Difference Between Ampex 620 and 2010 Amps?

[nikon f]

What is the difference between the Ampex 620 and 2010 suitcase amp/speaker setups?

 

[twiiii]

I remember them laying around the radio station and at the Hifi dealership, but I don't remember enough About them . Google them and you'll find pictures, schematics. As I remember our chief engineer at the station saying the 2010 used a JBL driver. I heard them a few times and they were surprising. The later models that were SS used a tweeter and woofer, and were better. But fr a full range speaker the 2010 was quite surprising. I have a AA 620 and some day I want a companion.

 

[mrwood200]

Looks like the key differences are the tube lineup & cabinet
620: (2) 6V6 (1) 12AU7 (1) 5879 and (1) 6AX5 Rectifier.
2010: (2) 6V6 (1) 12AU7 (1) 6267/EF86 and (1) 6AX5 Rectifier. (larger cabinet)

Here are some notes I have collected:

Very similar in sound to these (and cheaper on eBay) are the A692 and 2010 gray-case speakers.

• The A692 is the original amp design with the 5879 first stage.
  
  
• The 2010 is the second generation amp with the EF86 first stage. The gray-case speakers have a bit deeper bass. The original 620 was designed to be flat from 60hz to 10khz in open-air. The amplifier is designed to EQ-compensate for the cabinet. The same EQ circuit was used for the gray-case speakers but the cabinet has a bit more volume, hence the deeper bass.
  
  
• The 2012 and later dark-brown 621 speakers had ports to further extend bass and some employed a crossover a tweeter.
  
  
• These are wonderful amps for most vinyl listening, but they are not the sort of full-range speakers that modern ears like. The original 620's have an external speaker jack on the front that has a built-in switch activated by plugging the 1/4" connector in that defeats the tone-compensation network and thus renders the amplifier flat. In other words, you get the benefit of a nice 10W Williamson amp that you can use with a modern (16-ohm) speaker and you have your basic Ampex combo.
  
  
• The Ampex 622 is similar, but without the additional inputs and flexibility of the 620.
  

These were originally sold in the 1960s as monitors for matching Ampex tape recorders, but many have become separated over the past 40 years. Although they only extend down to the 60-80Hz region, this is a true entry-level high-end component and a real sleeper.

 

[johnblue]

From what I understand, plenty of people remove them from the box and remove the filter networks and make full frequency mono Amps with them. I think its pretty common practice even with the speaker to remove that compensating stuff.

Huge output transformers for just one 8 inch speaker.

In the end, I think after a tweak, as a stand alone amp. it would hold its own against any 15w amp.

Ampex is just rock solid gear.