16, 17, 18

Capacitor
1, 9, 12, 13, 15, 16, 19, 20, 24, 25


Other news] I found a two and a half page publication regarding the El Diablo, recently acquiring it for a few shillings and a kick in the groin.  It will be available in JPG once it arrives.  

*upcoming posts follow the anatomy of bias pcb and master connector map. 

Infinite everest : Tube bias #ultimate cut

I feel like an asshole -
the bias on my amp is getting 10 volts, somehow, and obviously the 50K bias pot doesn't have the scope to chop that down.  The user manual says something about setting the bias to .6 volts for an EL34 tube.  That's a whole lot of difference, and I'm guaranteeing is the source of what I've thought was a grounding issue for the last month; preamp issues for years prior to that.
Granted, all of this only started making sense recently.
I'm learning for the sole purpose of loving this amp forever.


-Having cut the bias PCB resistor (R28 schematic B) and testing it, it's fine.
+replaced R29 since it was cut
-bias diode tested ok
-bias pot tested ok
--BD3 was unresponsive, ruined.  along withe three spares residing on the spare board.  replacements ordered. F.

After staring at the bias board all day, just looking at it and making faces, I realized that after the brief space of time where the bias test points registered correctly (before the tube selector switch separated,) and I rebuilt said switch, I hard-shorted all three positions on the switch horizontally (where the switch contacts work vertically.)  This, I admit, makes me feel like a total doofus.

+cut shorts on switch between EL34 contacts.  Left one short due to ruined traces.
-accidenatlly soldered bias test points backward
+fixed bias test points

&I really want to try a set of 6L6 power tubes in this amp, but I've had so much sonic success with the EL34.   I'll switch if AMT makes a solid state analogue.

test after this day of debacle sent me like 24 volts across the bias.  I went to bed feeling defeated.

Sunrise
What I am now doing is drawing up a technical routing diagram for myself to figure out where each of the connector wires leads to, so I stop forgetting.  Also just now again rebuilding the switch again.
Also found a forum post on the 60/30 watt triode/pentode version, where someone was experiencing a similar issue with the bias being out of scope.  Amp bias measured 0.0 v with the power tubes removed.  The final suggestion was to replace the 10 ohm resistors, even if they were testing properly, due to component execution via over-volts.

+Tore out the four 10 ohm resistors, though they tested fine for resistance (doesn't mean under load, as we learned from the posts) and swapped them.

*F1 on the bottom of the power PCB is a test point derived from the bias multi cable connector.

&got distracted and tested a bunch of points, including preamp socket pins with tubes in.  Each preamp tube is routed differently but i'm getting significantly less resistance over combinations of pins 7, 8, and 9 on V1, as compared to  V2 and V3.  Visually brightens less quickly than the other two, and measurements are consistent when shuffling tubes.

Reassembled, bias tests with 0.00 volts.  Unfortunately, never took measurements before surgery began.  It measures correctly for the moment, amen.

tubes in, measures 14v.  at least we're getting closer.
next step is shuffle tubes.  still haven't received the test set.
next step is investigating the cathode resistor bypass capacitor.

shuffle and whatever I said before complete, still getting 14v across bias, basic assumption now is that it's the power valves.
Only game to play is wait for the test set to come in.

<3

Side track : Solid state tube equivalents

I just did a google search for my hottest wet dream
solid state tubes
and I got a hook --
AMT electronics produces a 12AX7 pre and 6L6 (maybe?) solid state equivalent tube equivalents.  I'm assuming it's a sealed epoxy.  With my brain.

Of particular interest is the 12AX7 model, as they're actually avaiable.  Preamp tubes are only ever slightly (or not at all) used to color the tone of whatever signal you're sending through it.  All they have to be is reliable.  A 12AX7 socketed, nearly indestructible, and aurally perfect tube apparatus is exactly what I want for christmas.

AMT Electronics

oopsie on me : impedance switch

Last post I probably regaled you with a tale that went something like "Just mash your impedance switch back together it's fine." knowing full well switchmashing these no-touchie switches caused me a prior failure.

