The King of Hybrid Amps .... the Stacker 2

[sacd lover]

The Stacker 2 arrived this morning!!

Initial impressions ....

I went with a pair of Raytheon 12FQ7s and a nice TS 5U4G rectifier. The amp powered up flawlessly and is dead quiet at my listening level. I am using my clock/ zap filter modded Sony 555es directly into the Stacker with my "Woodied" MS1. So, the Grados are definiely quiet with this amp even on my very high gain source.

The sound is not like anything I have heard in one package. The amp is a little tubier sounding than my BJT Millets; more like the MOSFET Max but something is different and better. There is no edge or grit or harshness or brightness to the treble. But, somehow the sound has abundant life and the perfect combination/ amount of the above traits. I am thinking the good traits I hear listening to live music. The Stackers presentation makes the sound both involving and natural without EVER being fatiguing.

The bass is not thick or slow but very taunt while retaining good weight and impactfulness. The amp does not sound tube rectified except for that hard to define smoothness and liquidity tube rectification imparts. There is a freedom from some subtle type of edge you hear with the other hybrids. The mids sound so right. Vocals are packed with inflection and subtle dynamic shifts yet no spit or sibilance.

Treble is a big deal to me and as I said above the reproduction is completely artifact free .... my first test. But, extension and resolution of space are up there with my Supra. The MS1 soundstage seems to be more open = less cramped with more seperation of instruments. The way the amp is both relaxed and refined while having PRAT and punch is awesome. You dont realize how well the dynamics come through this amp, at first, because the sound is so smooth and relaxed.

I am sure I can up the tubey factor with 12SN7s or a RCA 5U4G. But, the whole just sounds so right I dont want to take this tube set out. This may NOT end up being a tuberolling amp.

 

[Tridacnid]

YAY! Looks beautiful. This may become my amp for a bedside rig.

 

[sachu]

Congrats EArl..its a beauty of an amp and sweet sounding..Look forward to more detailed impressions

 

[jeffreyj900]

Very nice looking amp Earl! Are those another set of unpopulated tube sockets just behind the tubes up front?

 

[Tridacnid]

Quote:

Originally Posted by jeffreyj900 /img/forum/go_quote.gif Very nice looking amp Earl! Are those another set of unpopulated tube sockets just behind the tubes up front?

I believe they are for the 12SN7s he mentioned.

 

[sachu]

Quote:

Originally Posted by jeffreyj900 /img/forum/go_quote.gif Very nice looking amp Earl! Are those another set of unpopulated tube sockets just behind the tubes up front?

you can roll either octals or Novals on the amp..so if you feel like 6FQ7 clear tops then the novals.else the octals for tubes like the 12SN7GT

 

[jeffreyj900]

Gotcha!

 

[malldian]

Link to this or the first one?

 

[sacd lover]

Quote:

Originally Posted by malldian /img/forum/go_quote.gif Link to this or the first one?

Mine is the first received Stacker 2 of two Stacker builds. dBel84 built two amps but both were custom builds so the two are not alike. Mine has the two sets of tube sockets noted. Plus, my amp is also switchable (selector swith on the top plate) between 6.3 or 12.6 volts. The main tubes I can use are the 9 pin 6CG7/6FQ7/12FQ7/6GU7 .... or octal 6/12SN7 and 7/14N7 with an loctal to octal adapter. Both amps have tube rectified power supplies but I opted for the 5U4G/GB rectifier since I have a good supply of them. I also have an adapter to use the 5Z3 rectifier to sub for the 5U4G if I choose to do so.

The second Stacker has a single set of octal tube sockets and I think the amp is setup to use 6SN7GTs. Stacker #2 has selectable multiple inputs, a preamp output and both balanced and single ended headphone jacks. Stacker #2 uses a 5AR4 rectifier. Stacker #2 was going to use a stepped attenuator but I dont know if he went through with the stepped.

My amp uses a shunt modded Alps RK27 volume pot and I went wiith a loop out vs preamp outputs. We also used different coupling caps. My amp has a single input and a standard single ended 1/4" headphone jack. I liked my amp better without a transformer cover while Stacker #2 has a custom cover over the corner transformer.

Stacker 2 #1

Stacker 2 #2 (jp11801) ....

The Stacker Family ....

 

[tom hankins]

Very nice Earl! Have fun.

 

[sacd lover]

Quote:

Originally Posted by tom hankins /img/forum/go_quote.gif Very nice Earl! Have fun.

Believe me .... I am. You need to try one of these hybrids for a sweet bedside setup. The Millet MOSFET Max in particualr is inexpensive and so good. But, any of the better hybrids .... Millet Max, Millet Mini-Max, SOHA/ JISBOS, SOHA 2 are excellent.

 

[jp11801]

Dang the Stacker is one fine amp, I have been listening to mine since the postwomen dropped it off 4 hours ago. This may be the most transparent amps I have heard. Now without the luxury of my former amp in the room it's tough to tell. It will get out and about in the next few weeks to get thoughts about how it stacks (no pun intended) up.

The thing that strikes me about this amp is its absolute transparency, it is a wide open window to the music. Details that were there but previously really low level can be clearly heard. Tonally it rocks with a nicely textured sound, but best of all you forget it's there and sink into musical bliss.

Earl I'll have to hit you up for tube suggestions in a while. Right now I'm running sylvania 7n7s and an rca 5ar4

 

[sachu]

Quote:

Originally Posted by jp11801 /img/forum/go_quote.gif Dang the Stacker is one fine amp, I have been listening to mine since the postwomen dropped it off 4 hours ago. This may be the most transparent amps I have heard. Now without the luxury of my former amp in the room it's tough to tell. It will get out and about in the next few weeks to get thoughts about how it stacks (no pun intended) up. The thing that strikes me about this amp is its absolute transparency, it is a wide open window to the music. Details that were there but previously really low level can be clearly heard. Tonally it rocks with a nicely textured sound, but best of all you forget it's there and sink into musical bliss. Earl I'll have to hit you up for tube suggestions in a while. Right now I'm running sylvania 7n7s and an rca 5ar4

Ok, I agree, the stacker is one helluva amp.. I just switched over to it and it is so smooth across the freq range..the mids are effortless...the details just seem to flow out..The sound stage is so wide it surprises me sometimes.
The bass is tight and as good as it can get. I have two great amps sitting on my desk and I am spoiled proper by both now.

I am going to hate returning it to Don tomorrow.. At least I know I will have his EHHA to get me over the departure of the stacker for a while till that goes back to her owner too..




I hope to see more of these amps make into the hands of other headfiers once it becomes live..Alex designs some beautiful amps and they each deserve to get their recognition.
I have heard both your amps and they are both amazing. Have fun gents

Kudos to Alex for designing this sweet sounding amp and Don for executing it into such fine looking amps.

_Sachu

 

[WarriorAnt]

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[sacd lover]

Quote:

Originally Posted by WarriorAnt /img/forum/go_quote.gif Sorry for my ignorance. Where did you buy your Stacker 2?

Two of us had a head-fier do our custom Stacker builds.

More impressions ....

I agree with the transparency comment, but in addition, this amp has a tonal purity and freedom from edge that is unlike any of my current amps. My only other experience with this trait was a tube rectified SP prototype. So, I would attribute this characteristic to the tube recitfied power supply. The sound is so balanced and open you just dont think reproduced music. The music seems very real and alive. This is the first amp I can say I like as well as my SP tube amps.