I will answer my own question 🙂
"Quote:
Originally Posted by wayne View Post
Increase R8 and R4 from 4.75K to 10K will give you anothe 6 dB gain."
I guess this will do it.
Oh, thanks wayne.
This will be my preamp for driving the F5T. Just made myself a xmas present 🙂
This will be my preamp for driving the F5T. Just made myself a xmas present 🙂
After doing the +6 db mod by changing the resistors to 10k for both channel.
I got a modest gain with my F6, and it sings for 2 hours. Suddenly the right channel became distorted and cracking sounding. At first i thought its my F6, but later swapped another preamp and F6 sings normally.
So i have isolated to the right side of whammy, by removing the Opamp ic and injecting a signal directly to pin 1 and pin7. Left side got clean signal till clipping, right side very low output signal with thick sine wave on oscilloscope.
What could be faulty next, the Opto or the mosfets ?
Anyone encounter these ?
Thanks
I got a modest gain with my F6, and it sings for 2 hours. Suddenly the right channel became distorted and cracking sounding. At first i thought its my F6, but later swapped another preamp and F6 sings normally.
So i have isolated to the right side of whammy, by removing the Opamp ic and injecting a signal directly to pin 1 and pin7. Left side got clean signal till clipping, right side very low output signal with thick sine wave on oscilloscope.
What could be faulty next, the Opto or the mosfets ?
Anyone encounter these ?
Thanks
I have never seen an opto fail, you can check source resistors for voltage and compare to other side. This can be done with no opamp if you want.
An externally hosted image should be here but it was not working when we last tested it.
Strangely, measured voltage across R16,R22,R29 and R32 were around 519mV. So i suspected the Opto and decided to remove it.
It was a pain to remove both since i don't have a proper desoldering gun, I now put in the ic sockets for both optos.
It sings again ! Yay !
Use as a preamp as well as headphone amp
I'm contemplating picking up a Whammy kit from the store - one quick question: I'd like to use this as a preamp (driving an ACA) as well as a headphone amp. For wiring the preamp outputs - is it as simple as just connecting some RCA jacks in parallel with the headphone jack??
TIA, Rich
I'm contemplating picking up a Whammy kit from the store - one quick question: I'd like to use this as a preamp (driving an ACA) as well as a headphone amp. For wiring the preamp outputs - is it as simple as just connecting some RCA jacks in parallel with the headphone jack??
TIA, Rich
Whammy output
Hello mpeg2,
in my opinion you can parallel the output to the headphone jack and the rca-
jacks. But you should not drive a headphone and a poweramp simultaneously.
(Perhaps i am wrong?)
I did it with a switch. I used a japanese MIAYIMA- switch. (2-pole changeover
switch). Simple and effective. Also if you forget to pull out the headphone jack.
Will send you photos later. Battery of my camera is low.
Greets Dirk
Hello mpeg2,
in my opinion you can parallel the output to the headphone jack and the rca-
jacks. But you should not drive a headphone and a poweramp simultaneously.
(Perhaps i am wrong?)
I did it with a switch. I used a japanese MIAYIMA- switch. (2-pole changeover
switch). Simple and effective. Also if you forget to pull out the headphone jack.
Will send you photos later. Battery of my camera is low.
Greets Dirk
I would probably insert a resistor of 20-100 Ohms in series with the RCA jacks as a bit of isolation and oscillation prevention. It may not be needed but wouldn't hurt.
Normally the headphone impedance is very low (30-60 ohms) and the preamp impedance is very high (10k or more), so the line impedance doesn't really matter. However, you may get massively different volume levels between the line amp and preamp if they are driven simultaneously 😉
Dirk: Thanks - I figured it would be that simple.
I'd guess that there won't be any problems driving both simultaneously (the power amp would show a high input impedance & not really load down the headphones) - however, as long as you are in the habit of unplugging headphones while not in use, then a switch wouldn't be needed anyways.
I think I'll jump onto the pre-order in the store.
