In the last few months I've assembled 2 Hairball Audio Elements Coppers, 2 Hairball Audio Lolas, 2 DIYRE CP5s, and 1 CAPI VP28. I thought I'd post a quick summary for anyone interested in DIY 500 series preamp kits.

DIYRE CP5 ($150) - By far the easiest kits to assemble in the bunch. The guides are incredibly well written. It even comes with a simple component identifier so you can group your parts together quickly if you're not adept with resistor and capacitor codes. The PCB is labeled incredibly well. The payoff is pretty excellent. Clean pres with the standard features (phantom, pad, polarity) plus the added addition of the colour control. The colour module must be purchased separately, but it's functional without it. The final product feels of equal quality to the other kits, but cost much less.

Hairball Audio Elements Copper ($320) - This was the second easiest build to do. The main board was about as complex as the Lola and VP-28, but the op amps are pre-assembled for you, so that shaved off some time and components. All the Hairball kits have excellent build guides as well as well-labeled PCB's. I chose the Copper because it promises that Neve-ish character without the hassle of "staying true to the original" in every aspect like some preamps do. You get the standard 3 switches, a DI, gain and output controls, and, of course, transformers. This allows you to drive the Copper into saturation bliss. I also opted for the stepped gain control for more even control. That costs $25 over the stock $295 kit. The build quality is excellent, it feels sturdy, and the unit is completely shielded with sheet metal. I highly recommend it!
Note: The only complicated part is the base kit for each of Element preamps is the same across all models, so there are a few components that are different between the Copper, Brass, and Gold. Just pay attention to the BOM.

Hairball Audio Lola ($335) - This was a complicated build. You have to chose DOA options, and I chose the DIY 990's for cost purposes. Now if you don't know, the DOA boards cram a lot of components into a small package, and the PCB's are labeled about as well as they can be. However it's not super legible. Make sure you stick to the build guide on this one. Populating the Lola was straightforward. No real issues if you follow the build guide. Placing the attenuator and DI jack is slightly tricky as they are not flush-mounted to the PCB. With this preamp, you get all the features of the Element series with stepped gain control plus a dual DOA design complete with an LED meter. This preamp was a time killer, but if you look around the web, the Lola is getting a lot of love from engineers everywhere.

CAPI VP28 ($326) - This was the toughest build of the bunch. Compared to DIYRE and Hairball Audio, CAPI is lagging behind in documentation and the PCB overlay. It gets you there, but I found myself a little confused at parts. Plus the PCB overlay only gives you component numbers without component values. That's normal, but it requires you to flip through the BOM constantly. I ordered the kit with Litz wire output transformer and gar1731 DOA kits. The assembly was time consuming, but it was fairly straightforward. There are lots of components, but if you know how to read the resistor codes, it becomes easy to populate the PCB. Make sure you have a decent DMM handy though. It makes your life a lot easier if you test your components from the beginning. The final project is very sturdy. The finished kit looks and feels like an API preamp. If you're not scared of a little hard work, this preamp is a joy. It has the standard 3 buttons plus an output control, line/mic modes, and a HP filter with slope and frequency options. All-in-all, an excellent, full-featured preamp with amazing tone!

tl;dr:

CP5 - Easy and clean.
Copper - A little harder to build than the CP5, but ‪#‎neve‬.
Lola - Harder to build than the Copper, but sooo goood.
VP28 - Hardest to build, but stands with the Lola in quality with a few added features.


Great post...will be interesting to see the comments as it becomes populated.

I built a VP28 and found it fairly straightforward with the guide located at  http://groupdiy.com/index.php?topic=48610.0

It has been a great preamp

Have two CP5's to build and will look forward to side by side comparisons.

Cheers
Mac

I'll chime in as a newbie who has completed 2 VP312, 2 VP28, and 2 Lola and will say that I thought the VP312 was had the best cost & effort to payoff ratio.

Also as a tip to other newbies, don't build the op-amps yourself! Not f**king worth it! haha.

dmp

I haven't built any of these except the CAPI VP28 and 312.  I love the VP28 and would rather have them than 312s.
The NV73 could go on this list. Another difficult build, but an awesome preamp.

 

U forgot the vp26 from CAPI !

I have build 3 of these to have this sound from the vintage 70' console !

Super easy to build, great sound ! I have chosen the gar 1731 kit because of finance, not a big deal to build, just have to focus !

there's some great tuto for the gar on CAPI website !

I'm Finishing a lola element mic pre, it seems I having some troubleshoot, I have to find where it's not working !


Do you have some sound example?

In the last few months I've assembled 2 Hairball Audio Elements Coppers, 2 Hairball Audio Lolas, 2 DIYRE CP5s, and 1 CAPI VP28. I thought I'd post a quick summary for anyone interested in DIY 500 series preamp kits.