Last night I broke and dismantled the impedance switch, which had 86'd some power tubes not moments before.  During this operation, I discovered that this switch is built similarly (but not exactly) like the bias switch.  All day at work I did a cute drawing of the switch and how it's assembled and the terminal wiring.  On the same page are my plans for bridging the switch in position I desire it to live which for.
It looks like this[right]

*Final copy will have source information on each colored wire, near color information.

*Drew the rear of the switch terminal as if looking from top down at upside down amplifier.  llllllllllooooooooo

Factory switch,
mashed inside
but you can't see

Shitty, shitty bridge job
former solid barometer wire
rasped, tinned, flowed


So completes the tension headache forecast.

The Diablo bible work log says I'm supposed to take pictures of the FXloop pcb so I don't have to keep pulling it off to look at it, but I don't feel like pulling it off to look at it.
Attempting to establish contact with an engineer that developed the mf'n El Diablo, excited titter, and hopefully I'll get to hound him for the rest of our lives.
Ordered cheap JJ's from Antique Electronic Supply (shoutouthollaaa)
and some wicked cheap Chinese pre-amp tubes I'm excited to beat on.

!Need to find cheap, reliable, awesome Chinese tubes (power+pre) so if you hear anything, let me know.
Unless cryo tubes live as long as I do.



My final mount is not pictured and I do not recommend mounting this switch with any of the terminals shorted to the housing.
Don't do it.
Final stage for this one will be a printed plastic tray with chassis screws.  Fuck those tiny nuts.

Repairs

I had an unexpected afternoon away from work and was able to remove the three main printed circuits in my Diablo simulatneously, something I haven't ever done. Probs a Mayans in my party.

As soon as I got in, there were a lot of stupid obvious repairs I had to bake.

+Replaced TRS 6-terminal input jack - two bent paddles (ring and sleeve), flawless victory.  Or the majority of six hours whatever.  Factory jack is plastic bushing, plastic nut, a fiber washer betwixt.  

Picture left is new jack in place.  Lucky factomatching parts.

+Impedance switch had begun dismantling itself  -Before I started this blog, I had an issue with the bias switch failing to maintain structural integrity in the same way, mostly due to terrible mount design and component stress.  I ended up purchasing an OEM bias switch from KMC and subsequently had to rebuild it myself, anyway.  I plan on replacing these controls with something more hearty and substantial in future; is fine for now.  

3DEC2015 post contains information regarding OEM impedance selector switch.

[sorry]I would've taken pictures of a lot of this but by the time I thought of it, I was mostly done and didn't want to take the time to photographically document anything.  I'll get shots of the bias and resistance switches next time I have the chassis open.  Probably tomorrow.
I did, however, manage to get the pcb Connector Map completed, in pencil.  Two revisions and I'll ink it in the El Diablo bible, but it looked pretty swank when I was done.  It's just a complicated list, don't get me excited.  I'll try to verify my poor handwriting and get that posted soon.  

+solved and reflowed the three preamp tube sockets.  Without ruining a soldering tip.  I'm on the high score list now. 

+retensioned 1/4" FXLoop pcb jacks; 10 or 11 or something total.  Dental picks are your best friend for this task if you aren't a compulsive component popper, or CCP.  

+added star lock washers to each of the grounding positions; trace pad on the input pcb, beneath it on the preamp pcb, two on the poweramp pcb - one that terminates on the chassis and one that, in my amplifier, was soldered to a point on the FXLoop pcb; I moved it further down the circuit to a grid pin.  One of the ground bolts holds two connectors, I sandwiched a star lock washer between the two in order to ensure enduring ground.  I'm not entirely sure what was causing the chassis/static/record popclick noise I was recently hearing, but it could've been the bias switch, ground, or both failing simultaneously.  

+unplugged reverb in/out cables from preamp pcb, stored for later. 

+randomly solved and soldered joints across all pcbs, and one terminal on the 100/50 watt op mode switch.  

Now hoping I didn't miss a joint that I solved.  And that it doesn't explode or blow a tube or burn a capacitor or something.  Pretty much anything would put it on the bench for at least a week, again, and I really want it to not be that.  

Side track : Reverb Tank

For a long time,  I didn't realize one of the coils in my Ruby reverb tank had broken at the terminal and was not functioning properly.  Fortunately the tank connects with a set of standard RCA connectors (R/W).

 Reverb Tank above.  Reverb I/O taped connectors down-left.

Due to the broke ass tank, I began theorizing the insertion of different effects in the reverb position of the amplifier's circuitry.  

The pictured piece of breadboard is an old tremolo circuit from the amplifier portion of an Allen Classic organ.  The reason I was interested in it at all, in the beginning, was the 'more random motion' switch, as it had it's own placard and switch on the facade of it's original housing.  Who wouldn't be.  Right now I'm hoping it wasn't simply a control for the lesle motor on the horns, but I'm fairly confident in the efficacy of the components, upon rebuilding.

After experimenting with low mix/slow phasing, as well as low mix/shallow depth/high speed tremolo for texturing; being able to use the independent channel and global mix controls for a nonstandard effect for the position gives me a big rubbery one.  

Especially if that effect had an on-board switch for more random motion. The Diablo already features a reverb cancel 1/4" jack, making remote termination of the effect (performance) possible.  This is again just from observation -I have in no way tested the reverb cancel feature on the amplifier.  Hopefully it acts as an toggle for yes/no.

I still have to place an order with mouser for the components to rebuild the tremolo.
After replacing the Power PCB in the Diablo, I haven't had any other components marked as bad, however, I haven't tested all of them.  My primary concern was with noise, and so far we have a lot more headroom than we did.
This is a sidetrack.
Expect new rails.  

Minused emulation circuit

Number one answer, survey says...
Cutting the cap and resistor result in transparency from the amp.
Sounds fuckin' beautiful.
Still trying to wrap my head around equalizing the signal from a potential four points in the signal chain, but I'm trying for the least amount possible.  Of course, some inter-signal equalization is needed to clean up the sound of whatever, but that's collusion.

Resolving all of the solder joints on the LED bar via suction pencil, removal of LED lights, and resoldering each light remedied the three-year flicker.  Sometimes you just have to throw the right amount of amphetamines at something before it will get done.

In summation, two successful tests run since this posting.  Test was with unbalanced 1/4" at -30db setting, which is almost too hot for the Avid eleven rack to handle without clipping.  This makes me eager to test with the balanced XLR out of the Diablo > 11R XLR in w/ pad switch engaged.  The in-line gain control should help mitigate the overwhelming volume.
The unbalanced and balanced inputs are unsurprisingly loud due to their position in the circuit.  The typical use for these outs is for mixer > PA or similar setup.  Hopefully the provided controls are able to accomplish what I'm hoping for.



Upcomming posts:
-Capacitor and resistor master lists written out, after several corrections.
You can't get high and be an accountant; you make a mistake and cost people millions of dollars.
-Intentions of posting scans of handwrites and ctrl-z-able computer lists.  More than likely this will be when I post individually hilighted versions of the schematics for Resistors and Capacitors.
-PCB connector mapping - interconnectors aren't labeled or defined on schematic.  Will aid in general reassembly.

XLR frequency emulation

[23DEC2015 UPDATE : Frequency emulation components are as follows : R20, R21, R22, and C7.
*More information contained within post Ground Force One

In the El Diablo user manual, you'll find an entry that goes something like "...the balanced XLR output on your head is frequency compensated to emulate the sound coming out of your speaker cabinet."

I didn't think anything of this until I wanted to record silently with the head --the main out of any given tube head is essentially the set of cabinet jacks that follow the power tube compliment in the circuit.

With this in mind, and after research for days, I built a small "cabinet load simulator" or "power soak." This device emulates a speaker cab in that it accepts the current the speakers normally would and dissipates that current as heat with a simple resistor circuit.  (Potential post on that device, in the future.)

