Modified Laney VH100R lacks mids

[Emetal]

Yes Cameron I agree with you 100% I need A LOT more knowledge about amps but the thing is I am not trying to become a technician, I only got into this to reverse the Voodoo mod partilay and will not be doing this anymore Anyway with your guys help this came out pretty good, I have the sound where I want it, it's not compressed, pinched, nasal or whatever it was before, it opened up nicely and all I need to do now is finalize this deal by reducing microphonics that are little bit more prominent after removing 22pF. Yes I will go get the parts and try these suggestions and post here what is happening, I apologize to everybody for silly questions i have

[jelle]

Cameron's suggestion won't make you a technician, just a more informed person. And it is not too complicated if you skip the math. You will reach your goal fast and with confidence this way. Have fun!!

[Emetal]

Few more silly questions, I went to buy parts and did not really know:

-how many watts is suppose to be that 68K on the grid, somebody told me they are 0,5 Watts but 0.5 Watts they sell here are much smaller physically so I bought 1Watt, does it matter?
-that 680nF that I want to put in C7 what kind of cap is that? Electrolytic, polystyrene or something else... and what tolerance should it be?
-how many Volts should be these 100pf-500pF caps I am trying out over the plate resistor? I'm thinking not less then 400V ?

Stores here in Serbia only have +_ 10% tolerances for caps, and mostly polystyrene and some electrolytic..

[Colossal]

Few more silly questions, I went to buy parts and did not really know:

-how many watts is suppose to be that 68K on the grid, somebody told me they are 0,5 Watts but 0.5 Watts they sell here are much smaller physically so I bought 1Watt, does it matter?

1W is fine for that 68k grid resistor, 0.5W is typical.

-that 680nF that I want to put in C7 what kind of cap is that? Electrolytic, polystyrene or something else... and what tolerance should it be?

Polypropylene or polyester are common and go with 5-10% tolerance, or better.

how many Volts should be these 100pf-500pF caps I am trying out over the plate resistor? I'm thinking not less then 400V ?

You would want a 500V part, minimum. That cap sees a surge at startup so must be able to withstand those initial conditions plus carry the DC operating voltage. I don't know what the preamp B+ voltages are but 500V is typical of commonly available silver mica caps. Ceramics are available at higher voltages, but tone is a consideration.

Stores here in Serbia only have +_ 10% tolerances for caps, and mostly polystyrene and some electrolytic..

That will be fine.

[Emetal]

Great,

and that 680nF that goes in C7 position can be like 50 or 60 Volts right?

[Reeltarded]

Will be easier to find in a 160v cap or higher, well beyond what the voltages are in that position.

[Emetal]

Ok I am having lot of fun now

Did not have enough time to try everything, I will post all together at ones when finish, gotta have rehearsal between every change to evaluate the sound that way (bedroom levels are not how I wanna reference) One thing is standing up as a rule though if releasing the low-mid furry by reversing C6 and C7 one must definitely remove that extra gain causing 1uF from V2. Otherwise ridicules amount of gain is achived

Ohhh and btw here is a pic of that Voodoo Mod from C7, everybody were saying that has no logic (47K making cap invisible to signal)... well you can see the colors now.. PS I have removed the pic, out of respect to Voodoo amps.

[tictac]

Is that really a 47K? with that color coding it may be 4.7K. I've got blue MF's that don't coorespond to that color code so I'm not sure....
Did you measure it with an ohmmeter?

Also I know the cap says .47uF but it could be 47uF. Electrolytic caps are usually 1uF and higher...

Knowing the actual values of these parts would make a diference...

TT

[alvarezh]

You're right about most elect > 1 mF, but this one is 0.47, both values are correct.

Resistor is yellow, purple, black, red: 47000

Click and see this larger image.

All the best.

[jelle]

That might even be an error in the mod procedure....

I would try it with that cap and a 4.7k resistor. You will get more high mids, and that may just have been the issue.

If so, you may want to put all the other voodoo mods back in and give it a listen. Have fun!!!

[roberto]

47k+470n has no effect in parallel with 2k7.
I agree that it should be 4k7+470n (even if I don't like 470n as bypass).

[VacuumVoodoo]

47k or 4k7 or maybe only 47 Ohm?
It's your choice but my vote goes to 470 Ohm.

[jelle]

Look... New stuff to try!

[Trace]

I double checked and we did not receive an email from you regarding this. You are welcome to call the shop at 607-256-0465 if you have any questions or email trace@voodooamps.com.

The 22pF is there to prevent high frequency oscillation. You can remove it and install a cap across a plate resistor but depending on the cap value this boosts mids or bass response. The 22pF offered less effect on the tone at stage volume while ensuring the amplifier was stable.

I would respectfully ask that you not to post the Mods on the internet.


Trace Davis
President / Founder
Voodoo Amplification

[Emetal]

Well hello Mr. Trace, nice to hear from you, in the attachment you can see screen print of my E-mail that was sent out to you on 04/01/13. But off course I'll take your word that for some reason you did not receive it, and that your attention to this forum thread, after several days of discussion, was drawn just after I posted the mod photo. Not a problem, I understand you are busy and/or Hotmail for some reason did not deliver. As for calling over the phone, well that is impossible because phone calls from Serbia to USA are ridiculously expensive, so I had no choice but to ask for help from the community on forum. Anyway I will respect your wish, will not post pics here and I am sending you an Email to trace@voodooamps.com will not ask you any questions here.
Thanks