PAiA Stack-In-A-Box

This unit is just like the manual says - don't expect it to sound good right away, there are a few "sweet spot" controls. Unfortunately, I was very hasty to plug it in right after building it, and at first I was very disappointed with the sound. I tweaked every knob and tried every combination of switches I could, and could not produce the sound I was going for. I got frustrated and didn't touch the unit at all for a few days. The next time I used it, I didn't plug in a guitar, but rather I plugged in a synthesizer and started messing with the Lo-Z input and the crunch knob. This produced the overdriven effects I was looking for.
The manual is essential for constructing this unit. It offers a decent troubleshooting section.
For what it's worth, it's basically a tube drive effects unit inside a 2U rackmount panel. Using it is very easy, you just turn knobs and flip switches. Finding the "sweet spot" takes a lot of time, so this is why I gave Ease of Use a rating like I did.

I have the output of this unit going into my studio monitors. I'm not a guitarist so I don't have a "rig" of any sort.
It do hear a consistent humming noise when the unit is amplified to any sort of useful volume levels. No matter what settings I use, I can hear an AC hum. Even when the "crunch" setting is down all the way, the hum is still present. I used the wire that came with the kit, as well as the provided shielded co-ax cable properly. If this bothers me anymore, I might go and buy several feet worth of co-ax and swap every last flying wire and jumper with co-ax or any kind of shielded cable and see if that does anything. If that doesn't work, then it might be the vacuum tube itself getting AC voltage directly from the power source.
The effect does not always sound great. You have to really play around with all sorts of setting to get the tone you want. Also, I have unfortunately found that my guitar sounds absolutely heinous when I play it through this unit. This doesn't really irk me as much as it would other people because I don't play guitar all that much, I'm mainly a synth player looking for crunchy overdrive. No matter what I set anything at, my guitar sounds horrible through it. I've built fuzz circuits before from 12 dollar kits that sounded like this thing does. There is no sustain whatsoever, even if my synth sound has a long release, I hear the fizzling out and popping as the sound grows quieter. It sounds okay if you play nothing but palm muted guitar chords.
I get what I want from this unit when overdriving my analog synths through the Lo-Z output. I plan on swapping the 5K input crunch potentiometer with a much higher resistance pot, probably a 1 megohm since they are the only pots I can readily get my hands on... I've heard this helps in getting better distortion. Supposedly one of the guys at PAiA uses a 10 megohm pot for his input knob.
Overall, this unit is worthless for distorting my guitar. I haven't used any sort of pre-amp or buffer before going into the unit, maybe that might solve it. The unit seems to respond better to a higher input signal. I plan on using it to overdrive my synths and get a nice crunch out of them. If you're into power noise or industrial type music, you could run your drum tracks through this unit and get some nice distorted beats. If you want absolutely crushing distortion, don't get this kit. If you want subtle to somewhat harsh tube overdrive, you might want to look into it.

I have yet to build a full enclosure for my SIAB. I bought the panel and the kit, and that's all you get. There is no full enclosure for the back, just two brackets to hold the circuit board to the panel. I think I might make it with plexiglas for the heck of it. You could theoretically put the unit like it is in your rack, but I'm very wary about the flying power supply and the lack of protection of the circuit and components. I may keep this in the studio and use it occasionally for live shows. I'm not honestly thrilled with the idea of gigging with this live, which is odd because I tend to pride myself onstage over the fact that some of my gear is handbuilt.

I have dealt with PAiA in the past over another product, but not this one. They are very good with communicating with you and repairs are cheap if you fudge yours up.

I play industrial music, but I have been distancing myself from digital sound sources recently and focusing on more analog equipment. This unit provides me with some nice crunchy overdrive for my synths, but sadly, I have bought some guitar effects pedals for a lot less money than I spent on this kit that have more features and more sonic possibilities. They do not sound the same or "better" in my book, the Stack in a Box is very different than what the average $40-50 stompbox can do. It has its own sound and I know I will find a good use for it.
If it were stolen or lost, I'd probably buy a TubeHead kit from PAiA. When I compare the reviews for the TubeHead versus the Stack in a Box, the TubeHead seems to please people more. Even if you can't get the crunch of solid state circuitry out of the TubeHead, I'd still recommend that over the Stack in a Box if someone wanted to build a vacuum tube preamp. It fattens up my monosynth nicely, but still could sound better.
My suggestions would be to look up any modifications and try them out if you don't like what you hear. Either that or buy a TubeHead, because in the end that's roughly the same price (give or take a few dollars) as buying a Stack in a Box kit plus the front panel (the TubeHead kits come with their own enclosure).
Please read reviews and listen to people's demos online before you buy this kit. PAiA is a good company that produces a lot of top-notch kits, but this kit isn't the greatest they have to offer in my opinion.

It is very easy to get a great old overdrive out of this kit. If you are not good at soldering, you will probably kill this kit. It is a hybrid of Op Amps and Tube ciruits. The manual is OK. It is not a perfect beginner kit. You have to know components to put this together.

If you build this kit with care (meaning not a giant soldering iron with a temperature of the sun) it will work as advertised. I had no bad components and it gives a real nice overdrive tone much like Pete Townsend in the 70's. It is very quiet if you operate within the specs of this device. Don't expect huge crushing distortion. It was not designed with this in mind.

So far so good. I mounted this panel in a rack box with my BBE Sonic Maximizer and it has not failed yet. I have dragged it around from place to place and it hasn't failed yet. I don't gig anymore so I can't comment on the roadie factor. (This panel has ALOT of wires running loose. It is not board centric.) I don't know about gig-ability.

PAIA is incredibly helpful. You pick up the phone and tell them your concerns and a real person gives you advice. Practically unheard of today but they do it. I have to give them a huge plus here. I asked if there was a way to give me slightly more gain and they sent me parts and a drawing of what to mod. Wow! I didn't use all of their MOD parts but I increased the 10k input pot to 25k and it gave me that little kick of extra overdrive I needed.

I have been playing for 20 years. This is one panel that actually delivers the tone that it advertises. It is a nice alternative if you want to record a stack to actually using a stack for overdrive. Don't expect a huge overdrive. This panel will give just a nice subtle overdrive with a real nice crunch and a real nice stack model. It has a few switches that model a 4 x 12 nicely.

If you drive this thing to monster overdrive it will get unstable. It can do some really crushing compressed tones but a studio setting would be best for this. I don't think it was designed with this in mind. It works best as a Stack In A Box. It delivers nicely in this mode and it simulates a stack or complements added overdrive well with a real 4 x 12 cabinet amp.

If built as guided by the manual it will deliver a nice tone. I like it very much. It is in my effects loop on the clean channel and in the overdrive channel almost all the time. It can give that subtle clipping or enhance a tube drive very nicely.

REVISED YET AGAIN BY MRCHEEKS.

OK got the thing fixed and it sounds awsome BUT THE DAMN THING STILL SQUEALS LIKE A PIG IN HEAT AT ANY USABLE VOLUME LEVELS!!!!!!!!!
WTF good is it other than in the studio!?!?!?!?! I know now my pickups are microphonic and you will too if you buy or use it.
I really like the sound of it and its features but DOD has nothing on PAiA when it comes to squealing gear that makes it pretty much useless! Oh well I'll clean it up with noise reduction or just use it with my wireless system but still it was designed by Craig Anderton this guy ppl rave about and yet he couldn't manage to design a noise circuit for it. Oh well it gives a really great tube sound just gonna need something to run with it for all the noise.

Some of the kits parts were defective just as I suspected. Not only 1 but 3!!! Granted they were minorlow cost pieces but unless you were damn good with electronics or were someone who knew these units very well the typical builder would have never found what was wrong. Gig without a backup? YEAH RIGHT!! The things too damn noisy to even consider gigging with if your going to use it for any REAL amount of gain. It's a home and studio unit I really believe.

