Ah, great! Thanks for measuring and sharing 🙂
Still a healthy amount of power on tap for 99% of low impedance cans then.
I'm interested to see how it pairs with the new LCD-5 (90dB/mW; 14 Ohms) as my bedside amp.
I imagine it'll work great since from what I've read, people talk more about the need for instantaneous current delivery (power on tap) rather than huge RMS values. I imagine the healthy PSU in the WHAMMY might fare better than, say, some alternative HPAs with similarly spec'd power output figures.
Btw, @Martigane, did you ever end up exploring a lower/stock bias setting in listening comparisons? Looks like you briefly mentioned it with how it seems the unit seems to be happier when it's running cooler. IIRC, MOSFETs don't like to run too hot (for distortion figures anyways.)
Last edited:
Power at lower impedances collapses because of the losses across output stage resistors and mosfet's Rdson ; NOT because of the power lines sagging.
I have only compared 10 and 6.9 ohms subjectively, but then the regs and output transistor get quite hot at 6.9, and I did not like the sound when the unit was too hot (loose bass, congested mids, less pinpoint accuracy imaging). That was easy to test via leaving/removing cover, which I tried many times.
So I've ended up beefing the heatsinks; and making more holes on the bottom of the case to have better ventilation.
I also observed that THD increased a bit when decreasing load; something I do not understand given the fast feedback. Maybe that was a property of the Op Amp being pushed to higher voltages.
If I had to do it all over again, I'd go for the 15V transformer, naked regulator ; overkill heatsink on mosfets (maybe buy this case with lateral heatsinks), and play with output resistor.
At 14Ohms, I think you need to have output resistors as low as possible, otherwise it's a lot of output losses and compensation the Op amp has to do.
WE
Sounded awesome outside the case, but we will see what it now sound like later today.
This was so much fun to build, but I underestimated how much work with all the modifications
Have a pair of LM833 per 6L6's writeup in there for now and test others later.
I have s Preamp switch and a switch for balanced/unbalanced headphones.
Also, have adjustable gain installed to r12.
Do not have the 100ohm resistors on the preamp lines yet 🙁
Had to DIY the milling, learning as I went along, 😉
Cable tidy-up is also needed.
Will add MUSES volume with OLED display when parts become available and KHADAS DAC after.
Would have been lost without all the forum contributions, so thanks for all the help from as usual Wayne, 6L6, avdesignguru to name a few.
It is alive... no smoke so far.
Sounded awesome outside the case, but we will see what it now sound like later today.
This was so much fun to build, but I underestimated how much work with all the modifications
Have a pair of LM833 per 6L6's writeup in there for now and test others later.
I have s Preamp switch and a switch for balanced/unbalanced headphones.
Also, have adjustable gain installed to r12.
Do not have the 100ohm resistors on the preamp lines yet 🙁
Had to DIY the milling, learning as I went along, 😉
Cable tidy-up is also needed.
Will add MUSES volume with OLED display when parts become available and KHADAS DAC after.
Would have been lost without all the forum contributions, so thanks for all the help from as usual Wayne, 6L6, avdesignguru to name a few.
Attachments
Last edited:
Hi -- I'm done my second unsuccessful build & have started troubleshooting why I'm only getting audio from one channel.
I've spent a lot of time reading posts & looking at the different approaches to working with the board & the input / output options - but I'm a bit confused with some remarks on the drawing dated 08/03/2015. If I am using the recommended PS layout with the LED's in D6 & D5 ---------
I'm using the standard kit -- with the 833 opamp ----------- accrding to the drawing - C7 & C2 are optional -- I've left them blank ------
Should I short them with a jumper -- or leave them blank?
C26 and C27 are indicated as optional -- and if not used -- solder in jumpers. I have done this --- but in looking at a lot of the images of recent builds on the site -- I see most people using the same power scheme with the light diodes -- have caps installed in C26 & C27 -- I haven't noticed anyone leaving these out and shorting them -- & I assume they are using the 833 opamp -- but I could be mistaken.
