Crossover Capacitors for Accuton Tweeters - Solen -> ClarityCap -> Jupiter -> Duelund

@brownsfan As you know, the Franks struggled a bit with the load of the PREs.

To recap, I tried a Lyngdorf 3400, Atma-Sphere M60s, and a Pass Labs XA25, but in each case settled on the Franks despite their poor bass performance.  Eventually I decided to built a pair of DIY First Watt F4s.  They provide only current gain and my plan was to use them as a booster amp to power the PREs' bass units while being driven directly by the speaker outputs of the Franks.  Unfortunately, bi-amping just killed the speakers' coherency.  That was also true when I had tried using the active crossover of the Lyngdorf.

Surprisingly, when I tried the F4s as the sole amplifier of the PREs, they actually beat out the Franks and are my favorite amplifiers of the above list.  They retained a great deal of the sweetness of the Franks, improved the bass, improved clarity, & reduced distortion.  Soundstaging is roughly equal... maybe a very slight loss of front to back layering.  And maybe a small reduction in tonal color.  After having them in the system for a month, I put the Franks back in and it was clear that there was no going back.  Just finished selling them and all the upgraded tubes (separately because no one would bite on the full package) this week...  

It's also nice to have built my own amplifier.  Way cheaper (<$1800 for two F4s) and fun to learn about the circuits and parts.  Plus the Pass group at diyaudio is fun to interact with.  Instant technical service when something goes wrong, and people sent me free parts to help after I toasted a MOSFET because of inexperience.  I found the process a bit addicting actually.  Just ordered the parts to build a pair of DIY SIT-3s.  They use the same power supply and chassis as the F4s, so you just have to swap out a circuit board and you can try out a completely new amp.  Couldn't help myself despite my satisfaction.

Not sure if this (google photos) link will work, but here's a picture of the Duelund cap next to the Jupiter and original Solen, in case folks are curious about size:  https://photos.app.goo.gl/XRieYxBEng4nH4tFA

@charles1dad when I had the super eclipses, I never had any indication that the Frank's were straining in any way. Bass wise, I certainly had more out of that combination than I've been able to extract out of the PRE's. In part I upgraded because of the seduction of better sound, but I also moved and started pushing the SEs harder than they should. My living room is 19 x 16 with 23 ceilings and the 16 is fully open to the attached dining room, that's a 25' run to the front of the room.  The PREs are certainly capable of much more than the SEIIIs, but I'll always love the way the Frank's played music on the SEs.

@rauliruegas I've been a scientist for most of my adult life and certainly am biased towards truth. That said, if I could listen to every speaker/amp/source combination out there I'd probably choose the one that made the greatest percentage of my music "sound good", accuracy be damned. I don' know that system would include the Coincident PRE's though. They are intensely revealing.  I'm glad I have them though, because they don't cover up anything and it's allowed me to learn a lot about music reproduction. Definitely it's a journey trying to get them to where I think they can go.

@brownsfan Me too.  If not trying to find a booster amp to augment the Franks I wouldn't have ever tried the F4.  In the end, I just think it's a case of a particular design working well for a particular speaker. 

Of course there is this quote from Nelson in the manual:  "The combination of a simple Class A circuit operated without feedback and the good objective performance gives us a superb sounding amplifier. The low distortion, bandwidth extension, and high damping results in midrange clarity, treble detail, and control on the bottom end. While these are available from most good solid state amplifiers, the F4 also brings depth, imaging, midrange warmth and top-end sweetness. Overall, it is one of the best sounding amplifiers, and if you can live with unity voltage gain in your amplifier, it is possibly your best choice."

@charles1dad Also, I did compare a FW SIT2 (from reno) and the Franks back when I was buying an amplifier for the Super Eclipse IIIs.  I preferred the Franks as well.  I'm sure if the PREs were an easier load I'd never have moved on.  

This thread took an interesting turn... always good to hear everyone's opinions.

Interesting. I have been using my diy sit3 for a couple weeks and just switched back to the f4s. I lose a little bass energy, but gain warmth and smoothness. Still not totally sure which I prefer, but the F4 is just a fabulous amp if you've got the right speakers.  What are you driving with them?

@lewinskih01 Maybe a Mundorf in the EVO Supreme line?  They've got your large value caps and I really enjoyed the Supreme Silver Gold Oils in my linestage as output capacitors.  The only thing I didn't like was that they impacted bass performance... but everything else was just spectacularly beautiful.  Clean, quite, and rich sounding with just spectacular 3 dimensionality.  Clearly you don't have to worry about bass performance in this usage scenario.

And Mundorf has a lot of other cheaper options at that value in the film & oil lines if you want to start small and see what happens.

Plus AMT tweeters and Mundorfs are clearly a natural fit.

Well, no capacitor is certainly better than the most expensive, highest-quality option you could buy, assuming the tweeter is built to handle a full range signal!  Congrats.