10-23-2006, 12:43 PM
Hi Madghost,
There are some differences. Just glancing at the schematic the 70 volume control is in the antenna circuit. The 90 has its own 2nd detector and avc. The 70 looks to me that it doesn't. Also The volume is also controlled by changing the bias on the cathodes of two of the 24 tubes on the 70. The 90 also has two stages of audio amplification before the final output tube. The 70 uses the same tube as the 2nd detector and audio amplifaction.
I'm sure Ron and Chuck could tell you more. Both of my 90's play great. With a good antenna I pick up many stations across the dial. Sorry to say I have never listened a 70.
Hope this helps
Terry
There are some differences. Just glancing at the schematic the 70 volume control is in the antenna circuit. The 90 has its own 2nd detector and avc. The 70 looks to me that it doesn't. Also The volume is also controlled by changing the bias on the cathodes of two of the 24 tubes on the 70. The 90 also has two stages of audio amplification before the final output tube. The 70 uses the same tube as the 2nd detector and audio amplifaction.
I'm sure Ron and Chuck could tell you more. Both of my 90's play great. With a good antenna I pick up many stations across the dial. Sorry to say I have never listened a 70.
Hope this helps
Terry
