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Tube phono preamp DIY suggestions

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Posted on November 30, 2015 at 14:44:42
fredtr
Audiophile

Posts: 1987
Location: Phoenix
Joined: January 4, 2005
 I would like to build my own tube MM phono preamp. I looked through older threads about this and am wondering if there are any new suggestions. I did build one based on the Shure M65 and it came out OK but I am looking for a step up from the Shure. Thank-you.

 

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RE: Tube phono preamp DIY suggestions, posted on November 30, 2015 at 17:47:34
danlaudionut
Audiophile

Posts: 5480
Location: Schenectady
Joined: June 6, 2002
 I built the Hagerman Octal Cornet.
TWO 6SL7s and a 6SN7.
Very musical and clear.
Tube rolling is fun with this one.
PDF link on the thread linked below.

DanL



 

RE: Tube phono preamp DIY suggestions, posted on November 30, 2015 at 18:42:55
Janos
Audiophile

Posts: 478
Location: Honolulu
Joined: August 18, 2002
 I built the 12ax7/au7 version of the Cornet.
I love it - super quiet, easy to tweak and stands its ground to products costing way higher.

I also have an implementation of the RCA phono, with gas tube regulation.

I noticed that these two have quite distinct EQs: records that sound meh with one will sound great with the other.

This tells it all, different recordings were made with different EQs, thus there is no single solution for record playback.

All in all, the Cornet does reproduce the vast majority of the records, the RCA phono is better suited for some obscure old classical stuff.


I have built these two over 7 years ago.
Cornet uses a circuit board, the RCA phono PTP wireing.
I am generally sold on the idea of PTP, however, in a phono stage noise is extremely critical and Jim does a phenomenal job of making sure his layout does not pick any up. And he is super helpful.

The Cornet has been working without a hitch, perfectly and reliably. The RCA phono lost one channel and I was not able to trace what went wrong there. Will have to take it apart part by part - once I have enough time and determination for that adventure.

Have fun!

Janos



 

A Dutch DIY'er recommended me , posted on December 1, 2015 at 02:04:36
Bas Horneman
Audiophile

Posts: 4086
Joined: March 28, 2001
 Sasa Cokic of Trafomatic Audio phono.

Here reviewed by 6moons http://www.6moons.com/audioreviews/trafomatic11/1.html

So that is still in the pipeline for me.

 

Stephen Robinson's Izzy Wizzy, posted on December 1, 2015 at 11:44:10
Salectric
Audiophile

Posts: 1358
Location: East Coast
Joined: February 23, 2003
 Stephen Robinson in the UK has a great sounding phono design using a D3a and half a 5687 for each channel. The development process is described on his website (see link). Later versions are not necessarily better than early ones though. In particular I would recommend starting with the audio circuit shown as his Mk.15, and you can simplify that by using an output coupling cap instead of the transformer. I started with a version similar to the Mk. 15 some 6 or 7 years ago, and while it's gone through a lot of changes since then I still use a variation of it today. Even the earliest version sounded better than the Artemis PH-1 I was using at the time.

 

RE: Stephen Robinson's Izzy Wizzy, posted on December 1, 2015 at 11:57:34
fredtr
Audiophile

Posts: 1987
Location: Phoenix
Joined: January 4, 2005
 Thank-you for posting. The description says MC, I have MM cartridge, did I miss something? Is it configurable or switchable MM and MC?

 

RE: Stephen Robinson's Izzy Wizzy, posted on December 1, 2015 at 12:10:05
Salectric
Audiophile

Posts: 1358
Location: East Coast
Joined: February 23, 2003
 Just leave out the MC stepup transformer (TX 103) and you have a MM phono preamp. In my case, I use an outboard stepup transformer so the preamp itself is MM.

