Possible low watt tube amp in the making

wallyw26 · January 8th, 2007, 08:54 PM

An older relative asked if I would be interested in an old tape recorder he had in the closet. I had a look and discovered it was a 60's vintage Akai M-8.
It was pretty complete and in amazingly good condition. He told me he hadn't used it in years. One of the things he had was a Sams Photofact book with the complete schematic, parts list etc. I picked it up this past weekend and started reading the Photofact book about it. My mouth dropped when I looked at the amplifier circuit. First audio stage tube is a 6267 (it does have a high-Z microphone input). The second audio stage tube is a 12AX7, there's also a tube for the recorder's bias circuit, a 6X4 rectifier and a 6BQ5 for the output, rated at about 6 watts. If you've even seen this model (there were a couple on e-bay) you'll note it has 2 independent record/playback channels with the same tube compliment.

So it goes to work with me tomorrow and it'll spend the day on a variac.
I'll also open it up for a cleaning.

He also had a matching pair of speaker cabinets for the unit each with a 10" woofer and a 3 1/2" tweeter.

Time to brush up on the soldering skills, this could be fun!

wallyw26 · January 10th, 2007, 11:22 PM

First of all to Platefire....that thing is way cool. A lot of old tube tape recorders from the 60's have Hi-Z mic inputs which are a starting point for mods. On my project, The Akai M-8 survived the variac nicely. Transport works well and it plays back tapes. It's a keeper even if it won't transition into a low watt guitar amp. This weekend I'll start experimenting with it. I'll try to post pics. Thanks!

January 8th, 2007, 08:54 PM	#1 (permalink)
wallyw26 TDPRI Member Join Date: Dec 2006 Location: Texas Age: 56 Posts: 23	Possible low watt tube amp in the making An older relative asked if I would be interested in an old tape recorder he had in the closet. I had a look and discovered it was a 60's vintage Akai M-8. It was pretty complete and in amazingly good condition. He told me he hadn't used it in years. One of the things he had was a Sams Photofact book with the complete schematic, parts list etc. I picked it up this past weekend and started reading the Photofact book about it. My mouth dropped when I looked at the amplifier circuit. First audio stage tube is a 6267 (it does have a high-Z microphone input). The second audio stage tube is a 12AX7, there's also a tube for the recorder's bias circuit, a 6X4 rectifier and a 6BQ5 for the output, rated at about 6 watts. If you've even seen this model (there were a couple on e-bay) you'll note it has 2 independent record/playback channels with the same tube compliment. So it goes to work with me tomorrow and it'll spend the day on a variac. I'll also open it up for a cleaning. He also had a matching pair of speaker cabinets for the unit each with a 10" woofer and a 3 1/2" tweeter. Time to brush up on the soldering skills, this could be fun!

January 10th, 2007, 11:22 PM	#2 (permalink)
wallyw26 TDPRI Member Join Date: Dec 2006 Location: Texas Age: 56 Posts: 23	First of all to Platefire....that thing is way cool. A lot of old tube tape recorders from the 60's have Hi-Z mic inputs which are a starting point for mods. On my project, The Akai M-8 survived the variac nicely. Transport works well and it plays back tapes. It's a keeper even if it won't transition into a low watt guitar amp. This weekend I'll start experimenting with it. I'll try to post pics. Thanks!