Recommendation for input coupling caps


Hey,
I’m building a headphone amp and need a recommendation for a 0.47uF input coupling cap.
It is a discrete circuit and the output is direct coupled.

I have built this amp before and used Mundorf Supreme in this position.
I felt it sounded "compressed" and lacked dynamics (compared to other amps I built, albeit they were different designs).

Also, the headphones I will be using tend to be a bit bassy so would like something that is known for not bloating the bass and may bring the mids forward (if that is even possible to achieve by simply a cap).

Based on size and price, these seem like viable options:
Auricap XO
Mundorf Supreme Silver Oil
Jantzen Superior

I have also read about Jupiter and Sonicap Platinum but honestly can’t justify the price for this build.

I could be over-estimating the impact of this capacitor on the overall sound though, and can just go back to the same Mundorf Supreme.
Your thoughts are greatly appreciated

itsikhefez
Jupiter HT is very good. Less than the copper.  
The silver/oil pretty much is what you are looking for including the dry bass.
Audyn True Copper, but check the size.
I'm generally a big fan of the top of the line Clarity. Again, check the sizes.
Thanks for the comments.
Audyn True Cooper Max and the Tri-Ref were on my shortlist. They are bigger than the Mundorfs so I ruled them out.. although they may fit I've I'm creative. BTW, the True Copper (not max) only start at higher values and seem like they are intended for loudspeakers.

I will double check the sizes, right now I'm between the Silver/Oil and the True Copper Max (they are priced similarly as well)
Hang on, so you’ve not specifically qualified the effect (if any) of the input cap alone vs the overall "flat/compressed" amp sound signature; neither have you qualified the differential benefit (if any) of the Mundorf Supreme over a generic cap, yet you want to move to another? It’s your money but this seems dubious.

What design is this?
would add go with copper foil cap. either from audyn, Jupiter, Jensen or Dueland.

The most organic sound I have heard from any cap are the copper foils. The Duelands are physically quite large, so may not fit in your application.
Clarity MR or CMR (if they fit) may be a good choice.
@itsikhefez  If they fit, I have some Duelund .47uf tinned copper CAST capacitors I can sell you.  I tried them in my Coincident Frankenstein 300b amplifiers and they sounded great, but reduced the bass from the stock Solens.  Because I'm driving the Coincident PREs, my bass is already a little "shy", so I couldn't use them.  They've got about 200 hours on them, so they're just barely broken in...

https://www.partsconnexion.com/DUELUND-81946.html
Itsikhefez, I for one applaud you for trying different components. My experience is that MIT RTX styrene caps were most neutral, but that teflon caps imparted some brightness. The two teflons which I found most refined were Solen and RelCap teflon (tested by inserting in the RIAA circuit, different components in each channel).

Good luck!
Thanks for all the suggestions... hard to make a decision here.

My top budget would be in the price range of ~$40 per cap, which is already really pushing it as the entire build is not that high end.

@cal3713 thanks for the offer but those are way over my price range. (probably even at used price). they are also quite big, not sure if they would fit.

@terry9 the MIT RTX look reasonably priced at around $25 a cap, I'll take a loopk. The RelCap TFT's are too expensive at over $100 per cap.

@erik_squires @hifijunky will take an additional look at those MR/CMR's

@motokokusanagi the design is the RJM Sapphire v4. I participate in the build thread in DIY audio but most members there experimented with limited types of caps. My first choice (the Mundorf) was based on impressions there. Agreed that I don't have good evidence.. none the less am interested to try something else, which I could then compare to my current amp and see the if capacitor has the effect or not


Hi I am new here and is new to this audio components. I will have my first DIY amp pretty soon. As an analog engineer I am wondering what specifications of the cap that are important to the circuit are these options based on? Do these caps have specs that you can compare with? And do we know what those specs are that matters the most to achieve specific results?
 Again I'm not trying to say anything but just want to get more info before I start playing with the circuit.
Thanks
"Agreed that I don't have good evidence.. none the less am interested to try something else, which I could then compare to my current amp and see the if capacitor has the effect or not" - fair enough!  

Just one last thought, can the input cap not be omitted entirely if your source has no DC offset? 
@motokokusanagi Yes, I believe it can be omitted...
If I put a dac board in the same chassis and connect directly, probably safe. But since the source is connected externally and can be replaced over time, probably best to say safe
The only way that obviates the need for the input coupling cap is if all the sources used will be cap coupled, or have DC servos. DC in the signal path will surely have catastrophic results if there are no DC blocking caps. Hey lots of folks skip the condom, but once in a while it results in an itch that won’t go away.

Loayo, the primary measurement that quantifies the electrical performance of a cap is ESR, equivalent series resistance, which can be easily measured. Unfortunately, the caps with the lowest ESR are not always those that IMHO sound the best, so there are probably parameters that we have not evolved standardized testing for yet.
In my experience, DA (dielectric absorption) is negatively correlated with sonics (higher DA ==> worse sonics). Similarly for dielectric constant.  Think electrolytic caps: high measures and low sonics. Vacuum caps: low measures and high sonics.

Except for teflon. Neither explains why teflon caps tend to be bright.
Sure I get that. But it would be a simple test to hook up a safe source, replace the Mundorf with a straight wire, test for DC offset, then evaluate the effect the cap is having. If the unpleasant sound profile still exists, then the problem is the amp design itself not matching well with the headphones.