NOS Amperex 12AU7 in Crack...

[dstrimbu]

Hi gang,

I sprang for a NOS Amperex Bugle Boy ("Made in Holland") on eBay.  I just had to make that first "roll" a good one.  The stock Electro-Harmonix was smoothing out nicely, but still had a bit of edginess / brittleness on the HD-600s (stock cable) that I knew would never go away.  (At least I didn't think that it would; but then, the stock HD-600 cable is pretty 'brittle' on its own...)

Well, listening to Duncan Sheik's first album (1996, Atlantic 82879-2) via the Musical Fidelity A308CD, direct connected via 1m AudioQuest Copperheads, confirms (at least to my ageing ears) the Amperex legend.  There's a liquidity here that I never heard with the stock E-H (which is now clocking between 100-120 hours under drive, in circuit).

My dad and mom are out in Arizona for the winter... they love flea markets.  I'm going to send them on an Amperex quest... I'll see what other wonders are out there for the taking...

Cheers,

-don

[Lee Hankins]

Don,

I have rolled 8 different 12AU7's (including your Amperex) through the Crack, none come close to any 12BH7A that I have tried so far, even a made in Japan Toshiba.  Before you spend a bunch of money on the 12AU7 family I would recommend trying one of the following: Sylvania 12BH7 dark grey oval plate w/ thick O-getter from 60s and no copper grid posts, marked w/ red top; RCA 12BH7A long black plate w/ double wings & dimpled square-getter, late 50s, white lettering; RCA 12BH7A square black plate w/ double wings & O-getter, late 50s, red lettering.

Cordially,
Lee Hankins

[spear321]

Before I buy any, as anyone tried the 12BH7 in a stock (non speedball) crack?

Did it work? and how did it sound?

Paul

PS Have bought an Amperex bugleboy 12AU7 labelled made in England, is this possible?

[dstrimbu]

Hello Lee, thanks so much for the response.  As per Paul's reply, also - can we run the 12BH7 in a stock Crack?

From what I can discern, the 12BH7 has lower internal plate resistance than the 12AU7 (5300 vs 7700), which could / might be countered by the lower mu of the 12BH7.  So, how will the 'BH7s affect the overall gain structure of the Crack?  I've also read that circuits using anode resistor loads will generate higher gain from the 12BH7... but that's where my "skills" run out... :-)

I'll tell you why I ask:  I'm running my gain control around 9 o'clock a lot of the time, into the HD-600s... if I drop too much lower, I lose channel-to-channel balance.  Don't want to mod this Crack if I can help it; I plan to order another (with a Speedball) asap for further experimentation.

And Paul:  it appears that the cartoon bugle boy appeared on many Phillips "conglomerate" tubes over the years.  You need to check the etched markings on the tube base to discern the real source / mfg location...  I'm learning, too.  :-)

Thanks gents!

Don

[spear321]

Looked at the code after I posted, it is for Mullards Mitcham in London Factory, and looks as I have a short plate 13D5 to compare with like a long plate one.

Which is OK as I only paided

[Nocturnal]

I'd appreciate an answer to this as well .. will the 12BH7A tube work in a stock Crack?

[Lee Hankins]

Looks like no one wants to respond to your question.  I do not see anything that would not allow the 12BH7 to be used in a stock Crack.  The Speedball is just a C4S for the tubes, so if it works in the speedball it will work in the stock Crack.

Lee Hankins