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I have printed the preview of shannons manual and see there are two different blocks available to be built from this board. An EL34 and a 6550/KT88 amp. What are the bennefits and or tradeoffs between the two. I recently built shannon's st35 kit and love it, but am looking for a bit more overhead. Thank you for any impressions of the sound differences.

Blair

You can use the Poseidon board in a Dynaco MK-III or new clone, which is 60 watts with 6550 type tubes (I used KT-90's) or you can use it in an original or clone of the Dynaco MK-IV, a rare mono block which uses EL-34, and was 35 watts or so, and pretty much half of an ST-70.

There are pics of a pair of Poseidon MK-III clones on my website using the Sountastick chrome chassis at: http://mcnally.cc/amps.htm

The choice is all about power ! Also, from a practical standpoint, the parts for the MK-IVs will be cheaper, but I don't think there is a pre-made chassis, but you can get them for the MK-IIIs.

Hey Tom,

As usual, you have replied to my questions with positivity. I am not overly concerned with the monoblock version versus power as you stated, but here is a question you may be able to help me with . I found a toroid tranny that is 400 vct at 500ma with a 12.6vct winding. Assuming I change the rectification to SS and use a small tranny for the SS rectification, do you know of anyone who has built a stereo version of this amp? Will this work?

Thnak you ahead of time for any info,

Blair

Sorry, that is 800vct.

Blair

Hi Blair ...

I'm not sure what you mean about a transformer for the SS rectification ? If you want to build a stereo (one chassis) amp, why not go with the ST-70 board and a pair of EL-34's ? One of the reasons people go with "monoblocks" is that the weight gets out of hand with huge transformers. But, to pick a power transformer for a stereo amp, find something with the proper voltage for one side, but with double the current. I suppose if you only had a 12 volt filament winding, you could put sets of EL-34's in series and run them on 12 volts, and the driver tubes are already two 6 volt filaments inside the tubes, so you could strap them for 12 volts.

I don't think I've seen anyone build a stereo Poseidon, it would be BIG !

... tom

TomMcNally wrote:I don't think I've seen anyone build a stereo Poseidon, it would be BIG !

Howabout something like the Soundtastick chassis with a Poseidon driver, MKIII build, KT88s and one of the Antec toroids? Probably would use Hammond 1650Ns though they aren't as cheap as they once were. Viola - a very cheap modern Eico HF89 along with the chiropractic bill. :)

Hi All,

Just a FWIW: my first two (had to build a second to make sure the first wasn't a fluke) prototypes of the 2046--which is an HF-89 with minor modifications and my iron--weighed in at 46 pounds and were built on .050 Al Hammond chassis. Talk about 46 lbs of jello! Bottom plates made them a little more stable, but you an see the OTs leaning in toward the center of the chassis. I'll send pix when I have a chance.

Congratulations on the build! Basically, the problem you just mentioned is why I'm going to try and afford a couple custom jobs from a metal shop down in Dorchester. I'm just too lazy to draw out in CAD the layout for the tubes and transformers and stuff, but if I did, it'd be pretty sweet. My cheap Unibit-knockoff for the octal sockets kind of chews the metal...

separks wrote:

TomMcNally wrote:I don't think I've seen anyone build a stereo Poseidon, it would be BIG !

Howabout something like the Soundtastick chassis with a Poseidon driver, MKIII build, KT88s and one of the Antec toroids? Probably would use Hammond 1650Ns though they aren't as cheap as they once were. Viola - a very cheap modern Eico HF89 along with the chiropractic bill. :)

Hey Shannon,

I like building my own chasis so that is not an issue. Antek, as you suggested has a 800vct 500ma per winding tranny with two 6.3v secondaries, and EDCOR has some OPTs : CXPP60 that will work for the application. Weight is not an issue. I'm young and do not mind toting around a 65lb amplifier. The Antek is 10lbs and I assume the EDCOR are about 7 each so it should not weigh more than 50 pounds anyway. Will this 800vct tranny power both channels sufficiently? Will I need another small tranny to drive any of the additional tubes? I know I can run the KT88s and the 12AU7 and the 12 AX7 off the Antek, but what about the rectifier tube? Any suggestions or is SS a better option?

Thank you

Blair

Soren -

Have you used cutting oil with the UniBit ? It's messy, but it helps. I have a quart I got at Ace Hardware. I use an old Mouser catalog to soak it up.