Help: I can't find solution to this problem..

[uan]

Sorry guys, but i've searched around but found nothing related to this..


i have 2 problems :


I added Dc jack for my VOX v847 but am very disappointed at the quality of tone of the pedal. There is a very noticable noise heard from it when i use dc jack but no problem when using battery. The adapter is regulated and work very well for my other pedal. How to fix this?

another problem is, after doing some simple mods (100k for vocal, Red Fasel Inductor, 1.8k for low, and 0.015uF for high, 47k input) i lost 90% gain when i rock back the pedal. This happens when i play on high string at fret 12th and above.. the sound is almost like knocking a big empty can/tin..

thanks in advance..

-blue noob-

[LyleCaldwell]

I don't have time to get into the mods, but did you use a plastic or metal DC jack?  If metal, is it isolated from the chassis?  And are you sure you have the wires connected to the correct lugs?  It will work either way, but one way gives tons of noise.

[uan]

thanks for the quick reply,

I use the plastic one same like this -> http://www.generalguitargadgets.com/diagrams/rocket_lo.gif .. i follow that guide to wire up the connection..but i'll try to twist the connection..

[JimRayden]

another problem is, after doing some simple mods (100k for vocal, Red Fasel Inductor, 1.8k for low, and 0.015uF for high, 47k input) i lost 90% gain when i rock back the pedal. This happens when i play on high string at fret 12th and above.. the sound is almost like knocking a big empty can/tin..

At heel down, a wah pedal is supposed to roll off highs. The high E string at 12'th fret contains mostly high frequencies. The wah rolls them off and thus you lose gain. Simple.

Or is there anything I'm missing here?

----------
Jimbo

[Mark Hammer]

There is regulated and there is regulated.  Four diodes and a cap qualifies it to be regulated.  That cap could be 220uf, but it could also be 2200uf.  Both are called regulated but one is more stable than the other.  Indeed a wallwart with a 3-pin voltage regulator and caps before and after the regulator is no more qualified to call itself "regulated" (on paper) than one with 2 diodes and a 220uf cap.  Obviously one is beter regulated than the other but both can be called "regulated".

Your hum may be a result of having something insufficiently well-regulated for the pedal in question.

[johngreene]

Corrections is bold.

There is regulated and there is unregulated.  Four diodes and a cap qualifies it to be unregulated.  That cap could be 220uf, but it could also be 2200uf.  Both are called unregulated but one is more stable than the other.  Indeed a wallwart with a 3-pin voltage regulator and caps before and after the regulator is [delete] more qualified to call itself "regulated" (on paper) than one with 2 diodes and a 220uf cap.  Obviously one is beter regulated than the other but both can not be called "regulated".

Your hum may be a result of having something insufficiently well-regulated for the pedal in question.

A 'regulated' supply requires a voltage regulator, thus the term 'regulated'. Four diodes and a cap will fluctuate depending on load as will the amount of ripple.

--john

[uan]

thanks, i got to try new adaptor then..but i just found something:  see the crybaby JH-1 schematic below, it has some additional component at the power stage:



and this can't be found in vox schematic..:



what does this mean? is it contribute to the tone? sorry for this stupid question but i really have no idea..


for the missing 'gain' when the pedal heel down at high string, is it caused by biasing problem of the Q1/Q2?

[johngreene]

The 1K and .1uF//220uF cap will help with your noise problem. You 'problem' with low level on the high string with the heel down is normal. When the heel is down it is attenuating the high frequencies, this is what a wah does.

--john

[uan]

thanks john, means here the zener diode is disregarded, right?

roger n out..

[johngreene]

If you still have noise problems, and have greater than 9 volts from your supply, you can just add the zener. It will elminate any ripple that gets through the filter. You may want to plan on putting it in there.

--john

[uan]

Thanks john.. your solution is similar to what i just found:

# Power Supply Filtering and Polarity Protection Mods: To add some extra nose rejection and polarity protection to the circuit, I've added a 100-ohm resistor in series with the power supply before the power makes it to the circuit, and then I added a 100µF Electrolytic and 0.1µF Cermaic capacitor in parallel with the power supply after the series resistor. These two added capacitors provide superior noise/hum rejection for the circuit. I've also added a 1N4002 diode in parallel with the power supply after the series resistor to help prevent damage to the circuit in case the battery or power supply is connected in reverse polarity. To some these extra parts may seem like overkill, but to me they're piece of mind

from http://fuzzcentral.tripod.com/liquid.html

May this will help others newbie like me. Roger n out...

p/s: i'm still not satisfied with the wah thing.. i notice the problem didnt exist before do the mod.

