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PostPosted: Thu Feb 01, 2018 12:46 pm 
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Muriel
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Hi,

BillBrown wrote:
https://www.musicdirect.com/tubes/ifi-nos-5670-6922-vacuum-tubes-pr

I suppose the question is in testing and matching(?)


Not only, the iFi 5670 comes with an adapter to 6922/ECC88 pinout and yes, they run through a batch of processes.

Incidentally, once current stocks are sold the iFi 5670/6922 will be cancelled.

In our last volume purchase of 5670's one of the oldest, most reliable and reputed whole seller of NOS Tubes could only fill over half our order.

Even at a premium they could locate any more substantial stocks. So unless the US Army, Navy or Airforce sits on another job-lot of 100,000 5670 (and forgot about it), 5670's are about to become VERY expensive. Get them while you can.

https://www.head-fi.org/threads/ifi-aud ... t-13988555

We have been bunkering fairly substantial stocks over time, but it's still not enough vor volume use and retail sale.

Ciao T

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PostPosted: Thu Feb 01, 2018 2:42 pm 
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Sheep

Joined: Sun Aug 18, 2013 6:08 pm
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Thorsten,

I certainly didn't mean to imply a lack of value in the ifi branded ones, or even really compare the prices. I was thinking more in the context of which is the necessary tool for the job in a DIY, one-off effort. I'd love to have a supply of your tested and matched ones!

Bill


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PostPosted: Thu Feb 01, 2018 10:40 pm 
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Sheep

Joined: Sun Aug 18, 2013 6:08 pm
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The UL plate curves sure do get strange at higher g1 voltages; they begin to look "pentode-like," with a sort-of knee; and at Vg1=0 look quite funky. Perhaps related to low Va relative to the screen(?).

I wondered if, with higher RL/flatter curves, you can even get the grid to 0V or what would happen; perhaps that is the source of the tops getting "crushed" and the amp saturating(?).

Interesting stuff.

Bill


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PostPosted: Sun Feb 04, 2018 2:45 pm 
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Muriel
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BillBrown wrote:
I wondered if, with higher RL/flatter curves, you can even get the grid to 0V or what would happen; perhaps that is the source of the tops getting "crushed" and the amp saturating(?).


It is clipping, but the clipping is rather soft.

I'm usually concerned with an amplifier clipping behaviour insofar that I like the amp to exit clipping cleanly and to clip gracefully.

Ciao T

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