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aussievintage

Cheap phono preamp review - with photos

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2 hours ago, oztayls said:

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?

 

Well, since it is 18V, then there is no extra "juice".  If you are referring to the current rating, that is simply a rating indicating the maximum it can deliver.   Your equipment draws as much as it needs, no more, from the power supply.

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Uh-oh, I'm the idiot. The adaptor is 18VAC, not 18VDC 🙄

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3 minutes ago, oztayls said:

Uh-oh, I'm the idiot. The adaptor is 18VAC, not 18VDC 🙄

ooops :)

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2 hours ago, oztayls said:

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?

 

17 minutes ago, oztayls said:

No, it's definitely 18V.

PhonoBox-EN.pdf

IMG_3905.JPG

 

Yes, it definitely says '18v' on the case ... but the specs that af posted, say 12v!  Can you measure what is the output of the PS you used to use?

 

4 minutes ago, aussievintage said:

Well, since it is 18V, then there is no extra "juice".  If you are referring to the current rating, that is simply a rating indicating the maximum it can deliver.   Your equipment draws as much as it needs, no more, from the power supply.

 

^^^ what he said!  :thumb:

 

However, if you fed 18v to something that wants only 12v ... that would certainly fry it!  :(

 

Andy

 

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Especially if you feed it 18v AC

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2 hours ago, andyr said:

 

 

Yes, it definitely says '18v' on the case ... but the specs that af posted, say 12v!  Can you measure what is the output of the PS you used to use?

 

 

Mine is a different preamp to the one AF posted the specs for. But it doesn't matter now anyway because I used an AC adaptor instead of DC. I posted the PDF link above for the preamp I have and it's definitely 18VDC. I'll try the correct 18VDC adaptor and see if it has survived the experience, but I'm not hopeful!

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46 minutes ago, oztayls said:

Mine is a different preamp to the one AF posted the specs for. But it doesn't matter now anyway because I used an AC adaptor instead of DC. I posted the PDF link above for the preamp I have and it's definitely 18VDC. I'll try the correct 18VDC adaptor and see if it has survived the experience, but I'm not hopeful!

 

Very easy mistake to make, oz.  :(  But probably one you will only make once!  :thumb:

 

If it makes you feel any better, on Saturday I blew up one channel of a stereo amp that I was measuring on the bench ... by carelessly touching the earth lead from a CRO - instead of the 'live' lead - to the live side of the dummy load I had connected to that channel's output terminals.  :(

 

Andy

 

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34 minutes ago, andyr said:

 

Very easy mistake to make, oz.  :(  But probably one you will only make once!  :thumb:

 

If it makes you feel any better, on Saturday I blew up one channel of a stereo amp that I was measuring on the bench ... by carelessly touching the earth lead from a CRO - instead of the 'live' lead - to the live side of the dummy load I had connected to that channel's output terminals.  :(

 

Andy

 

Ouch! 🤯

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Thanks for good advice. Maybe I'll buy this phono preamp. But I have limited space and I need to pick the right size. I plan to buy it in Europe, so I will need to convert the dimensions from centimeters to inches on the site - https://cm-to-inches.org/))

Edited by drake654

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54 minutes ago, drake654 said:

Thanks for good advice. Maybe I'll buy this phono preamp. But I have limited space and I need to pick the right size. I plan to buy it in Europe, so I will need to convert the dimensions from centimeters to inches on the site - https://cm-to-inches.org/

885021B4-C1BA-4BD0-B091-2FDBB3ADF8FA.png

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On 08/01/2019 at 9:15 AM, audiofeline said:

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
 

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)

 

To clarify, these are the specifications I posted are for the "PRO1387 Pro2 Riaa Phono Preamp with AUX Preamp" aka Jaycar "Digitech" that was in the original post. 

 

They are NOT for the Pro-Ject phono preamp that the thread diverted to discussing (perhaps another topic should have been created for that discussion). 

 

 

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I just bought one of these and have spent an afternoon playing LPs. $49 via Amazon. My DIY valve preamp is in need of a repair and this is a stop-gap while I get around to it.

This cheap little preamp is in much fancier company: It is feeding home-made 300B mono amps which are feeding 15" Tannoy Monitor Golds in 300L reflex boxes. The source is a Garrard 301 on home-built heavy plinth, SME 3012 arm, top of the line Nagoaka cartridge. 

I could do with more gain as I am using it directly into power amps. It plays only just loud enough for ordinary listening but that is not the pre-amp's fault. My home-build power amps have little gain and my home built pre-amp compensated for that with more gain. This device is intended to add a phono stage to an aux input and to only use its volume knob to adjust the level to match other sources. I doubt that gain would be a problem when used more conventionally. 