[RaceDriver205]

Easy John, youve got guts correcting Mark Hammer.
The phrase "There is regulated and there is regulated" did not need to be corrected, it means that differences exist between things under the same title "regulated".
I also have a feeling that manufacturers market 'regulated' power packs that do not have voltage regulators in them.

Also your corrected statement:

"Indeed a wallwart with a 3-pin voltage regulator and caps before and after the regulator is [delete] more qualified to call itself "regulated" (on paper) than one with 2 diodes and a 220uf cap.  Obviously one is beter regulated than the other but both can not be called "regulated".

Is also invalid.
You have said that a wallwart with a 3-pin voltage regulator in it can not be called regulated.

Hammer has 4000+posts to his name for a reason. Perhaps you should be more thoughtfull in your "corrections".

[Paul Perry (Frostwave)]

The land of stompbox is fraught with terminological confusion, but I personally wouldn't call a power supply 'regulated' unless there was a regulator in it.
Incidentally, that resistor value in the power supply looks pretty big to me!! 1K!! Can that be true? because, even if the current draw was only 3mA, there's three whole volts gone!!!

[uan]

yeah.. i read at fuzzcentral that they put 100ohm for the same purpose.

[johngreene]

Easy John, youve got guts correcting Mark Hammer.

Honestly, I don't think it takes guts. Mark is a nice guy and wouldn't hesitate in responding likewise to any of my posts (as he has in the past). I tend to think we have a mutual respect between us and if I post anything he disagrees with or finds fault with, he would just simply let me know. No big deal.

The phrase "There is regulated and there is regulated" did not need to be corrected, it means that differences exist between things under the same title "regulated".
I also have a feeling that manufacturers market 'regulated' power packs that do not have voltage regulators in them.

Unfortunately you are taking that phrase out of context. You need to include the part that follows with regard to the four diodes and a capacitor for it to have the correct meaning. "Regulated" means it has a regulator of some kind. Four diodes and a cap does not and therefore is "unregulated".

Also your corrected statement:

"Indeed a wallwart with a 3-pin voltage regulator and caps before and after the regulator is [delete] more qualified to call itself "regulated" (on paper) than one with 2 diodes and a 220uf cap.  Obviously one is beter regulated than the other but both can not be called "regulated".

Is also invalid.
You have said that a wallwart with a 3-pin voltage regulator in it can not be called regulated.

I think you need to re-read that. I'm saying the opposite. I deleted the word 'not' between 'is' and 'more' and inserted it between the words 'can' and 'be'.

Hammer has 4000+posts to his name for a reason. Perhaps you should be more thoughtfull in your "corrections".

How nice of you to stick up for Mr. Hammer. Although he needs no defending from me what-so-ever.

regards,

--john

[RaceDriver205]

Forgive me for hijacking your thread uan, but yeah just use a better regulator. Im sure RDV will come along soon and call me a troll/thread derailieur.

I post anything he disagrees with or finds fault with, he would just simply let me know

k fair enough.

The phrase "There is regulated and there is regulated" did not need to be corrected

Unfortunately you are taking that phrase out of context.

I disagree and dont see how that that qualifies as out of context. Please clarify.

I think you need to re-read that.

Nope, you have refered to a voltage-reg wallwart and a wallwart with diodes and cap only, and then you have definately said "both can not be called regulated".

I also prefer "putting things straight" to "defending MR Hammer" as the former is more apt and more my objective than the latter. No hard feelings or anything.

[Peter Snowberg]

I've read the whole thing so here's my 2 cents.

While larger caps in a wall-wart will provide more regulation, that is a very different thing from a wall-wart that is actively regulated.

John is correct in all the statements he has made in this thread.

A "regulated" supply contains an active regulation element. This can be a switching regulator, a linear regulator (like the 7809), a discrete transistor regulator (a DIY linear reg.), or a simple shunt regulator like a zener diode and resistor. If there is no active regulation then it is simply not a regulated supply. End of story.

If you have a supply with a big caps, the voltage is sort of regulated relative to the voltage it had 10 milliseconds ago by the reserve power in the cap. This type of supply does not provide any regulation of the absolute voltage at the output. Such a supply is better titled "stabilized" or "filtered" to be even more propper. The cap size sets the frequency of a low pass filter.

We all make mistakes from time to time. When I get corrected after mistyping something, I am grateful.

Mark is many things, but above all he is a gentleman.