Home » Sponsored » OddWatt Audio » Valve Phono Preamp
Valve Phono Preamp [message #68202] Thu, 16 June 2011 17:26 Go to next message
gofar99 is currently offline  gofar99
Messages: 1419
Registered: May 2010
Location: Southern Arizona
Illuminati (3rd Degree)
Hi Fellow vinyl lovers. A work in progress is nearly ready to field. I have been designing a valve based phono preamp for addition to the Oddwatt Line. As is my personal policy it will also show up as a diy project. Not a simple project, but from what I saw at LSAF, it should be ok with many of the folks there. It is a MM design with the expectation that if you use MC cartridges you will most likely use a step up transformer. Some teasers, three stages, two are SRPP, passive equalization, tracking with the RIAA curve is within about a half db from 30HZ to past 20K, at 20 it is up about 0.75 db from the curve. I will be taking care of that before I post the project. Wide-band S/n is in the -90 dbv range. It has been running for about 3 weeks now in my main system and I like what I hear. Cool I still need a name for it so if you want a chance to have input and maybe a lasting contribution to audio send me your suggestions. Nod



Good Listening
Bruce
Re: Valve Phono Preamp [message #68214 is a reply to message #68202] Fri, 17 June 2011 16:10 Go to previous messageGo to next message
Shane is currently offline  Shane
Messages: 1109
Registered: May 2009
Illuminati (3rd Degree)
How about the GrooveWatt?

I'll think up some others shortly!


Re: Valve Phono Preamp [message #68216 is a reply to message #68214] Fri, 17 June 2011 18:57 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17402
Registered: January 2001
Illuminati (33rd Degree)

BAM! - That's a freaking awesome name for an OddWatt phono stage. Can't top that!

Re: Valve Phono Preamp [message #68218 is a reply to message #68216] Fri, 17 June 2011 21:36 Go to previous messageGo to next message
gofar99 is currently offline  gofar99
Messages: 1419
Registered: May 2010
Location: Southern Arizona
Illuminati (3rd Degree)
Hi Good name, let's hear from some others, I might even throw in a genuine Oddwatt "T" shirt. Smile ...SpinWatt? V Watt?

Good Listening
Bruce
Re: Valve Phono Preamp [message #68221 is a reply to message #68218] Fri, 17 June 2011 22:20 Go to previous messageGo to next message
Shane is currently offline  Shane
Messages: 1109
Registered: May 2009
Illuminati (3rd Degree)
Thanks. Hard to find something phono related that goes with Watt. How about KillaWatt? Just kiddin. That's kind of a stretch. Guess GrooveWatt is my go to name for the time being. I thought of SpinWatt as well this afternoon at work, another good name.

That's a fine offer of a T-shirt if someone comes up with something good. What I need to do is set some money back to build that ForeWatt of yours. I've got a bunch of Kiwames and Gen 1 Sonicaps that I hoarded for a pre project that fell thru that are just calling out to be used.


Re: Valve Phono Preamp [message #68225 is a reply to message #68221] Fri, 17 June 2011 22:52 Go to previous messageGo to next message
gofar99 is currently offline  gofar99
Messages: 1419
Registered: May 2010
Location: Southern Arizona
Illuminati (3rd Degree)
Hi Shane, The Forewatt is also a diy project and you can check it out on the diyaudioprojects.com site. It can be built rather inexpensively if you have lots of parts hanging around. I am always happy to assist folks with their builds. There are no funky parts in the preamp and the transformer (often a pricy thing) is under $20 from Edcor. You do need to shield the circuitry from it, but there are many cheap ways to do it. It would be interesting to hear how Sonicaps sound in it. So far I don't know of anyone who has used them. I use Jantzen Silver Z in mine. With only one cap in the signal path the choice has a big effect on the sound. One diyer found this out the hard way, by using a brand X 50 cent one. Then complained about the sound. I was polite and did not tell him what to do with his soldering iron. Laughing I suggested that maybe some better ones at least $2 might work better.

Good Listening
Bruce
Re: Valve Phono Preamp [message #68227 is a reply to message #68225] Fri, 17 June 2011 23:21 Go to previous messageGo to next message
Shane is currently offline  Shane
Messages: 1109
Registered: May 2009
Illuminati (3rd Degree)
I liked the look of the unit at LSAF. Thoughtful layout on everything I thought, and if it sounds like the one you were using with the remote volume it'd be a treat to own.

Here's a shot I took of it when I was there.....I wish I had taken a good straight down shot of it for reference.

http://shanemoorephotography.smugmug.com/Electronics/LSAF-2011/i-rtqgRsD/0/XL/DSC7725w-XL.jpg


Re: Valve Phono Preamp [message #68235 is a reply to message #68227] Sat, 18 June 2011 09:29 Go to previous messageGo to next message
gofar99 is currently offline  gofar99
Messages: 1419
Registered: May 2010
Location: Southern Arizona
Illuminati (3rd Degree)
Hi Shane, Yes the one I was using was remote controlled. It is one of two prototypes. We had quality control problems with the remote sections and decided not to offer them at this time. The builds were complicated and really only one of them behaves properly. (the other has a ground loop issue with the control section) I'm still looking into other sources for the remote control section, but have not found any that are suitable right now. The best of the lot is one I have here presently. It is all relay switched for volume and input. Problem is .... it is 16 inches wide. Nice digital display and all, but would require a much larger chassis. A maybe. I can't see a line stage preamp in a box big enough for a kilowatt SS amp. As a front end for a stereo KT88 amp perhaps. A dual mono version of the Oddblocks with built in Forewatt. Could work. It would be massive - something in the order of 60 pounds and be rather costly - I would guess in the $2500 range. Not exactly an affordable kit IMHO.

If I can get the other remote control Forewatt to behave, I may sell it off. I really don't need two.


Good Listening
Bruce
Re: Valve Phono Preamp [message #68248 is a reply to message #68235] Sat, 18 June 2011 21:14 Go to previous messageGo to next message
Shane is currently offline  Shane
Messages: 1109
Registered: May 2009
Illuminati (3rd Degree)
Moved to a new topic to keep the focus on the new phono pre.

Re: Valve Phono Preamp [message #68421 is a reply to message #68221] Fri, 01 July 2011 22:06 Go to previous messageGo to previous message
gofar99 is currently offline  gofar99
Messages: 1419
Registered: May 2010
Location: Southern Arizona
Illuminati (3rd Degree)
Hi Everyone, I posted the diy project version of the Phono Preamp in the tube section. I like Shane's name for it - so that is what it is called. I owe you an Oddwatt "T" shirt so let me know (PM me) on where to send it. Eventually a kit will come out for this preamp, but it will be a number of months away as it takes time to do the cad work on the design and get suppliers to fabricate the PCBs, chassis and other parts. I'm sure there are some of you who could build it in a weekend. I believe you will like the sound.

Good Listening
Bruce
Previous Topic: Forewatt
Next Topic: Integrated Preamplifier
Goto Forum:
  


Current Time: Tue Mar 19 11:00:50 CDT 2019

Sponsoring Organizations

DIY Audio Projects
DIY Audio Projects
OddWatt Audio
OddWatt Audio
Pi Speakers
Pi Speakers
Prosound Shootout
Prosound Shootout
Smith & Larson Audio
Smith & Larson Audio
Tubes For Amps
TubesForAmps.com

Lone Star Audiofest