MC prepre with submini tubes

PTSOUNDLAB · 20th April 2009, 09:30 AM

Hello

does somebody tried subminiature tubes like 611,6112,6021,5703,... for MC prepre ?

Thanks

Best Regards

Pascal

Geek · 20th April 2009, 11:02 AM

Hi,

IMO, the very low Gm inherent of the submini's mixed with a MC sounds like a baaaaaaaad idea to me

Cheers!

kevinkr · 20th April 2009, 09:13 PM

Most of the types listed have higher Gm than older garden variety audio tubes, however the 5842 and D3A will be much quieter, and have much higher Gm. I have used 5744 and 6021 in MM phono stages and found them barely quiet enough - I also did not like the sound that much.

tinitus · 20th April 2009, 10:27 PM

Didnt the Italian magazine TNT have a preamp design with nuvistor tubes, or is that completely different

But pure low output MC, isnt that still done with stepup trafo

Eli Duttman · 21st April 2009, 12:48 AM

IMO, the idea of any tube in a LOMC prepre ("head") amp is very bad. S/N ratio is the diety in this situation and tubes simply are not up to the job.

Either you use a step up trafo (SUT) in front of a tubed MM level phono preamp or you use Allen Wright's hybrid cascode.

JesseG · 21st April 2009, 01:16 AM

The most recent UHF mag (No. 86) has a review of the Allnic H-1200 phono pre which uses 6112 and 6021 twin triodes. There is a fairly good photo of the innards in the review.

It uses step-up trafos for the MC stage - probably to get 'round the noise issue.

They had some nice thigs to say, but my overall impression was that they were trying to find nice things to say. However it was not a disaster.

So, it can be done

HollowState · 21st April 2009, 02:16 AM

Quote:

Originally posted by JesseG
It uses step-up trafos for the MC stage - probably to get 'round the noise issue.

So, it can be done

The original question was could submins be use for an MC preamp. Since the stepup transformer is the MC amplification stage, then they're not really doing it.

I believe that a transformer is the only really neutral sounding device. I've had the oppotrunity to use several active MC preamps including the AR MC-33 as well as SS battery powered units. All the active units, to my ears, added their own color or flavor to the overall sound as compaired to a good transformer. By good I mean a transformer specifically made for very low level signals from a MC cartridge like Lundahl's or the Cotter I still use. Not UTC's. And I'm willing to sacrifice a tiny tiny bit of speed for the neutrality of a transformer.

EC8010 · 21st April 2009, 05:45 PM

The other huge advantage of an MC transformer is that the input can be made balanced and floating. If you use at a valve at MC sensitivity hum becomes a serious issue.

grhughes · 21st April 2009, 05:50 PM

They are too prone to oscillation. I used a AKG-Norelco C12 condenser microphone that used 7586 (I think). One mic howled right out of the box. The other one developed the same howl after about 50 hours. I used a Moviola-Magnasync dubber recorder that used the submin glass tubes with good success with long life. Ray

Alastair E · 21st April 2009, 08:06 PM

Built with Nuvistors many times, --Never had any oscillation problems at all....

Great little devices, But the American ones suck big-time. Go for some nice quiet Russian ones.....

20th April 2009, 09:30 AM	#1
PTSOUNDLAB diyAudio Member Join Date: Dec 2001 Location: FRANCE / TOULOUSE	MC prepre with submini tubes Hello does somebody tried subminiature tubes like 611,6112,6021,5703,... for MC prepre ? Thanks Best Regards Pascal

20th April 2009, 09:13 PM	#3
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	Most of the types listed have higher Gm than older garden variety audio tubes, however the 5842 and D3A will be much quieter, and have much higher Gm. I have used 5744 and 6021 in MM phono stages and found them barely quiet enough - I also did not like the sound that much. __________________ www.kta-hifi.net

21st April 2009, 12:48 AM	#5
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	IMO, the idea of any tube in a LOMC prepre ("head") amp is very bad. S/N ratio is the diety in this situation and tubes simply are not up to the job. Either you use a step up trafo (SUT) in front of a tubed MM level phono preamp or you use Allen Wright's hybrid cascode. __________________ Eli D.

21st April 2009, 01:16 AM	#6
JesseG diyAudio Member Join Date: Jul 2005 Location: Mid coast of British Columbia	The most recent UHF mag (No. 86) has a review of the Allnic H-1200 phono pre which uses 6112 and 6021 twin triodes. There is a fairly good photo of the innards in the review. It uses step-up trafos for the MC stage - probably to get 'round the noise issue. They had some nice thigs to say, but my overall impression was that they were trying to find nice things to say. However it was not a disaster. So, it can be done __________________ "If we crashed our cars as often as we crashed our computers, we'd all be dead!"

21st April 2009, 05:45 PM	#8
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	The other huge advantage of an MC transformer is that the input can be made balanced and floating. If you use at a valve at MC sensitivity hum becomes a serious issue. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

20th April 2009, 11:02 AM	#2
Geek diyAudio Member Join Date: Sep 2004	Hi, IMO, the very low Gm inherent of the submini's mixed with a MC sounds like a baaaaaaaad idea to me Cheers!

20th April 2009, 10:27 PM	#4
tinitus diyAudio Moderator Join Date: Nov 2005	Didnt the Italian magazine TNT have a preamp design with nuvistor tubes, or is that completely different But pure low output MC, isnt that still done with stepup trafo

21st April 2009, 05:50 PM	#9
grhughes diyAudio Member Join Date: Mar 2005 Location: Cubicle Sweet Cubicle, SW, MO, USA	Wouldn't touch nuvistors with a 12 foot mic boom! They are too prone to oscillation. I used a AKG-Norelco C12 condenser microphone that used 7586 (I think). One mic howled right out of the box. The other one developed the same howl after about 50 hours. I used a Moviola-Magnasync dubber recorder that used the submin glass tubes with good success with long life. Ray __________________ "The gift of imagination is the gift of the gods imparted to a few for which they receive innumerable kicks in the a$$ their entire life." Le Corbusier (Edward Jenneret)

21st April 2009, 08:06 PM	#10
Alastair E diyAudio Member Join Date: Feb 2004 Location: South Wales	Built with Nuvistors many times, --Never had any oscillation problems at all.... Great little devices, But the American ones suck big-time. Go for some nice quiet Russian ones..... __________________ Das Beste Oder Nichts

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