Modifications to improve gain of ASL mini phono.

I'm late to this forum, but recently bought an ASL Mini Phono. I'm a big fan of tube phono stages and figured this was a bargain for $200. I'm not aware of any other $200 tube phono stage with a decent power supply like this one has. Mainly, I want to see how good this unit can sound with some modest upgrades.

I'm going to replace the cheap Bennic caps with 0.1 uF KY40 for the input and 1.0 uF Dynamicaps for the output. I'm also going to change all the resistors to low noise PRP and swap in Silver Mica and Relcap for the RIAA caps. I'll also upgrade the cheap electrolytics with low ESR Panasonics. All told, I plan to spend about $75 on parts. If it compares favorably with a Bottlehead Seduction, I'll be very happy.

I'm sketching out the circuit diagram. I'd be happy to share it with anyone along with my modifications which are easy to do. Just shoot me a message.

-Mark

12 O'clock is 50% of the max. vol. with Shure V15 type 5 (3.5 mV). I think the ASL phono stage gain is about 40 dB which is about the same as my Sonic Frontiers SFP-1. Both of these phono stages are dead quite. When I place my ear about 5 in. from the speaker I can barely hear the statics. I got this after resolving the grounding wire attachments. I found that SS phono stages give me lots of gain but without the clarity and sweet tube sounds. I have not try expensive SS phono stage yet. Thanks

IS the 12 o'clock position the maximum position on your dial? If it isn't I don't think you have a problem. If that is the max position on your dial, then you may need a linestage (not a phonostage) with more gain. you don't want a hair trigger volume control.

What cartridge are you running? want is the mV output? how much gain does the ASL phono have? 40dB? it has been my experience that most cart+phonostages do not seem to give you the same volts RMS (? <1v) that a CD player (2-4V) will give.

If the phono stage is noisy, the ground wire may be not firmly connected to the tube housing. I opened the 2 tubes casing and solder the ground wire to its screw attaching it to the circuit board and the housing. This ground wire is not firmly attached to the screw because there is no spacer underneath the circuit board to keep pressure between the wire and the screw. Does anyone know the function of the adjustable pots in the power supply unit?

I think there may be trade off for gain improvement, i.e. noise, microphonic. My preamp doesn't have much noise at 12 O'clock. I wonder if anyone compare the old and new version of the ASL mini phono?

I believe you can contact the distributor, Divergent Technology, and they can increase the gain. I can't remember by how much or the charge to do this.