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ALBQ 14th May 2006 02:25 PM

Mint Tin Phono Amplifier
 
All,
Pictures and schematic of my mint tin phono amplifier. Circuit is a simplified Vinyl Addicts (Thorsten Loesch) El Cheapo phono stage with a TLE2426 rail splitter power supply section to enable operation from a single 9V battery. Because the amp is a prototype, I tried to balance cost verse performance so, opamp is a AD823, resistors are standard 5% carbon film, filter caps are high quality polypropylene and coupling caps are small 50v Nichion electrolytic cross over caps. Amp is dead quiet and for such a simple/compact circuit, I was absolutely amazed at how good it sounds
Cheers -ALBQ

http://mywebpages.comcast.net/gilles...hono-Front.jpg

http://mywebpages.comcast.net/gilles...ono-Inside.jpg

http://mywebpages.comcast.net/gilles...-Schematic.jpg

infinia 14th May 2006 04:36 PM

Hi
Looks good. How do you get the rails up to +/- 8 V using a TLE2426 and a single 9V since TLE output is 1/2 Vin. Have you compared the sound to using just 2x9v batteries? (i.e. what is the sonic impact of the TLE2426 part).

ALBQ 14th May 2006 10:29 PM

Supply rail
 
Infinia,
Sorry about that, Eagle CAD schematic still showing 9V. Originally sized PCB to fit two batteries in the tin but, would not work with RCA plugs. I have not tried a higher supply voltage although pretty happy with how it sounds at +/- 4.5.
Cheers -ALBQ

hacknet 15th May 2006 01:41 AM

have you tried the opa2228, i had much better experiences with the 2228 at low voltages.. it seems the 2134 sounds flat and un happening at 4.5v...:)

ALBQ 15th May 2006 03:08 AM

Op Amps
 
hacknet,
I have tried the AD823, OPA2132 and OPA2227. Of the three, the AD823 is the most detailed but, can be a bit abrasive on certain material, the OPA2132 is detailed and warm but, somewhat muffled and the OPA2227 is the somewhere in between. 9/10's the detail of the Analog Devices while retaining most of the warmth of the Burr-Brown (Ti) op amps. OPA2227 is a untiy gain stable version of the OPA2228/OPA2227 series.
Cheers -ALBQ :cool:

infinia 15th May 2006 04:26 AM

Seems like you could fit 2 batteries in there if you eliminated DC block electros. Moved the power switch to same side of RCA's and scooched PCB just underside of RCA center pins. Looks tempting to build.
I wonder if anybody has tried a LT1057 dual Op-amp in a RIAA amp like that? It's little pricey at 9 duckets a pop though.

ALBQ 16th May 2006 02:47 AM

Mint Tin Phono
 
Infinia,
I designed the PCB so that it would fit in the tin with two batteries so, I am sure that if I arranged the power switch and RCA's, should fit without a problem. Also, one of the reasons I used this circuit is it is easy to roll opamps. Can change the sound quite a bit with different opamps and any 8 pin dual opamp will fit so, many choices.
Cheers -ALBQ

graeme uk 19th May 2006 07:37 PM

out of curiosity, how long will the battery last?

infinia 21st May 2006 04:01 AM

Much longer than an IPOD except when you forget the switch.:D

ALBQ 22nd May 2006 03:44 AM

Mint Tin Phon EagleCAD PCB File
 
All,
In case you would like to build one, EagleCAD PCB Board file for Mint Tin Phono Amplifier.
Cheers -ALBQ

http://mywebpages.comcast.net/gilles...o-BlankPCB.jpg

http://mywebpages.comcast.net/gilles...o-EagleCAD.brd;)


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