[shokunin]

First Impressions:

Here were my first impressions with the Son of Ampzilla that we listened to at the Southern Cal listening session.  John Casler was kind enough to bring over his proud "Son" to give him the appropriate shower, he was dressed in baby blue.  

Tubistors?  Damn yes, this thing does sound like a tube amp, smooth, very smooth and had quite a bit of warmth which I was not expecting.  The speakers (Onix Ref 3's) already had a sense of warmth to them and the SoA simply added to it.   However, I can see that with the VMPS ribbons that this is a good thing.  In my opinion, in my room, my perferences with the RM40's is to pair it up with a warmer sounding amp.  The ribbons are unforgiving and edgy solid state equipment tended to drive me out of the room or introduced listener fatigue much more quickly.  The SoA had a sense of ease, and relaxed quality to it that was a distinctively different than the Rowland M201 monoblocks.  

The Rowlands which uses the B&O ICEmodule and other digital amps like the Tripath chipset have a distinct sound to them, different than tranditional SS and Tubes.  It wasn't surprising that the SoA sounded different.  the Rowlands had more "excitement" but the SoA seemed to be more natural.  In the end, it'll be personal preference as to which is preferred.   The SoA seems to have some of the "magic" of tubes along with the the ability to control the bottom end in SS fashion, best of both worlds?  I think so.

I hope to get some more auditioning time with the SoA, especially on Johns' 626R's or hit RM40's (when they arrive)  to get a better feel on imaging and soundstage.

[jgubman]

shokunin,

I noticed you just sold your 201s over on agon (they went quick!!!).

Should we take this as an endorsement of the SoA?

[shokunin]

Hey Jon,

I sold the Rowlands to try a different setup, more than likely a 20W+ SET tube / SS bi-amp. The Ampzilla’s are still contenders, just not sure how things are going to synergize once my RM/x’s arrive.  One thing I do like about the Ampzilla, oddly enough, is the RCA/XLR switch.  I have both a vinyl setup where my phono stage has volume control using RCA’s and my digital prepro into the XLR.  No need for a preamp as you could switch between the two, but it’d be a manual toggle every time.  In the long run, I think I’ll be happier with a remote passive preamp (placette/bent) and some tubes.

I'll probably keep my Pass X-250 and use it as my bass amp and simply get a tube amp or SoA for the mids/highs.

[shokunin]

hmmm Since the SOA has a twice as large transformer as the Pass, I wonder how the SoA would do as a bass amp or am I kidding to think the SoA could power the woofers on the RM/x?  Hmmm...

[John Casler]

hmmm Since the SOA has a twice as large transformer as the Pass, I wonder how the SoA would do as a bass amp or am I kidding to think the SoA could power the woofers on the RM/x?  Hmmm...

Ask TKP, he has just set up a pair of RM/x's to be bi-amped via 4 AMPZilla 2.5K's

One pair runs the woofs.

TKP are you out there???

[tkp]

John,

I have not had any time to setup the RMX with two pair of A2K yet.  Hopefully, I can get to do this next weekend.  My wife has been working me to death on the weekend.  She has been watching home decorating/modeling show for the past two months and she wanted me to remove the wall paper from the three bathrooms and then sponge painting them.  The sponge painting was/is the easy part.  Removing wall paper and preping the walls for painting was/is simply pain.  I just finish the second bathroom and I will be on the third one next weekend.

[shokunin]

Hi Tkb,

just curious, were you clipping often with just one Ampzilla on the RM/x?

[tkp]

Hi Tkb,

just curious, were you clipping often with just one Ampzilla on the RM/x?

Shokunin,

The pair of RMX are for a friend of mine (who lives about 10 minutes away).  We never tried a single A2K with the RMX.  My friend decided to go for two pairs of A2K to drive the RMX.  He is waiting for me to come over to his place to setup the A2K with the RMX.

[Sedona Sky Sound]

If you do a search of the forum you will see that I started off using a single pair of Ampzilla 2000s to run my RM/Xs. However, I quickly learned that one pair was not quite enough for the incredibly power hungry RM/Xs. On extremely bass heavy music (i.e. Blue Man Group) it was not difficult to clip the Ampzillas at moderate listening levels. I am currently using 2 pair of Ampzillas and quite happy with the performance and have yet to see a clipping light come on even at loud levels. The pair running the mids/tweater is definitely overkill and never get above idle warm (I think the SoA is a better choice for the mids/tweeters but don't have mine yet).

Julian
www.sedonaskysound.com

[shokunin]

Thanks for the info Julian.   Looks like my X-250 might be adequate for the bass, we'll see once they arrive, otherwise I may be looking for a better bass amp.

[tkp]

There a few things that impressed me about the A2K are:

-  High gain:  Its gain is 32 db.  This is very good for passive preamp.  I use the Bent passive preamp so this is almost a must.

-  Decent input resistance:  50 Kohms.  This is also very good for passive preamps, especially for passive biamping purposes.  Most sources can drive load of 10 Kohms or higher without probem.  This was one of the reason why I did not mess with Pass amps because the input impedance for SE input of Pass amp is 11 Kohms.

-  AC couple.  This is to prevent accident DC at the source output which could blow the speakers.  There are a few amps out there that could potentially better than the A2K but this come at the cost of DC coupling.  I would love to remove the AC couple circuitry of the A2K to see how it would sound but James Bongiorno probably will void the warranty of my amps immediately.

The SOA is great amp but it has much lower gain than the Ampzilla2000 (26 db versus 32 db) hence it might not a good match for passive preamp as far as gain concern.

I would like to see JB to come out with the SOA in the same design topology but running in pure class A.  This probably will result in dual mono design to add additional heat sink for heat dissipation.  A great setup would be:

-  The A2K for bass of the RMX
-  The SOA2K in pure class A mode driving the midrange/tweeter of the RMX.

If you ask JB which is his favorite of all time he will tell you it is the GOLD that he designed 30 years ago.  This is a 125 watts pure class A amp.