Here is another for MM, with LM381 or LM387, a dedicated PCB is not necessary, given the simplicity of the connection, but the values of the components must be calculated ......
Informacion electronica.: Preamplificador RIAA con LM381 o LM387. Calculo
Informacion electronica.: Preamplificador RIAA con LM381 o LM387. Calculo
In response to your post 27, "fine" dust will not be a problem, as long as the vinyls are properly sealed inside their sleeve. A simple Cecil.E.Watts type wiper arm (yes, it's very vintage, ha) will remove it while you listen. But that dust is not audible, at least on my system. The problem is large embedded debris and / or recycled vinyl as we discussed earlier. The vinyl envelopes must be folded at the ends (on the side that penetrates the record) in the shape of a wedge, and on that side insert them inside the cover. Impossible for dust to enter if stored like this. I've listened to LP's stored like this for years and they didn't accumulate "thick" dust, just some of the fine dust, which would already be inside the envelope.
Sorry to the OP for diverting the topic.
Sorry to the OP for diverting the topic.
No problem academia50,
Diversions are part of life, and thread topics are not immune.
For my LPs, after I insert them into the inner sleeve/liner, that now goes into the cardboard cover with the liner opening 90 degrees to the cover opening.
I never had an issue with dust that way.
As for the various posts of "other" preamps, particularly the "home brew" ones, I'll stick to the Technics versions.
Surely THEY have the knowledge, skills, and laboratory equipment, and I'm sure listening tests, to provide a suitable product.
They've been in business for decades, providing great products through the years.
My original post here about that preamp...
I have one of those RIAA pre-boards, installed in a BSR changer/Shure cartridge, a long while back, powered by a simple 7815/7915 regulator that I designed, all into the base of the changer.
Haven't used it in years..
The other week, I pulled it from its dusty shelf to check it out.
Hooked it up, put a good record on it... wow, it really surprised me!
I just sat there, enjoying the music for a while.
That same RIAA design is in my main (Technics) stereo too.
And with an Audio Technica cartridge on my Kenwood linear tracker... just awesome pleasing sound.
Diversions are part of life, and thread topics are not immune.
For my LPs, after I insert them into the inner sleeve/liner, that now goes into the cardboard cover with the liner opening 90 degrees to the cover opening.
I never had an issue with dust that way.
As for the various posts of "other" preamps, particularly the "home brew" ones, I'll stick to the Technics versions.
Surely THEY have the knowledge, skills, and laboratory equipment, and I'm sure listening tests, to provide a suitable product.
They've been in business for decades, providing great products through the years.
My original post here about that preamp...
I have one of those RIAA pre-boards, installed in a BSR changer/Shure cartridge, a long while back, powered by a simple 7815/7915 regulator that I designed, all into the base of the changer.
Haven't used it in years..
The other week, I pulled it from its dusty shelf to check it out.
Hooked it up, put a good record on it... wow, it really surprised me!
I just sat there, enjoying the music for a while.
That same RIAA design is in my main (Technics) stereo too.
And with an Audio Technica cartridge on my Kenwood linear tracker... just awesome pleasing sound.
My experience with recommending audio stuff is that you hardly find 2 guys hearing simillar things on the same system on a continent ...
I plugged the values from Technics RIAA circuit in the original post into a circuit simulator. If you run the signal thru the RIAA equalizer, then thru an ideal inverse equalizer you should end up with a flat response. This is the response I get from that circuit. Usually you shoot for +/-0.25 dB from ideal. This one is about 0.5db down in the 5-10 kHz range. It has a little bit of boost below 100 Hz, but really that could be a good thing for many systems. But it's not entirely accurate. There's nothing wrong with the basic circuit, but I would choose different component values. There are online component calculators out there if you search for them.
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So what you're saying is that the Technics designed a pretty damn good equalizer.
Considering the fact that records themselves are all over the map as far as equalization due to the engineer's fingers on the master controls.
In other words, a fraction of a decibel from perfect RIAA tracking is not worth the bother, when the plant decides to finalize the master (to their tastes) anyway.
Yet, audio people go absolutely nuts over trying for the "perfect" RIAA design.
This I know.