The sound is clear and uncoloured. It is hard to find any particular flaw. Being picky, I'd say it seems to lack a bit of the weight and solidity and warmth and dynamics and 'air' of my usual pre-amp but that is a valve circuit with components and design that would not be found in a commercial product for under a grand. 

Certainly this pre-amp is good value at the price. 

 

Edited by PeterCam

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PS. Also very handy when used as intended that you don't lose the Aux input. For my stop-gap purpose, it is handy that it gives me phono plus one line level source with switching and volume control.

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40 minutes ago, PeterCam said:

I just bought one of these and have spent an afternoon playing LPs. $49 via Amazon. My DIY valve preamp is in need of a repair and this is a stop-gap while I get around to it.

This cheap little preamp is in much fancier company: It is feeding home-made 300B mono amps which are feeding 15" Tannoy Monitor Golds in 300L reflex boxes. The source is a Garrard 301 on home-built heavy plinth, SME 3012 arm, top of the line Nagoaka cartridge. 

I could do with more gain as I am using it directly into power amps. It plays only just loud enough for ordinary listening but that is not the pre-amp's fault. My home-build power amps have little gain and my home built pre-amp compensated for that with more gain. This device is intended to add a phono stage to an aux input and to only use its volume knob to adjust the level to match other sources. I doubt that gain would be a problem when used more conventionally. 

The sound is clear and uncoloured. It is hard to find any particular flaw. Being picky, I'd say it seems to lack a bit of the weight and solidity and warmth and dynamics and 'air' of my usual pre-amp but that is a valve circuit with components and design that would not be found in a commercial product for under a grand. 

Certainly this pre-amp is good value at the price. 

 

Good to hear your experiences with it.  I normally use my own home built valve phono preamps, and I can kinda agree with you assessment, particularly the "air" that the valve circuit lends to the experience.

 

The thing is, if I was to build my own cheap op-amp phono preamp, it wouldn't be much different to this one, and would end up costing more.

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23 hours ago, PeterCam said:

PS. Also very handy when used as intended that you don't lose the Aux input. For my stop-gap purpose, it is handy that it gives me phono plus one line level source with switching and volume control.

Now I have tried it with an Apple airport express as its Aux source as a switchable alternative to my turntable. The Apple airport express has a headphone/aux output and connects to a home wifi set up. Any audio streaming from a CD, hard-drive or internet via my laptop is now an option. This arrangement still does not go loud with my low gain power amp but it is loud enough for my usual listening levels. With a power amp of more normal gain you could probably be happy with this simple set up. 

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5 minutes ago, KalahariDessert said:

@aussievintage how's the jaycar preamp holding up? Stuck between it and the behringer pp400 since the latter has a 3 year warranty

Mine still works fine, and I suspect it will go forever. I opened it up and it's quite a quality built unit. Unfortunately the Project Phono Box it replaced went to God after stuffing it full of AC instead of DC.

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Mine is still doing fine as a stopgap while I still have not got around to fixing my home-built amp. I also opened up the box and agree that it is well made and appears to be robust. 

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Have had mine for 6 months now and no issues so far. Happy camper.

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5 hours ago, KalahariDessert said:

@aussievintage how's the jaycar preamp holding up? Stuck between it and the behringer pp400 since the latter has a 3 year warranty

 

I have two and both are fine. 

 

The Behringer has neither a level control nor a switched aux input.  

 

 

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5 hours ago, oztayls said:

Mine still works fine, and I suspect it will go forever. I opened it up and it's quite a quality built unit.

 

Yes that's my impression as well.

 

It would be interesting for someone to compare it soundwise with some more expensive units.

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2 minutes ago, aussievintage said:

 

Yes that's my impression as well.

 

It would be interesting for someone to compare it soundwise with some more expensive units.

I'd be very surprised if it hasn't been reviewed somewhere already as it's a popular unit that appears under various brand names. The best phono pre-amps do as little to the sound as possible, and merely amplify the sound from the cartridge/pickup and the power amp takes it from there. I get very suspicious of those that are housed in a big box, but I'm no expert on them. I just trust my ageing ears, still!

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I just swapped it and my valve power amps out temporarily for a Luxman R-3055 late 70s solid state tuner-amp. It is hard to ascribe any change to the phono amps alone since all other amplification changed too but I would not say the sound is any better. If anything a bit harsh, not quite as clean, even though Luxman have a reputation for being lush and smooth, but I am comparing to my home-built 300B single-ended class A amps. From that I think you can conclude that this cheap phono preamp is not embarrassed in the company of decent gear but not much more. 

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