My A/V receivers are too modern and no longer have ports for phono input. I'm looking for a reasonable solution to get my turntable phono output up to line level.

My son-in-laws are both riding the vinyl trend and since I still have my turntable and vinyls, I'd like to put them to use so we can share that fun. My old vinyl LPs are certainly classics.

I thought finding a RIAA pre-amp would be easy but wow, it's quite a rabbit hole. There are tons of options and prices run from under $20 to goofy audiophiles offering products for hundreds of dollars. I'm sure the components included in older equipment got the job done for a few dollars or less. Maybe that's apples and oranges to those audiophiles but I'm skeptical that spending more than say $50 would give a noticeable improvement.

I'm looking hard at this one:
https://www.amazon.com/Pyle-Phono-Turntable-Preamp-Preamplifier/dp/B004HJ1TTQ

Do you have any experience or insight?

Background literature:
https://sound-au.com/project06.htm
https://www.andyc.diy-audio-engineering.org/phono-preamp/index.html

 

https://www.parts-express.com/home-...dhUFFAHzfDcB790OdrAUKlq_Kz5kMf1-goypbI2JJAWKB

It's only a RC network with a signal buffer to normal line level signals usually.
https://www.tubecad.com/2021/07/blog0540.htm

My very modern Denon still has the phono input.

 

I'm looking hard at this one:

The specs for that device seem good, so I think it should work fine.

An RIAA preamp has two functions -- amplify the low level (a few mV) phono cartridge signal to the normal amplifier input level of about a volt, and provide the two 1-pole equalization filters which boosts the bass and attenuates the treble from the record signal which was recorded with the inverse filter function.
Not difficult in principle, but requires a low-noise audio op amp and careful design and grounding for a low-noise, low distortion output.

 

My very modern Denon still has the phono input.

Yes, I misspoke. My Denon does as well. The Yamaha it replaced had it on the higher end models that year, but not mine.

 

Of course to properly listen to Vinyl, you should be using an all tube amp and preamp.
That will add the proper amount of hum and distortion to the output.

 

https://www.parts-express.com/home-...dhUFFAHzfDcB790OdrAUKlq_Kz5kMf1-goypbI2JJAWKB

It's only a RC network with a signal buffer to normal line level signals usually.
https://www.tubecad.com/2021/07/blog0540.htm

My very modern Denon still has the phono input.
View attachment 352599
View attachment 352600

My local thrift had the same Technics linear tracking turntable for $150.

I wasn't sure of two things:

1) Is it worth the price?
2) Does it work, and are phono cartridges still available for it (assuming that would be the most likely part requiring replacement).

I skipped on the purchase, but I still think about it.

 

My local thrift had the same Technics linear tracking turntable for $150.

I wasn't sure of two things:

1) Is it worth the price?
2) Does it work, and are phono cartridges still available for it (assuming that would be the most likely part requiring replacement).

I skipped on the purchase, but I still think about it.

1. Yes, if it's in very good condition and it's something you want. I paid a less for mine used.
2. It works fine but I did a tune-up on mine a few years ago.

This my spare cartridge

https://www.audio-technica.com/en-us/at81cp

 

Of course to properly listen to Vinyl, you should be using an all tube amp and preamp.
That will add the proper amount of hum and distortion to the output.

It doesn't sound as it should unless you paid at least £10000 for the turntable, and the platter is so heavy that the little motor can't start it on its own. And don't forget the "directional" signal cable and the mains transformer wound with silver wire.

 

Of course to properly listen to Vinyl, you should be using an all tube amp and preamp.
That will add the proper amount of hum and distortion to the output.

I have an old Fender Tremolo amp but I'll be selling that when I get a chance. Turns out it might be worth a couple grand.

 

2) Does it work, and are phono cartridges still available for it (assuming that would be the most likely part requiring replacement).

That's my next issue. Pretty sure my old Shure cartridge has lost its diamond tip. Prices aren't what they used to be 50 years ago!

 

That's my next issue. Pretty sure my old Shure cartridge has lost its diamond tip. Prices aren't what they used to be 50 years ago!

Yes, they are usually cheaper in relative dollars (70's) for very good clones thanks to the return (never really left) of Vinyl.
https://www.audio-technica.com/en-us/cartridges

In the early 1960s at Tokyo’s Bridgestone Museum of Art, curator Hideo Matsushita hosted LP listening concerts, where people would experience vinyl records played on high-quality audio equipment. Matsushita was moved by the positive reactions guests had to the music, but was frustrated that the expense of high-fidelity listening prevented many people from experiencing it.
In 1962, Matsushita founded Audio-Technica with the vision of producing high-quality audio for everyone. And following this vision, he soon created the first truly affordable phono cartridge, the AT-1, in the company’s small flat in Shinjuku, Tokyo.

 

An off-brand replacement stylus for my Shure cartridge costs about as much as my turntable did. Sigh...

 

Hello,

You van find a collection of phone preamp schematics on the following page of ESP:
https://sound-au.com/project25.htm

Bertus

 

An off-brand replacement stylus for my Shure cartridge costs about as much as my turntable did. Sigh...

There's a reason why divorce and a replacement stylus is expensive, it's worth it.

 

Another source of circuits for phono inputs is in the "audio" section of the "schematicsfrofree" website. It is one of the few sites that actually is free and does not try to sell you stuff. So treat it with respect. There are both "circuits" and also circuits of "products", so you can get a good education as to how it was done on commercial products. Both tube and transistor.

 

The Pyle preamp gizmo that I linked in #1 has arrived and I got it hooked up. For evaluating it I can only rely on memory as there's no A/B test I can do. So I can confirm it works, not much else. Seems fine. Waiting on my stylus upgrade.

Now I can listen to poppy, scratchy vinyl. Yay.

 

So I can confirm it works, not much else.

As long as it doesn't have noticeable hum or hiss, and amplifies the cartridge signal sufficiently, that's all you need.

Now I can listen to poppy, scratchy vinyl. Yay.

Ahh, the nostalgia of it all.

 

I found several circuits for the RIAA playback equalization function today. Both transistor and tube versions.All in the "schematics for free" AUDIO section.

 

Side Nostalgia Note:
A few eons ago I build an Allied Knight-Kit tube integrated audio amplifier with preamp (here).
It basically worked fine but the treble sound was excessive when using the RIAA phono input, and would only sound okay if I turned the treble control way down.
I then looked up RIAA equalization circuit design (don't ask me where, since this was well before the internet) and compared it to the amp's circuit.
It was similar to one of the reference 2-resistor, 2-capacitor, anode-grid feedback designs expect it somehow lacked the capacitor for the high frequency rolloff.
So I added the missing cap, and the treble was then okay.

The question I could never answer is, how could they could design, test, and sell the amp without anyone noticing that the high frequency response of the phono input was way off?

 

Side Nostalgia Note:
A few eons ago I build an Allied Knight-Kit tube integrated audio amplifier with preamp (here).
It basically worked fine but the treble sound was excessive when using the RIAA phono input, and would only sound okay if I turned the treble control way down.
I then looked up RIAA equalization circuit design (don't ask me where, since this was well before the internet) and compared it to the amp's circuit.
It was similar to one of the reference 2-resistor, 2-capacitor, anode-grid feedback designs expect it somehow lacked the capacitor for the high frequency rolloff.
So I added the missing cap, and the treble was then okay.

The question I could never answer is, how could they could design, test, and sell the amp without anyone noticing that the high frequency response of the phono input was way off?

Probably they just tested it with a signal generator at 1kHz.
Was it built on tag-strip or on a pcb?