DIYRE CP5 ($150) - By far the easiest kits to assemble in the bunch. The guides are incredibly well written. It even comes with a simple component identifier so you can group your parts together quickly if you're not adept with resistor and capacitor codes. The PCB is labeled incredibly well. The payoff is pretty excellent. Clean pres with the standard features (phantom, pad, polarity) plus the added addition of the colour control. The colour module must be purchased separately, but it's functional without it. The final product feels of equal quality to the other kits, but cost much less.

Hairball Audio Elements Copper ($320) - This was the second easiest build to do. The main board was about as complex as the Lola and VP-28, but the op amps are pre-assembled for you, so that shaved off some time and components. All the Hairball kits have excellent build guides as well as well-labeled PCB's. I chose the Copper because it promises that Neve-ish character without the hassle of "staying true to the original" in every aspect like some preamps do. You get the standard 3 switches, a DI, gain and output controls, and, of course, transformers. This allows you to drive the Copper into saturation bliss. I also opted for the stepped gain control for more even control. That costs $25 over the stock $295 kit. The build quality is excellent, it feels sturdy, and the unit is completely shielded with sheet metal. I highly recommend it!
Note: The only complicated part is the base kit for each of Element preamps is the same across all models, so there are a few components that are different between the Copper, Brass, and Gold. Just pay attention to the BOM.

Hairball Audio Lola ($335) - This was a complicated build. You have to chose DOA options, and I chose the DIY 990's for cost purposes. Now if you don't know, the DOA boards cram a lot of components into a small package, and the PCB's are labeled about as well as they can be. However it's not super legible. Make sure you stick to the build guide on this one. Populating the Lola was straightforward. No real issues if you follow the build guide. Placing the attenuator and DI jack is slightly tricky as they are not flush-mounted to the PCB. With this preamp, you get all the features of the Element series with stepped gain control plus a dual DOA design complete with an LED meter. This preamp was a time killer, but if you look around the web, the Lola is getting a lot of love from engineers everywhere.

CAPI VP28 ($326) - This was the toughest build of the bunch. Compared to DIYRE and Hairball Audio, CAPI is lagging behind in documentation and the PCB overlay. It gets you there, but I found myself a little confused at parts. Plus the PCB overlay only gives you component numbers without component values. That's normal, but it requires you to flip through the BOM constantly. I ordered the kit with Litz wire output transformer and gar1731 DOA kits. The assembly was time consuming, but it was fairly straightforward. There are lots of components, but if you know how to read the resistor codes, it becomes easy to populate the PCB. Make sure you have a decent DMM handy though. It makes your life a lot easier if you test your components from the beginning. The final project is very sturdy. The finished kit looks and feels like an API preamp. If you're not scared of a little hard work, this preamp is a joy. It has the standard 3 buttons plus an output control, line/mic modes, and a HP filter with slope and frequency options. All-in-all, an excellent, full-featured preamp with amazing tone!

tl;dr:

CP5 - Easy and clean.
Copper - A little harder to build than the CP5, but ‪#‎neve‬.
Lola - Harder to build than the Copper, but sooo goood.
VP28 - Hardest to build, but stands with the Lola in quality with a few added features.

It's been a few years since I build these, so I thought I'd give a short update.

CP5 - I find myself only using these on demos or stereo instrument inputs like guitar amp simulators, keyboards, and drum machines. I have the 70s transformer colour module which is quite fun to play with for some vocals as well, but typically I'm recording dry and adding the particular distortion flavors later. These are too clean and neutral that I end up forgetting about them for most sessions. Would recommend for someone filling out a rack, although I might end up switching to some 3-in-1 Colour Palettes in the future and loading them up with some transformer options. That could put me in Mono Gama territory. :)

Copper - The flavor is great. Tend to use them on guitars, bass, and anything I want a little less pure sounding. Sometimes room mics and such go through here as well. I don't love them on vocals, but that's mostly because the Lola has ruined everything...

Lola - Good gravy, I challenge you to find an improper use for this preamp. It sounds incredible. It's not too clean. It's not too colored. It's just a better version of whatever you're recording. I've never once regretted using it. They pair very nicely with the Fathead ribbon mics for plenty of low-noise gain and fidelity. I've been using that combo for drum overheads and acoustic guitars. It's even become my go-to for vocals. I cannot stress how perfect this preamp is. The only thing I have that sounds remotely similar is my Aphex 1100 mk2 (which is underrated IMO). They both do the clean thing well without being sterile.

VP28 - I mean, it's the full-featured API thing. I need more of them. It's as simple as that. The only thing stopping me is the build time and cost. The kits aren't exactly cheap, but the final product is excellent. Guitars and drums all day through this baby.