 

RE: Stephen Robinson's Izzy Wizzy, posted on December 1, 2015 at 12:17:44
fredtr
Audiophile

Posts: 1987
Location: Phoenix
Joined: January 4, 2005
 That's excellent, thank-you. It looks like we both have Shure M65 like preamps, can you compare the sound to that, or maybe some other phono stage preamps? Another preamp I am considering is the World Designs (WAD) phono 3. If you are familiar with it, any comments?

 

RE: Stephen Robinson's Izzy Wizzy, posted on December 1, 2015 at 12:24:56
Salectric
Audiophile

Posts: 1358
Location: East Coast
Joined: February 23, 2003
 The D3a/5687 is in a different league than the Shure M65. Even a scratch-built M65 like mine which uses pretty much cost-no-object parts has less detail and a smaller soundstage than the D3a/5687. Plus any 12AX7 based phono has noise issues. The SR design is very quiet, actually much quieter than any of the solid state phono preamps I have tried in my system. I have even run my 0.35mv output MC directly into the SR and while no longer super-quiet it had a lot less noise than I expected.

 

RE: Stephen Robinson's Izzy Wizzy, posted on December 1, 2015 at 12:35:09
fredtr
Audiophile

Posts: 1987
Location: Phoenix
Joined: January 4, 2005
 Thank-you for the fast response. Your suggestion has my interest. I hate to bother you, I'm not that familiar with the magnetics, would it be possible to post part numbers?

 

RE: Stephen Robinson's Izzy Wizzy, posted on December 1, 2015 at 13:39:24
Salectric
Audiophile

Posts: 1358
Location: East Coast
Joined: February 23, 2003
 I am not sure what transformers and choke Stephen used in his build, but there is nothing sacred about his selections. I used standard Hammond power transformers and chokes in my preamp, but my power supply is quite different (simplified) compared to Stephen's. The circuit will operate fine with a B+ ranging from 225 to 285 volts. How you build the power supply to get there is pretty much up to each builder.

 

RE: Stephen Robinson's Izzy Wizzy, posted on December 1, 2015 at 13:48:34
fredtr
Audiophile

Posts: 1987
Location: Phoenix
Joined: January 4, 2005
 OK, thank-you for answering. I think I will try this, thanks again for the recommendation.

 

RE: Tube phono preamp DIY suggestions, posted on December 1, 2015 at 18:32:01
Jim McShane
Dealer

Posts: 5910
Location: Chicago
Joined: January 13, 2003
 Why don't you take a look at Eli Duttman's Improved RCA? It's a very solid design and people who built it like it a lot.

 

RE: Tube phono preamp DIY suggestions, posted on December 2, 2015 at 06:26:46
lugnut1
Audiophile

Posts: 132
Location: Austin,TX
Joined: September 24, 2011
 I recently finished the RCA/Duttman/Yourison phono and I highly recommend it. Nicely balanced and very good sounding. I'm looking forward to trying different tubes and a tube rectified B+ with a 6ax5 tube.

 

Vacuum Rectified B+ PSU, posted on December 2, 2015 at 09:18:51
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000



I'm uploading a low cost vacuum rectified "300" VDC B+ PSU schematic. The 60 mA. available should be quite sufficient for preamps.


Eli D.

 

beware of dc, posted on December 3, 2015 at 09:08:32
youngshooter
Audiophile

Posts: 84
Joined: May 1, 2006
 The circuit use battery for grid bias, without the transformer DC will appear at the cartridge, a blocking cap is required.

 

RE: A Dutch DIY'er recommended me , posted on December 3, 2015 at 13:57:04
Lew
Audiophile

Posts: 10912
Location: Bethesda, Maryland
Joined: December 11, 2000
 That's a very cool idea. Thanks. I wonder if it could be built using a hybrid cascode input stage, instead of the pentode, using a transistor on the bottom and a hi-Gm triode on top. Unfortunately (for me), I would not know how to change the values of the RIAA to make the change to the gain stage.

 

117Z6 rectifier-voltage doubler, posted on December 3, 2015 at 18:14:07
FenderLover
 Never heard of this tube. Are good ones easy to find?

Thanks!

