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Cheap phono preamp review - with photos

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I needed yet another phono preamp for the back room, so I decided to try this cheapie from Jaycar from Digitech.   https://www.jaycar.com.au/phono-stereo-preamplifier/p/AC1591

 

Then I thought I'd have some fun and do a small review, so, here's what you get in the box.

 

IMG_2573_01.jpg.eecd9cd131366d8a1dfed80f44ae47b0.jpg

 

The case is, impressively, solid steel and weighty.  A small plugpack supplies power (12 VDC) and you even get a packet of screws if you want to screw the preamp down (it has flanges on each side to allow this).

 

There is a push on / push off button to select phono input or Aux input.  A switched pot powers it up and  allows output level control (a bonus for those wanting a minimal system - you could feed this straight into powered speakers).  The ground terminal post is a knurled knob so you don't need a screwdriver to attach the ground wire.

 

Opening it up, it comes apart like so...  revealing a very neat quality looking circuit board using SMD opamps.

 

IMG_2552.jpg.1e74b73c4d2900eae3412bbddc63491a.jpg

 

IMG_2569.jpg.c790c2db4b80db7d2b1e0ea6cceb564c.jpg

 

There are no markings on the opamps, so no idea what type they are.  Everything looks well made.

 

IMG_2565.jpg.32d2ed39af56c0e932c1c257123984dd.jpgIMG_2555.jpg.171654811459515403c199e14cae7e77.jpg

 

So listening to it.   Not too shabby at all, and I guess there's no reason it should not be OK, given the typical opamp design.  Noise wise, it is nice and quiet.  Not sure the best way to test this, but with gain at normal to loud listening levels, I need to put my ear closer than 6 inches to hear any noise from the speakers.  This is with standard audio cables I had to hand - the sort you'd buy for about $30 or less.  The turntable was my cheap Pro-ject Essential II.

 

I'd have to say I'd be tempted to recommend this for someone starting out.  It's half the price of the Pro-ject phono box E as well.

 

Still listening as I type - and it's very enjoyable.  Bach Brandenburg Concerto playing in the background now.

 

A couple more pictures.

 

IMG_2570.jpg.1465e8729b3d6e3310a5edf14548f909.jpgIMG_2572.jpg.827086d0412fdf2c44355ed8f6f322e5.jpg

 

 

 

Edited by aussievintage

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I have been looking at the photos and I think it's possible to figure out the basic circuit.

 

On the right it seems to have a C-L-C filter on the power supply (nice to see an inductor used for filtering), then a resistive divider (2 x 100k) to obtain a virtual ground for the opamp split supply. Seems to be a diode in there - maybe reverse polarity protection?

 

The Phono inputs on the left seem to go to the first opamp chip (dual opamp). Looks like a straightforward feedback RIAA network around it - the green caps and associated resistors. The output of the phono amp, and the aux inputs go to the big switch.  The switched output goes to the level control pot and then to the second opamp chip (I am guessing this is a low or unity gain buffer) then to the output.

 

A nice practical circuit.

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Thanks for this review, I have just bought myself my first turntable (a Dual 506) and this phono amp could just fit the bill to get me going.

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1 hour ago, Rustee said:

Thanks for this review, I have just bought myself my first turntable (a Dual 506) and this phono amp could just fit the bill to get me going.

 

Welcome to the vinyl club :)  Hope you enjoy it.

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23 hours ago, aussievintage said:

 

Welcome to the vinyl club :)  Hope you enjoy it.

Cheers! 

Just wondering if you've ever had the opportunity to test a Behringer PP400 pre? It's also a cheapie.

I'd have to order the PP400 on line where as the Jaycar one I can get locally.

 

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3 minutes ago, Rustee said:

Cheers! 

Just wondering if you've ever had the opportunity to test a Behringer PP400 pre? It's also a cheapie.

I'd have to order the PP400 on line where as the Jaycar one I can get locally.

 

No I haven't tried the PP400.

 

The fact that Jaycar have something locally often helps me decide what to buy :)  Even if I can get it slightly cheaper elsewhere.

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1 minute ago, aussievintage said:

No I haven't tried the PP400.

 

The fact that Jaycar have something locally often helps me decide what to buy :)  Even if I can get it slightly cheaper elsewhere.

Yep agree. Always prefer to buy local where I can too.

Cheers,

Russ

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Thanks for this! I have lost the power supply for my Pro Ject Phono Box DC. I can't find an 18V 200mA power supply anywhere, so I think I'll just go an get this Jaycar one :)@aussievintage

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43 minutes ago, oztayls said:

Thanks for this! I have lost the power supply for my Pro Ject Phono Box DC. I can't find an 18V 200mA power supply anywhere, so I think I'll just go an get this Jaycar one :)@aussievintage

 

Have you looked at the 'Meanwell' range?  They may have an 18v one (I use a 12v one on my DAC and a 48v one on my TT motor control).

 

Andy

 

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I wonder if the gain control would provide enough oomph for an MC cart? Has anyone tried it?

