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Stacker II


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Guest sacd lover
Posted

I have a Stacker II due around the end of January. This is a hybrid tube amp that goes well beyond the already excellent Millet and SOHA/ SOHA 2 hybrid amps. The Stacker has a true high voltage tube gain stage attached to a discrete transistor output stage .... and in my case a tube rectified power supply. I cant get enough of the SOHA/ JISBOS hybrid or maxxed Millet Starving Student with my woodied Alessandros .... the sound is delightful.

Here are some pics ....

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Pdrm2986-1.jpg

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Posted

Nice looking build, although I'd encourage the use of grommets on the holes as the trafo wires pass through the aluminum top plate. Kind of late to put them on now but frayed high voltage wires plague my build nightmares.

Guest sacd lover
Posted
Wow, that is one mighty amp !! I hope to build one someday..

Can you tell us what tube complement it will use ?!

There is one set of 9 pin and one set of octal sockets for the gain section. You choose to use ONE socket set and leave the other empty. The 9 pin sockets are optimized to use the 6CG7/6FQ7/6GU7/12FQ7 .... while the octal sockets are set up for the 6/12SN7GT.

The tube rectified power supply will use a 5U4G/GB. I also have an adapter that will allow me to use the 5Z3. The 5Z3 has the same specs as the 5U4 but uses a 4 pin base. I seem to be able to find more desireable tubes with the 5Z3 hence the reason I hunted down an adapter.

Guest sacd lover
Posted
Nice looking build, although I'd encourage the use of grommets on the holes as the trafo wires pass through the aluminum top plate. Kind of late to put them on now but frayed high voltage wires plague my build nightmares.

Thanks I will mention that to Don. JP#s is getting one of these too. I dont know what colors, tubes or extras he chose. Maybe he will comment? I like the 6CG7/ 6FQ7/6GU7 alot and I have a huge number of these tubes as well as a bunch of 12SN7s .... so the 6CG7/6GU7 and 12SN7 choices were a no brainer.

Posted

Nice!

I've yet to own a tube amp though I keep promising to make a Starving Student one of these days whenever I get some free time, as a small living room amp.

Posted

my build differs in a few ways I think as I had it set up for 6sn7/7n7 use

and had these parts included in mybuild

teflon tube sockets

vcaps

dact stepped attenuator

pre amp out

4pin xlr hp out

3 rca inputs

should be nice if the proto build I heard is any indication of the final sound I'll be a happy camper

Guest sacd lover
Posted
my build differs in a few ways I think as I had it set up for 6sn7/7n7 use

and had these parts included in mybuild

teflon tube sockets

vcaps

dact stepped attenuator

pre amp out

4pin xlr hp out

3 rca inputs

should be nice if the proto build I heard is any indication of the final sound I'll be a happy camper

Mine has the two sets of tube sockets, plus, mine will run at 6 or 12 volts. I can use 6CG7/ 6GU7/ 6922/ 6SN7/12FQ7/ 12SN7/ 8416 etc...

I went with the same teflon tube sockets and a shunt 50k volume pot vs a stepped attenuator. I have a loop out vs a preamp out. I only have one rac in and one rca out.

Guest sacd lover
Posted
Damn nice looking builds both of you!

Keep us posted.

Here is the latest update ....

Pdrm3101.jpg

Pdrm3098.jpg

Guest sacd lover
Posted
Earl that is a sweet amp congrats

Thanks ....

I forgot to mention the caps I used. I went with these ....

Obbligato aluminium-foil MKP 630VDC

Posted

Thanks for all the kind words folk, and of course to Earl and JP for pushing me to build these amps. They are a variation from the original Stacker II design and that is all I will say at this time.

Here is the money shot of Earl's amp and I have good faith that anyone who gets to hear it will be suitably impressed.

PDRM3119.jpg

A few specifics

5mm aluminum top sheet, 3mm front and rear panels from FPE, side panels are walnut finished to 350 grit and sealed with satin Arm N Seal (oil urethane)

PSU is 5U4G with 290V on the plates ( possible to go higher )

both 12V and 6V tubes can be used. Attenuation is via a shunted RK27 , headphone jack is the barrel version that Ti used in his B22. Interstage cap is the copper obligato as Earl has noted. Buffer is set to 43mA class A with BD139/140 in the driving seat. Tube sockets are phenol with gold contacts - I am truly impressed with the quality of these. The current tubes are 12SN7 biased to 10mA , this can be reduced easily with socketed resistors.

Hopefully I will be back in the not too distant future with JP#'s amp completed too.

..dB

Posted
Thanks for all the kind words folk, and of course to Earl and JP for pushing me to build these amps. They are a variation from the original Stacker II design and that is all I will say at this time.

..dB

:-(

Posted
:-(

x2

sorry folk, I am really not being a hard arse. I gave Alex my word and he will break the silence when he is ready ( not long ;) )

Thanks smeggy, the orthos love this amp ( as do any other headphone I have thrown at it ). We will have to get together someday, enjoy a pint and play with the various creations.

..dB

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