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PostPosted: 26 Jul 2019, 14:28 
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Joined: 18 Jan 2017, 18:55
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I think I have a noise from my turntable. without the groovewatt connected system is silent. If I hook up the outputs on groovewatt and leave inputs unplugged remains quiet, just very faint white noise on high volume.
When I then plug in the inputs from TT I get a loud buzz that is audible even with turntable turned off and then unplugged.
Turntable is a Rega Planar 2 with Carbon cartridge. I have seen other online post of this player being noisy. I think I may just get a different TT as I have already spent way too much time trying to figure out how to make this table quiet with my current system. System sounds like a dream with digital input. At my prior home I had TT isolated and on feet, granite countertop, was much quieter but still not ideal. Any suggestions for a good player under $1K that is likely to make a better choice or a possible fix for current player?
Thanks


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PostPosted: 26 Jul 2019, 14:39 
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Joined: 18 Jan 2017, 18:55
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Just a follow up. I moved TT 5 ft from rest of my system and still have a mild buzz but is not audible with music playing at low volume. Totally acceptable for me. I think I just need to work on placement and damping of my table as you pointed out.


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PostPosted: 26 Jul 2019, 20:19 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi, It sounds like you have some grounding issue now with the turntable. If it has an external ground connection are you running a wire from it to the Groovewatt? Also check to see if the right channel ground lead from the cartridge is connected to the external ground if there is that wire. Lots of cartridges (usually a green marking on the right ground terminal) have a ground tab that connects to the chassis ground. There is not much you can do in that case. But some turntables internally connect that channel to the ground as well to simplify the connection to phono preamps. Unfortunately it sometimes does just the opposite of what is intended. If there is no external ground wire you might consider adding one that attaches to the chassis of the turntable and attach the other end to the Groovewatts ground terminal.

Good listening
Bruce

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PostPosted: 03 Aug 2019, 17:46 
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Joined: 18 Jan 2017, 18:55
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Table does not have a ground but few months back I added one. I placed a ground to chassis and ran it to Groovewatt, helped quite a bit. I even experimented with hooking to cartridge ground but didn't help any further than chassis ground.
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PostPosted: 04 Sep 2019, 22:59 
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Joined: 22 Mar 2016, 11:17
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Hi all - built the Groovewatt almost 2 years ago (see my posts on forum page 55). Still sounding great btw.

Figured I'd share...

Being a nerd I like to test/adjust my audio systems. Thru much trial and error I've found ease and great results in using pink noise and TrueRTA software. I use pink noise as input, adjust EQ to obtain flat frequency response, then further adjust EQ accordingly to my personal liking.

Since phono preamp corrects for RIAA curve and I'm definitely amateur I've never tested my build for frequency response like Bruce has previously mentioned...well, came across an old CBS labs pink noise vinyl (STR 140). Still much testing to do on overall system but just from turntable output to Groovewatt output looks pretty good.

In pic, both channels shown. Lower curves are turntable output and upper curves are Groovewatt output. Some rolloff at higher frequencies but no peaks/dips. Future plan is to put a graphic EQ between Groovewatt and my antique cabinet to further adjust to my liking. To be clear, no complaints from the Groovewatt, just like to have adjustability in setups and the antique cabinet only has treble/bass adjustment and I'm itching for more...maybe one day I'll build a full tube system but I dig the old stuff...and hey, still sounds good to me.

Todd


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PostPosted: 20 Nov 2019, 02:39 
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Joined: 11 Sep 2019, 10:56
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Hi

I have a200v 50mA transformer that I would like to use for a Groovewatt. However its filament output is only 6.3v 1.5A CT compared to 8v from the Edcor XPWR083. Will it be okay to use? If so are any mods required to the 2016 circuit?

Thanks

Rog


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PostPosted: 26 Nov 2019, 15:21 
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Joined: 24 Oct 2010, 07:05
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IMHO, even the specified XPWR083 is not enough. I know that Bruce stated many times that Edcor makes more powerful transformers than writes in datasheets. But I wouldn't extend that confidence to all transformers.


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PostPosted: 29 Nov 2019, 15:44 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi, Yeah I hear you Poty and would normally agree, however the 083 works fine and has been used in many builds. It is going into the commercial phono preamps (shortly available). I have several personal ones set up for long term use and with over 6 years on them there have been no issues. Now the one the poster has may not be enough.. For one the 6 volt winding will not give enough head room to use a DC regulator to get the required heater power. Generally I trust Edcor, others...up for grabs.

Good listening
Bruce

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PostPosted: 13 Apr 2020, 19:52 
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Joined: 03 Feb 2018, 00:47
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Location: Brisbane, Australia
I am planning my Groovewatt build. Got chassis, tube sockets, tubes, filter caps, resistors etc. As much as IO love Edcor, I am in australia and 4 times the cost of the transformer to get it here just doesn't sit right with me. So I have finally found somebody who might wind one or two for me over here.
Any reason to increase the specs over the stated ones? Fully metal enclosed better for noise I guess?
Anybody else in Aus interested? Let me know if so.
Glenn.


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PostPosted: 13 Apr 2020, 20:44 
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Hi Everyone, I tried to post this a bit earlier, but ran into internet issues.

As part of extensive testing of the commercial pre-production versions of the preamp I revisited the design. I made a number of changes. Mostly component updates. I altered the RIAA section for lower noise and made a small change in how the heaters were fed the protective B+. The attached schematic shows the changes. The response is now within +0/-0.3dbv from 20HZ to 20KHZ and in both the ones I modified here actually +0/-0.2dbv. Roll off on the bass is 1 db at 10HZ and -3db at 6HZ. This may pose an issue for anyone with turntable rumble. If so change the 0.33uf coupling capacitors to 0.1 or 0.15uf and this will shift the roll off up a bit. The high end response is way more than needed and extends to 50KHZ at -1 db and the -3db point was around 70K. I considered bringing it down a bit, but for this application it didn't seem needed and I was concerned that some sort of sonic issue would raise its angry head. To compensate for the slightly reduced gain caused by the RIAA modifications I added a 100uf bypass capacitor on the second stage. One on the input stage tended to increase the noise level so it was not done. The gain is the same as before at about 38db (1K HZ). The worst case S/N in any of the modded preamps (3) was -70db at 180HZ. This peak is a bit dependent on the method of construction (think grounding) and in the other preamps was at -79db. It is not audible in my system. I had to go to "0" db on my gain to even hear it right at the sub woofers. My system has flat response to 22HZ so if it was audible I would hear it. My normal listening level is 45 db lower than that. For information that some folks might not know, the max S/N of a phono cartridge has been calculated many times and is right about 70 db. The typical LP has a S/N of about 50-55 db. So the worst case noise is buried about 20 db below what is audible. The change in the power supply was to attach the B+ feed to the junction of a pair of 100 ohm resistors. One end to the hot and one to the negative side of the heaters. (remember they are not grounded). The preamp is quiet, detailed (AKA fast) and really lovely to listen to. On my Empire turntable with Origin live arm amd a Dynavector 23Karat MR-RS (and SUTS BTW) it is stunning.

Good listening
Bruce
Attachment:
Revised Phono Preamp 4-2020.jpg


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