"WHAMMY" Pass DIY headphone amp guide

[Zen Mod]

that is logical, but only when done in controlled way:

measure what is voltage difference between these two points, for your particular case;

(as I said, here that's difference of Ugs voltages of N and P mosfet and it can be variable , not one Vbe as in case of linked circuit of Bonsai)

decide what amount of current you want to invoke from opamp output stage

calc resistor value (as R=U/I [Ohm,V,A]

place it in circuit, listen measure

I'm not expecting much difference if not having at least 1mA ........ in fact, I remember not hearing much of difference without resorting to greater level of current

frankly, eons ago , when I fiddled with OP, and it was simple/common arrangement, not bootstrap

 

[2 picoDumbs]

Draw a circuit of what you actually have, then we can comment with greater confidence.

 

[bajjisw]

OpAmp Supply

Apologies in advance if this isn't the best place to ask this question.

When I was looking at a Sony DVP-S7000 DVD player, I measured the OpAmp supply (for diff. to SE part, not LPF) to be non-symmetric: 7V and -5V . Is there an advantage or disadvantage to doing this, compared to a symmetric supply as in the WHAMMY.

Thanks

 

[Mark Johnson]

Some DIY regulated power supply circuit boards have independent adjustment of V+ and V- so you can try both (option A): V+ equal to V- ; and also (option B): V+ 2V greater than V-.

Then listen to both options and decide which one sounds better TO YOU.

 

[adydula]

Does anyone when inserting or removing headphones get a "popping" sound...when I remove cans i get fairly loud "pops" or static sounds?

Volume down, no affect. The only way to get rid of this is to plug and unplug cans with power off.

Ideas? Thoughts?
Alex

 

[rikiheck]

I think that's fairly normal. I am no expert, but I am guessing that maybe a large value resistor between the outputs and ground would deal with this. The B1 uses such a resistor (1M) with the inputs.

 

[AudioSan]

Do you plug and unplug the rest of your system with the power on? You should not.

 

[Martigane]

I only had this issue when using sub-part Op Amp that had some DC offset. (keeping the amp ON, and plug/unplug headphones).
Typically, you can start to hear a small plop when you plug with ~2mV, and a large plop with DC ~20mV on the output. (depends on headphones).

I have < 1mV DC on both channels output and hear no plop, regardless of the volume knob position.

Did you keep C26/C27 to keep unity gain at DC?

I strongly suggest to disconnect your headphones and measure the DC, or you might be damaging your headphones if something is wrong with your amp.

 

[adydula]

It turned out to be a interconnect cable issue from the dac.

Dead silent, no dc "pops" when removing or inserting headphones.

Thanks for the thoughts..

Alex

 

[thomasnadeau]

It turned out to be a interconnect cable issue from the dac.

Dead silent, no dc "pops" when removing or inserting headphones.

Thanks for the thoughts..

Alex

I've built 3 now. They should be absolutely silent to your ears including over time with any of the higher-end OpAmps, and you should be able to experience that with the volume set anywhere (with 0v input). If not, you need to look at your build because in my experience every time I've had any noise, hum or otherwise, its been due to something I messed up during the build.

Wayne's design is really well done; its us mortals who aren't executing it properly.

--Tom

 

[Martigane]

Hi all,
I have some cool thermal pictures of my whammy in its latest and greatest state.

• 
  Burson audio v6 vivid 76°C (naked, without plastic cover!. I subjectively prefer it this way)

• 
  Regulators 53°C

• 
  Output mosfets 42°C

• 
  Transfo 40°C

Subjectively, touching the burson hurts in <1s, and touching the regs start to hurt after 10s (basically just tickles a bit).
Ambient temp was 19.5°C, and the case is in the open on my desk (well ventilated)

Details on my build:

87mA output bias (6.9ohms output resistors)
22v transformer
LED psu config
IRF9610PBF/IRF610PBF mosfets
The heatsinks installed are 40% bigger than the stock ones.
Output DC was <1mV
I verified that there was no oscillation with scope.

 

[adydula]

I've built 3 now. They should be absolutely silent to your ears including over time with any of the higher-end OpAmps, and you should be able to experience that with the volume set anywhere (with 0v input). If not, you need to look at your build because in my experience every time I've had any noise, hum or otherwise, its been due to something I messed up during the build.