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22 hours ago, andyr said:

 

Have you looked at the 'Meanwell' range?  They may have an 18v one (I use a 12v one on my DAC and a 48v one on my TT motor control).

 

Andy

 

 

22 hours ago, andyr said:

 

Have you looked at the 'Meanwell' range?  They may have an 18v one (I use a 12v one on my DAC and a 48v one on my TT motor control).

 

Andy

 

 

22 hours ago, andyr said:

 

Have you looked at the 'Meanwell' range?  They may have an 18v one (I use a 12v one on my DAC and a 48v one on my TT motor control).

 

Andy

 

I see now why the darn things are so hard to find. They are 18v/200mA! Almost unobtainium at that power rating :(

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1 minute ago, oztayls said:

I see now why the darn things are so hard to find. They are 18v/200mA! Almost unobtainium at that power rating :(

 

Sorry, an 18v supply which delivers 200ma is piss weak!  The 12v Sbooster LPS that I use on my miniDSP 10x10HD delivers 3a!

 

BTW, Sbooster does make an 18v version - see here: https://www.sbooster.com/botw-pp-eco-18-19v/

There's a list of compatible devices - and if yours is not on it ... simply email Karen.  But they are a lot more money than a Meanwell.

 

Andy

 

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8 minutes ago, oztayls said:

 

 

I see now why the darn things are so hard to find. They are 18v/200mA! Almost unobtainium at that power rating :(

 

 

Are you aware that , as long as it is 18v,  it only needs to be greater than the required current rating,  so the examples I linked to will all work?

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I wonder if the gain control would provide enough oomph for an MC cart? Has anyone tried it?
The problem will be the input impedance
For mm about 50k ohm
For mc about 100 ohm
You won't get enough gain

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1 hour ago, aussievintage said:

 

 

 

Are you aware that , as long as it is 18v,  it only needs to be greater than the required current rating,  so the examples I linked to will all work?

OK thank you, I was not aware how these things work, so thank you for "uncomplicating" it for me!

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2 minutes ago, Colin Rutter said:

The problem will be the input impedance
For mm about 50k ohm
For mc about 100 ohm
You won't get enough gain

Mmm, thanks. The destructions don't mention MM or MC so I was wondering...

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By the way, I picked up the Digitech Audio AC1591 from my local Jaycar this afternoon and tried it between my ERA 5055  and old Pioneer SA5300. It is a ripper of a preamp. The sound is very flat, ie. uncoloured, so  just what you want from a Phono stage. 

 

My ultimate plan is to offer these with my restored turntables, together with the cheap US$33 Kinter Tripath K2020A+ (class T) amps, for those people that don't have a suitable stereo amp and just starting out in vinyl. I've been in contact with Kinter over the past few months and I think I've finally convinced them to build a phono stage into one of their mini amps, preferably with the Tripath TA2020-020 chip as that is the one that is making all the fuss and the great sound. The problem that Kinter sees is that the supply of Tripath chips is fast running out, so they are saying they may have to run with the TI 3118 chip from Texas Instruments. Still good and cheap, but not in the same league as the amazing Tripath. 

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34 minutes ago, oztayls said:

OK thank you, I was not aware how these things work, so thank you for "uncomplicating" it for me!

No problems.  I only just realised why you were having problems finding one you see.      A bigger (power wise) supply that is capable of more current can always be used provided the voltage is correct.

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On 22/12/2018 at 6:41 PM, aussievintage said:

 

 

 

Are you aware that , as long as it is 18v,  it only needs to be greater than the required current rating,  so the examples I linked to will all work?

Mmm, I bought an 18V 1A power supply and I think it's fried the Pro-Ject Phono Box. Started smelling and smoking soon after plugging it in. Maybe the Phono Box circuit can't take the extra juice?

Edited by oztayls

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Did you check that the polarity was correct for the Phono Box?

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Yes, the centre pin is positive.

 

Edited by oztayls

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Here are the Specifications for the phono preamp, from the Radio Parts page:

https://www.radioparts.com.au/product/60850435/pro1387-riaa-phono-preamp-with-aux-preamp-with-aux-input#.XDPci2kRXRY
 

Edit (10 Jan 2019):

These spec's are for the "PRO1387 Pro2 Riaa Phono Preamp with AUX Preamp" aka Jaycar "Digitech" that was presented in the original post.  [To clarify confusion in subsequent posts, it isn't specs for the ProJect preamp.]

 

Input Impedance 47K ohms
Output Impedance 100 ohms
Phono Amplitude Gain 40 dB (@1kHz)
AUX Amplitude Gain 6 dB
Maximum Input 50 mV pp
Output Level 5V pp
Frequency Response 20 Hz to 20k Hz
Signal to Noise Ratio 70dB
Power Source 12V DC ( INCLUDED )

Size

 

 

145mm(L)* 96mm(W)* 31mm(H)

 

 

Edited by audiofeline
Clarification, the original post caused some confusion in latter posts.

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