That perfect circuit simulator probably don't count the cartridge loading capacitor and impedance, which can make a hugh frequency response difference.
I have no idea who those people are...yet i have seen better graphs in cheap commercial units.
Yes, it's OK. It has a bit flatter response than some cheap phono stages like the Pyle PP999 or Behringer PP400.
That's not the preamp's job. The preamp should match the interface spec. It is the cart designer's job to do the best he can from there.
My sims show +/-0.33dB, which is better than claimed. For an All-Standard-Values design it is very good. The 5kc-10kc slump is very mild and may be a brand-preference.
Cartridge loading is a good reason to build or buy a phono stage as opposed to using the one in your receiver/amp. I measured a cheap 6 foot cable that has a capacitance of 500-600 pf, and that is way too much for most cartridges. I have to admit that's exactly the situation I probably have with my turntable. If you have a small separate phono stage, it's easier to locate it next to the turntable. You can make your own very short cable and maybe get the cartridge loading somewhere in the ballpark of the usually specified 100pf.
@msubully82
No it is not! The best commercial phono preamp I know only has a100pf series with 100 ohm input loading capacitance,just a switch for resistive loading at 33k,47k and 100k.The reason for that being that at the peakof vinyl reprodution in late 70's most turntables would come with a preffered cartridge mounted at the factory,and the connection DIN or RCA cable from the turntable would be the exact capacitance needed toload the cart minus 100pf that almost all phono preamps found in receivers or control preamps would have at the input.When changing the cart on a turntable change the cable or load it straight at the tonearm cables input inside the turntable in case of MC cart use.Changing and aligning a new cart is not an easy task so you get the chance to work on the turntable's wiring too.Besides, loading the cart straight at the tonearm wires output makes the whole system quiter.
No it is not! The best commercial phono preamp I know only has a100pf series with 100 ohm input loading capacitance,just a switch for resistive loading at 33k,47k and 100k.The reason for that being that at the peakof vinyl reprodution in late 70's most turntables would come with a preffered cartridge mounted at the factory,and the connection DIN or RCA cable from the turntable would be the exact capacitance needed toload the cart minus 100pf that almost all phono preamps found in receivers or control preamps would have at the input.When changing the cart on a turntable change the cable or load it straight at the tonearm cables input inside the turntable in case of MC cart use.Changing and aligning a new cart is not an easy task so you get the chance to work on the turntable's wiring too.Besides, loading the cart straight at the tonearm wires output makes the whole system quiter.
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100pFd per foot is absurdly high. Is the insulation loaded with metal flakes? (I see this figure is used as an example on many websites.)
I can't imagine putting the needle more than arms'-length from the volume control. For needle-drop reduction, and because that line is VERY sensitive to buzz. The preamp goes in the middle somewhere. So about 3 feet of cable. Ordinary cable is 30pFd/ft. So 100pFd here. Another 100pFd in the 6SC7/12AX7 first tube we always used. Indeed older carts liked 200-300pFd.
My Kenwood automatically mutes, prior to arm lift in 100msec, via a set of transistors, and releases the muting about a second after needle touchdown.
Nice delay too, you can hear the silent starting grooves gradually kick in.
And then................ MUSIC MUSIC MUSIC!
Nice delay too, you can hear the silent starting grooves gradually kick in.
And then................ MUSIC MUSIC MUSIC!
I did not remember the mute when the needle falls, it seems fantastic to me, nothing more annoying than that violent "plop", also (it depends on how close the needle falls to the beginning of the recording) if we previously lowered the volume, when we later raised it, " the show has already started "!
msubully82 , the sl1200 technics had a phono cable recall. Instead of the one meter / about 100pf (about 30 pf/ft) value, the wrong cable was soldered with a capacitance in the range of the 300pf. Djs started to take their tt for service since their "new" turntables were not loud enough. The repair/ engineer shop notified Tehcnics.(freely paraphrased from kab.com)
I just replaced one of my sl1200 signal cable; most recommended cables (I got a mogami svhs grade) are 15-40 pf/ft
(freely paraphrased from kab.com)
I just replaced one of my sl1200 signal cable; most recommended cables (I got a mogami svhs grade) are 15-40 pf/ft
(freely paraphrased from kab.com)