[adydula]

I have built the Whammy, the ACP +, BH Crack, BH Mainline and a dozen other DIY headphone amps.
All great in their own right.

The ACP + is a really very simple and easy to build kit from diyaudio.com
You cant go wrong with this amp.

I have mega-buck amps and have many others here as well....all across the spectrum.

I love building and soldering...Nelson Pass has created a really strong but simple design with the ACP +.
Class A all the way, with matched parts.

Its optimized for 32 ohms impedance but its easily modified for other impedances like HD 650 300 ohm with 4 resistors.

I have mine setup this way for my HD650's and its absolutely stellar performing!!

 

[bmwpowere36m3]

I have built the Whammy, the ACP +, BH Crack, BH Mainline and a dozen other DIY headphone amps.
All great in their own right.

The ACP + is a really very simple and easy to build kit from diyaudio.com
You cant go wrong with this amp.

I have mega-buck amps and have many others here as well....all across the spectrum.

I love building and soldering...Nelson Pass has created a really strong but simple design with the ACP +.
Class A all the way, with matched parts.

Its optimized for 32 ohms impedance but its easily modified for other impedances like HD 650 300 ohm with 4 resistors.

I have mine setup this way for my HD650's and its absolutely stellar performing!!

I saw you posts regarding the Whammy... sounds like their all good. I think I've settled on the Whammy. Looks like the ACP+ would be a better preamp. Though I'm not fully up on the benefits, but having input/output selections and master volume would be nice.

Any suggestions on Whammy and ACP+ builds?

 

[adydula]

Well with the Whammy you get to play with different op amps. Its like tube rolling of sorts on the solid state side. There are long discussions on both of these designs over at the diyaudio site. You should spend some time reading them.

The Whammy is a kit available from time to time at the diyaudio store but has been not available for many months now and several parts are on a long back order at mouser.com and digikey etc...so this is a consideration.

The Whammy is selling for $189 with no case which is another $30-$50 at least. The ACP + is $199 and its a "naked" naked design but you can out it into a case if you desire + cost etc.

The ACP + has less power than the Whammy but both drive most headphones well....the Whammy works over a wider set of impedances and the ACP + is optimized for 32 ohms, but easily modified for high impedance if you want...manually changing resistors. Some use it at the 32 ohm design with higher impedance cans and love it like this.

IMO I like it better with the 300 ohm setup, its one of the best if not the best SS amps for the senns...and I have tried 30+ amps over the years.

WIth the Whammy I added a gain switch to go from a low to high gain...for some harder or less sensitive headphones (in my case it was the HEDD headphone).

Good luck and have fun building!
Alex

 

[bmwpowere36m3]

Putting together the BOM has been tricky, but I ordered the Whammy PCB. Some substitutions on parts, but I think I'll have what I need. Going with a 18V 25VA transformer as the 22V ones are NA. Picked up a few op-amps to try out: LM833N, OPA2107AP, AD746JNZ and the stock RC4580IP.

What gain settings did you use? I thought about making it switchable.

 

[adydula]

The standard gain it is built with is really ok, I had a set of Hedds that I wanted to try a higher gain so this is why I did this.
There is a few posts in the diy whammy thread and I found out what value resistors were needed etc.

gain is A=1+(R8/R12) [V/V,Ohms]
see yourself for second channel, simple as that
if you want to change gain, alter R8 value
all ref to schm in post #1

and

For unity gain, remove R1 & R12, fit links in place of R4 & R8; C2 & C7 and C26 & C27 are redundant and can be removed.
I haven't tried it, be careful, some opamps aren't unity gain stable.

Also read post #3310 fro Nelson Pass.

My post:
I changed R1 and R12 this morning from 1K to 10 K to get 1.5 gain, reduced from the 5.75 gain with the 1K resistors in R1/12.
I wanted to get the volume pot travel more in the middle of the pot travel

This did the trick here.

Have fun and be careful
Alex

 

[A Jedi]

What gain settings did you use? I thought about making it switchable.

I have it at default setting. No issue with sensitive and not so sensitive cans (Elegia, HD600, Diana V2).

 

[bmwpowere36m3]

The reason I asked about gain, I'm finding with the AMB Gamma1 DAC and Mini3 with 6XX I'm only at maybe 9-10 o'clock and its loud enough. By default I believe the Mini3 has a 5x gain (14 db) which is same as Whammy. Mini3 uses a 10k pot and for the Whammy I was planning on a 50k.

 

[frank2908]

Would the acp+ sound good with hd800?
I'm new to this diy amp stuff, does the acp+ has anything similar in topology with the Amp Camp Amp? The reason I ask is that I saw many people recomend the ACA as mono amps as it bring it to another level and fighting above its weight. So does it benefit in a similar way building 2 acp+ as balanced headphone amp?