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-   -   Behringer PP400 mods? (http://www.diyaudio.com/forums/analogue-source/162990-behringer-pp400-mods.html)

lossfound 11th March 2010 04:45 PM

Behringer PP400 mods?
 
I've searched the forums and the 'net generally but can find no hobbyist input on the PP400 phono preamp. Well, I just gambled $20 on one and, to my surprise, it's not horrible. Noise is low, detail is OK, and output is not as overly hot as I'd been led to believe. Channel separation / imaging seems a bit mediocre, and it does seem that it's lacking some oomph in the low registers.

Has anyone done any modding or experimentation with one of these?

Zero Cool 11th March 2010 05:49 PM

one question....Why? hate to be that way but for $20 plus the price of mods, i think you could build a better sounding pre!

lossfound 11th March 2010 08:20 PM

Yeah, I've always thought I should be able to build a well-regarded pre for about $5-10 in parts. Over the last two years, such a plan has not come to my attention.

I bought the Behringer as a gamble to resolve an "emergency" left by the death of a beloved receiver in a room that sees 2-3 hours of vinyl time daily. But ultimately, $20 about is the cost of an enclosure, jacks, and a cheap power supply, plus shipping... and since I have Amazon Prime, I didn't even need to pay the latter on the PP400.

And if a replacement cap value or two has been discovered that would improve its abilities vastly... well, I just thought it was reasonable to ask :)

coolmaster 12th March 2010 04:34 AM

Hello all, I had a go with this thingy and looking at its PCB, its basic single chip dual opamp implementation, as basic and good as its price point. No audiophile caps of any sort. There isn't any input load shunt nor capacitance to match the cartridge loading. A little mod here may do some good. The opamp is smd, the wall wart is cheap skate, unless you can swap it for something better, there may be some hope. In stock form,don't expect stellar performance with this. Its cheap and useable, nothing more.

lossfound 12th March 2010 05:29 AM

Thanks so much, coolmaster. What would be the primary audible benefits of adding capacitance in this case? I can solder stuff to points if the Internet says it's OK, but when it comes to comprehending the electronics theory behind the mods, I'm pretty dumb.

coolmaster 12th March 2010 08:38 AM

Hi, google cartridge loading, there's much to read and learn. :)

lossfound 12th March 2010 11:51 AM

Will do. Thanks.

Freedom666 19th November 2017 07:07 PM

Hello,

I bought the Behringer PP400 just to compare it to a WBE DIAMOND No.36 STUDIO Phono Preamp which I own for my Rega 3 with Goldring 1042.

Complete hifi chain is: amplifiers are WBE Essence No.300, preamp is Adcom GFP-555II, loudspeakers are Pfleid FRS20S with modified PP100 (point source fullrange loudspeaker with integrated subwoofer).

So the PP400 from the scratch (costs 30 dollars) is a pretty thin and faint sounding device. From the theory there should be no audible difference between audio op-amps. So both phono preamps should sound quite similar. But it is far from that.

The WBE Phono preamp has an OPA627 (driven into class a) and sounds superb, and has a regulated power supply. The Behringer has a V4580 op amp from cool audio and no regulated supply.

The Behringer PP400 got better with an added 12v regulator 7812 and 15 Volt power supply source (2A).
Then I added to the opamp a 2,2mfd electrolyic across + and -, the sound got a little more body, clearly audible.
At last I changed two 4,7mfd electrolytics against WIMA MKS, C11 and C12. This helped a lot against the lack of body in sound and bass, now it got hifi quality.

There are some more electrolytics to change against better types in the Behringer PP400 but desoldering is a bit difficult because with the original solder used in this device so I stopped my modding and listening marathon.

Result: the biggest differences in sound are not from the op amp but everything around it. Could be that at last the OPA627 makes a difference but it was a nice test for me.

collection of websites on the pp400:
De Beterhringer PP-400 phono-pre – The sweet spot
PP400|Tamesuke-Goto Maker的Blog
http://cdn2.bhphotovideo.com/lit_files/84924.pdf
https://www.hobbielektronika.hu/foru....php?id=110260
Bought a cheap preamp to play with... - Bry - Vinyl Asylum

Yours, Dragan from Germany

Freedom666 19th November 2017 09:49 PM

Hello,

I tried to short the input and output coupling elecrolytics c1 to c4 with a wire as desoldering and changing against other types is difficult - this is no good idea. DC is coming through, no output.

I changed the 2,2 mfd across VCC(+) and VEE(-) to 22mfd with a Panasonic FC-type.

Now the sound became more analytic and much more substantial in the bass. Now the Behringer PP400 sounds with full power in the bass. I did not expect that. Lossy types of electrolytics certainly sound nicer here than the Low-ESR-Panasonic.

Result: op amps sound quite different only by changing the decoupling, the influence in sound is huge. I wonder if this could be measured. By listening the difference is quite obvious.

Subjectively the difference in sound between the original Behringer PP400 and the modded one with decoupled op amp is 10db in the bass. This is really a huge difference(!)

http://3.bp.blogspot.com/-GYyVTGU9x6...120723_004.jpg

Bye, Dragan

Freedom666 19th November 2017 10:41 PM

Ah, Tamesuke has on his Blog a schematic of the Behringer PP400. And a jpg of a modded Behringer ;-)

PP400の画像 | Tamesuke-Goto Maker的Blog


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