Wayne's design is really well done; its us mortals who aren't executing it properly.

--Tom

Tom,

When you listen for noise, hiss or hum with zero input do you ground the inputs?

Alex

 

[jameshillj]

Hi Matigane,
Having 76*C on the Bursons is excessively hot (IMHO) - they should draw about 16mA at 25*C and rails of +/- 15v - the max ambient operating temp is listed as 52*C so I'd suggest reducing that IC temp by at least 40*C for reliability and longevity.

 

[wayne]

16 mA at 30 Volts is almost .5 watts and that will get toasty. A three watt resistor at a Watt gets pretty warm also.

 

[MEPER]

About the current draw for Burson V6 data sheet says about 14 mA for a dual V6 but my own measurement in Whammy was 27 mA at -+15V or so. I raised the value of the serial resistors a bit to be sure the voltage got below the max. specification (I use red led as voltage ref. so have >16 V from regs). I wrote a mail to Burson about my measurement which is about double up compared to data sheet but got no response back on this one......apart from that they have been responsive.

I think the Burson V6 dual will survive many years. As I don't sell amps but only build for myself I am not too concerned. If it should break down one day I will take it as part of the fun. It sounds very good.

 

[jameshillj]

I think the current consumption specs on the Burson site are for the +/-15volt rails and the 600R load (that they use for measured results) - I have no idea why you would use nearly twice the current at approx. similar rail voltages in this application.

Yeah, they're tough little things and have a great sound - very dependent on the quality of the rail supply.

 

[Martigane]

Yes, 76C is uncomfortably high, but consider that the ambient temp in the case is well below 30C, and that I removed the plastic cover which definitely helps the thermal dissipation.
So I would indeed be worried about running the burson in a not so well ventilated case and above 15V.



My measurements are fully in line with MEPER's,

PSU before the R36 is +/-16.8V.
After the R36, the voltage seen by the V6 Op Amp is +/- 15.4V.

Having 1.35V drop across R36 (47ohms), my V6 consumes 28.5mA. (I see the same value during idle/playback)
This is consistent with the second V6 vivid I measured, and the V6 Classic was more in the 26mA ball park.

If some of you want to try, you can remove the plastic cover by gently sawing the bottom, as seen in the picture.
Subjectively, I preferred the naked V6 vivid (I have a stock one for comparison): there was less bloom / bleed of bass and mid into higher registers, and the high are also less strident, which is my main reproach to the V6 vivid.

Interestingly, doing the same on the V6 Classic did not change the sound based on a quick test.

 

[lawil]

Hi Guys I just ordered the PCB from the store, and using the BOM list at the first few post of this thread to put together the parts (first time buying my own parts for a DIY project). Two items are unavailable on Mouser and if any of you can point me to a good substitute for those that would be great.

(2) .1UF C13, C23 .1uF 505-MKP2D031001FKA00

(6) RESQ R1 R2 R7 R10 R12 R14 1K 71-RN55D-F-1.0K

Also regarding the Transformer, ‎70065K‎ Talema Group LLC, is the only one I can find on Digikey/Mouser, are there any substitute on Mouser so everything can be on one site to avoid extra shipping cost? Much appreciated !

 

[Martigane]

For the 0.1uF, i used this one:
https://www.mouser.be/ProductDetail...=sGAEpiMZZMv1cc3ydrPrF7l45uRd9dVhAJeTpZZsyAc=

For the 1k resistor, those ones should work well:
https://www.mouser.be/ProductDetail/Vishay-Dale/RN60D1001FB14/?qs=vEZPefDgUPkcBU7jWJvieQ==
Or
https://www.mouser.be/ProductDetail/Vishay-Dale/RN60C1001DRE6/?qs=2uw1TgnqFv4VHf2oHt50Pg==

For the transformer at the time I only found on digikey i used:
TE2261-ND

 

[Martigane]

And here s a close up of my RN55 and RN60 resistors which both fit nicely in the pcb holes, as this seemed to be a concern for you.
(The output resistors are RN60 10 ohms and a piggy back RN55 22ohms)