Author Topic: Phono Preamp 12AX7 tube help  (Read 2049 times)

Offline Putz

  • Obsessively Audiophilic
  • ****
  • Posts: 330
Phono Preamp 12AX7 tube help
« on: August 17, 2017, 08:07:37 PM »
So I bought a used Zesto Andros 1.2 Phono Preamp which I am absolutely loving. It uses 4 12AX7 tubes split between input and output stages. The OEM tubes are •Four (4) Gold pin JJ ECC83S/12AX7 vacuum tubes with high quality gold pin ceramic sockets. My cart is LOMC 0.4 mv.

I'd like to do some rolling. Zesto manual says: Only a 12AX7/ECC83s type will work and we recommend that it is high gain/ low noise tube. Zesto recommended rolling the 2 Input tubes would have the most effect.

Looking at currently available NOS and nearly NOS tubes, most of them are labelled ECC83.

My questions:

1. Are ECC83 and ECC83s the same type of tube? Other than the JJs, not seeing many tubes labeled ECC83s.

2. How do I tell if a tube is high gain/low noise?

3. I was looking at these tubes on ebay:Amperex ECC83 12AX7 Holland Fisher Tube Amp Pair--Test 1400/1600 & 1400/1700 where min good is 875 on Hickok 539C. Are these tubes something that would work well in the Zesto?

I sent an email to Zesto with these questions and am awaiting a reply, but AN members probably know more anyway.

I'm not looking to spend a fortune on these tubes. Looking to keep it around $50 a tube.




Offline rollo

  • Industry Participant
  • *
  • Posts: 6982
  • Rollo Audio - Home demo the only way to know
Re: Phono Preamp 12AX7 tube help
« Reply #1 on: August 18, 2017, 10:28:46 AM »
  First I would consider the tonal character of what you have now to what you desire. Is it warm, bright, lean, fat, neutral what ? Once you have determined your character choosing a new tube becomes easier knowing the character of the new tube.
Amperex are kinda in the middle character wise.


charles
contact me  at rollo14@verizon.net or visit us on Facebook
Lamm Industries - Aqua Acoustic, Formula & La Scala DAC- INNUOS  - Rethm - Kuzma - QLN - Audio Hungary Qualiton - Fritz speakers -Gigawatt -Vinnie Rossi,TWL, Swiss Cables, Merason DAC.