Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: softwarejanitor on November 09, 2010, 08:48:58 pm
-
I won another Motorola tube amp from an old console record player in an eBay auction last week... It should be here in the next couple days... Its an HS-475 which is a 1956 model. It uses 5Y3 rectifier, two 6V6 power tubes and the pre-amp section is 6AU6, 12AU7, 12AU7 driver/inverter. I've got another HS-475 I've already converted to a guitar amp with two 12" Motorola Golden Voice branded Heppner speakers in a tweed covered combo cabinet I built. This one is coming with a Jensen 15" speaker and I am planning to build a tweed covered combo cabinet for it. I will mod the circuit similarly to the other one I have... removing the "loudness" compensation circuit from the back of the volume pot, replacing the feedback resistor at R26 from 5.6k ohm to 22k ohm and swapping out the 2nd pre-amp tube from a 12AU7 to a 12AT7. I'm planning to take pics of the conversion process and building the cabinet as I go along this time and post them.
-
I'll look forward to seeing the pictures of your amp conversion. Thanks for being willing to share that.
With respect, Tubenit
-
I received the HS-475 chassis and Jensen 15 today. They look even better than I expected. Other than a little dust they look virtually brand new. I stopped by Fry's today and picked up the rest of the parts I need for the guitar amp conversion... 8' 3 prong power cord, 250V ON-OFF toggle switch, 250V fuse holder, a pack of 2A fuses, a couple packs of 1/4" mono jacks and a pack of 1W 22K ohm resistors. I will start work on the conversion later this week or this weekend and will be taking pics of the process to post. After that I will start on building the cabinet and take pics to post of that as well.