I just built my first power amplifier. It works fine with line level devices (cd players, radio tuners, tape decks, etc.) As of now it is powering two Sony 3-way bookshelf speakers. It is my beefed up computer sound system. Anyway, can anybody recommend a good moving magnet stereo preamp? I want to play some of my vinyl through my new amp. My turntable is an old AR with a Shure M97XE cartridge.
NAD 1020 pre or 3020 integrated or similar NAD integrated amps with phono and pre-amp jumpers. The later integrated amps have better rear panel RCA connectors, the 1020/3020 have stupid elevated RCA's that tend to fail.
Jeff
Jeff
I sure like my Hagerman bugle. I spent about $65 and an hour building it. I don't have anything decent (my old integrated's phono section doesn't count) to compare to.
pj
pj
Since you've already built an amp, making a MM stage is
very doable. I think you'll like the OP27. I used the OP270 from
Analog Devices (an OP27 follow on) and loved the sound over
the ever popular OPA2134 op-amp based phono stages...
http://www.geocities.com/rjm003.geo/rjmaudio/diy_pho4.html
An external AC supply is critical. Next is a low noise bipolar regulator.
Dont bother with 7815/7915 regulators. Consider LM317/337 regulators. Even better, use a buried zener reference based
supply like this:
http://www.lcaudio.com/index.php?page=69
-- Jim
very doable. I think you'll like the OP27. I used the OP270 from
Analog Devices (an OP27 follow on) and loved the sound over
the ever popular OPA2134 op-amp based phono stages...
http://www.geocities.com/rjm003.geo/rjmaudio/diy_pho4.html
An external AC supply is critical. Next is a low noise bipolar regulator.
Dont bother with 7815/7915 regulators. Consider LM317/337 regulators. Even better, use a buried zener reference based
supply like this:
http://www.lcaudio.com/index.php?page=69
-- Jim
MM preamps?
Were you thinking DIY or something off the shelf? Any cost goal?
I've seen nice kits around, such as at Borbely audio or Marchand Electronics. And Hagtech has a nice kit or bare PCB for not too much $$. Sorry, but no idea how any of these sound.
I have a Rolls Bellari VP129 that I really like. I looked at all the kits before I bought this one, but got lazy. (plus the local shop loaned it to me and I liked it) Luckily I got it before the price increase - though I would have bought it even for the new price 🙂
It has volume control and headphone output too if you like that kinda thing.
Rolls also makes a neat little cheap VP29 that is only around $50. It's probably all op-amp, but it may not be too bad??
Of course there are plenty of decent phono preamps available from all the usual suspects NAD, Rotel, Cambridge audio, etc...
-Chris
Were you thinking DIY or something off the shelf? Any cost goal?
I've seen nice kits around, such as at Borbely audio or Marchand Electronics. And Hagtech has a nice kit or bare PCB for not too much $$. Sorry, but no idea how any of these sound.
I have a Rolls Bellari VP129 that I really like. I looked at all the kits before I bought this one, but got lazy. (plus the local shop loaned it to me and I liked it) Luckily I got it before the price increase - though I would have bought it even for the new price 🙂
It has volume control and headphone output too if you like that kinda thing.
Rolls also makes a neat little cheap VP29 that is only around $50. It's probably all op-amp, but it may not be too bad??
Of course there are plenty of decent phono preamps available from all the usual suspects NAD, Rotel, Cambridge audio, etc...
-Chris
If you're going to hear the differences between op-amps, it's
going to be in a phono preamp! These are simple enough
to build that you ought to try it. Battery power is very attainable
and gets you out of the tyranny of AC power supplies, noise, etc.
You still however, need good regulation.
The VSPS Phono pre is a great starting point. For a selection
of op-amps to try out, try the ADI OP270 or the BB OPA2134
in the gain stage. The ADI AD826 makes an excellent unity gain
buffer for driving the cable between your phono stage and preamp/integrated.
If you want a far easier way to do the project, go purchase a
Gemini PA-7000. It has a handsome brushed alum case and
features a line stage and phono preamp. The PA-7000 is very
easy to "upgrade" 🙂
-- Jim
going to be in a phono preamp! These are simple enough
to build that you ought to try it. Battery power is very attainable
and gets you out of the tyranny of AC power supplies, noise, etc.
