Sir Alexander. . . . .

Specifications:

Audio Output Transformer

Model: EI-19

Catalog #: 273-1380

(Frequency range of 300Hz-10kHz.)

Soooooo, if you want a strong bass, this may not be the best choice.

No lets further clarify that . . . . as not strong, but just PLAIN bass . . . as that 300~ is just at the bottom of the typical male voice range.

That micro unit is for a TRANSISTOR application and also doesn't set to well in the low impedances being involved with its use. . . . in its interfacing into a high Z tubes grid circuitry.

Now, I was thinking of the use of a filament transformer as well, since we KNOW that one of them is having enough "core materiel mass " to be effective on down to 60~.

But my mind was also onset of the TYPICALLY PHYSICALLY LARGE size of the transformer that Radio Shack would be offering.

Now a 500 ma or 250 ma secondary would be just absolutely fine on its finitely MEAGER secondary current rating requirements, but nowadays I don't see that small of a transformer being readily available . . . .adjunct with a secondary MAIN criterion of being . . . cheeeeeeeep.

Now in taking a page out of my current book, I am presently snapping up every switch mode power supply that I run across in a WALL WART type of construction.

I have got most of my frequented thrift shops and pawn shops letting me know that they have one/some in and and readily accepting my bid of "fiffy" cent apiece.

SEEMS that they see the typical window shopper is asking for a preeee-cisely EXXXXX-ACT number or else one that is mating up to a very SPECIAL connector, so they just don't move units very well at all.

Me, I just confirm the dual 240-120AC input spec, as well as confirming with its very light weight and go for it.

Why ? . . . because I can salvage the internal switch mode IC with its power FET driver inside, its CHEAPER that I can order one plus its postage/handling . . . plus the additional isolative transformer and the other nanosecond rise time diodes and gooodies also included inside.

Now keeping in that perspective of a WALL WART. . . . just find one of that is having an ~10-12 V output range and the all important aspect of a 120 VAC primary winding on a conventional iron core transformer being inside.

You can typically additionally determine that by comparing the weight aspect, pick up a switch mode unit and you will find it being as light as a popcorn fart, in their relative weight comparisons.

Sooooooooo . . . look into salvaging a conventional iron core power transformer that is inside of a conventional 120 VAC wall wart. It has small size, as required . . . .'nuff metal to work into the low audio spectrum . . . along with your not getting "scalped" if even you're having to pay out a WHOLE buck for it !

You additionally need to look into the disconnecting of the transformer from the tie in to the volume control / tube 1st grid circuitry, EVEN if using a DC isolative input coupling capacitor in series with the transformer secondary winding.

Since, if left in circuit during radio playing, its presence will severely siphon away 'most all of your treble response of the radios audio.

ASIDE . . . in the general direction of Sir Marvin

" But do you recommend a disconnect from radio audio or just a quiet spot on the dial, when using the mp3? "

A disconnect, just by virtue of the above info.

The "tuning" to a quiet place on the dial only worked with my '55 Crown Victoria, wherein I had built an enclosed rectangular housing under the center dash.

That housing containing a pull out drawer which had a RCA 45 automatic record changer mounted upon a block of foam rubber. A Terado DC to 117 VAC 60~ vibrator type inverter powered the phono motor . . . OR my electric razor.

The phono cartridges audio output was routed up to an new RCA input jack going into the high side of the volume control.

No problem here, with an infinitely high cartridge Z interfacing into tube circuitry.

Mechanico-Debugging consisted of a counterbalancing of the arm, with an adjustable weight on a threaded rod behind the tone arm to be able to EQUALLY balance out the lateral MASS of the arm . . . as being referenced to its support and pivoting axis.

That balancing procedure, precluded the arm swinging across the record grooves, on any other than a fast and HARD turn.

The very front of the arm had a tiny felt pad cemented upon it, so that the end of the tone arm was continually riding in grooves of the record.

The final alteration was then the additional floating of the cartridge by a cross a pin at its rear, such that only the actual weight of the cartridge proper itself was producing the resultant stylus tracking weight.

A few years later, Chrysler came out with an OPTIONAL record player in a car . . . Now can you imagine such ?

(Captive market special records too !)

ON THE RADIO SHACK ISOLATION TRANSFORMER ASPECT:

Now, the above unit contains (2)X of :

And those two units additionally have the same blasé reponse as the aforementioned 1273-1380 RS output transformer:

300Hz to 5KHz response

Impedance 600-900 ohms

Also take note of the matching impedance of the units, being . . . way . .way . . . WAYYYYY above the MP-3 input impedance, along with the unit additionally being a 1:1 match and no upping of Z towards approaching that infinitely higher tube input impedance.

(HOWEVER . . . that units 600 Z would be RIGHT ON, if being used for for telephone work or making a Hams phone patch.)

I still prefer the very initially mentioned 60~ power/filament/wall wart transformer with what voltage and Z step up that it will additionally be affording.

73's de Edd