Hi folks
I just obtained a pair of the AMaudio boards to build a phono preamp.
Unfortunately no schematic or list of parts appears to be available, I've checked their website, sent an email (which was returned as recipient unknown) so I'm a bit stuck.
The circuit is 'based on' the Boozhound, but is clearly slightly different as it includes a transistor and diode that the Boozhound doesn't.
Can anyone help me with supplying the correct schematic? I don't want to use the one below as it's for the Boozhound and this AMaudio one is slightly different, so I don't know for sure what value corresponds to what resistor - i.e. is R7 a 10ohm resistor on the AMaudio like it is on the Boozhound?
I just obtained a pair of the AMaudio boards to build a phono preamp.
Unfortunately no schematic or list of parts appears to be available, I've checked their website, sent an email (which was returned as recipient unknown) so I'm a bit stuck.
The circuit is 'based on' the Boozhound, but is clearly slightly different as it includes a transistor and diode that the Boozhound doesn't.
Can anyone help me with supplying the correct schematic? I don't want to use the one below as it's for the Boozhound and this AMaudio one is slightly different, so I don't know for sure what value corresponds to what resistor - i.e. is R7 a 10ohm resistor on the AMaudio like it is on the Boozhound?
Attachments
Okay, my mistake, there was a printed schematic and list of parts included but my dad threw the paperwork away with the envelope before I got to see it. So after a while rummaging in the rubbish bin, I've found them, cleaned the mess off them and can get to work.
The BJT listed is a BC550, which I don't have in my parts stash, the NPN BJTs I have are BC337, 2N3906, 2N1613, S8050, 2SC1815GR, would any of these be a suitable alternative?
BC550 Transistor Pinout Diagram, Equivalent, Features, Uses & Other Details - Components Info gives 2SC1815 as an equivalent, any reason why it wouldn't be a suitable replacement in this application?
The BJT listed is a BC550, which I don't have in my parts stash, the NPN BJTs I have are BC337, 2N3906, 2N1613, S8050, 2SC1815GR, would any of these be a suitable alternative?
BC550 Transistor Pinout Diagram, Equivalent, Features, Uses & Other Details - Components Info gives 2SC1815 as an equivalent, any reason why it wouldn't be a suitable replacement in this application?
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I'd just order some BC550's from RS Components. Buy a bunch - you can use them for all kinds of things later, like a cascode CCS.
The thing with RIAA stages is getting the R's and C's exact so that your RIAA Equalization is accurate. This sometimes requires you to parallel some C's to get as close as possible to the RIAA time constants so you have an accurate equalization transfer function. This is where an LCR meter comes in handy, as well as a stockpile of Capacitors and Resistors (in a kit/selection) to pick mates from.
The thing with RIAA stages is getting the R's and C's exact so that your RIAA Equalization is accurate. This sometimes requires you to parallel some C's to get as close as possible to the RIAA time constants so you have an accurate equalization transfer function. This is where an LCR meter comes in handy, as well as a stockpile of Capacitors and Resistors (in a kit/selection) to pick mates from.
Ian, you can always send AM-Audio a message through ebay (Canada). Also, I built the complete kit about a year ago and still have all the paperwork that came with, if you need any of that.
I powered mine with 2, 12v SLA batteries in series, BTW. It took a while to burn in and open up but sounds pretty good to me. I wrote a little about building it on audiokarma - AM Audio’s RIAA JFET Phono Preamplifier Kit | Audiokarma Home Audio Stereo Discussion Forums
I was thinking about building another one, soon.
Duane
I powered mine with 2, 12v SLA batteries in series, BTW. It took a while to burn in and open up but sounds pretty good to me. I wrote a little about building it on audiokarma - AM Audio’s RIAA JFET Phono Preamplifier Kit | Audiokarma Home Audio Stereo Discussion Forums
I was thinking about building another one, soon.
Duane
@MisterDK
Would you mind sending a picture of how you hooked upthe 6 wires to your back panel. I have some questions that this could answer. I am not sure how to Hook up a dual mono system actually and I want to validate.
I ended up using a modified for 24v silent switcher hooked up to a regular 5v cellphone battery pack so no mains!!! Hooking this up tonight.
Would you mind sending a picture of how you hooked upthe 6 wires to your back panel. I have some questions that this could answer. I am not sure how to Hook up a dual mono system actually and I want to validate.
I ended up using a modified for 24v silent switcher hooked up to a regular 5v cellphone battery pack so no mains!!! Hooking this up tonight.