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AUDIO FORUMS >> General Discussion and Support >> Hazen enabled??
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Message started by bumpy on 05/02/21 at 13:19:30

Title: Hazen enabled??
Post by bumpy on 05/02/21 at 13:19:30

Can someone explain to me please in very simple terms what Hazen enabled means.

My reading suggests that it allows the use of cheaper Russian valves in a Zen amp but the downside is that it shortens the life of modern tubes. How much of this is fact?

Title: Re: Hazen enabled??
Post by Lon on 05/02/21 at 14:47:27

Here's the original paper on it:

https://www.decware.com/newsite/paper146.html

I don't know about shortening the life of tubes, modern or vintage.

Title: Re: Hazen enabled??
Post by MrDerrick on 05/02/21 at 14:48:34

Cheaper Russian Tubes?

The Hazen Grid Mod is also explained in the manuals for the;

SE84UFO25 which applies to using the SV83.
SE34I.5 which applies to using the EL34.

What cheap tubes?

Title: Re: Hazen enabled??
Post by CAJames on 05/02/21 at 15:37:33

It's a way of wiring 6P15P tubes so they sound better. It works for "cheap Russian tubes" aka 6P15P but not for EL84s which work in the amp but don't sound as good.

Title: Re: Hazen enabled??
Post by bumpy on 05/02/21 at 16:58:52

It's a way of wiring 6P15P tubes so they sound better. It works for "cheap Russian tubes" aka 6P15P but not for EL84s which work in the amp but don't sound as good.

Just to clarify then, do the EL84s sound worse in the Hazen modified amp than the amp without Hazen mod.

Title: Re: Hazen enabled??
Post by Steve Deckert on 05/02/21 at 17:07:21

Let's take some confusion out of this by eliminating the "cheap" Russian 6P15P, which Decware has never used.

Decware only uses 6P15P-EV

EL84's would so no different in an amplifier with the Hazen Grid Mod than in one without it.

Also the Hazen Grid Mod has ZERO effect on tube life.

Steve

Title: Re: Hazen enabled??
Post by will on 05/02/21 at 17:27:07

I think the Hazen mod sounds really good in the Decware amps that use EL34 types I have heard, NOS tubes or not. These same amps can sound great with other power tube types as well, so much so, I can't even recall which EL34 variants work with the mod, and until yesterday, I had not used EL34s in years in my Toriis. I just pick a tube that sounds great in my setup at the time. But the Hazen mod adds a nice refinement when using EL34 types. After a lot of system refinements over a few years, I put in some Brimar labelled RFT EL34s with short black bases, and they sound really sweet...amazing open/complex tops and rich mids.

Title: Re: Hazen enabled??
Post by bumpy on 05/03/21 at 08:51:08

Thanks guys and in particular Steve for taking the mystique out of this. Like all subjects one searches for on the Internet there is a lot of misinformation out there.
Cheers

Title: Re: Hazen enabled??
Post by canonken on 05/05/21 at 03:19:54

Appreciate Steve clarifying, and his own words from the UFO2 product page (mainly addressing the EL84 comment). I will assume this means knock yourself out, try some different tubes and enjoy:

"This amp is shipped with premium quality N.O.S. 6P15P-EV output tubes with gold grids rated at 5000 hours. These Russian military spec tubes are the top grade of what we came to know in this country as the SV83. You can also use EL84's without adjustments of any kind.

You'll find the 6P15P-EV to be unparalleled in speed and detail - in part because it is a video tube with much wider bandwidth then a normal audio tube. We think these are the best sounding most transparent tubes available today. The EL84 (6BQ5) is a bit warmer sounding giving the amp a different signature by just switching output tubes."