Hey like I said pryor to this these guys have been really cool to me and gave me a fairly detailed description of what was wrong. I have also found plenty of sites where guys have just dealt with them for this and that and rave about their helpfuness. Simply put, they get a gold star.

Great tube pre but needs something done about the noise otherwise it would still get straight tens from me. If you aren't using it for gain just the tube compression and clipping it's an excellent unit and actually could be used for gigging that way but who would buy this thing without intending to use it for tube distortion? I KNOW I DIDN'T! Anyway it is a good learning experience but for a first timer wiring the front panel is a total fucking bitch! Saying it's a bear is an understatement!! All in all I'm not sure about getting it again. Honest I would say no but there's nothing within its price range that does what it does on the market. I think from now on I'll just use schematics and instructions guys throw on the internet cuz it's WAY WAY cheaper and I've found bout everything ,including tube pre's, you could ever want to build for guitar and more.

DONT LIKE THE SOUND OR NOT HAPPY FOR WHATEVER REASON??? CHECK THE MOD THE GUYS AT PAiA GAVE ME

Very easy to use. Has an effects loop and a small variety of cabinet simulation switches. Manual was very easy and useful.

Ok let me start by saying this. Mine did not work QUITE properly but did work. If you don't seem to be able to get enough gain and compression its
very easily solved. change your input pot with a much higher value one! The guy at PAiA I talked to uses a 10 meg ohm pot!!!! I only use a 5 and it gives an unbelievable amount of gain and compression now. I think they give you the wimpy pot for a higher proffit racio. I was also disapointed at first until I made this simple mod. You can go from hollow classic tube sound to thick raunchy overdriven screaming leads and power chords. I MEAN WHY THE HELL WOULD YOU USE A COMPRESSION PEDAL WITH A TUBE???? THE TUBE GIVES YOU COMPRESSION!!!!!
Granted this is after the mod but still if ya built the damn thing I would think you'd have some idea of how tubes work!!!! Anyway once you mod the input pot you can get great sounds from this unit. The cabinet simulation switches along with a few others along side them are actually quite useful and give you a decent variety of sounds. I must say though my unit was defective and would only work with the Low -Z input so its been sent back to have the guys at PAiA take care of it because after going over the schematic 40 something times... I DIDNT DO A DAMN THING WRONG!!!! I do have one complaint though and that is noise. I don't understand because originally it wasn't really noisy but when I last hooked it up b4 sending it in it was screaming, squealing and generally just making more noise than a virgin on prom night. It was to the point I couldnt even use it at a useful volume level!!! I dunno...never had this problem b4 so when I get it back I expect it will be gone.

OK so like I said my doesnt work EXACTLY right but it does work and has been very reliable though it sat for some time when I finally go so frustrated of trying to fix it though there appeared to be nothing wrong.
My opinion is that some part of the kit was defective and I got hit by the odds for who gets one. Sent it back and they are fixing it so time will truly tell.

These guys are really great! I wasn't happy with the amount of gain it got(like the other reviews) so I contacted one of the tech guys and he told me how to fix that no problem. Unit wasn't working quite right and after reviewing the schematics and directions more times than most anyone would I contatced these guys and they issued a one time only RA number for it to be repaired FREE OF CHARGE!!!! Still waiting to get it back and hopefully everything will be in working EXACTLY the way it should.

