Upgrading an AE phono kit

[carlmart]

I am thinking of using some ready made phono stage preamp kits sold by Aliexpress to carry one some RIAA projects simulated on LTSpice.

Some of them are interesting to use as a base to experiment with several circuit geometries and values, having first simulated them in LTSpice.

Let's begin with this Aliexpress RIAA Kit.

https://pt.aliexpress.com/item/3296...ac!12000017359672389!rec&gatewayAdapt=glo2bra

They do not supply complete circuits as they used to do. So you have the option to buy just the PCB, PCB + parts Unassembled, and PCB + parts Assembled.

For the sake of this project I would pick the second choice: just pcb and parts. When they get here I could fill in the parts values on the basic diagram.

See below the basic schematics for power supply and RIAA preamp. The preamp is a classic passive eq two stage design.

As some time ago I did a lot of LTS simulations with several circuits, I will definitely try the parts Walt Jung recommended for passive RIAA preamp.

But the kit as it is has only ONE major problem: The IC they used: OPA2134. You won't get good quality for phono preamp.

Though I think I found a way out on a (I think) recently released chip:

https://www.mouser.com/ProductDetail/Texas-Instruments/OPA1656ID?qs=vLWxofP3U2zhtl9DpaFfKw==

This is a very low noise dual chip with FET input. You can also get it from AE with DIP8 adapter, which this is ready for.

https://pt.aliexpress.com/item/1005...list.product.mainProduct&gatewayAdapt=glo2bra

The larger modifications will be to the kit power supply, as I don't think is as low noise as this preamp demands.

I'm open to comments, critics and feedback.

Carlos

 

[lcsaszar]

I don't see any problem with OPA2134, provided it is genuine.

 

[DNic]

Yep, Many people use that chip in phono upgrades. The Chinese chip is not bad, but for long term use the genuine one should be bought.

Cheers

 

[dreamth]

You don't need a fantastic power supply with these Ic's they have enough PSRR and CMRR to work without any regulation once the ground traces are drawn correctly.
Your schematic is basically following lme49710 app note.If you want to go that route you could build their fanciest regulator , but I strongly advise you to start by supplying your preamp with unregulated supplies to make sure it is done correctly.If it's executed the right way you won't hear any noise with just a simple rc first order filter like 100ohms and 220uF capacitor.

 

[carlmart]

I want to use a dual SOIC8 opamps (two ICs in one opamp) soldered to dual DIP8. But I can't get the right name to look for it. I don't know if ou you know what I mean.

What I find are DIP8s where you solder two single SOICs, one of the top and one of the bottom of the DIP8. But not what I describe above.

Can you help me find what I want?

Thanks!

Carlos

 

[lcsaszar]

You can find it at Mouser:
https://hu.mouser.com/ProductDetail/Aries-Electronics/08-350000-10-HT?qs=WZRMhwwaLl8V7yq2J81PUA==
(or Aliexpress 😉 )

 

[lcsaszar]

Dual SIOC and DIP have 8 pins just like singles. Only the pinout is different.

 

[MarcelvdG]

As you want to use OPA1656 and one of the schematics has no input capacitor, see

J

Thread 'OPA1656 Phono Preamp: Split from OPA1656 thread'

2021-09-14 11:32 pm

I have an OPA1656 story that may be interesting especially to whomever wants to build the RIAA preamp example in the apps section of the data sheet. I did build that and the slightly modified schemo is attached. I used the attached blank proto board. The Layout is attached. Of the three independent rails on each edge the outside L and R were used for -15V and +15V, resp. The inner two were 0V, center Gnd, branched at power entry at the top. The rails are heavily post-filtered and bypassed and the P/S is external. The DIP8 socket has 0.1uF X7Rs pin 8→gnd, pin 4→gnd and pin4↔pin 8...

• JRA
• Replies: 605
• Forum: Analogue Source

• 

particularly post #106. The fact that you have some fixed gain in the first stage should help, though.

 

[carlmart]

You can find it at Mouser:
https://hu.mouser.com/ProductDetail/Aries-Electronics/08-350000-10-HT?qs=WZRMhwwaLl8V7yq2J81PUA==
(or Aliexpress 😉 )

A bit expensive at $15.58 each!

 

[lcsaszar]

There must be cheaper:
https://www.hestore.hu/prod_10037910.html

 

[carlmart]

Yes, those on Aliexpress are much cheaper indeed. I just to seem find one for a dual SOIC8 chip, only for two singles. I already bought some.