I have built the Valve Caster circuit. I am having a horrible fuzz coming from my speakers. How can I fix this?

This is a question that adds on to a previous discussion that involved a custom tube circuit using a 12AU7 tube.  I have gotten the Valve Caster to have output sound. signal goes from the guitar to the Valve to the preamp then to the amp. The amplifier did not have the fuzz until the Valve was put in. now I have a fuzz that sounds similar to that of rushing water. how can I fix this? I was contemplating putting the Huminator circuit in to correct this but I didn't know if that would work for this. the amp layout that I have here is roughly the same layout as it is in in reality

Picture of I have built the Valve Caster circuit. I am having a horrible fuzz coming from my speakers. How can I fix this?
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iceng4 years ago
The Huminator is a Low-Pass network But first you need
a sound to pass through it...

You are a nice polite guy but hung up on a 9v circuit of dubious
internet engineering, when the 12AU7 or any gas tube has a break
over voltage some where in the 50 VDC range.

Are you sure that there is a true 12Volts going to the heater ??
IF not ALL Bets are off this table.

fastcar123 (author)  iceng4 years ago
Actually I have 9vdc running through my heaters. I have 3 transformers in play right now (9vdc, 12vdc, 15vdc) when I connect my tube to my 12vdc, it draws so much current that it completely robs the amplifier of all power. I could find a second 12v power source just to try it though
The Valvecaster circuit has been built by hundreds of DIYers (including me), and generally works fine with 9V for both heater and plate voltage. You'll get more gain with 12V, but I don't think that's your problem.

The 12au7 heater draws 125mA (0.15A), which isn't much power. If only adding 125mA to your power supply effects the power amp so much, maybe the amp itself is overtaxing the power supply, which could be leading to some of your problems...

Transformers themselves can introduce noise, so the placement of them (assuming they are inside the amp cab) can be problematic...
fastcar123 (author)  gmoon4 years ago
What do you suggest I do?
Find a bigger, more capable 12V power supply, preferably a quiet switching supply...
fastcar123 (author)  gmoon4 years ago
From where would I find a quiet switching power supply? I have a 500mA wall wart in now but it lacks the ability to power both the tube and the amplifier board. The 12v power supply also supplies things such as power LEDs
Check ebay for a switching supply. Thrift stores usually have a bin of wallwarts for a dollar or so, I like to check those periodically (most switching supplies there will be 5V, but sometimes you get lucky).

500mA is definitely too small for a 15W amp (and is that continuous or peak?). Assuming 50% efficiency, 30W/12V == 2.5 amps.
fastcar123 (author)  gmoon4 years ago
what exactly is a switching supply?

im not sure it was advertised as 15watts per channel. so I imagine that's the peak however it is louder than my other 2 15 watt amplifiers so im stumped

as for your equation it would explain why I cannot power the amp with the 12v source and why I cant crank up the volume with out getting an identical transformer failing sound (pulsing loud hum alternated with complete silence)
A Good Question from anyone, 
especially a nice polite guy hung up on 9Volts :-)

There are two general types of (PS) Power Supplies ;
  1. Analog PS use a transformer that is rated for the output current and mains frequency.  A 12V 5A PS in the UK  50 Hz will be heavier then a 12V 5A PS in the USA 60 Hz
  2. Digital Switcher PS uses a High Frequency transistor switching at 20KHz_to 250KHz and only needs a small transformer to step down the voltage to produce 12V 5A.

The switcher PS may be less then a fifth the weight of an Analog PS
UK or USA and less expensive too.  
So why are people still buying and using Analog PS ??

fastcar123 (author)  iceng4 years ago
so basically a switching PS is simply one that uses a bit more electronics (such as a wall wart) and costs less and weighs less. correct?
Correct in Every thing but  [ wall warts = Analog ].

Wall Warts which as a rule are Unregulated failure prone transformers
with a DC bridge, known as TR (Transformer Rectifier) units.

gmoon iceng4 years ago
Not so true, anymore. Just about all wallwart cell phone / Ipod / mp3 chargers now are switching power supplies. I have several external USB harddrives, and all but one have switching warts.

The largest selling 9V guitar effect box PS (the 1Spot) is also a switching supply. I own two of 'em.

