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Old 7th October 2013, 06:36 PM   #1
mltube is offline mltube  United States
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Default Groovewatt-Valve RIAA Phono Preamp?

Considering building this preamp for a Pioneer PL-71 that I have just dusted off... bought for a really low price.

Has anyone here built the groovewatt preamp? How does it sound?
I have searched here a bit for the groovewatt, but did not see much, perhaps it was my search keywords selection. IDK

I have an AT-95 cart on its way since the ADC unit on my PL-71 was missing the stylus anyway.

This is the first decent TT I have acquired...
I will be building a few tube preamps starting with the Groovewatt design, and then explore other options.

My goal later this winter is to build a phono pre-amp using the 3a5's into a 71a power amp driven by the 112a. These are for now... just ideas floating around.

Have a desire for perfecting an all DHT set up, but until then exploring other circuits of IDHT designs.

Phono preamps are new to me so this is a new journey.

Thank you.. and have a great day!

Michael
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Old 7th October 2013, 09:08 PM   #2
roline is offline roline  United States
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Default Groovewatt RIAA

I did a version of it and it sounds great.
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File Type: jpg pcb4.jpg (578.0 KB, 427 views)
File Type: jpg riaa-pcb11.jpg (807.5 KB, 410 views)
File Type: jpg pcb001.jpg (937.0 KB, 394 views)
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Old 8th October 2013, 12:20 AM   #3
mltube is offline mltube  United States
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Default Thank you!

Much thanks roline for your input...
This is my first that I will be building, and then phonodude preamp.
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Old 10th October 2013, 04:45 PM   #4
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Is the PC board available for sale? Who/where?
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Old 10th October 2013, 05:13 PM   #5
6L6 is offline 6L6  United States
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The PL-71 is a very nice table. It's motor is fantastic , the arm is wonderful and the rest is quite nice.

You will probably need to re-cap the 'table near the speed pots and such. Pull the old ones and replace with fresh.

Also play around with mats and feet. They make a marked difference on the '70s tables. At the very minimum try some vibrapods.
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Old 10th October 2013, 07:45 PM   #6
roline is offline roline  United States
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The PCB is a toner transfer etched in ZIp-Loc bags, DIY.......
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Old 11th October 2013, 04:08 PM   #7
mltube is offline mltube  United States
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Thank you 6L6 for the info about replacing the caps! After the new AT cartridge arrived, I was so excited and could not wait to play. The speed control setting seems to hold steady, and it sounds fantastic! I found the service manual and will change them soon.

Thanks again
Michael
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Old 11th October 2013, 04:15 PM   #8
6L6 is offline 6L6  United States
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Replace the 35yr old electrolytics and you won't have to worry about them for the rest of your life.

Then start playing around with the mat and feet. I like the Funk Firm Acromat, but there are lots of others out there. Herbies, etc... As for feet, like I mentioned, vibrabods, sorbathane, it all makes a fantastic difference on a solid table.

And also look into wall racks - they are simply amazing... you will not believe how much clearer things get when the table is properly suspended/isolated.
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Old 23rd April 2014, 09:36 PM   #9
JoeDJ is offline JoeDJ  United States
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Quote:
Originally Posted by 6L6 View Post
The PL-71 is a very nice table. It's motor is fantastic , the arm is wonderful and the rest is quite nice.

You will probably need to re-cap the 'table near the speed pots and such. Pull the old ones and replace with fresh.

Also play around with mats and feet. They make a marked difference on the '70s tables. At the very minimum try some vibrapods.
This is an old thread but......

Keep in mid that I do not subscribe to audio fads and gadgets but.........

I just got some #2 "Vibrapods for my Poineer 112D

I created the "sandwich" using a half inch bamboo cutting board (about the same size as the plinth) which is supported by the Vibrapods. I got lucky and found just what I needed for about $7. It's rock solid and perfectly flat.

The TT is on the cutting board supported by cones (with bases). I originally got the adjustable cones mainly for leveling the TT (the floating (platter and tone arm assembly).

Now... the floor in my ground floor apartment is a concrete slab under the carpet so, floor vibrations are not a problem .
However, my audio rack is not he most stable and the (glass) shelves are prone to slight vibrations at times.

So yes the vibrapads did make a bit of an improvement..
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Old 24th April 2014, 02:16 AM   #10
gofar99 is offline gofar99  United States
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Default Groovewatt

The preamp is a project on the diyaudioprojects.com site and a lengthy thread is on that forum. Be sure to read the thread as there are a number of updates in it.
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