Substitute for RK27 potentiometer
Has anyone tried one of the PEC carbon pots? I just finished another board yesterday...yes, idle hands are the diyAudio store's delight...and I used one of these in place of the Alps. They're tighter spec'ed and feature a hot molded carbon element. Nice alternative to stepped. But I'm thinking I now hear why people still use carbon resistors...there's a little more music to be wrung from this little amp. Hoping someone else can confirm this...I wouldn't use the Alps now after trying it. Yes, you need to hardwire it in, but still...KKA5031S28 Precision Electronics Corporation | Potentiometers, Variable Resistors | DigiKey
Has anyone tried one of the PEC carbon pots? I just finished another board yesterday...yes, idle hands are the diyAudio store's delight...and I used one of these in place of the Alps. They're tighter spec'ed and feature a hot molded carbon element. Nice alternative to stepped. But I'm thinking I now hear why people still use carbon resistors...there's a little more music to be wrung from this little amp. Hoping someone else can confirm this...I wouldn't use the Alps now after trying it. Yes, you need to hardwire it in, but still...KKA5031S28 Precision Electronics Corporation | Potentiometers, Variable Resistors | DigiKey
The Sonic Labs 994Enh Ticha op-amp arrived today. Nicely made bit of kit 
Listening to it now as I write... Out of the box it sounds very good. Vocals are sweet and clear, smooth mids, nice punchy bass. I will leave it on for a few hours to burn in.
The 994Enh can run on +/-24V rails so have upped the Cap MX output to +/-17.5V for now, The MX has very low drop out so will push to 18V later leaving just under 2V for the MX. Right now I wished I had gone for 18V or 22V transformers for the extra headroom!
Listening to it now as I write... Out of the box it sounds very good. Vocals are sweet and clear, smooth mids, nice punchy bass. I will leave it on for a few hours to burn in.
The 994Enh can run on +/-24V rails so have upped the Cap MX output to +/-17.5V for now, The MX has very low drop out so will push to 18V later leaving just under 2V for the MX. Right now I wished I had gone for 18V or 22V transformers for the extra headroom!
Attachments
The small circuit attached to the pot is a Danyuk passive crossfeed module supplied by EUVL as part of his kits.
It works by mixing the channels slightly with a frequency delay effect that will ideally make the music image more comfortable and 'realistic', in the sense that the sound is more in front of your face as it would be with properly placed speakers. There is depth to the sound, vocals at the front, instruments slightly recessed back... it works well with some recordings and definitely with a good film score and dialogue. You can certainly listen for longer it seems.
I do like the crossfeed but having the option to switch on and off would be good.
I am using Moode music app for RPI and there is a crossfeed DSP feature people can try.
It is under configure/audio/MPD.
It excels at where musical instruments are playing in one channel only and not in the other.
Crossfeeding makes it more natural to my ears when listening with headphone.
However it degrades the rest of music a bit from my point of view.
I have turned it off forever since 99% of my album does not have this extreme recording.
It is software based so hardware Crossfeeding maybe a different story.
It is under configure/audio/MPD.
It excels at where musical instruments are playing in one channel only and not in the other.
Crossfeeding makes it more natural to my ears when listening with headphone.
However it degrades the rest of music a bit from my point of view.
I have turned it off forever since 99% of my album does not have this extreme recording.
It is software based so hardware Crossfeeding maybe a different story.
For anyone interested in trying a Cap Multiplier board in their Whammy, some more PCB's have arrived. Rest of the components are still to come but the new boards will be supplied with all SMD parts fitted, 2 x 1K Bourns 3296 trimmers plus TIP41/42's and a few caps.
Cost per PCB kit is £10, standard shipping anywhere is around £5 tracked is around £10
Cost per PCB kit is £10, standard shipping anywhere is around £5 tracked is around £10
Attachments
Sonic impressions about changes are difficult...sometimes there just aren't words. But I was immediately struck by what seemed like a little more body to the music. Almost like what makes people enjoy tube audio...not that I'm saying this change makes it sound tubelike. The only differences between this and my first was the 6 Nichicon KMA caps in the psu versus UFG Gold in the first one...not really a big deal. Other than that, it's the same...even the OPA2604 amp...which I've taken a shine to. So I was left with only one conclusion...the carbon pot was a good choice. This combination really favors my HD650's. We're all just looking at working with that last 5%...and this change got me a couple of points. Just hoping someone can confirm my impressions. And the PEC pots get a lot of love from guitar amp guys, from what I had seen. Yes, they aren't liquid smooth mechanically like conductive plastic, but the sound makes up for it. Definitely worth trying.
Last edited:
OPA627 dethroned?The Sonic Labs 994Enh Ticha op-amp arrived today. Nicely made bit of kit
Listening to it now as I write... Out of the box it sounds very good. Vocals are sweet and clear, smooth mids, nice punchy bass. I will leave it on for a few hours to burn in.
Good looking! Did you compared the Whammy with and without the Cap Multiplier?