It's kinda freaky how light a switching wall wart is--no big iron inside...
fastcar123 (author)  gmoon4 years ago
So everyone is sure it's the power supply?
What about when I connect it to the golf cart battery. Wouldn't that be the most direct current that could possibly be available?
A charged golf cart battery is the ultimate steady ( smooth ) DC supply.

fastcar123 (author)  iceng4 years ago
Then it can't be the PS because the fuzz is still there even when the PS is a large 12v battery
A battery replaced all the power supplies?

Regardless, You'll need a higher capacity PS for your power amp. 550mA isn't near enough for a 15 watt amp.

Personally, I would pull the Valvecaster from the boxed-up amp, and try it (by itself) with your other amp. And use the battery for the 'caster PS.

If it still sounds wonky, you've narrowed it down to the tube project. Then it's something like a wiring error, bad tube, bad cap, bad socket, wrong resistance value, or lack of shielding in the Valvecaster.

If the 'caster works OK with the external amp, but not in the boxed up project, then it's responding to noise in the component stages--PS noise (maybe em), ground loops, shielding problems, wire routing, etc.

And noise problems can be cumulative, i.e., come from multiple interactions...
fastcar123 (author)  gmoon4 years ago
Resistance values? Take a look at the valve caster project. My R4 consists of 3 resistors that were supposed to be 470k ohms. However all of my 470k resistors were below specification. They all measure around 150k- 200k. I thought putting the 3 together would make a 470k. Now that I actually measured it it measures 1123k which has me bamboozled. What exactly does R4 do?
R4 on the Valvecaster is part of the RC network (coupling) that connects the first to the second stage. See RC filter calculator. 1M or 470K, going to more R is probably not a big difference in this case. Other resistors (such as plate load or cathode bias) would be more critical.

Looking at your photo, I see a lot of connections that are just twisted together. If you haven't, you really need to solder connections. Cold solder joints (or no solder joints!) are another source of noise...
fastcar123 (author)  gmoon4 years ago
Actually what you're seeing is in fact soldered joints with electrical tape wrapped around them to prevent short circuiting. I don't think I have cold solder joints either. The way I solder 2 wires together is I have the iron on the joint, I push in about a half inch of solder and leave the iron on the joint for a while after
OK, that's good (cold solder joints can still cause noise).

Best I can suggest now is that you test the different stages separately, to see if you can narrow down the source.

Keep in mind, though, that PS noise could come from a different power supply than you're using with the Valvecaster...

As you have found, noise issues with audio eq can be really difficult to troubleshoot.

fastcar123 (author)  gmoon4 years ago
After Christmas im going to change out the PS replace the heater wires and signal in and out wires for wires 2 gauges thicker, put in a never used tube and resolder ever joint I have on the caster. If that doesn't fix it I doubt anything will
I always use little clip-on heat sinks when I solder capacitors. Too much heat during assembly can damage them.

Just another thing to think about...
fastcar123 (author)  gmoon4 years ago
What do you mean clip on heat sinks?
 They are small aluminum clips; mine don't match, but look close to the photo below.

I don't know your location--Radioshack in the US has something different that works, too. Or searching for "soldering heatsink" will turn up something.

Anything similar to an alligator clip will help sink the heat--aluminum is preferable, but a steel clip is better than nothing...
iceng gmoon4 years ago
Yes it cannot be the PS,
leaving the wiring, the components and the design.

Now what ?
iceng gmoon4 years ago
I will agree PC, Camera, Apple and related equipment will be using
HF switcher supplies But a good many cheep warts are the
unregulated analog type..
fastcar123 (author)  iceng4 years ago
I will be ordering it after christmas
Avoiding the XMAS chaotic shipping surge is smart
fastcar123 (author)  iceng4 years ago
I would need something like this but the 3A model?
A good deal !
iceng iceng4 years ago
When you are ready i will gladly explain 4 terminal PS like the 3A you like.

i'm pleased to help you because of your excellent
Modding and cleaning an electric guitar ible which
taught me some things I did not know :)
fastcar123 (author)  iceng4 years ago
thank you im glad I was able to teach you some things :D
iceng gmoon4 years ago
BTW 125ma = is actually = o.125A just under o.15A

Looking through your ibles I see your more then adequate at electronics
a superb craftsman and guitar player.

Still I have the hardest time believing that a tube will conduct gas ions at 9V..

