nuvistor MC step up

reinhard · 30th September 2004, 07:00 AM

Hello tubies,

can anyone help with information on nuvistor MC step up amplifier. As I know Conrad Johnson has made such things in the past. What about noise? Is the nuvistor a good part for that application?

Reinhard

SY · 30th September 2004, 11:37 AM

Difficult to find, expensive, and really microphonic. Oh, yeah, and not super quiet.

A better choice is something like a 417A.

Geek · 30th September 2004, 12:39 PM

Try four paralleled (8 sections) 12AX7WB's

jlsem · 30th September 2004, 01:22 PM

A pair of cascaded 8056 nuvistors with battery B+ can provide a very quiet MC phono pre-amp. Has anyone ever tried battery coupling? I've always thought this tube is a good candidate.

John

reinhard · 30th September 2004, 01:23 PM

Hello,

think that is what Aesthetix is doing. Is that really low noise or should I go for 6C45 or 437?

Reinhard

What can I do with my 40/40 pcs. of 2C51/2C52?

reinhard · 30th September 2004, 01:26 PM

Hello,

what do you mean with cascaded? SRPP, u-follower, cascode
or two stages?

Reinhard

jlsem · 30th September 2004, 01:31 PM

Two stages; the 8056 has a mu of 11 but can be operated very linearly with 12-24 vdc on the plate.

John

analog_sa · 30th September 2004, 01:36 PM

Quote:

Is that really low noise or should I go for 6C45 or 437?

Don't know about the noise but a 6S45 will absolutely kill paralleled 12AX7 soundwise. IN any case the noise will be very dependent upon PS noise.

fdegrove · 30th September 2004, 01:45 PM

Hi,

Quote:

Don't know about the noise but a 6S45 will absolutely kill paralleled 12AX7 soundwise.

If the datasheet is anything to go by req is ~100R which is extremely low.

If the curves are linear at Vg0 you can ground the cathode and couple the tube straight to the cartridge, one less cap in the signal path.

Otherwise it's an amazingly good tube for low level signal applications. Certainly one to consider for anything phono.

// 12AX7s is about the last thing you'd do for an MC stage IMHO.

Another candidate is the 6DJ8 which is what I used prior to the availability of the USSR special tubes.

Cheers,

SY · 30th September 2004, 01:48 PM

As a rule, voltage noise runs about 2.5/g_m. It takes a lot of 12AX7 sections to equal a proper high transconductance triode.

30th September 2004, 07:00 AM	#1
reinhard diyAudio Member Join Date: Dec 2000 Location: Germany	nuvistor MC step up Hello tubies, can anyone help with information on nuvistor MC step up amplifier. As I know Conrad Johnson has made such things in the past. What about noise? Is the nuvistor a good part for that application? Reinhard

30th September 2004, 11:37 AM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	Difficult to find, expensive, and really microphonic. Oh, yeah, and not super quiet. A better choice is something like a 417A. __________________ If there's a sucker born every minute, where do the rest of them come from?

30th September 2004, 01:23 PM	#5
reinhard diyAudio Member Join Date: Dec 2000 Location: Germany	8 paralled section of 12 AX 7 Hello, think that is what Aesthetix is doing. Is that really low noise or should I go for 6C45 or 437? Reinhard What can I do with my 40/40 pcs. of 2C51/2C52?

30th September 2004, 01:26 PM	#6
reinhard diyAudio Member Join Date: Dec 2000 Location: Germany	cascaded Hello, what do you mean with cascaded? SRPP, u-follower, cascode or two stages? Reinhard

30th September 2004, 01:48 PM	#10
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	As a rule, voltage noise runs about 2.5/g_m. It takes a lot of 12AX7 sections to equal a proper high transconductance triode. __________________ If there's a sucker born every minute, where do the rest of them come from?


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30th September 2004, 12:39 PM	#3
Geek diyAudio Member Join Date: Sep 2004	Try four paralleled (8 sections) 12AX7WB's

30th September 2004, 01:22 PM	#4
jlsem diyAudio Member Join Date: Jun 2003 Location: Dallas,TX	A pair of cascaded 8056 nuvistors with battery B+ can provide a very quiet MC phono pre-amp. Has anyone ever tried battery coupling? I've always thought this tube is a good candidate. John

30th September 2004, 01:31 PM	#7
jlsem diyAudio Member Join Date: Jun 2003 Location: Dallas,TX	Two stages; the 8056 has a mu of 11 but can be operated very linearly with 12-24 vdc on the plate. John

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