Black Lion SM Pro Audio PR8E mod

[frans]

I have a BLA modded Motu 828mk1 and the pre´s went from ugly to clean. I don't doubt that your gear will benefit from the mod, but i don't think it will get it in the range of the Audients.

[thermos]

I had 1 PR8E modded by my tech here in LA, and the other is at BLA as we speak. I'm pretty sure they are going to do something pretty similar to what my tech did, but I figured I'd see what the differences were.

All I can say about my modded unit vs the unmodded one (I've had them like this for about 8 months and use them for live stuff) is that the modded one sounds pretty good (nice freq range and transient response) and the unmodded one sounds like a lousy sounding piece of crap. The difference is about as big as you can get.

[thermos]

I have never heard the audients, so I don't know if they will end up in the same league.

[Funky Animal]

I'm 100% sure I won't get them up to the same level.
That actually isn't the intention. It's just to make them better.

But thanks for the update..

Thermos, I read that your tech did it. Do you have any schematics on what needs to be changed? I also know someone who's up for the job and is interested in doing it and has the knowledge. I only need to get schematics and stuff.

Thanks for your responses..

[thermos]

Honestly, I am not 100% sure that the PR8E isn't better. It could possibly end up better after the mods than an audient. I know my tech looked at the schematic and said it looked a lot like the soundcraft design for their mic pres, and said he thinks its a fairly good design. I'm sure audient has to cut costs on some of the components, whereas BLA doesn't have to.

He changed the input/output caps (Put 100microferet i/o caps to open up the response) changed the crappy chips to THAT chips (don't remember the model #) We tried like 10 different chips, and the THAT chips smoked them. Silkier highs and a more expensive sheen (without being brittle) than any of the Burr Browns we tried. Also there are 3 resistors to take out. Thats the main one, do that and the sound immediately improves 10 fold. Unfortunately I don't have a schematic, and I don't think he does either. He used the info found on the prodigy-pro forums for the PR8 and found the differences (which are not that big between the Pr8 and the PR8E).

[thermos]

Got my unit back from Black Lion. It sounds real good! I spent a few minutes testing it against my portico on acoustic and electric guits with a fathead (part of the same ups shipment). Black lion did a better job than my local tech, the noise is way lower and the freq response is more similar to my portico rather than drastically different.

It's not in the same league as the portico unfortunately, in smoothness or bigness (or air for that matter) but it is pretty damn nice for the money. I definitely prefer it to my memory of the rnp. So $500 for 8 channels makes it pretty smokin' if you ask me.

Oh, the fathead mic is insane for the price. It seems to have more air than the nady types I have tried. Doesn't sound as cloudy and muted. I'm impressed.

[thermos]

Oh, and for the nerds. I opened it up and they black out the values. I was hoping to maybe put some of my favorite chips in there, but they are surface mounted. It sounds cool though, so I ain't trippin'.

[XLR2XLR]

I have been trying 2 different opamps which do improve the sound
somewhat, comparing with the VLZ XDR pre's they don't sound quite as
open up top, though they are a little thicker sounding which is no bad thing.
And they have lost the mid range edgyness of the original JRC4558D.

I am now planning to remove all the ceramic caps in the unit and replace them
with the same values but higher quality versions. Parts are on order.

I will happily report results, anyone else been trying home mods of this unit?

Interested in your results.

[camerondye]

I got one modded a while back and haven't tried it out yet. I need to break it out and see what happens. I do a lot of writing on my system mainly and use the 1 channel Great River that I have which sounds amazing.
Cam

[XLR2XLR]

I can fully understand that, if the GR does the business, its the one
to use.

I am very interested in any mods , BLA or otherwise on the PR8E unit as the
build quality of the unit is actually very high, decent metalwork, fibreglass PCB's
discrete components (other than the IC's), non surface mount design, fully balanced
I/O, decent connectors, firmly nutted knobs, 1pct resistor tolerance throughout and the PSU looks like a decent design using the quieter IC's you might see.

BLA mod users can you explain the sound compared to other pre's you might have.

Without the chip changes it's a little cloudy above 14kHz with the 4558's in there,
the new chips help but it's not quite what I would ultimately like. I do like the
extra body it has over the Mackie, but would like the extra HF extension.