Can anyone comment on the proper direction for C26/C27 when using the recommended power supply layout with the red diodes
Also -- the build guide is based on a 22V power supply -------- the kit comes with a 18V supply ------- is there anything in the guide that changes based on using the 18V vs 22V transformer
thanks
Bart
I've spent a lot of time reading posts & looking at the different approaches to working with the board & the input / output options - but I'm a bit confused with some remarks on the drawing dated 08/03/2015. If I am using the recommended PS layout with the LED's in D6 & D5 ---------
I'm using the standard kit -- with the 833 opamp ----------- accrding to the drawing - C7 & C2 are optional -- I've left them blank ------
Should I short them with a jumper -- or leave them blank?
C26 and C27 are indicated as optional -- and if not used -- solder in jumpers. I have done this --- but in looking at a lot of the images of recent builds on the site -- I see most people using the same power scheme with the light diodes -- have caps installed in C26 & C27 -- I haven't noticed anyone leaving these out and shorting them -- & I assume they are using the 833 opamp -- but I could be mistaken.
Can anyone comment on the proper direction for C26/C27 when using the recommended power supply layout with the red diodes
Also -- the build guide is based on a 22V power supply -------- the kit comes with a 18V supply ------- is there anything in the guide that changes based on using the 18V vs 22V transformer
thanks
Bart
Hi bartgilchrist
To quote the mantra,
Post some well-lit good quality photos of your build.
If possible, show the top side and bottom side of your boards as well as all connections.
It seems doubtful that your power supply is the issue if you are getting sound from one channel.
Hi. I would like to know whether EPOS (TDK) Mouser item:
Is there any magic in the 0.22 uF or can a 1.0 uF be substituted?
871-B32653A4105J Film Capacitors
Can be substituted for the transformer snubber C20 for the WHAMMY with a 120 VAC mains system. I have a 22.5 mm pin 1.0 uF which is rated 400 VDC/200 VAC.Is there any magic in the 0.22 uF or can a 1.0 uF be substituted?
thanks for the reply ------- I isolated the issue ( old pair of AKG headphones for testing that I hadn't used in 20 years -- one side was dead -- so they're in the trash -- and the unit now works fine.
I'm using a Lampizator Big 7 DAC -- with a Y splitter outlet to feed the HPA --------- and I've got way too much gain -- I can only rotate the volume dial about 5% & it's too loud.
I assume the best way to remedy this is to replace the 2.2k resistors at R39 & R40 ----------- Can someone suggest an ideal resistor rating that will tame the volume and allow me to use more range on the volume knob -- I'm using a pair of LSA HP1 phones that are rated 40 ohm.
The output on the Lampizator DAC is also fairly high when fed into my linestage pre-amp ( Modwright LS36 DM ) -- but it has a lot more range on the volume pot than I get with the Whammy
thanks
change R4 and R8 to 1K, that way you're having gain of 1V/V , 0db
from your explanation, I didn't chase actual data or specification, having that sort of swing outa DAC is matter of manufacturer irresponsibility ...... I don't care how good it sounds
from your explanation, I didn't chase actual data or specification, having that sort of swing outa DAC is matter of manufacturer irresponsibility ...... I don't care how good it sounds
Thanks for the direction ---------- I'm wondering if there might be something else causing the huge volume from the DAC --
Below is the info from the manufacturer on the mating / matching to amps or pre-amps ----- ( my DAC has no volume control)
My existing preamp has an input impedance rating of 50k & works fine with the lampizator ------ what changes to R4 & R8 would put the whammy in the same range -- in other words -- with 4.75 k in R4/R8 -- what is my input impedance & what would it be with a 1K resistor instead
What would I do to the whammy to provide the 100 k "ideal input impedance" suggested by the DAC manufacturer ?
