Recent content by audmod01

I had to cut some edges of the 3/4" thick plywood using a skill saw. My cutting efforts were not the straightest and when some pieces were placed against each other the surfaces were not straight and smooth. I have a stationary belt and disc sander that I used to get the edges smooth and...

Before beginning I read through Roger's article several times to get a general understanding of the sequences to assembling the IDS-25 speaker systems. I used some thin foam adhesive backed tape on the back side of the outer plastic flange beyond the rubber cone surrounds of each speaker. This...

I progressed far enough to be able to test my DIY IDS-25 speakers. They do indeed produce the listening results mentioned by Rich Andrews. Currently I am in the process of completing the installation of the 22 baffles in the cabinets. Each cabinet has 11 baffles mounted horizontally to help...

I thought I would post here as I am in the process of constructing a copy of Roger Russell's IDS-25 speakers. I contacted Roger while he was still living and discussed using the Tymphany TC9FD18-08 3 1/2" drivers available from Parts Express. Roger confirmed my choice and noted that the design...

Terry; I can see up inside behind the front panel, but do not see the two nuts and lock-washers you mentioned. Even with a flashlight and moving the panel as much as I dare, I just do not see those items. This is after I have already loosened the 1/4" hex head machine screws on the left and...

I looked up the service information on the Marantz 4240 and it appears that its FM front end uses a 2SK19Y JFET RF amplifier transistor. I was unable to find any data on that transistor which showed typical noise figure. I did find some review data...

Just about any modern FM receiver or tuner made since the early 1970s has an RF front end that is as sensitive as any of the RF preamps. Adding a preamp just increases the chance of causing cross-modulation of RF signals and adding distortion as a result. Also do not use an amplified or "active"...

I was unable to repair the ultrasonic transmit transducer in the remote control hand unit. So I am into plan B now. I found that Murata makes a set of ultrasonic transducers intended for use in automobile proximity detectors. It operates in the 40kHz region just like the original transducer and...

For an AM antenna, I used one from a Fisher 610ST that was being sacrificed for parts. The AM rod antenna on them is the same electrically as that of the 800-C, so all I had to do was create a way to mount it. I wound up making a new bracket for its mounting (the original pivot bracket was...

ginshin99; Yes the high level input sensitivity of the A-300 is 125mv. Even the A-500 has a high level input sensitivity of 200mv, so both amps have high gain in their line amp stages. What I would suggest in the case of the CD player is get a stereo 500K ohm audio taper volume control and...

I replaced both C8 and C18 with polypropylene metalizedl film capacitors made by Panasonic. In the serial number sequence that I bought, H-K used film capacitors there instead of ceramic disc, so evidently the version you saw was a production change (maybe due to bean counters). The only...

Thorne; Excellent work! There are some areas of the receiver that are very difficult to work in. One is the MPX decoder circuit MPX-65. Over the years of production the early ones had many discrete parts packed in so tightly that it makes troubleshooting difficult at best. The later production...

I had been trying to clean up the knobs on the A-500. There were some spots of corrosion on the area covered by ridges on each knob. I tried using chrome polish on them more than one time and never managed to get them to look bright and flawless like they were originally. The knobs are somewhat...

Today I brought out a Technics SL-23A belt driven turntable equipped with an Ortofon cartridge and listened to some Tijuana Brass and then Emperor's Concerto by Beethoven, Arturo Rubenstein and Eric Leinsdorf (1964 RCA Dynagrove) with the A-300 connected to my AR-2Ax clones and enjoyed some nice...

The set of Metric Forstner bits arrived yesterday. Today I drilled the holes in the jack mounting plates and installed the new RCA Jacks. They look nice and so do the brass 4-40 screws I used for mounting the plates to the chassis. I may just leave them as is. After I tightened the retaining...