Many market-side speaker cabinet simulators feature a headphone jack to utilize the rig (Head and cabinet sim) as a headphone amp.  While I could have achieved this, I wanted to keep the resistor circuit simple, making potential future troubleshooting easier.  Also, that signal chain would have made me super nerves.  

Power soak in hand, the next step was signal chain.  TED has so many fucking outputs, it couldn't be difficult. 

Partial wrongs. 

What I sometimes settled on was using the Global FX Send as the output of the head; this is after trying both the balanced out and the GFXS before and after stomp and rack effects.  My reasoning for trying both and not swearing by the XLR is that THE XLR OUTPUT OF THE HEAD IS FREQUENCY COMPENSATED.

This means that, regardless of what you put in to the head, it is going to limit and color the signal in a way you cannot manipulate conveniently.  Or at all, unless you have some serious brain knows.  Or know an electrical engineer.

After my recent and successful battle with signal chain noise, I decided to endeavor toward the balanced XLR out of the head.  That, and the realization that if I'm taking the signal from just after the preamp, it isn't being processed by the power tubes. 

Taking it straight from the GFXS is the signal from everything up to the end of the preamp --gain then eq, then FX send.  

So, I says to myself, Self, I says, let's find that goddamn frequency compensation circuit and eliminate it.  

If you don't know by now, I intend to run the head in to a speaker cabinet emulator.  This way, I need the output to be as transparent as possible, i.e. not pretending it is doing any good boosting or limiting any of the signal in a static manner, after the power tubes, for 'aesthetics.'  Because if I need to eq the signal, I will.  

Don't force it up my ass.  

With all of that out of the way, here is the solution.

Capacitor and resistor compose the frequency compensation circuit, as you can see in the included pictures.  Note that I cut R20 before I took the picture because I get excited easily.

updates with tests on xlr and 1/4" unbalanced sans emulation to follow.

Potentiometers

Here's a list of the pots:
01: 500K-A (warm gain)
02: 50K-A (warm volume)
03: 50K-B (low eq)
04: 25K-B (mid eq)
05: 50K-B (high eq)
06: 50K-B (warm reverb)
07: 500K-A (hot gain)
08: 100K-B (hot volume)
09: 250K-B (contour)
10: 50K-B (low eq)
11: 25K-B (mid)
12: 50K-B (high)
13: 50K-B (hot reverb)
14: 100K-B (attack)
15: 100K-B (reverb master)
16: 50K-B (master volume)

In the beginning

I begin this blog in hopes that other fanatic jacks, unable to find the information they are looking for, find me in their last throes.  

The item of my focus, now and forever, amen, the

Genz-Benz El Diablo 100 H

Granted, I'm sure the 60H and combo versions function on the same principles, but I haven't asked KMC for the schematics to those, because I don't own those, and I don't care.

Not even really sure where to begin here.

I want to provide as much information as possible, both functionally opinionated as well as technically factual, about the tube head model printed above.  

Having played guitar seriously through my early teens and being shit raking poor, I handled a lot of equipment.  Not just the penises of traveling underwear salesmen, I also refer to audio ... stuff.

Not going to gloss over that nonsense because this is what the destination happens to be.

Bought my Diablo in 2011, so by then that specific head was already five years old. (PCB date says 2004.)   I'm fairly certain it was either a lemon or someone spilled a beer directly in to half of the tube sockets and then rearranged all of the metal film capacitors.

I practiced, blew tubes, played shows, and made love to it set up this way for... three years.  Thinking back it was the source of a lot of frustration for a long time.  But when it was good, it was so great, you know, and it only hit me to let me know it loves me.  Just those six times.

Joking aside, all of the troubles with the amp were worth the way it sounded when it was working properly.  The clean channel alone is something only Jesus should be able to hear.

As Genz-Benz was purchased by fender, you are no longer able to purchase parts from the amplifier's manufacturer.  I can't, at least, since apparently everybody only gets one.

BTW

I'm a big fan of re-purposing things, and do not promote buying parts from the manufacturer, anyway.  If you're handy, there are infinite spare parts.  Except capacitors.  Fuck.  Anyway.