Posted by Walt N

August 07, 2022 - 10:25 am

I'm using the Cortina to digitize my LP collection (probably stupid). Anyhow, only the Cortina preamp is being used, which feeds over to the Line Input on my computer where it's recorded by Audacity. I generally listen via the computer speakers. So, this noise (which is like a hiss) is infrequent so I'm not sure how to isolate it. I'll leave the Cortina's speakers on from now on to see if it comes from there or from the computer's speakers. Could be glitch in the computer speaker setup.

Posted by Steve L.

July 25, 2022 - 01:49 pm

Hi Walt, Without more info about the nature of the sound, it's hard to say much. However, I sometimes hear noises from vintage equipment which fit your description. Those typically make kind of a scratchy sound and may be accompanied by a hiss of varying level. Like yours, I've heard them end with a pop sometimes. I take those to be a flaky resistor or intermittent connection or solder joint. They usually go away on their own. As long as the Cortina is working well and the noise is gone, I wouldn't worry about it. But if you were determined to hunt it down, using heat and cold on the board(s) might bring it out or make it go away.

Posted by Walt N

July 25, 2022 - 11:08 am

I had an odd occurrence with the Cortina. I'm using it mostly to move a bunch of LPs to digital. I turned it on (set to phono) as usual. I suddenly noticed a noise coming from the speakers, then there was a pop. The noise is hard to describe. It now seems to be fine. Any ideas?

Posted by Steve L.

June 04, 2022 - 11:42 am

It's nice to hear that you've been enjoying the Cortina. [By the way, I trust you did modify the output stage bias as discussed in the article, else that would explain the warm chassis.] And overlooking the PC line out level settings isn't stupid at all! It's not unusual to overlook something, even if it seems obvious after discovering it. I've overlooked turning the power supply on once or twice in my time. By the way, I've thought about you and the RP-100 a few times. NOT that I intend to restore mine--that would be a huge commitment. But I wondered what it might take to improve the record/play amps and what low-noise transistors were available then. This was triggered again yesterday as I was reading Chuck Penson's excellent book, Heathkit Hifi and Stereo Products. He covered their AD-16 tape deck, which was competitive with the Eico RP-100 for 1966-1968. The transistor list for the AD-16 included four 2N2613s, which was a low noise germanium PNP transistor. That might improve on the 2N407s which Eico used. (But it might also require some redesign.) That tended to answer the question about low noise transistors. Now, I probably shouldn't have mentioned this because I'm certainly not prepared to dive into it right now, so it's just idle talk. It's also off-topic for the Cortina article, so I apologize about that too!

Posted by Walt N

June 04, 2022 - 10:27 am

Couple of "don't matter" things. I did not need the second line amp for line out from my computer. I can adjust line out to anything I want (duh). The RP-100 has plenty of input if I crank line out a bit. Stupidity strikes again! Second thing is I've been using the Cortina quite a bit, and it's still going strong! Gets quite warm, but doesn't seem to hurt it.

Posted by Steve L.

March 28, 2022 - 03:21 pm

Hi Walt, Yes, replacing the C103 caps is well worth doing. Hi-K ceramics are only good for applications in which distortion and accuracy don't matter at all, like power supply bypassing. Their capacitance can change markedly with time and voltage. Eico really shouldn't have used them in this application.