Most of your ibles provide great videos however not on the V-caster ???
gmoon iceng4 years ago
Yeah, that's just mistyped (dropped the 2), not a lack of understanding that milli means 1/1000. ;-) I still hate the fact that we cannot edit posts here. It's a shame; an oddly lacking feature for an otherwise professional website.

Still, I am not an EE (not an engineer of any kind), and perfectly aware of my hobbyist stature...

The valvelitzer is my project, not the valvecaster (the inspiration, though). Fastcar123 is trying to build the 'caster. I've tried to help fc123 in the past, with mixed results. It's tough to debug over the internet, especially with limited photos...

My ValveLitzer video lacks real-time footage because I was going for better audio quality, which my cheesy camera lacks. I have excellent still cameras, but not video. It's probably time to revisit that project, which was only a prototype--make a few changes, a more professional look, and new video.
fastcar123 (author)  gmoon4 years ago
I tend to get frustrated with things, and with limited knowledge and supplies it makes things harder to debug
iceng gmoon4 years ago
Likewise I do that too,  .....  but not as often as I would like...
gmoon4 years ago
There's nothing wrong with your audio signal chain--so long as it worked before you added the tube stage. All guitar amps have internal preamplifiers (and you've built your own amp), so...

Valvecaster->preamp->power amp

...is correct. The Valvecaster is an external "stompbox" effect, so it's generally first.

Unless there's something suspect about the preamp stage, such as low input impedance, it stands to reason that the problem was introduced with the Valvecaster build. Here's a couple thoughts:

--All these starved-cathode tube effects suffer from noise. Try the Huminator--it's a filter on the power supply, not the audio signal. Of course you can use it.

--Make sure the tube is good. Always have a backup tube.

--Recheck the Valvecaster wiring.

--The wiring on your homemade amp isn't good. You can certainly shorten a lot of those leads.

--DId you check how the valvecaster stage works before you boxed it inside with the amplifier? Proximity to that rat's nest can add noise...

Lastly, if you add an op amp stage (which won't solve your problem unless there's something wrong with your existing preamp), don't use the 741, it's noisy. Instead use a TL07x (TL071, TL072, TL074). It's pretty much the standard for guitar projects when a "clean" op amp stage is required.
I can't help but think this thing is going to attenuate the incoming signal significantly, hence sticking some front-end gain in strikes me as a good idea.

The 741'll work for a tryout, its cheap and easier to find than the TL07X - though I still have around 1000 in tubes at work.

The NE5534's very goof, but he's only trying out ideas.
Valvecasters are above-unity; they have more gain than you might expect.

Going by the datasheets, it shouldn't work at all--but it does. Depends somewhat on the internal construction of the tube itself. The higher gain "standard guitar preamp" 12ax7 tubes don't work well at all at these voltages.

You can try goosing the signal pre or post the effect, but with a typical guitar amp (input impedance >500K) the valvecaster alone should work fine.

They are VERY susceptible to noisy power supplies, though...
fastcar123 (author)  gmoon4 years ago
Aside from the huminator what else could I do?
Switching power supply, or some sort of regulated PS.
fastcar123 (author)  gmoon4 years ago
such as what exactly? a PC or Xbox supply?
Valves were before my time, and I've never been that much of an audiophile that I don't prefer my John Linsley-Hood 150W MOSFet amp I built at University 25 years ago.

I'm fascinated by this in some sense though. Its like operating a FET below the knee then ?
I guess so--it's definitely not in the linear portion of any of the characteristic curves...which is OK, it just happens the distortion produced by low voltage operation sounds pretty good, for guitar, anyways.

Probably wouldn't sound so great for any other audio applications, though...
fastcar123 (author)  steveastrouk4 years ago
The noise still comes even if I have the tube out side of the amp. There is no hum only fuzz and I imagine placing the tube near the transformers would cause a hum. So this tells me that the tube is far enough away. Would the huminator work for this? I have a second AU7 tube so ill plug that one in just to see if it sounds anydifferant, however both tubes were purchased from an audio store brand new. For the valve caster, I was able to get signal to come through it after many many tries. I'd rather not have to completely rewire it but I will if I need to. And for the huminator I have everything except the diode so I think I'll build it with out and just make sure I connect it right
For the record the amp did work with little to no fuzz, hum or noise before I had the tube in place
One reason for noise is that the circuit hasn't got enough signal to work with, and when you turn up the amp you end up amplifying the cruft out of the front end, as well as the tone from the guitar.
fastcar123 (author)  steveastrouk4 years ago
What if I placed it after the DS-1 Keeley moded distortion would tha help or would I still need more power?
fastcar123 (author)  gmoon4 years ago
my amp layout is at the top
A few suggestions:

-- use shielded wire for the audio signal paths between stages. Shorten signal wires where you can.