The noise floor is very low, its virtually noiseless.

I think this unit could end up with a bit of a low end cult following.

Thanks users !

[thermos]

I will explain a little more. The bla unit sounds very good for the price (I used it on a live recording the other day). Compared to my portico, the mids are definitely edgier, and it lacks the low mid tranny depth and smoothness. At the same volume on playback next to the portico, the portico sounds louder and fuller, but also more dynamic. Its just not as pleasing all around. The transient response is great though, and it seems to get all the way up there freq response wise.

As I said, they blacked out the component values, so I am guessing based on sound that they put 5532s in there. This is purely speculative, based on the way I remember them sounding in my other PR8E unit when I was trying different chips. They sound a little edgier in the mids than the linear tech ic's that I ended up with in my other unit. If I'm bored and crazy someday, I might try switching them out (though they are surface mounted). But overall the unit sounds better than the one my tech did. MUCH lower noise floor, as evident by my tests with ribbon mics. I'd say if I had to make an album with this box, it could definitely be done.

I would try it for yourself, as its pretty cheap, and the improvement far outweighs the cost.

[XLR2XLR]

Hi Thermos, I don't think I made myself clear, I have 3 of these units !
and have put new opamps in, an Analog Devices 22V/uSec slew rate device
and TI5532's in some of the channels.

I have now ordered some new higher quality ceramic capacitors which I will swap
out too, the PR8E has 8 per channel.

I have even ordered new input transistors (50 x for $10.00) so it's so cheap.

I do this sort of thing for fun really and if it turns out well, it's a bonus and so far
a great improvement over the 4558's has been heard but you know how it is sometimes you just want to push it to see what you can get for peanuts.

I am not a electronics expert but pretty good with a soldering iron and all these
changes are fairly straight forward.

I have more time, than bands to record at the moment!

[thermos]

Cool, did bla do them, or did you have someone else do them?

[XLR2XLR]

I just desoldered the chips and I put DIL8 sockets in popped
the new ones in.

I plan to do the caps and transistors when they arrive.

I will try 1 channel and see how it works out and do some rec/listening tests
in between.

[Glowingfish]

Guys, here some pics from the BLA mod on Ebay, pictures good be helpfull for DIY mod that will save a lot of money.

The replacement of the opamps in the pre and post stage is a very good start and I will let my PR8E be modified by a real technicican and also the PSU design will be modded, always very very important in a device.

Any news is also welcome and I will keep this forum updated with any news.

[Glowingfish]

and pic from my PR8E PCB and link of EBAY auction:

Black Lion Audio Modified PR8E Microphone Preamplifier - (eBay item 180132820251 end time Jul-01-07 18:00:00 PDT)

[Glowingfish]

and a picture of the back of the PCB, maybe it will make it easy to draw a schematic (signalflow)

[XLR2XLR]

Link to my cap changes, I did not like the polypropylene sound
(a bit whistly for me)

Flickr Photo Download: PR8E Mod Top

[jeronimo]

One question...
does the mod fits both EP-84 and PR8 MkII ?

[Aerophone]

Sorry to revive this old thread but i just bought a pr8e.
My pr8e is slightly different from the one in the photos (bla mod) mine has some more diodes and some jumpers behind the input caps.
I can see in the photo that bla used lm6172 with the ceramic caps removed. Did they solder some caps on the lower side of the PCB or does the lm6172 holds in this circuit without oscillation?
And what's up with the paralleled transistors? Are they the same transistors from the original pr8e or other ones? What does one achieve with that?

Do you guys think is a good thing to upgrade output caps from 47uf to 100uf also, like the input? (BLA has not done that).

And upgrading the Gain pot cap from 470uf to 1000uf?

Sorry for my english for all these question.

thanks!

PS: just upgraded all the opamps to NE5532's and input caps to 100uf and it made a big difference! :D I don't have a 150$ sounding preamp anymore.

[lore_effe]

Originally Posted by Aerophone

Sorry to revive this old thread but i just

PS: just upgraded all the opamps to NE5532's and input caps to 100uf and it made a big difference! :D I don't have a 150$ sounding preamp anymore.

Good to know!