Amp8EX-P v2 mod (The Elna-edition)
This is my version of Whitigir’s amp8EX v2 mod. It is based entirely on his design but some key alterations have been made to render, what I think is, a dramatically different sound. Where Vince’s v2 aims to bring out musicality without sacrificing fidelity, this edition strives for purity without sacrificing musicality. I have to say, the results smashed though my expectations and delivered a level of SQ that is shockingly good. So, here are my notes for amp8EX-P v2—the ‘P’ stands for “pure.”
Introduction:
As this is fundamentally Whitigir’s mod, I will refer you to his build guide found here:
https://www.head-fi.org/threads/dx200-220-amp8-amp1-ex-modifications.898918/page-12#post-15067193
All the Kemet tantalum replacements are the same. I will only enumerate where my version deviates from the above.
1) ECHU @bypass caps
The first change has to do with the Panasonic ECHUs which replace the stock ceramic caps. If you haven’t yet been turned on to film capacitors, they represent a real advance in performance for audio applications. Take a look at this graph from Panasonic:
The issue however is that though ceramics are noisier they are also faster than film which have a warmer sound. So ceramics need to be retained for clarity at either the line level caps (top-near connector) or the output bypass caps (bottom-under the jack). The line level caps have greater influence in shaping the sound and, in his v2, Whitigir chose to move the ECHUs there for a more natural/musical presentation. I opted to keep ceramics at line level for greater clarity/transparency, and retained the placement of the ECHUs at the bypass caps as in his v1 mod.
So for this version put the ECHUs in the location Whitigir outlines here.
https://www.head-fi.org/threads/dx200-220-amp8-amp1-ex-modifications.898918/page-2#post-14901178
2) Elna @Line filtering and power smoothing
A) Build notes:
This is the most critical part of this entire mod, so I’ll take some time to explain the choice of these caps. iBasso quietly made some minor, but important, upgrades to the newer versions of amp8 starting from amp8 v. 5 (v.4?). You will know if you have this improved model by the presence of these additional resistors and upgraded coil inductors that Vince circled in red.
According to him, these improvements to the power rails and feedback circuitry allow us to jettison the tantalums entirely from the line filtering caps. These took the four Kemets at 22uF in v1. These caps on the top of the board near the connecter can now be replaced with cleaner aluminum electrolytics. The new amp8 also gives greater flexibility in these caps as well as the main power smoothing caps in the center of the top of the board. This allows us to use Elna caps that don't fit in the case at the stock values.
In choosing these critical caps I settled on Elnas because they have garnered a legendary reputation as the heirs to Black Gates as the best capacitor for audio. Many feel that they have even surpassed BGs, and, unlike BGs, they have the benefit of currently being in production. You can read an evaluation of Elnas and a 45 page discussion of their place among the best modern capacitors here:
http://tech.juaneda.com/en/articles/electrolyticcapacitors.html
https://audiokarma.org/forums/index.php?threads/electrolytic-capacitor-shoot-out.381961/
Elnas represent the best of audiophile caps that are just in a different world than the rest of the small general purpose parts that fit into DAPs. These recent change to amp8 by iBasso gave the opportunity to track down Elnas that might fit the diminutive casing of these amp modules.
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For the four (4) line filtering caps, I installed Elna Simic IIs at 47uF/10v. As with Vince, I did not bicap them with tantalums, so as not dilute any of their effect. The Silmic IIs are readily available and can be purchased here:
https://www.mouser.com/ProductDetail/555-RFS10V470ME3#5
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For the power smoothing caps at the center of top of board I put in an Elna Cerafine at 100uF/10v. Since this is not enough capacitance I did bicap here with a Chemi-con 470uF. The Chemi-con is an organic polymer cap and works beautifully with the Elna. It can be ordered here:
https://www.mouser.com/ProductDetail/661-APSF160E471MHB5S
Cerafines are sadly no longer in production but can be ordered worldwide from Parts Connexion in Canada:
https://www.partsconnexion.com/ELNA-72677.html
Please note you have to stick to these precise values for the Elnas, because if you get larger capacitance or voltage they will not physically fit in the case. The maximum clearance you have for amp8 is 8mm in diameter.
