poor man's source

[Stunch]

Stupid question, but maybe not. I just completed a Dynaco ST-35 build with Dave G's EFB and so far so good - at least with some shorted input plugs and some 15 ohm resistors on the output. I don't have a source with variable output like a preamp or a CD player with volume control - I just have a phono stage right now and my TT is a few weeks from being usable - and was wondering if I could use a portable CD player that has a headphone volume control. It has 0.6 volt output. Would it work, but with a fixed output level into the amp? Is the volume control only for the headphones which would be bypassed? I'm sure any output would be minimal and possibly distorted.

I also have an old Advent 400 table radio with a detachable speaker. It has a few watts output I think. It has an output jack on the back which can be used into a conventional preamp. Would the volume control on the radio work into the Dynaco and act as a preamp would? Or is the output level too much? I don't have the specs on this product.

Thanks.

[rmyauck]

I think the radio preamp idea may work setting it's output with the volume control as you will have some decent power. 3 yrs ago when I got an Eico HF-12 I tried a with a portable CD player and it didn't sound so good using the headphone output and volume control . Probably too low an output as you thought! I was trying to see how it would sound at the tape input, so it would work like an HF-14 which doesn't have the preamp section.

Can't hurt to try it.

Randy

[nyazzip]

i have an '80s CD player that also has a 1/4" headphone jack, with a mini volume control. i used a 1/4" stereo jack-to-stereo RCA adapter, into my st-35, and it worked great. to tell the truth i can't seem to hear the difference between that route, and the proper RCA line outs in the rear of the unit...

[Stunch]

A belated thanks guys. Is the headphone output of a portable CD player AC or DC. I'm thinking AC, but is it possible there's a little DC offset? I don't have a DC blocking cap on my Dynaco ST-35.

[rmyauck]

I bet that was the problem with mine!

Randy

[paart]

The headphone output from a CD player delivers an AC signal. All audio signals are AC. However, there's a possibility that there is also a DC component from the output at certain times, if not all the time. It sounds as if you removed the C1 capacitors from your ST-35. Personally, I would never bypass this input cap, at anytime a solid state source is used with this amplifier. It's risky, and the type of damage this can cause to speakers is very real. I doubt that you would notice any difference in sound quality if you used a .1 mfd polypropylene cap in this position. The voltage rating of this cap is unimportant.

[corndog71]

A good starter preamp to try is the Bottlehead Quickie. It's only $99!

[Stunch]

The headphone output of my portable CDP works really well into the ST35. With the volume control all the way up, it's a little too loud for me at times, but then again I'm not exactly young anymore!

It seems a good way to break in the amp and tubes before it gets hooked into my all analog system. It sounds surprisingly good.