Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

His Master's Noise: A Thoroughly Modern Tube Phono Preamp
His Master's Noise: A Thoroughly Modern Tube Phono Preamp
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 7th February 2019, 03:34 AM   #561
TUBESMAN is offline TUBESMAN  Philippines
diyAudio Member
 
TUBESMAN's Avatar
 
Join Date: Apr 2004
Location: Muntinlupa City
I think I have a better one. Two will give a mu of 78 a Ra of 2700 transconductance of 30ma/V Rnoise 140ohms. Sy said it is a good tube but can be microphonic. It is a 6**5.
__________________
"The two most common elements in the universe are hydrogen . . . and stupidity."
Cordwainer Bird (May 27, 1934 – June 28, 2018)
  Reply With Quote
Old 12th February 2019, 11:37 PM   #562
jerrybenko is offline jerrybenko  Hungary
diyAudio Member
 
Join Date: Mar 2012
Location: Budapest
Read through this whole thread and really enjoyed it.. Not to mention the HMN design itself! Boy a few times I did read that first post.. Thanks a mill Sy for your contribution!
Inspiration implanted, parts are on the way (using Siemens E280F second generation + Tesla E88CC no.32), hope to build it in 1-2 weeks. Curently having an Ortofon X1-MC to start with which is a HOMC at about 2mV.

Now I have a question: Is it mandatory to use the DN2540 N channel depletion MOSFET? These buggers are nowhere to be found in my vicinity and I was thinking about simply using either a BJT-NMOS or a BJT-BJT CCS of course both implemented with low noise transistors matching the operating voltages and currents.
Would this make any significant difference..?

Thanks & regards,

Zsolt
  Reply With Quote
Old 13th February 2019, 12:56 AM   #563
jackinnj is offline jackinnj  United States
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
His Master's Noise: A Thoroughly Modern Tube Phono Preamp
Quote:
Originally Posted by jerrybenko View Post

Now I have a question: Is it mandatory to use the DN2540 N channel depletion MOSFET?
The depletion MOS has impedance in the tens of megOhms, but you could just as use a resistor. The advantage of DMOS is that it offers tremendous PSRR. If you use a nicely regulated power supply you can achieve much the same result.

I think SY was trying to make a point, but he has left us wandering in the desert.
  Reply With Quote
Old 13th February 2019, 07:20 AM   #564
jan.didden is offline jan.didden  Europe
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Westende Resort, BE coast
I just happened to run into Stuart ;-). He says:

Yes, it helps the PSR, but it also makes the biasing automatic. Since Merlin's paper came out on noise optimizing, if I were to do it again, I'd drop the current of the first stage to 10mA and the second stage to 5mA. The cathode follower could continue at 10mA.

The use of depletion mode MOS makes setup of the CCS easier, but if one wants to work out a new biasing scheme, other CCS configurations can work, there's nothing magic about the depletion mode cascode CCS other than simplicity. FWIW, Mouser has DN2540 at about a buck each, in stock.


Jan
__________________
Cable: a potential source of trouble interconnecting two other potential sources of trouble - Erik Margan
Linear Audio pubs and articles . The SilentSwitcher now at diyaudio store SilentSwitcher. Keeping in touch with SY.

Last edited by jan.didden; 13th February 2019 at 07:29 AM.
  Reply With Quote
Old 13th February 2019, 08:00 AM   #565
jerrybenko is offline jerrybenko  Hungary
diyAudio Member
 
Join Date: Mar 2012
Location: Budapest
Many thanks Jack, Jan (and Stuart - remotely )

For some reason it's difficult to find N-channel depletion mode mosfets around here (Hungary) and I try to avoid shipping from abroad as that takes time and I'm impatient having all esle in my possession.. But I'm gonna check again for DMOS transistors here and - duhh - order online if need be. I mean this design deserves to make no compromise.

In the relevant datasheets I see that the internal plate resistance of the E280F is 1k8 and the D3a has 1k9 (both triode strapped). Should this difference worry me in terms of driving the the RIAA network?
  Reply With Quote
Old 13th February 2019, 08:09 AM   #566
jan.didden is offline jan.didden  Europe
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Westende Resort, BE coast
Did you check TME electronics? They pretty big in your part of Europe.

Edit: they have the SMD version for 0.7 euro:

Transfer Multisort Elektronik - On-line Catalogue | 250 000 products offered.

Jan
__________________
Cable: a potential source of trouble interconnecting two other potential sources of trouble - Erik Margan
Linear Audio pubs and articles . The SilentSwitcher now at diyaudio store SilentSwitcher. Keeping in touch with SY.

Last edited by jan.didden; 13th February 2019 at 08:12 AM.
  Reply With Quote
Old 13th February 2019, 11:49 AM   #567
jerrybenko is offline jerrybenko  Hungary
diyAudio Member
 
Join Date: Mar 2012
Location: Budapest
Thanks Jan, brilliant, TME even have the TO-220 version for about EUR 1.5 a piece!
DN2540N5-G MICROCHIP TECHNOLOGY - Tranzisztor: N-MOSFET | TME Hungary Kft. - Elektronikai alkatreszek

(On a side note, literary none of the local shops have any depletion mode devices...)
  Reply With Quote
Old 13th February 2019, 01:48 PM   #568
frankwilker is offline frankwilker  Germany
diyAudio Member
 
Join Date: Nov 2011
Location: Duisburg
Hi,
There is a seller in GB, where you can get the D3a for a little more than 20€ a piece.
  Reply With Quote
Old 13th February 2019, 01:58 PM   #569
frankwilker is offline frankwilker  Germany
diyAudio Member
 
Join Date: Nov 2011
Location: Duisburg
I used also the 6J52P (6Z52P). Very nice. But i donīt measured the RIAA curve.
  Reply With Quote
Old 13th February 2019, 04:19 PM   #570
jackinnj is offline jackinnj  United States
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
His Master's Noise: A Thoroughly Modern Tube Phono Preamp
Let's say you want to use the 20k resistor, but have a tube with anode resistance of a different value. Here are some fundamental relations.

R1/R2= 6.877
C1/C2= 2.916
C1= T4/R2 = 318e-6/R2

If you have a tube with Rp of 10k, R1 has become Rp + 20k = 30k, thus:
R2 4.36k,
C1 72.9nF,
C2 25nF
  Reply With Quote

Reply


His Master's Noise: A Thoroughly Modern Tube Phono PreampHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Low noise transistor and noise figure Real_Macgyver Solid State 28 27th July 2012 09:42 AM
noise planarboy Analogue Source 2 11th February 2008 08:06 AM
Still have noise. pjanda1 Chip Amps 40 17th March 2006 03:16 PM
Help with noise davidlzimmer Chip Amps 25 5th March 2006 09:39 PM
Noise Bukitoo Analogue Source 2 17th March 2004 02:37 PM


New To Site? Need Help?

All times are GMT. The time now is 05:36 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki