[Jon L]

I read about under $500 are free of charge, do you confirm it?

Not sure about $500 vs what I read, $800.  I CAN confirm that stuff I have recently ordered around $300 and under still have not increased in price. 

[FullRangeMan]

So seems they lowered the $500 to $300.
How many per cent are the $800 tax?

[jk@home]

I realize I said the amp is running but without any pic!

Good to hear they are working for you. I may try this amp with my Fast 15s. Then I can move the W4S M-amps, which are way over kill here, back to the LS50s (now in the HT system).

[renaudrenaud]

Whaaaa! Beautiful! Can you describe a bit your speaker system? Or is there any link?

I can't wait your return about the FU19 running your speakers.

[jk@home]

No links but I've posted a few time on the OB section. The baffles are 20" wide x 2" deep, made from 1-1/2" butcher block countertop (from the Home Depot) and an extra 1/2" baltic birch ply laminated on the back for extra support. Used maple veneer edge banding, stained with Minwax Fruitwood stain, for the sides. Then satin water based polyurethane sealant paint to finish.

The Lii drivers are supplemented with double Eminence Beta 15s, in a compound setup, for the bass. I have some Heil AMTs to add to the highs, which will make the speakers a 3-way. The Dayton plate amps are for the Betas, the W4S M-pre/M-amps are driving the Fast 15s, and the little Fosis will be used for the Heil.

The subs on the sides are Dayton Ultimax UM-15s in undersized aperiodic boxes. They will be driven by Crown amps, hidden in the closet. Haven't hooked them up yet. Also have IB manifolds in the ceiling, just in case...

The front end is a Bluesound Node (or Oppo disc player) to MiniDSP SHD Studio to dual SMSL dacs.

This setup is in a 180 square foot spare bedroom, almost nearfield. I had smaller Magnepans in here before (thus all the wall treaments) and wanted to try OBs. So far lots of fun.

[renaudrenaud]

Thanks for the details. So, if I understand, you use the MiniDSP as a numeric filter... Ha just went there https://www.minidsp.com/products/streaming-hd-series/shd-studio to understand more on the subject.

Back to the amp, I am not a good boy: I forget to switch off the amp most of the time. Do you now the number of hours the tubes can run, approximately? Not a big problem anyway, they are so cheap, I just have to order in advance.

[jk@home]

Thanks. Yes I am using the Studio as a pre-amp, crossover, and EQ unit. But haven't played around with any EQing for the Fast-15s yet, they sound pretty good from the get go (as long as I'm slightly of axis).

Here's another question about the amp... should a tube cage be installed over it, for safety reasons?

[FullRangeMan]

Here's another question about the amp... should a tube cage be installed over it, for safety reasons?

There is kids or pets in the house?

[jk@home]

Dogs and occasionally young grandkids, but neither are allowed in the room. Thinking about the tube leads on top, and my fat fingers getting in the way.

[jk@home]

I stand corrected, the Lii driver price (on Amazon) is higher now...
Anyway just ordered the amp similar to renaudrenaud's from Flyinsky on Amazon.

[renaudrenaud]

Good news, I am impatient to read your comments.

Since I changed the 6n2 tube (one channel broken) with a new one, I find the amp is  even better with more nice highs and a better definition.

Here is a pic of the new one:

[jk@home]

Shipping is saying 3-4 weeks, that about right. Took the Lii drivers around 3 weeks to get here (East Coast) from China.

[Jon L]

0327252257 by drjlo2, on Flickr

Curiosity got myself the latest TPA3255 wonder, Douk Audio A5, which multiple reviewers have preferred over Fosi/Aiyima.  I even got the upgraded 48V GaN power supply. 
Well, the FM30 tube amp COMPLETELY destroys it in terms of refinement, nuance, micro-texture, lit-from-within presence, and just the desire to keep listening to music. 

I WILL improve the Douk with a bunch of discrete opamps I received as well as 36V battery power supply in the mail, but yeah, buy the FM30 amp 

[jk@home]

Due to a scheduling conflict, I cancelled my Amazon order for now (the amp would of showed up while we were outa town).

The good news is I once again tried the old S.E.X. amp on the Lii drivers, just to get an idea of going from the "D" to tubes. 2 watts and driving them fine.

So yeah I plan on re-ordering when we get back into town.

[Jon L]

How do you like the Fosi vs Bottlehead and any opamp rolling yet?

I rolled in some SX52B discrete opamps from Ali, and the Douk is heading in the right direction.  When my battery power supply gets here, things might get interesting..

0328251615 by drjlo2, on Flickr

[jk@home]

I haven't tried the Fosi amps on the Lii drivers yet...I could easily though. Should probable try just to make sure the amps work. 

I bought them to drive the Heil AMTs that I plan on mounting on top of my baffles. According to the review on ASR, these amps perform differently on 4 ohm vs 8 ohm loads. Flatter on 4 ohm loads (like the Heils). If all goes as planned, I will then choose what Opamp upgrade that would benefit the frequency range I end up using for the Heils. I know you have quite a bit of experience with your Heils, from reading diyaudio. What amp worked best with them for you?

https://www.audiosciencereview.com/forum/index.php?threads/fosi-audio-za3-amplifier-review.52139/

 

[renaudrenaud]

When I arrived in China 2 years an half ago, I wanted to build a Chinese system: Lii drivers, Topping and SMSL things... And bought a FOSI BT20 Pro for less than 60$. It was working really nice with the Lii drivers. When I bought a turntable (again) few months ago, I told myself, why not a tube amp. Then I replaced the FOSI amp with the FU19. I prefer the FU19 tube amp, but the FOSI was not ridiculous at all, from my point of view.

[Jon L]

I know you have quite a bit of experience with your Heils, from reading diyaudio. What amp worked best with them for you?

The Heils sound pretty good with just about any good amp, but I did settle on the FU30 amp in the end.  For optimum results, room correction/DSP will be needed in most room setups IMO, but that's true with my other drivers as well.

[jk@home]

Tried the Fosi amps (stock) vs the Bottlehead on the Lii drivers...still preferred the latter.

So I re-order the FU amp (need to come up with a different name, that doesn't sound nice  ).

[Jon L]

Tried the Fosi amps (stock) vs the Bottlehead on the Lii drivers...still preferred the latter.

So I re-order the FU amp (need to come up with a different name, that doesn't sound nice  ).

One of the reasons I got the Douk instead of others is only two opamps are needed.  Fosi V3 monos have 6 opamps (4 if not using RCA input).  Opamp rolling costs can add up quickly, so unless one already has a bunch of Burson V7, Sparkos, Staccato opamps, I can recommend the very reasonably priced AkLIAM LC6 discrete dual opamps in Douk A5 (and likely other Tpa3255) amps. 

Good discrete opamps all seem to get rid of opamp grain, which LC6 also does while adding density and richness, all good things for class D amps.  I did prefer slightly my very old DEXA discrete opamps, but the difference was small and I'm not even sure where to buy any more of them.  In this configuration, the Tpa3255 amp is sounding WAY nicer, and if one needed even more liquidity of tone, just add batteries 

0402251726_1743641549878_1743641598021 by drjlo2, on Flickr