Overall its a really cool unit. Its simple and very easy to assemble but wiring the panel was a real pain in the ass I must say. I own a lot of gear and thoughb this unit probably will never see the stage it is definately great for studio, a jam room or just practice at home or where ever. I really like the cabinet simulation and voicing switches plus its got an effects loop and a variety of output options including XLR, standard quarter jacks, volume output and polarity switch. I do wish it had a 3 band EQ though because then it could be doubled with a n amp, solid state or valve and mod'd into an amp head. I also wish it had a back panel for protecting the electronics but you can easily make one out of plexi, wood or whatever. Initially it didnt have a noise problem but as I mentioned above it surfaced the last test run b4 sending it in for repair. With as cool as the guys are I expect this to be gone as well. I feel this is a great unit for the budding musician that want to start building their own gear. It's easy, doesnt take TOO long and has a very good sound with the simple mod mentioned.
I would buy it again but honestly just the face plate because I can buy the parts and pieces from electronics suppliers for under 20 bux!
A great first project.

2-stage AX7 guitar-oriented preamp with optional 19" rack,
double-height face.Crunch, efx loop level, & output level pots.
4 op amps if you're religious about such matters.
Hi/lo-Z inputs/outputs. +/- polarity on outs with 'flip-it'
switch.

The only reason I don't give it a 10, is that the speaker sims,
fat, bright, & polarity switches really aren't that useful & make
wiring the panel/cab a real bear. I started out by putting the
thing in an aluminum floor case (used an old SONET rack power supply!)
which was painful. I've now put it in the rack panel. I plan to
mount it into a Tweed 5E3 kit I'm building as to have the preamp
& amp in the same cabinet -- if it sounds good. If it doesn't, I
guess I'll have to fashion an aluminum box for it. It's too fragile
to leave everything exposed.

Manual is very good. No firmware. Website is very good for info.

NB I HIGHLY RECOMMEND TINNING THE CIRCUIT TRACES ON PCB BEFORE
STARTING. If you don't know what tinning is: cover back of board
(traces) with flux paste, lay a thin layer of solder over each
trace, wash board throughly. This will prevent corrosion & make
the through hole soldering a lot easier. I did not see this in
the manual, but perhaps it's common knowledge in some circles.

I use single/humbuckers with microverb in efx loop->4track/PC.
SIAB->amp/reverb. SIAB->VG88, VG88->SIAB. Initially, I only
recorded my strat with microverb in efx loop. Couldn't get much
crunch out of it, which surprised me because starved plate voltage is
30V & op amp (crunch control) drives first stage. Clean sound
was wonderful. After putting it in the panel, I tried my Ibanez
Artist. Wow, it really crunches now. However, after a while,
I became very sensitive to a metallic harshness. This was
both through an amp & my VG88. I wondered if this is the op amps
operating in a non-linear region?

Pretty quiet. Can get a really good clean sound using efx loop
direct to 4track/PC. Crunch is fun with humbucker/harshness
caveat above.

I don't recommend anything in front of this puppy. I tried
some signal boosting on the front end & I got that old
transistor fuzz which I assume was the op amp being
driven out of its comfort zone.

Can't really nick them too much here. It is a kit. The parts are
pretty much boiler plate: op amps, AX7 tube, hex inverter package,
diodes, resisters, caps, 12V AC power supply. The circuit board is
through hole & provides plenty of room for an intermediate solder
jock.

However, I don't see anything in the design of the kits or
components which is a root cause for failure except for the
complexity of the panel wiring. The complexity of the panel
wiring could be simplified (or more useful features added
like EQ), which would help novices to build a more reliable
product.

These guys are great. Tech support recommend a design change
to get more crunch. My unit worked first time, but I got the
feeling they would help me out if needed.

Great for clean styles & warming up direct recording.
I need to play the crunch with by humbuckers a little
more, but it sounds like a crunched amp & is quiet pleasing
at first, but I hear a (maybe subjective) harshness after
a while. Never used tube preamps so I cannot compare its use.

If it were lost, I don't know if I'd make the investment
of time to build it again. Part of the fun of these things
is building them & I've only used it for direct recording so
far. I'll post a followup if i mount in the tweed clone
cabinet.