B) Rationale
Are Elna caps really worth the trouble of fitting them into the amp8EX mod?
I've come to classify all the components I've tried into two categories: 1) Elnas, 2) everything else. I think Elnas may simply provide the single biggest gain in sound quality of any of the component upgrades in these mods.
The Silmic IIs are quieter, richer, cleaner, more detailed with a vastly, vastly larger stage. They perform far and away better in every conceivable dimension except maybe speed. The Silmics are simply the best sounding and most musical component I have ever heard. They have the sound of the very highest performing tube. And, you figure that for all this analog gorgeousness you would sacrifice accuracy but it’s quite the opposite. The word that keeps coming to mind is:
control. The Silmics dominate every sonic component in the music with a precise rule. If I listen to the Kemet tantalums first, they sound—fantastic—but compared to the Silmics they are undisciplined: muddy, noisy, blurry, and closed.
Then the Cerafines, ah sweet Cerafine. That's a song right? It should be. They immediately hit you with a wave of clarity. It is very much like a window was opened and you are no longer looking at the performers through glass. They image so well they make you feel blind. "Why can't I see the vocalist, she sounds like she's right there?" The Cerafines are simply the most transparent component I have ever heard with absolutely crystalline highs. It is true that the Silmics alone can sound so pretty that the sound seems slightly air-brushed. I could bliss out on them, but with the Cerafine it is like the picture popped right out of the magazine cover. The Cerafines are the mirror twin of the Silmics, because you figure all their accuracy would come tethered to coldness and sterility, but it is also quite the opposite. They have the sound of the richest solid state amp. Instead of a dry thin rendering there is actually a sweet and dense mid.
Nevertheless, the Cerafines require a controlled dosage as too much will invite that noisy ceramic sibilance. So just one cap is perfect, and beautifully mates with the Chemi-con’s liquidity and density. The result is is a fluid clarity without edginess or grain. This Elna configuration also exploits the high fidelity smoothness of the ECHU film while dissolving any of its congestion, esp. in the low-mids. The ECHU’s delicacy and extended reverb tails synergizes rapturously with the overall increased resolution and refinement.
All the pieces drop into place. Everything is full and weighty, analog, but with a vast, clear, open, and controlled sound. Tone extends from basement to chimney and timbres are fulsome, fleshy and life-like. Dynamics hit hard and micro-details swim in a sea of iridescent plankton. If the transparency is like someone opened a window, then the staging is like they also knocked out all the walls as well.
It is as close to perfect as I’ve heard from headphones. It’s reference without sterility; analog without haziness: a creamy-clarity, dreamy-reality. The sound is… pure.
3) TDK
My personal opinion on the noise suppressing sheeting is that it is a case of there being “no free lunch.” (I think the team at iBasso agrees with this). It is so effective in bringing down noise but it also dampens energy overall. If you have a harsh/bright system it might come in to play as a means of “tuning.” However, for me, with every upgrade in components I’ve been removing the sheeting little by little till there’s none left.
Bottom line: with this mod, you do not need the TDK sheeting. The background is just about as black and noiseless as you would like.
4) GRP
You definitely need Vince’s ground return mod. The stock amp8 doesn’t use it; with all the ceramics the sound would be too bright/sibilant. In this mod, it only provides a clean high end sparkle.
5) WBT
The solder of choice for the EX mods has been Oyaide SS-47 with good reason. It is a wonderful sounding solder. However, if a solder can be musical to warm, this is it. I switched to WBT silver-leaded for this mod because, though it is not quite as high-grade, it sounds clear to bright. It also has the added benefit of a slightly lower melting temp making it a joy to work with.
Well, that’s it. If you happen to do this mod, I hope you enjoy it, and please post your impressions here.
