[quote author="Andybot"]Thx for all the replies.
I already tried taking a line out of an external speaker jack with a transformer on the input. To noisey. I suppose what im looking for are suggestions to reduce the noise floor.
Thx[/quote]
If its got AC filament voltage, do the dc conversion thing with a bridge rectifier, whatever appropriate amperage, 25, 35 amps. That will quiet things down considerably.
[quote author="Andybot"]Thx for all the replies.
Its a series 2 or 3 reel to reel. I already tried taking a line out of an external speaker jack with a transformer on the input. To noisey. I suppose what im looking for are suggestions to reduce the noise floor. My preferance would be to build a pre from scratch that I could use in my studio but my budget says tinker and learn something .
Thx[/quote]
Series 2 schematic, you can get rid of the bias/erase tube, valve 6 tetrode. There's a little output xfrmr in there for an internal 15 ohm speaker, the speaker jack outputs at 2.3ohms. There's three pentodes, a dual triode and a tetrode, cool, very un-Ampex like. Specs indicate resistance Input 1 (mic?) is 1 meg and input 2 (radio?) is .5 meg. EQ is nested between valves 1&2; input 1 goes to grid on valve 2, input two goes to plate (?) on valve two. Stewart said:
If you have two inputs on the front, one for mic and one for line, then you can tap a signal out after the first gain stage by just using the 'line' input as an output.
Yeah, try that and tell us what it sounds like.
At a glance it looks like valve 1 is the first gain stage for playback head and also the record head, dependent on control switch. Valve 3 is the input tube for the onboard speaker amp, single ended, valve 4 is the power tube, tetrode, 2 &1/2 watts. What tubes are in there???
Controls are hard to read on the photo, looks like two knobs on the left are eq, and then one gain control knob. Nice knobs! You could yank that socket and put another pot there for output attenuation...I can't read what the jack below and just to the right of the gain control is, speaker out? Just wire it for DI out. Anyway, I'd wire it for two ins one out, a little mixer, one output xfrmr. You could use the amp for DI? One input balanced for mic, one switchable balanced mic/instrument (which could also be switched out of the preamp circuit to the di jack.) Use one half each valve 5 dual triode as input gain for the two pentodes. Give the transport to the nearest ferrograph fan and figure out how to save the part of the case that houses the electronics and maybe make a lid from the old lid. See if you can salvage that transformer thats in front of the grid on tube 1. Leave the EQ in there for input 1. RatShack unbalanced to balanced xfrmrs, like PRR said, makes it real easy. What color is the paint?
Interesting machine!
Hey, now I want one! :!: