Newbee w/ Modified 4311B's

[KenMiles]

Hi Zilch, Bo, Rusnzha, JBL enthusiasts-

Here is my latest experiment. The PAS-3 and ST-120 are newly aquired eBay additions. The PAS-3 still needs four 12AX7, and the ST-120 is in need of Dynaco's TIP revision. I aquired a second ST-120 because my older one is in cosmetic pain, plus Homer said it was ugly.





Homer wasn't aware of the Dynaco TIP mod until he got the unit and connected it. It distorted wildly on certain music passages. But that's the beauty of buying used electronics on eBay- there's so much to learn!

Homer says it'll be a couple weeks before everything is ready to run.

~~~~~~

I hope I'm heading in the right direction with this. When I play Public Image Limited's live recording 'Paris au Printemps' on my other ST-120, I'm finding the aged Dynaco amp wholly inadequate. It seems to run out of headroom at the volume level Public Image Limited demands. The ST-120 has a sweet, natural sound, but may not have enough grunt to feed the appetite of my modified 4311B's.

The PIL record does come to life when my JBL's are driven through the Sansui AU-717.

ThanX,

KenMiles

[Rusnzha]

I'm not really familiar with that amp, but it looks like it may be missing one of it's power output transistors.

[KenMiles]

Hi Rusnzha

Yeah, looks funny, huh? The power circuit shares the heatsink design used for the left and right channel circuits. The left and right circuits are opposite each other on the chassis layout.

A buddy of mine thought his ST-120 was missing a transistor. An enterprising eBay seller offered to sell him one!

ThanX,

KenMiles

[Thom]

I have no idea.

The D123 was designed for a specific purpose. That said, the 4311B was designed with the 2213H. You are on your own...

Did you model the woofers using their Thiele-Small parameters and the 4311B dimensions? What do your models say...?

Never could have been a D123 unless someone took a saw to the frame. D123's won't front mount without heavy modification.

[Don C]

I don't know when the change was made, but later versions of the D123 had the frame changed to allow front mounting.

[speakerdave]

I don't know when the change was made, but later versions of the D123 had the frame changed to allow front mounting.

The black-framed D123 can be mounted on the front of the baffle board; I think the frame is shared with the 123a-1.