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PostPosted: 24 Jan 2020, 21:59 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
I’ve lost count of how many are happy with this preamp.

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PostPosted: 25 Jan 2020, 08:55 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi Mark, I have not seen (heard) that one. I have an ATF7 which is quite nice and an AT33-PTG. Both are LOMCs. The 33 is quite a step above the 7 as expected, but the 7 was a good buy. I believe it was about $250US. My three go to cartridges (only 3 TT hooked into the system) in order of liking are a Grado Sonata II, Goldring 1042, and Dynavector Karat23MR-RS. The Goldring is a sleeper. A MM with replaceable stylus. Not high priced but it has a Geiger stylus and has a really nice clean sound. I got mine from an EU source (JUNO) about 6 months ago for $225US. Why a DJ place had them is unknown, but a deal is a deal and the shipping by air was cheap.

Good listening
Bruce

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PostPosted: 20 Apr 2020, 23:07 
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Joined: 14 Jul 2014, 13:18
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Location: Arizona
Another extremely satisfied build of this preamp.

I went with the battery powered version using rechargeable 9v x 2.

Very happy with the results - using it with a Goldring 1042.

Thanks again for your work, Bruce.


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PostPosted: 25 Nov 2020, 21:55 
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Finally complete with only one little stuff up that was soon fixed. A mix of MKT, Polyester and low ESR electro caps. All carbon film Rs through. Differential PS onboard. Genuine OPA2134 from RS and machined milspec socket. Two 9V batteries for about 50 to 100 hours play depending on battery type. I often use eBay lithium’s first 100 hours.
 
Cast Al enclosure with bituminised heavy Al in the bottom for resonance and vibration control. Paint is Epoxy Enamel with an etching primer. The finish is gloss and tough. This one is also called “Carbon” for obvious reasons. 
 
Some don’t like carbon film resistors but I find they produce a very smooth sound but still let instruments shine in their own space. The preamp is new and requires about 50 hours to burn in. Listening to it now with late model Rega P3 and Gerrott P77i cart. Very nice and to think it will improve. 
Attachment:
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[attachment=0]FA20C979-C1EE-4FB8-84A2-A1E9FADE91BE.jpeg
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9ADEAB4E-3610-473A-90A4-15DD6ABA7D6F.jpeg


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PostPosted: 26 Nov 2020, 12:35 
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Location: Arizona, USA
Hi Mark, deceptively nice sounding preamp. I have a few around here still and sold a few as well. Feedback from one user indicated that he really liked the one I built with Auricap XO output caps, I use Audyns in mine. A bit difficult to get the TrueCoppers in a small case though. I also use a multistage DC to DC filter power supply with a wall wart to power mine. I tend to forget how many hours are on batteries and they are dead when I want to use something. I suppose I could use rechargeables and a relay that cuts them off of the mains when I use the device.

Good listening
Bruce

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PostPosted: 26 Nov 2020, 18:24 
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gofar99 wrote:
Hi Mark, deceptively nice sounding preamp. I have a few around here still and sold a few as well. Feedback from one user indicated that he really liked the one I built with Auricap XO output caps, I use Audyns in mine. A bit difficult to get the TrueCoppers in a small case though. I also use a multistage DC to DC filter power supply with a wall wart to power mine. I tend to forget how many hours are on batteries and they are dead when I want to use something. I suppose I could use rechargeables and a relay that cuts them off of the mains when I use the device.

Good listening
Bruce

Generally I have an external battery test point at the front. I’m yet to add it here.

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Projects: “Mantra” - tube MM phono preamp | "Carbon” - MM phono preamp | 180W RAW Class D amp | "Illusion" - 6SN7 SRPP preamp in a plastic jiffy box |


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PostPosted: 12 Dec 2020, 22:34 
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http://retro-thermionic.blogspot.com/20 ... reamp.html

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PostPosted: 13 Dec 2020, 08:59 
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Hi Mark, I just build (actually modified ) one of the IC based phono preamps to use rechargeable batteries. It uses 6 type 18500 clells for just under 24 volts. These are 1500 ma 3.7 volt lithium cells. With a full charge the thing ought to run forever. But I added a zener diode/LED combination to let me know it the terminal voltage dropped below 22.5 volts when in operation. The LED goes out then. It uses only 3 ma in operation. I also added a way to recharge the batteries. I used a LM317 and a series resistor to regulate the output and insure safe area charging. I considered a CCS but it seemed overkill. I use a DPDT to switch between charge and run. In the charge mode the batteries are disconnected from the preamp to protect it from Mains junk that might slip through. Since the S/N is already in the over 100db range, I really can't determine if it is any quieter than the one with the AC/wall wart. But it is convenient not to have to find a power source for it.

Good listening
Bruce

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PostPosted: 13 Dec 2020, 16:43 
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gofar99 wrote:
Hi Mark, I just build (actually modified ) one of the IC based phono preamps to use rechargeable batteries. It uses 6 type 18500 clells for just under 24 volts. These are 1500 ma 3.7 volt lithium cells. With a full charge the thing ought to run forever. But I added a zener diode/LED combination to let me know it the terminal voltage dropped below 22.5 volts when in operation. The LED goes out then. It uses only 3 ma in operation. I also added a way to recharge the batteries. I used a LM317 and a series resistor to regulate the output and insure safe area charging. I considered a CCS but it seemed overkill. I use a DPDT to switch between charge and run. In the charge mode the batteries are disconnected from the preamp to protect it from Mains junk that might slip through. Since the S/N is already in the over 100db range, I really can't determine if it is any quieter than the one with the AC/wall wart. But it is convenient not to have to find a power source for it.

Good listening
Bruce

I’ll assume some images and a schematic to follow if you intended to share. I’d thought about the same idea some years back but so easy to build these without the added complexity I’ve never bothered. Enjoying mine new one (Carbon) and recently completed another Radi0kit tube phono preamp. What have found with the tube version is a lot more colour and life in the sound. Not sure if the tubes are adding something that’s not there or bringing to life that which is in the groves.

Love the Mimics for the honesty and simplicity and love the tubes for their colour and vitality. If forced at gun point to choose I’d go for the tubes. But at many times the price and added complexity. Takes nothing from the Mimics.

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Projects: “Mantra” - tube MM phono preamp | "Carbon” - MM phono preamp | 180W RAW Class D amp | "Illusion" - 6SN7 SRPP preamp in a plastic jiffy box |


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PostPosted: 13 Dec 2020, 16:49 
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With battery test point. The silver small bolt head is connected to battery positive. Test is between RCA earth and this test point for one half of the diff supply.
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