6SN7 and the Poseidon amp

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6SN7 and the Poseidon amp

Postby Blair » Wed Aug 22, 2007 8:21 am

Is there any reason I can"t change the 68K dropping resistors and get the B+ up a bit and run 6SN7s in place of the 12AU7s? It seems as though it would be an easy enough mod with not too much headache.

Thanks for any info,

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Postby Blair » Wed Aug 22, 2007 8:35 am

I'm sorry,

I just realized that the 12AU7 is a phase inverter and not the first stage amplifier. Dumb question Yellow_Light_Colorz_PDT_02

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6sn7

Postby logos47 » Fri Sep 28, 2007 2:08 pm

Blair--just a question as to why you thought about changing tube type in the first place. Is it a change in sound you were seeking?
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Postby Blair » Fri Sep 28, 2007 2:14 pm

I'm just playing around and have some spare glass laying around. I've moved on now, and am building a SE 6550 amp. I'm not overly familiar with tubes, and prefer speakers actually, but it is fun to tiunker. I also have a preamp I'm building with a remote control volume and input selector. Pretty neat stuff.

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Postby Blair » Fri Sep 28, 2007 2:15 pm

I'm just playing around and have some spare glass laying around. I've moved on now, and am building a SE 6550 amp. I'm not overly familiar with tubes, and prefer speakers actually, but it is fun to tiunker. I also have a preamp I'm building with a remote control volume and input selector. Pretty neat stuff.

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Postby logos47 » Fri Sep 28, 2007 2:21 pm

I see. The remote is a great idea--little servo motor?
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Postby Blair » Fri Sep 28, 2007 2:42 pm

Actually, you can get an assembled board odd ebay that runs off 6-12v easily. Comes with a remote and an ALPS motorized pot. I am installing it in my preamp, but am also thinking about using another one for a passive preamp with remote volume control for DIY events and such. HEre is my amp based off the POSEIDON boards, and I'm building the same amp this evening for a friend:

Image


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Postby Blair » Fri Sep 28, 2007 2:54 pm

Since then, I purchased a larger choke mounted between the OPTs, and Bought a matched quad of SED and am using Mullard/Amperex 12AU7s. I love this amp! It is always a nice feeling to show up to DIY events with this guy:

Image

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Postby logos47 » Fri Sep 28, 2007 5:07 pm

This fellow would be welcome at our diy events here in Knoxville, for sure. Myself, I am like Sesame Street's Elmo (a relative newby working on the soldering skills). My Poseidons are running in my MK IIIs, having converted them after two other driver board versions and with many many other upgrades...time to roll some tubes. Are the Mullards worth it, and which models do you use?
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Postby Blair » Fri Sep 28, 2007 6:00 pm

Honestly, I can hardly tell the difference between the NOS GE tubes and the Mullards. I have NOS Amperex/Mullards I got for $5 a piece from a local surplus store.

It is also the phase inverter tube, and less critical to the sound than the AX7. Wish I came across those instead. I've only been DIYing for about 1.5 years now. It is fun, but my passion is for speakers hence all the woodworking. Before you go nuts rolling tubes, make sure they are interchageable with these guys here. They will steer you in the right direction.

Do you guys have a good sized group of DIYers there? We have quite the gatherings here in Dallas. I organize the Dallas Audio Club among some other personal ventures with the speaker geeks Yellow_Light_Colorz_PDT_01


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Re: 6SN7 and the Poseidon amp

Postby Shannon Parks » Sat Sep 29, 2007 5:58 am

deicide67 wrote:Is there any reason I can"t change the 68K dropping resistors and get the B+ up a bit and run 6SN7s in place of the 12AU7s? It seems as though it would be an easy enough mod with not too much headache.


Sure! The 6SN7 makes a great driver. See the Eico HF-87, HF-89 and Eiclone amps.
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