I would like to see a slighty different flavor of this kit:
trash all the post AX7 switches and lo-Z ins/outs, add another
AX7 tube and EQ, remove the op amps if possible to prevent any
source of 'bad' distortion. Maybe upgrade the power supply if
necessary.

Couldn't get much simpler....Output level, Crunch and Gain controls. Lots of input options (guitar, lo-z) and two (one regular, one inverted) outputs. It took about 6 hours for me to put this one together.

This was my first entry into tube distortion, so I can't compare it with confidence to the few "tube amps" that I have messed with...perhaps this is a good thing. The only thing I could compare it to is sounds from CDs that I like. This unit is great...if you use it as a preamp, as it is designed to be used. Can you hook up a power amp to the output and get a "stack" sound? Nope. But if you use it as a preamp to a few other effects, you get a very decent sound (I use the "rythmn" distortion, a little chorus and a lot of compression on my Zoom 505, AFTER the SIAB...it sounds fantastic).

Well...no problems so far, but the fact that there is no complete enclosure (just the rack front panel with the circut board mounted to it) kinda scares me. This thing has survived a trip back to PAiA (I "failed to notice" an addendum to the instructions that included a wiring change fromt he manual), so it should be pretty solid. I would definitely want to build the backup if I was using this to gig, but for my use in the studio, it seems solid.

The guys at PAiA are fantastic! I would give them an 11 in this category if possible. They were able to answer some questions by e-mail and when I wired a couple of the jacks incorrectly for the replacement parts in the kit, they were able to fix things in a timely manner. Way to go guys!

The SIAB gives great "bang for the buck". I played with a few other tube preamps and while the more expensive ones have some other useful features (built in compressors, extra gain stages, etc), the SIAB more than lived up to my expectations, especially for the price.

This is mono tube, two space rack pre-amp kit that you build. You definitely want to have some soldering experience and patience before tackling this project; although, it is satisfying to build and goes together well. There are knobs for Crunch, Drive and Level and several slide switches to imitate different speaker set-ups. Hi and lo-z inputs and polarity switch for outputs, 1/4 inch jack and XLR. Definitely alot of features for the money and relatively easy to use once you realize what each control really does. I give it an (8) mainly because of how labor intensive it was to put together. Manual is well put together, but I wish more space was dedicated to operating it properly.

I tried running this device several ways. Les Paul-> SIAB -> Crate VC5212 (tube amp)... decent, but I never really got much usable distortion until I put a Boss Compressor in front of the SIAB. It seemed to need alot of punch upfront to drive the tube to get much overdrive that didn't sound crackly and unusable. I will say that the level control will crank an incredible amount of volume on the output side. I was really hoping for some smoother sounds. It might be great just as a clean preamp going into a P.A., but again it was awfully noisy going into my amp clean even with the output lowered. It did not seem to do anything great for my guitar's sound. The overdrive sounds that it did create were poor in my opinion, but hey I'm no audio expert I just know what I like when I hear it.

This unit comes with no rear enclosure, everthing is mounted to the front panel, so you definitely need to mount it in a rack case of some sort. I was a bit concerned about banging it around too much with the tube in it and being careful not to accidently hit the circuit board when I was patching things in from the rear, but that never seemed to be a problem. I had a few problems keeping the tube socket soldered in properly, but that had more to do with how I put it together than anything. I would only consider gigging with this if it was being run direct into a P.A., it might be more usable that way and for recording.

This is where I have to give PAiA high marks. They have always responded quickly to my emails with questions and I had really good success with a Buffer Project I bought from them. I would buy from them again with no problem, but the Stack-In-A-Box was not for me.

I've been playing guitar for about 20 years in bands, solo, etc. I have been building some of my own equipment for over a year now and have enjoyed that immensely. I'm a big fan of Voodoo Lab products by the way, price/quality. PAiA does make some good stuff. The Buffer Board (Spluffer) is one project that worked out really well for me. This is one project I would not buy again.