Rich
I'd guess that there won't be any problems driving both simultaneously (the power amp would show a high input impedance & not really load down the headphones) - however, as long as you are in the habit of unplugging headphones while not in use, then a switch wouldn't be needed anyways.
I think I'll jump onto the pre-order in the store.
Rich
Whammy output switchable
some pics.
My WHAMMY sounds super! As a headphoneamp as well as driving a
poweramp.
And I am challenging! I was used to listen to a STAX-headphone on a good
poweramp.
Big Thanks to Wayne Colburn
some pics.
My WHAMMY sounds super! As a headphoneamp as well as driving a
poweramp.
And I am challenging! I was used to listen to a STAX-headphone on a good
poweramp.
Big Thanks to Wayne Colburn
Attachments
Is there anything else that be could done to make it a better preamp? Like increase the rail voltage etc.?
Whammy higher rail voltage
Hello labjr,
I think this depends on the opamp you want to use. Many opamps do not want
to handle more than +-15 Volts on the rails. Perhaps Wayne can answer this?
Greets
Dirk
Hello labjr,
I think this depends on the opamp you want to use. Many opamps do not want
to handle more than +-15 Volts on the rails. Perhaps Wayne can answer this?
Greets
Dirk
Whammy higher rail voltage
And I think it doesn't sound better only by increasing the voltage on the rails.
It sounds very very good as it was designed by Wayne.
And I think it doesn't sound better only by increasing the voltage on the rails.
It sounds very very good as it was designed by Wayne.
I read in the Pearl 2 thread that it's possible to improve the noise floor with an adjustable regulator circuit. Has anyone tried that with WHAMMY and found a noticeable difference?
Chassis
I've pre-ordered a Whammy kit from the store - now thinking about what to put it in. I've got a bit of gear from Bottlehead that I like the looks of - all built on a aluminum plates with a wood base.
I notice that many of the builds I've seen in this thread are pretty tight in their cases.
Would there be a heat issue if I had the PC board attached upside down to a top plate (maybe with some holes for heat escape)? This would have the heat sinks hanging down from the PC board. The bottom would be completely open.
Rich
I've pre-ordered a Whammy kit from the store - now thinking about what to put it in. I've got a bit of gear from Bottlehead that I like the looks of - all built on a aluminum plates with a wood base.
I notice that many of the builds I've seen in this thread are pretty tight in their cases.
Would there be a heat issue if I had the PC board attached upside down to a top plate (maybe with some holes for heat escape)? This would have the heat sinks hanging down from the PC board. The bottom would be completely open.
Rich
Hello labjr,
I tried different voltages on my WHAMMY-prototyp before the official pcb
came out. I have built a regulated PSU very similar to Waynes design.
I used the 'oldtimers' LM317 / LM337 to make the voltage adjustable. You can
see the blue trimmers on the photo.
My opinion is: it was very difficult for me to hear a difference in the sound
depending on the rail voltage. I tried between +-15 to +- 17.8 volts (depending on the opamp). But i am pretty sure you can measure a difference.
But I could hear a big difference in using different opamps at the inputstage.
Every opamp had its own 'character'.
And I am a friend of high rail voltages.
But that is my experience. Yours can be different.
My opinion is: build the WHAMMY and try it. You will like it.
And try different opamps....
Greetings from Dirk
I tried different voltages on my WHAMMY-prototyp before the official pcb
came out. I have built a regulated PSU very similar to Waynes design.
I used the 'oldtimers' LM317 / LM337 to make the voltage adjustable. You can
see the blue trimmers on the photo.
My opinion is: it was very difficult for me to hear a difference in the sound
depending on the rail voltage. I tried between +-15 to +- 17.8 volts (depending on the opamp). But i am pretty sure you can measure a difference.
But I could hear a big difference in using different opamps at the inputstage.
Every opamp had its own 'character'.
And I am a friend of high rail voltages.
But that is my experience. Yours can be different.
My opinion is: build the WHAMMY and try it. You will like it.
And try different opamps....
Greetings from Dirk