You still however, need good regulation.
The VSPS Phono pre is a great starting point. For a selection
of op-amps to try out, try the ADI OP270 or the BB OPA2134
in the gain stage. The ADI AD826 makes an excellent unity gain
buffer for driving the cable between your phono stage and preamp/integrated.
If you want a far easier way to do the project, go purchase a
Gemini PA-7000. It has a handsome brushed alum case and
features a line stage and phono preamp. The PA-7000 is very
easy to "upgrade" 🙂
-- Jim
I want to build something relatively inexpensive that can run off a 12-0-12V 50VA transformer I have lying around. I already have a small chassis that I can put it in. The transformer is an EI type. Any special considerations for that?
sounds like the Hagerman bugle or the circuit that Jim posted a link to would be good.
I think the only consideration for the transformer would be a little extra attention to shielding or keeping it a bit further from the preamp circuit. - but that's good practice anyway.
Unless you go crazy on expensive op-amps, you should be able to build this for pretty cheap. You already have the most expensive parts ;-)
I think the only consideration for the transformer would be a little extra attention to shielding or keeping it a bit further from the preamp circuit. - but that's good practice anyway.
Unless you go crazy on expensive op-amps, you should be able to build this for pretty cheap. You already have the most expensive parts ;-)
Think- You should go look at pics for the Gemini PA-7000.
It's a phono pre + line stage for DJs. The insides are pretty
good. Thick glass epoxy PCB. For $99, you are paying for
the nice aluminum case, the knobs, switches and what not.
The base guts are very nice to work with... All 8-pin DIPs (4558s).
Radial caps. No SMD stuff. The phono circuit is essentially the
VSPS. 🙂 Simply replacing the op-amp and then swapping out the
R's and C's with precision components to get as close to the RIAA curve is a major improvement.
The line stage is just a 4558 unity-follower... There are muting
transistors on the follower to shunt the line out to gnd for 15 seconds
during startup (no thumps. Nice feature!).
The tone stack can be very easily bypassed by simply moving a
ribbon cable and shorting two jumpers.
The PSU is an 18VCT tranny and the usual 7815/7915 pair.
The XLR out drivers are mounted on a daughter card and uses
a inverting 4558 for "balanced out".
Improving the Gemini is cheap and easy... There's tons of extra
room in the chassis to work with. I'd buy a Velleman 8042 PSU
kit (LM 317/337 supply). Drill some holes and put it in.Get rid of
the 7815/7915 reg. Just desolder all the 4558s and put in sockets.
Dump the inverter for the "XLR out" and use a pair of SSM 2142s.
I really liked the ADI OP270 in the phono opamp socket and
the AD826 in the line-out driver socket.
-- Jim
It's a phono pre + line stage for DJs. The insides are pretty
good. Thick glass epoxy PCB. For $99, you are paying for
the nice aluminum case, the knobs, switches and what not.
The base guts are very nice to work with... All 8-pin DIPs (4558s).
Radial caps. No SMD stuff. The phono circuit is essentially the
VSPS. 🙂 Simply replacing the op-amp and then swapping out the
R's and C's with precision components to get as close to the RIAA curve is a major improvement.
The line stage is just a 4558 unity-follower... There are muting
transistors on the follower to shunt the line out to gnd for 15 seconds
during startup (no thumps. Nice feature!).
The tone stack can be very easily bypassed by simply moving a
ribbon cable and shorting two jumpers.
The PSU is an 18VCT tranny and the usual 7815/7915 pair.
The XLR out drivers are mounted on a daughter card and uses
a inverting 4558 for "balanced out".
Improving the Gemini is cheap and easy... There's tons of extra
room in the chassis to work with. I'd buy a Velleman 8042 PSU
kit (LM 317/337 supply). Drill some holes and put it in.Get rid of
the 7815/7915 reg. Just desolder all the 4558s and put in sockets.
Dump the inverter for the "XLR out" and use a pair of SSM 2142s.
I really liked the ADI OP270 in the phono opamp socket and
the AD826 in the line-out driver socket.
-- Jim
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