12v/24v RIAA MM preamp

[bichela]

It has been awhile. I haven't done much with the 6bm8 amp yet but I do have the 12ax7 tubes for the RIAA phono stage.

I don't have the HV 250+ supply yet but I want/need to create a RIAA phono preamp for my R25XT magnetic cartridge as my only preamp in my SSM-1250 DJ mixer is kaput. (the mixer got damaged by a power surge that left skid marks on the audio board. some traces are disintegrated. Might even tubeify the thing later on.

I want to build a RIAA preamp that uses 12Vdc or 24vdc power supply to provide preamp/riaa for my cartridge. Is there such a circuit? Looked on the net but I didn't see a low voltage RIAA circuit but I do have a few standard 250+v ones that I wonder if I could modify to do the job.

 

[Sodacose]

I think there was a sub mini phono pre on the board somewhere that used a very low B+. By koifarm maybe?

 

[Eli Duttman]

A bipolar PSU of 12 V. each side of ground should be adequate for something opamp based. I'm thinking of something along the lines of Jim Hagerman's Bugle2, which employs passive EQ.

 

[Sodacose]

Here's what I was thinking of:

http://www.diyaudio.com/forums/analogue-source/255041-mini-me-second-edition-tube-phono-preamp.html

48V b+

 

[BinaryMike]

Jan Didden's Linear Audio volume 10 has a relevant article by Ronald Quan. Well worth the read if low voltage tube operation is a subject of interest.

 

[bichela]

Just a note, there are 12v dc-dc boosters that can produce high 250+. I saw several in Ebay However, I want to keep it all tube. I could try a space-charge tube but, right now I got 12ax7 tubes. Which space charge tube is similar to a 12ax7?

 

[petertub]

It has been awhile. I haven't done much with the 6bm8 amp yet but I do have the 12ax7 tubes for the RIAA phono stage.

I don't have the HV 250+ supply yet but I want/need to create a RIAA phono preamp for my R25XT magnetic cartridge as my only preamp in my SSM-1250 DJ mixer is kaput. (the mixer got damaged by a power surge that left skid marks on the audio board. some traces are disintegrated. Might even tubeify the thing later on.

I want to build a RIAA preamp that uses 12Vdc or 24vdc power supply to provide preamp/riaa for my cartridge. Is there such a circuit? Looked on the net but I didn't see a low voltage RIAA circuit but I do have a few standard 250+v ones that I wonder if I could modify to do the job.

Yes there is :
DC10 32V to DC ±45 390V 780V Dual Output Adjustable Converter Capacity Charger | eBay

 

[jackinnj]

Which space charge tube is similar to a 12ax7?

here's a list of low voltage tubes:
Space Charge and Other Low-Voltage Tubes

i don't think any have the gain of 12ax7 (mu=100)