Posts Tagged ‘Preamp’

Nux AS3 Modern Amp Simulator

Monday, November 17th, 2014

Nux-AS3-MAS

What is it?
Nux AS3 Modern Amp Simulator. Made in china around mid to late 00’s

I don’t know what it is. I really can’t point my finger to one particular thing on these and say; “this is why i like Nux Effects!”. But i do. Or least i did. I recall talking to people about how Nux is the solid brand that can turn the low brand value, cheap chinese pedals around. Unless they decide to start OEM’ng their designs to other brands that have low brand value to begin with. This, one of my mildest nightmares came into reality in mid october 2014. I noticed that at least one chinese retailer was offering the Force and Core series effects with another brand name. No. Please don’t do that. Nux was the only modern chinese brand that didn’t have a six year old graphic designer and they didn’t save money on all the wrong places (just on few key places, but not on all). That day was very sad day for me. But what can i do? Nothing. So let’s just forget that misfortune for now and focus on the unit on hand.

This Cherub/Nux series that i like to call “The First Series” hasn’t let me down yet. The overall feel of the boxes is solid and firm. The cheapest feel comes from the battery compartment lid, which in my opinion is placed rather geniously. The user can change the battery without lifting or even tilting the pedal. Not that i know a lot of people using batteries, but still. I think this is just the kind of ingenuity these factory built pedals need today. More on the feel, the pots in this series are not the cheapest kind and they feel solid too. Now, to open this puppy up.. Modern autorouted look. But still neater and more solid looking than current Bosses. And the rest of the manufacturing methods leave no bad word in my mouth.

Nux-AS3-MAS-guts1

And once the board is flipped over.. Awww. It reminds me of US made DOD FX series board. Warm and fuzzy feeling with its all analog, all through hole construction. The pots are mounted on their own daughter board.

Nux-AS3-MAS-guts2

I’m not aware of the exact topology of the circuit and thus, can’t analyze it much further at the moment. Looks like this has two TL072s and one 4558 for opamps. The D2-D3 silicon diodes look like they might be clippers. I’m not going much further in this guessing game, but even the design looks rather solid. While i do like this box like a young man likes his date, there is one caveat.

How does it sound?
And it is the sound. This is most likely a predecessor of the black AS-4 from the later series and the circuit has been revamped for that release. This earlier one works nicely as a light dirt driver, but it’s hollowness and mids leave a lot to wish for. While this pedal is way greater than its follower on the outside, the better version made its way to the cheaper feeling later version. The bright side is that the EQ section is powerful and working well (i’m guessing gyrators). So i’m left with mixed feelings. As an overdrive effect, this is a lot better than many Tubescreamer derivatives, but as a full blown preamp, not so much. I believe these have out of manufacturing line for a while now. So if you can score one for ridiculously cheap, i’d suggest you go for it. It may not sound like much, but there is some usability in there.

Plus this unit reminds us all what potential Nux had before they changed to cheapest parts and resorted in OEM manufacturing for even lower end brands. World is a cold place.

DOD Overdrive Preamp 250 (reissue)

Thursday, September 12th, 2013

DOD-250

What is it?
DOD Overdrive Preamp 250, 90’s reissue in yellow first series style enclosure. Made in china.

This is one of those boxes that everyone should play with at some point in their life. If for anything else, for the feel of that heavvy duty box. The base design topology is pretty much verbatim with MXR Dist+ and probably a hundred other boxes from end of the 70’s up to today.  There are differences though. And good thing there are. As in my opinion, modern Dunlop made Dist+ reissue with UA741 and Ge diodes just suck. But before anything else. Let’s just open this up and see what’s inside.

DOD-250-1guts1

Looks quite modern with neat thin circuit traces and connector. Plus the blue jacks. Sadly, no date printed on the board. I really wish that it had a date in there. Would make the guessing process less valid. Components are often good place to start the process. So let’s see what lies underneath that board!

DOD-250-1guts3

There is a dual opamp  in here!

Some documented units here at the internet have KA4558 chip instead of RC-branded one, so that should be a clue. Oldest Fairchild Semiconductor’s datasheet for KA4558 chip i could find is dated 2001, so i do believe that the units featuring Texas Instruments RC4558P are older than 2001. Drop a comment if you know the exact dates when these were made with KA and RC branded  chips. I’d be more than interested to know. The print on the chip is 66CRDYN, which tells me absolutely nothing. I’ve read that usual way for printing manufacture date on the chips is with four digits. Two for year in question and other two for the week of that year. Apparently not for TI chips.

The dual chip can be found only in these reissues. Original design is with UA/LM741 single opamp. Schematic for both versions (one with old single opamp and the one with dual opamp) can be found online, and checking them both out would be recommended. The dual opamp version just omits the other half of the chip completely by grounding the inverting input and shorting the output and non-inverting input. The other half is used as in original. So it is basically just wasting the other half, while staying true to the original.

The box itself is quite loyal copy of the original with the stamp on the back. But there’s also a aluminium sticker that tells us where this unit came from.

DOD-250-2backplate

How does it sound?
Just amazing. For me, this one sounds way better than any of the single opamp versions i’ve tried. I actually cloned this version of the circuit for myself and i’m using this clone on my main pedal board. Once cloned, i can have standard 2,1mm DC jack and an indicator LED – Wouldn’t want to harm my original to incorporate those features. I use it to boost the rhythm riffs on choruses. Just a tad of boost and mild overdrive in addition to my mildly overdriven base sound. It just brings the songs alive. In my opinion, this is just the perfect overdrive/booster. Better than all the rest. I know some people will disagree. And they are welcome to disagree all they want. I just don’t see myself fastening any other design to my board as an overdrive anytime soon.

Ibanez CR5 Crunchy Rhythm

Friday, August 2nd, 2013

CR5What is it?
Ibanez CR5 Crunchy Rhythm from Soundtank series in metal enclosure, made in Taiwan around 1989-90.

It is a design that differs from usual TS and/or Voodoo Labs overdrive topology. Boosting, bluesy overdrive with discrete differential pair to determine which parts of the signal get to Si diode hard clipping before the tone driver. Since the 70s and early 80s, it’s been hard to come up with even remotely original overdrive designs, but this one has some out of the box thinking incorporated. Schematic can be found on the 8bitsindgenug site. It is well worth taking a look for what’s happening in there. The gain/distortion stage makes me smile, as it’s definitely something you don’t see in every OD design around.  My unit is in a metal case and has very small number as a serial. I think it’s safe to assume that this particular unit was made in 1991, when the first (metal boxed) Soundtanks were introduced to the public.

CR5-guts

JRC4558 is there to drive the tone control and other half is used as output buffer. Not sure why the IC half is used as a buffer, as it could have been just as well used as the first gain stage – instead of the lone 2SC1815Y that drives the differential pair. This is part of the reason i care deeply for Ibanez boxes. Even the commercially dullest, most underrated pedals can have good sounding, innovative stuff inside them.

How does it sound?
Not too far off from likes of Boss BD-2, even though these two designs are completely different. Resemblance to few other “dumble” styled overdrives should be mentioned here. It has good output level, and real nice, softer texture to the dirt. It keeps the frequency responce well in tact, so it can be used as a really good sounding preamp in beginning of your effects chain. All that in a metal box that just rocks. This model is getting rarer every day, especially the one in metal enclosure. So if you get a chance to score one for cheap – do it without hesitation. It will be worth it. Definitely one of the greatest boxes in Soundtank series.