 

RE: 117Z6 rectifier-voltage doubler, posted on December 3, 2015 at 18:54:46
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 The 117Z6 is not commonplace, but it is inexpensive. I doubt anything NOS is other than excellent. I've got a couple of Sylvanias on my pile. RCA or TungSol will (obviously) be good too.

I believe the type was primarily used in power transformerless radios that needed "serious" B+. My 1st exposure to the 117Z6 was as a youngster. I salvaged the tube from a radio of my father's that had crapped out.

Jim McShane's price is $6.50 and his stock is either RCA or TungSol. RES shows a $5.00 price. AES shows a $6.36 price, discounted from $7.15.


Eli D.

 

RE: beware of dc, posted on December 3, 2015 at 23:33:01
Stephen R
Audiophile

Posts: 1428
Joined: January 11, 2002
 Or move the battery in series with the grid. No cap needed.

 

RE: beware of dc, posted on December 4, 2015 at 03:47:11
Salectric
Audiophile

Posts: 1358
Location: East Coast
Joined: February 23, 2003
 The Artemis PH-1 used battery bias that way---in series with the grid of the input tube (6DJ8).

 

How committed are you to tubes?, posted on December 5, 2015 at 14:26:04
1973shovel
Audiophile

Posts: 10117
Location: Greenville SC
Joined: February 25, 2007



I know it's blasphemous to suggest this here on the DIY Tubes Asylum, but if you're willing to consider something else, then I'd suggest taking a look at Pete Millett's ETF 13 LR (no caps in the phono EQ network) phono stage.

I finished (albeit roughly) mine up last weekend. I had to wait a month for CineMag to build the inductors. So far I'm very impressed with the results, particularly the bass, which is better than another SS phono I'm using.

I wrote Pete to give him my initial sonic impression, and here's what he wrote back:

"One of the joys of the LR architecture is that the LF response is excellent. Compared to two of my other phono stages, and also to a Borbely, I've found it to be much nicer. Also quieter. Even though I am a tube guy, sometimes, opamps are better."

Also, from the article on the project (link below), he writes:

"Recently, after listening to it compared to a couple of different tube and hybrid preamps (some of which I designed), I came to the conclusion that the solid-state LR unit sounded better than the others."

Pete's a respected DIY tube guy, and I suppose he could just be saying that to sell circuit boards, but that's a bit of a stretch.

My experience with tube phono preamps in my system has been limited to the 12AX7 variety (Audio Research SP3-A-1, Dynaco PAS, both stock and modified, etc.). I generally prefer a good SS phono into a tube line stage. They're quieter, and give me greater detail than the tube phono stages I've tried. And certainly in the case of the Millett LR, better bass.

Just some food for thought. Good luck with your search.

(Edited for spelling)

 

RE: How committed are you to tubes?, posted on December 5, 2015 at 15:26:26
lugnut1
Audiophile

Posts: 132
Location: Austin,TX
Joined: September 24, 2011
 What SS preamps are you comparing to the Millet LR? Have you tried the RCA/Duttman or the Lounge LCR?

 

Output resistors, posted on December 5, 2015 at 20:48:11
morinix
Manufacturer

Posts: 528
Joined: October 19, 2000
 What kind of resistor did you use for R27 and R28?

 

Texas Components TX2575 (nt), posted on December 5, 2015 at 21:18:00
1973shovel
Audiophile

Posts: 10117
Location: Greenville SC
Joined: February 25, 2007

 

RE: Texas Components TX2575 , posted on December 5, 2015 at 22:24:42
morinix
Manufacturer

Posts: 528
Joined: October 19, 2000
 Give that type of resistor (but make it 47k or 50k) a try in the R1 and R2 position.






 

If I decide to go with this circuit, posted on December 6, 2015 at 04:41:45
1973shovel
Audiophile

Posts: 10117
Location: Greenville SC
Joined: February 25, 2007
 I'll make the investment and give them a try in that position. Thanks.



 

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