Just trying to learn something here - as I don't have a lot of experience or background
COOPERATION WITH THE PREAMP The DAC with volume control should sound audibly cleaner and more direct without any preamp between the DAC and the amp. The preamp, however good, will veil a lot of the DAC’s natural clarity, speed and directness. If you feel you need the preamp nevertheless, use DAC at the full volume or order your DAC without volume module. The load presented by the preamp or amp or simply the next analog component that the DAC sees, should be as high as possible. It is measured in kilo-Ohms and 100Kilo Ohms is a perfect ballpark value. More is VERY rarely seen. 47 K is next common value, and it is great too. 20 K is kind of on a low side, but we can handle that. Lower than 20k is bad news. We must configure the DAC with additional cathode follower buffer stage. The DAC will not be damaged in any way, but at around 10K of load the dynamics of the dac will start to fade away. Having said that - every properly designed amp or preamp keeps the load value above 40k. And if it doesn’t - we simply don’t choose such amp because it was not designed with audiophiles in mind.
thanks again Zen Mod
Bart
Just built the Whammy OMFG ! Im running this with the Sash Tres - WOW the detail, emotion and bass... Just so impressed with this setup. Wayne Colburn a tip my hat to you sir ! LEGEND!
Hi, I am planning to venture into headfi a bit. I plan on getting audeze lcd xc, as those seems to fit my requirements at a good price too. Thinking that a Whammy would be fun to build to drive those, but they are at 20 ohms so perhaps an edge case for this amp? Anyone tried those cans with this amp? I could perhaps go for a double-whammy in balanced mode if the basis version will sruggle with them. The xc''s are said to be easy to drive despite the lowish impedance, but perhaps that is true because it is an almost purely resistive 20 ohms and not much inductive peaks and valleys to deal with.
Hello,
I decided to try the SparkOS Labs op amp in my Whammy. I like the sound of it but I was getting very high DC offset at about 160 mV. Andrew at SparkOS suggested changing R3 and R5 from 100K to 10K. I did so and the offset dropped to about 8 mV. If I try other op amps and the DC offset still reads reasonably low, can I assume I am not causing any unintended bad consequences by having lowered R3 and R5? The other op amp I intend to run is the Burson V6 classic.
Thanks,
Alan
I decided to try the SparkOS Labs op amp in my Whammy. I like the sound of it but I was getting very high DC offset at about 160 mV. Andrew at SparkOS suggested changing R3 and R5 from 100K to 10K. I did so and the offset dropped to about 8 mV. If I try other op amps and the DC offset still reads reasonably low, can I assume I am not causing any unintended bad consequences by having lowered R3 and R5? The other op amp I intend to run is the Burson V6 classic.
Thanks,
Alan
Due to the XC's high sensitivity, you'll have no issues at all with the stock WHAMMY. In fact, I'd wager that it would be an awesome pairing.
Now, the LCD-5 is going to fun to test at it's 90dB/mW rating @ 14 Ohms. But even with that I don't think I'll be stressing my WHAMMY.
I feel like WHAMMY's power supply is what lends itself to being able to deliver lots of power at minimal distortion. When you look at some other affordable, popular amps you'll notice that the ones which use wall warts tend to lose steam at higher output levels, even tho they're marketed for higher levels than the WHAMMY. I'm of course making an oversimplification. Just trying to convey that this amp is capable of handling all headphones aside from the most inefficient planars which require full on speaker amps.
I'd also be curious to know the answer to this question.
I'm driving a set of Sash Tres at 16ohms.. no problem.. Had so much gain I've had to change values around the opamp.. to lower the gain
I'm assuming that you have C27 and C28 shorted as one would have for using a FET Op Amp. True? I'm using the Sonic Imagery Labs 994Enh-Ticha Dual Discrete Op Amp and I am super happy with it. It is also a BJT device and if I short C27 and C28, I see 11mV and 13 mV but with those capacitors in circuit there is zero offset when looking at three digits right of the decimal point.
Any thoughts on how DC offset affects headphone drivers? I'm curious to hear anyones thoughts on this. I'm using what I can only think to call "FrankenGrado" 32 Ohm headphones. They were constructed from scratch using upgrade parts for Grados but the ear pads and the cable are the only true Grado parts. I must say that I really enjoy them.
EDIT: I must add that when testing the DC offset at the output of the Whammy the two input connectors are shorted tip to shield the input level pot is turned all of the way up.
Last edited:
This is fine to do it just lowers the input impedance the volume pot sees. The low frequency may roll off a bit, but if you are happy with it great.