Would a Cassette Player Pre-amp serve as a good phonostage?

[Saket]

Dear FM,

We know that even a cassette player has a pre-amp which is connected to the stereo head by shielded cables. I was wondering that if I disconnect the stereo head & feed the MM cart output to those shielded cables & then to the pre-amp, would that not serve as a good phonostage? Can anyone put some light on the output voltages of MM cart & the output of a stereo head? Because if that were true, we could get good phono at reasonable costs.

Thanks & regards,
Saket.

 

[jls001]

No.

Phono preamp needs to reverse the process of RIAA equalisation which is "pressed" into the record at the pressing stage. Tape head preamps will not be able to do the same equalisation curve so you will get a weird sound, assuming it has enough gain in the first place.

 

[jls001]

sachu888 has wonderful phono preamp kits for both MM and MC cartridges, and they don't cost a whole lot of money. The performance of the MM pre is claimed to be equal to or better than a popular Cambridge Audio phono preamp (I forgot the exact model) - as per some owners.

I think you can't really go wrong with the CNC phono pre.

sachu888 himself can probably give you a comparo of the CNC v/s his Technics integrated's relative performances.

IMHO, try not to think on the line of AVR with in-built phono.

 

[reubensm]

Cassette tape heads and Moving Magnet Cartridges have just about the same output of around 5-7mv so if you take a one-dimensional view, then you would get some positive results. However, you need to keep in mind 2 factors:

1) impedance mismatch
2) equalization

Impedance: Tape heads and MM cartridges have different impedances and hence, input loading would be different. I remember, many years ago, when I constructed a tape head preamp, I used a 4.7k load resistor. However, while looking up my Shure M44-7 datasheet, I came to understand that they recommend 47k with 450pf. This is the kind of difference you will be looking at.

Equalization: Phono cartridges require RIAA equalization as all vinyl records are cut with RIAA equalization standards. Like I mentioned before, there is a de-emphasis while recording and emphasis while playing back. A playback tape head also needs equalization, i.e. bass boost. However it uses a curve very different from RIAA standards, more likely to be either NAB or IEC equalization curves. Also, the head preamplifier needs to be as close as possible to the tape head, otherwise (due to the high gain and strong bass boost) it will pick up hum that is difficult to overcome. This is unlike phonostages which allow you to use longer cables between the cartridge and phonostage.

To sum up, if you connect your MM cartridge to a cassette head preamp, you may hear some music coming out of your speakers, however, the quaility of reproduction is anyones guess

Thanks

 

[Saket]

Yes jls001,

I had a word with sachin on the forum itself. Read about his DIY phono. Sounds really really tempting and at the given cost, its a must takeaway...but I am not an expert with assembling electronics, (though have restored some old lesser complex tts like philips & HMVs & murphy and sachin himself is busy with some of his own projects.
So was looking at other options..
Thanks & regards,
Saket

 

[sachu888]

Thanks Joshua for kind words.I advised him to get a basic set up first.Later he can optfor any good quality outboard Phonostage,otherwise he will not know the importance of a good Phono pre.BTW: CNC is growing in Lanco heaven as well see review here http://www.lencoheaven.net/forum/index.php?topic=9021.15 Two channel amp is very important for Vinyl playback as Joshua suggested.You will not get a good performance with AVRs.

Regards,
Sachin

 

[jls001]

BTW: CNC is growing in Lanco heaven as well see review here http://www.lencoheaven.net/forum/index.php?topic=9021.15

Good to know that you've spread the good words there. Lenco Heaven is full of DIY freaks always ready to try out a good thing.

 

[Thad E Ginathom]

To sum up, if you connect your MM cartridge to a cassette head preamp, you may hear some music coming out of your speakers, however, the quaility of reproduction is anyones guess

It's easy to guess: It will be a high-pitched tuneless noise. No perceivable bass content at all.

RIAA equalisation can be done in software. Actually I have have had quite good results using the preset in Audacity. In the process, I've listened to un-RIAA-ed LP sound quite recently.

We know that even a cassette player has a pre-amp which is connected to the stereo head by shielded cables. I was wondering that if I disconnect the stereo head & feed the MM cart output to those shielded cables & then to the pre-amp, would that not serve as a good phonostage? Can anyone put some light on the output voltages of MM cart & the output of a stereo head? Because if that were true, we could get good phono at reasonable costs.

No, No and No . Even if you increase the voltage sufficiently the RIAA thing means there is no substitute for a proper phone stage. You just cannot listen to music from vinyl without one. They are not necessarily costly.

ps... mine's a Musical Fidelity V-LPS II

 

[quad]

Yes jls001,

I had a word with sachin on the forum itself. Read about his DIY phono. Sounds really really tempting and at the given cost, its a must takeaway...but I am not an expert with assembling electronics, (though have restored some old lesser complex tts like philips & HMVs & murphy and sachin himself is busy with some of his own projects.
So was looking at other options..
Thanks & regards,
Saket

If you want to buy a ready made one to get started without spending too much, look at
the Art DJ preamp available on Amazon.

Or maybe some one can assemble the CNC kit for you locally - TV mechanic
or an engg student.

 

[vinaygat]

Dear Friends...

As per my experiment, A cassette player stereo preamp stage can be used as a good phono stage without any problems.

My Toshiba phono stage was not working when i brought it from a scrap yard. Diamond needle was in good condition so i purchased it.

Later i connected the cartridge output to LA 3161 preamp stage using shielded wire.
Then i used a variable 10K POT at the output stage. Then fed the signal to the amplifier.
Varied the POT until i got clear audio output.

This is working fine from 6 months without any problems.

The audio clarity is really good

So LA3161 Sanyo IC simply rocks

 

[Thad E Ginathom]

A cassette player stereo preamp stage can be used as a good phono stage without any problems.