-- plug in, pick up the amplifier and move it around; tilt it, etc. Move the guitar around. Try a different mains outlet.  If the noise changes, you're picking up an external source. Or your guitar is inherently noisy at that gain level.

-- move the input jacks away from the power supplies.

-- try other power supplies, if you can. Noise issues with a low-voltage tube projects can usually be traced to the power supply.

-- If you have a different amplifier, try using the valvecaster/PS with it to compare.
fastcar123 (author)  gmoon4 years ago
I've done the first 2 and I've put the input at the boss pedal and that didn't seem to help I've tried a large sized golf cart 12v battery and that also did not help and I have actually tried playing it through my. Modeling amp and it sounded very metallic and still fuzzy. I haven't yet tried putting in a new tube but I doubt that is the problem. I may try another wall wart but im not sure what will work and what wont
I think, like Gmoon, you really need to look at your PSU to begin with. You should draw a complete circuit diagram of your system for your own reference, as well as ours. That random looking collection of wires isn't doing you any favours.
fastcar123 (author)  steveastrouk4 years ago
Again im using 3 wall-warts not a PSU I haven't got any knowledge about power sources made from scratch
....which is why we're saying sort out your PSU properly. Start by drawing a decent diagram of what you HAVE, then we can refine it.
fastcar123 (author)  steveastrouk4 years ago
I have my amp diagram at the top now
fastcar123 (author)  steveastrouk4 years ago
Ok. Just for future reference I do not have specific circuit designs. My preamp was store bought and my original solid state amplifier burned up so I replaced it with a store bought amp.
No, preamp- caster-power amp is what I said.
fastcar123 (author)  steveastrouk4 years ago
the preamp has my master volume and separates my left and right channels. I have a mono input that goes into the left and right channels
Have you any gain between the guitar pickup and the valvecaster ?

fastcar123 (author)  steveastrouk4 years ago
The preamp produces no gain and the only gain that can even be present at that level is the tone on the guitar
A preamp with no gain is a non-sequitur ! The word "amp" is a clue.....
fastcar123 (author)  steveastrouk4 years ago
its more of an equalizer than a preamp. does that matter
Yes, you need some oomph to push the valvecaster.
fastcar123 (author)  steveastrouk4 years ago
what can I do? I cant purchase too much more parts right now?
Stick a dirt cheap 741 amp in, cost you a dollar or less.
fastcar123 (author)  steveastrouk4 years ago
perhaps something of this caliper?
Similar. Just try "op-amp guitar preamp" in Google. You usually have a circuit that has lower gain at higher frequencies.
fastcar123 (author)  steveastrouk4 years ago
I found this that looks pretty easy to do.
Yes. Should be a good plan.
fastcar123 (author)  steveastrouk4 years ago
Awesome that's what I'll do
fastcar123 (author)  steveastrouk4 years ago
ok on a completely unrelated matter this is what my amp currently looks like. its a rat's nest of wires and tape. not only does it look terrible but its obviously difficult to work in. Im strongly considering doing a full rewire overhaul. so my question is other than an easier place to work in what else could benefit from this? would it help in my current problem of having horrible fuzz?
for the reference so you are aware of what all this is it is:
3 wall wart transformers, Gibson tone selector switch, Keeley All seeing eye DS-1 distortion pedal, Valve Caster, "preamp", 15W stereo amp

Yes, its probably a major factor in your buzz problem.
fastcar123 (author)  steveastrouk4 years ago
Other than making everything neater what else could I do to improve it
Design/use a good quiet PSU.
fastcar123 (author)  steveastrouk4 years ago
I have a few of them but they won't output 15vdc which is what I need for my "preamp"
fastcar123 (author)  steveastrouk4 years ago
found on ebay I presume?
A 741 will cost less than 50c.
fastcar123 (author)  steveastrouk4 years ago
I found 741 amp chips but it seems that's all I found. I have basic knowledge of ICs and things of that nature but I do know that with a socket and capacitor it will be more than just a few dollars and right now I need money for Christmas unless theres something that I can get prewired for around $5