search for cheap phono preamp

[Original Burnedfingers]

I found something called Luckydog Transimpedance Phono preamp.

Anyone ever heard of it? If so is it worth making?

How would it compare to the relic from the 1970's?

The relic is from the Barney oliver amplifier produced in around 1972 for HP

employees.

[Michael Bean]

The luckydog wouldn't work well for moving magnet cartridges that expect to be loaded by about 47k resistance, but may work OK for moving coil if circuit noise is low enough (but I doubt it). The other one might be alright, but proper ciruit layout would be critical.

Maybe something like this would be a good alternative:

http://www.national.com/ds/LM/LM4562.pdf

Mike

[Original Burnedfingers]

Turntable Forum :: View topic - A Novel Mm/Mi Phono Preamp - Transimpedance

Here is the article

[jcx]

mc or mm is the 1st question, after that "cheap" neds some parameters - are you only buying $0.30 op amps?

some would consider even a OPA627 design "cheap" at $20 ea - especially if you buy new parts for power, case, connectors and include any implicit labor rate for the ordering/build time

[Original Burnedfingers]

Parameters....MM not MC

Cheap down and dirty 5532's

something that would better the $18 ebay china models

build on perf board for trial

[Salas]

In case of input op amp failure, the cart goes. I would add an output coupling cap since there is enough gain for the second op amp to multiply dc offset and there is no servo.

[tubelab.com]

I hate to admit this, but...

I had been tinkering with a rather complicated vacuum tube design sent to me by another forum member. It didn't work right and was rather microphonic. I lost my patience and built a little chip amp that goes inside the turntable and works too good.

Just grab the data sheet from National Semiconductor and built it. It's on the front page of the data sheet and on this page too. I made an SMD version, but DIP's and even round metal cans are available.

LME49720 - Dual High Performance, High Fidelity Audio Operational Amplifier

[Michael Bean]

6BG6GA,
What cartridge are you using, and what are the manufacturers loading specs?

Mike

[Michael Bean]

Hi Tubelab,
Yep, that's the same thing I posted, only difference is that National renamed the old LM4562 to LME49720 for some reason.
Great minds think alike.
Mike

[tubelab.com]

Yep, that's the same thing I posted

Didn't realize it was the same chip. Now that I see the data sheets they are the same. The National Semi rep was in the plant trying to sell us some power management chips. I didn't bite on those since we use custom chips but I got some fancy clock synthesizer chips for work stuff. We started talking about audio and he told me about these chips and got me a few samples.