What is doing the RIAA eq?

 

[Saket]

So support what vinaygat has said, I would like to state my experiment too. But the thing is that mine experiment was done on a CERAMIC CARTRIDGE. This was done to my old HMV Fiesta whose built-in amp went kaput. It was a simple circuit inside & I didnt want to spend more than the cost of circuit itself just to repair it. SO I thought for an upgrade in sound. I wanted to change the circuit with a stereo cassette player's kit and the cartridge with a ceramic; but stereo cartridge. I did find a 40W/40W stereo kit to handle the amplification part but unfortunately couldnt find a stereo cartridge which can be put in a Fiesta, so the cartridge remained the same mono one.
When I placed this new kit in the player with a 12V DC transformer & a simple custom made power section including just 2 diodes & a capacitor, the output from the speakerS (though technically a mono due to cart, the stereo kit had L+R speakers) was highly distorted. To solve this, what I did was a fluke. There was a resistor place in the connector under the tonearm of the player. I placed this resistor between the 2 points of the cart. output.
Now the sound started flowing...& since then I have been using my fiesta with this kit only. Externally I have made no changes to this system, but inside there is a cassette player's kit doing the duty & I must say that the 40/40 kit sounds much powerful & better than the original miniature amp of the HMV Fiesta.
I started this thread because I had no idea if this would also work with a MM cart, but I can confirm that it works beautifully with ceramic cart, of course with 'that' resistor.

Thanks & regards,
Saket

 

[omishra]

Dear Friends...
...
Later i connected the cartridge output to LA 3161 preamp stage using shielded wire. Then i used a variable 10K POT at the output stage. Then fed the signal to the amplifier. Varied the POT until i got clear audio output.
This is working fine from 6 months without any problems.
The audio clarity is really good
So LA3161 Sanyo IC simply rocks

That IC has frequency dependent output. It bumps LF while cutoff HF. Moreover it has electrolytic input caps which comes in path of cartridge output. So what output you get is equalized but not RIAA complaint though. Also noise figures are not audible until you listen to real phono stage.
Otherwise we could have smallest phono stage ever made from this chip. Though I successfully used it as microphone and guitar preamplifier.

 

[sachu888]

Also noise figures are not audible to you until to listen to real phono stage.

100% agree with Om

Regards,
Sachin

 

[Thad E Ginathom]

That IC has frequency dependent output. It bumps LF while cutoff HF.

Ahh, you looked at the data sheet too. I thought the same thing from looking at the graphs, but I am not at all experienced in assessing such data, so it is nice to have confirmation.

Even the cheapest vinyl playback system will have RIAA eq incorporated in it. Without that, one might, by some other means, be able to produce something that seems listenable, but it will not be any sort of fidelity.

Phono preamps may be very costly, but they do not have to be. Those without budget could try something like this: phonopreamps.com*. I was very tempted to try one of these, but, like many of us do, I eventually plumped for a hifi brand

Anything that applies a proper RIAA curve is bound to be better than ...something that doesn't. This is absolutely fundamental to vinyl playback.

*That company's FAQ page is well worth a visit by those on the beginning of the TT road

.

 

[reubensm]

I must add that those inbuilt germanium transistor amps in the HMV popular and fiesta series were very basic and built to a bare minimum (obviously to keep costs as low as possible). I remember once opening up an old HMV popular record player to find a simple 2 stage preamp without any feedback loops (simple voltage amplifier) with a 1meg resistor and 0.1mfd cap in parallel, wired across the input were the mono ceramic cart was connected. Guess this was for some kind of load balancing, matching. The sound that came out was so low in fidelity that any modern IC based kit available at common electronics stores would sound way way better. My opinion is that inbuilt philips and HMV record player amp stages cannot be used to benchmark the effects of equalization. I honestly believe, RIAA equalized sound should be better in theory. However, what sounds best to one's ear is what one should invest in. I still remember my father's DIY preamplifier back in the day with loads of feedback loops hanging out of the bottom.

 

[kuruvilajacob]

I have noticed that many of the old integrated amplifiers of sansui, nad,marantz have excellent phono stages. Whenever I get any such amps with complaints in the power section, I buy them and give them to those who do not have phono stages in their main amps to be used as phono stage. Even though there may be some loss, they sound better than some of the new phono stages.
kuruvilajacob

 

[Thad E Ginathom]

I have noticed that many of the old integrated amplifiers of sansui, nad,marantz have excellent phono stages.

From the days when hifi meant having a turntable. All else was secondary.

 

[quad]

I have noticed that many of the old integrated amplifiers of sansui, nad,marantz have excellent phono stages. Whenever I get any such amps with complaints in the power section, I buy them and give them to those who do not have phono stages in their main amps to be used as phono stage. Even though there may be some loss, they sound better than some of the new phono stages.
kuruvilajacob

Discrete preamp circuits do sound very good. There are some excellent
ones which one can DIY too. Like the Salas phone pre, or the TC750,
based on low noise bipolar transistors.

http://beavishifi.com/articles/phono-preamps/

 

[vinaygat]

Believe it or not...

LA3161 preamp stage which am using is giving good output with good clarity.
I also have Technics Cassette Deck (RS-M216)
So the output of LA3161 preamp is given to "line in" connector of Technics Cassette Deck.
Then The Output of Technics is given to Power Amp.

I can record LP to Cassettes also ! My friends always ask me to convert vinyl records to Cassettes. (Most of my friends are Cassette Player Freaks )

Even i like Technics cassette player. It has original MX head and the output sound is really good. Even in this Blu Ray Era i always love to listen audio in Cassettes and Vinyls.

The music feel and the fluorescent display looks are simply amazing, which cannot be explained