Posted by John K.

February 17, 2024 - 09:29 pm

I don't know how I tripped across this, but it brings back memories! I bought the cortina kit in 1968, when I was in 9th grade. I used that thing all through college until 1976 when I had a real job and bought a Pioneer Sx-1250... I always had a bunch of power transistors around for when someone would inevitably short wires in my dorm. I use the equipment in the school lab to match beta. Great little amp... nice sound.. lots of memories... thanks for the tour after all these years!

Posted by Steve L.

August 07, 2022 - 02:35 pm

Hi Walt, I agree, that narrowing the possible sources of the noise to either the Cortina or the computer equipment is a good move. While the Cortina is suspect because of its age, there is so much more complexity on the computer side, it incurs risk as well. I don't see anything "stupid" about digitizing the LPs. Makes them more accessible and portable. Back in the 1970s, I used to record each new LP at the very first playing. That preserved the (hopefully) pristine pressing and made play more convenient. With Dolby (B) and CrO2 tape, my Hitachi D800 could reproduce the new record almost perfectly.

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!