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I'm finally getting around to changing the phono in my '56 Magnificent Magnavox mono console. As you can see from the pics at the link below it has a Collaro changer w/piezo cart which sounds like poo. What you can't see is the spot where the TT goes is only 14 X 13 inches.I thought this nice Garrad Lab 80 I got free would be great in there. No way it will fit. In fact it is a linear tracking TT or nothing. I got a nice Technics DD linear tracker to fit there and will be putting one of these phono preamps in it. I wanted that kit w/sub mini tubes from Oatley but evidently they don't make it anymore. This kit is $12 on the bay so less than $20 total w/ the two battery holders.
It needs +/- 9 to 15VDC so I'll use 2-10AA battery holders. They'll last a long time. I'll put the board into a plastic p-box w/TiShield and use resistors to sum to mono. No RCA jacks, I'll hard wire bare cable to the connection points. Gain is 30-50db adjustable.The Magnavox has hi level phono in w/ 4 position EQ (LP,RIAA,FFRR,78) and a plain aux in. I'll try both for grins. There is a company named Edcor that makes a nice transformer for stereo to mono summing that is small,for line level signal and only $10.43 but they want 20.79 for the cheapest shipping! I cannot do that.
Edits: 03/11/15Follow Ups:
If the choice of EQ is worth anything to you, you might consider modifing your little phono stage to remove the RIAA points of inflection and making it an imperfect integrator with a bass shelf at 50 Hz to convert the constant velocity magnetic output into constant amplitude like a ceramic and run its summed output onto the high-level phono input.
May I ask why you are getting rid of the period changer? You could put a decent magnetic into it.
Phil
I'm not getting rid of it. I'll box it and if I ever sell it will include it for the new owner. If you've seen one of these Collaros you'd know why it's getting replaced. I already rebuilt it w/new idler, stripped and relubed. It sounds like crap like all of those things do. Please don't bother trying to convince me otherwise.
E
T
You could try summing the 2 channels of a stereo cart., in the headshell. Another possibility is to buy a mono cart. with a "spherical" 0.7 mil stereo stylus.
Maybe you can build a 1 channel preamp for less than that kit, along the lines described in the linked opamp data sheet. The metal can version could be NICE, on a piece of perf. board.
Another power option is a pair of 006P form 9 V. batteries. FWIW, a lithium cell stack 006P was better in a "Little Rat" than an alkaline 006P. However, a 7 cell rechargeable NiMH 006P form battery is better than the lithium stack. My guess is that lower internal impedance accounts for the perceived differences.
Eli D.
I would have strapped the channels on the cart if it was a standard headshell but it is a P mount like on most linear trackers. I have access to AA's free so I went that route.
E
T
So, strap the channels at the TT's cable connection points.
Eli D.
This would have been great. Except they want to hammer you on shipping. The thing is 10.43 but they want 20.79 to ship it!
E
T
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