Turtlerock Forum

OK, so it looks like several of us are interested in getting a 51x rack group buy/DIY project off the ground. Some of us (eg Myles) have already built them and can provide expert advice when/if needed.

The discussion started in a different thread, but to keep the topic coherent I'll move what we know over here. Thanks to Myles and Ben M for their contributions which are replicated below.

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What is a 51x rack? - it is a DIY version of the chassis for the popular API 500 series format. It was developed by members of Group DIY.

There are some modifications, the most important being the ability to use alternative voltages. All commercial 500 series units will fit a 51x rack. However there are a number of 51x-only modules as well (meaning they won't go into a commercial 500 rack).

Cost - ( The following is subject to correction from those better informed than me). When fully outfitted a 51x rack is not dramatically cheaper than equivalent racks from API/Purple etc. However it can support a wider range of voltages and has more juice, so in performance terms it is much better value.

What's involved? - There are two main steps, building the rack chassis, and bullding the power supply. Beginners can consider tackling the rack, but the power supply needs more expertise.

intro to the 51x:
http://www.51xaudio.com/alliance/index.html

Thread about the 51x from Group DIY
http://www.groupdiy.com/index.php?topic=33849.0

Newbie builds 51x rack
http://www.groupdiy.com/index.php?topic=41617.0

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(I'm no expert so I may have made mistakes above. Please let me know).

I believe Myles made a rack using a JLM supply instead of the 51x supply. around $100 w/ tx etc instead of a few hundred. Worth looking into.

Yes I used the jlm 5 rail power supply with the larger rectifier and additional diodes as outlined on his powerstation page. Will power one 51x rack (all 4 voltages) and the phantom rail and the power supply needs good heatsinking. It can be quite small though and both units I've built run flawlessly.

Not much time to extrapolate but....I like the idea of 51x rack and JLM powerstation...full stop

I am also running a 51x rack with JLM power supply. I am using Joe's 500 series 5 pin adaptor though with just the standard +/- 16v. I don't have any modules that need 24v, so i never bothered. Works great for me!

One thing worth mentioning, if you plan on putting traditional 15 pin 500 series modules in your rack use just a 15 pin edge connector! ...not the 51x 18pin one. While they will work with 18 pin connectors, the edge card slips and twists when the rack is moved and you can easily end up with a short across the power rails. I found this out the hard way. Either your PSU, your module or both will spew out smoke. A lot of 500 series DIY modules actually have the 51x footprint as standard.

The JLM Power Station
http://www.jlmaudio.com/shop/index.php? ... oductId=12

60 bucks, or 100 bucks assembled and tested. If that's not a bargain, then I don't know what is.

Can someone tell me what "rail" in this context means? I think I understand it, but I'm not sure.

Manning wrote:The JLM Power Station


Can someone tell me what "rail" in this context means? I think I understand it, but I'm not sure.

Rail simply means a single voltage supply. With the powerstation there are 5 rails. With the 51x project we need to supply +48v, +-16v, +-24v which makes 5 rails. These rails on the powerstation can be set with the trim pots anywhere between +/-2v to 37v. Which makes it very useful PS for many projects. Looks like we would need to use the optional rectifier/diodes like Myles has to beef this baby up. And heatsink big time.

Sweet - my understanding was more or less correct after all.

Sammas, Myles - where does your power supply actually sit? Is it in its own rack enclosure, or is it nestled as a "module" in the rack itself?

A standard power amp heatsink will do the job, Joe has a calculator for his powerstation which is linked on the powerstation page which shows transformer VA, heatsink rating etc based on how many amps/voltages you need.

Power supply is in its own enclosure. One of mine is in a standard jaycar box with a heatsink mounted on the side, the other is built into what looks like a car amp case with thick aluminium extrusion so that the whole box acts as a heatsink. Jim Smiley built this one for me as I needed it pronto and didn't have the time. Both have performed flawlessly with a selection of 500 and 51x modules. Some of the diy 500 series stuff comes with 18pin edge connector with the last three pins going nowhere for stability but I haven't had any issues with the 15pin edge in the 18pin socket, just make certain that it is seated correctly on installation and then screw the faceplate in and there'll be no problem.

Just got an email reply from 51xaudio.com. They have plenty of rack kits in stock.

I'll be looking to order in mid-Jan or so. I'll get back to everyone on prices as soon as I can.

Manning wrote:Just got an email reply from 51xaudio.com. They have plenty of rack kits in stock.

I'll be looking to order in mid-Jan or so. I'll get back to everyone on prices as soon as I can.

Consider me down for 1 possibly 2.

I'm thinking 2 as well.

Sidenote The guy from 51xAudio (Cemal Ozturk) told me he is going to register here on T'rock so he can join in our discussions. That is cool.

Cemal Ozturk looks very much like a Turkish name, which is doubly cool. If it is, then it will be pronounced Jemal. (For those who don't know, I'm married to a Turkish girl and have learned very limited, very bad Turkish. It's a truly, truly beautiful language by the way).

Cemal is a good guy. I've bought a couple of things from him before and he is really easy to deal with. Would be great to have him on board.

Cemal is good value and I too have bought from him in the past.

Well I have since learned that Cemal is definitely Turkish, he has lived in the UK for 25 years. So now you all know to pronounce it as "Je-mal". From experience, Turks really appreciate it when you get the "C equals J" thing right. Getting the silent G in names like Sofuglu (Soff-oo-loo) is also appreciated.

He said he'll be signing up next week to keep an eye on us clueless newbies

Myles.... what's been the most useful of the 51x modules you've built for your rack?

nv73, capi vp26, and most recently the germanium jensamp. All excellent though the jensamp is fast becoming my favourite. I also have 2x 5003 EQ which are also brilliant and will be adding a solid state pultec and 1176 style comp soon for a pretty sweet tracking channel. Seriously though I dont think you can go wrong with any of the DIY units as they are all designed by people who really care as they are essentially designing them for themselves rather than for a 'market'.

Thanks for that Myles. I'm pretty keen to fill my rack with 51x projects (24v). Some good leads there. The germanium jensamp sounds like a solid choice. I'll take a look through the build.

Thanks

Links to Jensamp (chiefly for my future reference):

http://audio.kubarth.com/jensamp/
http://www.groupdiy.com/index.php?topic=45341.0

Here's my 51x kit on location. From left to right, nv73x2, vp26 with JLM hybrid opamp x2 (running at 24v), VP25 with blue dot, Jensamp x2, FiveFish Audio x-12 x2, VP26 with red dot x2. For those interested, beneath that is a nite PreEq4, summit audio 2ba221 and TLA-50, 4 channel MCI mic pre (racked by me), 4 channel Neve 3415 (racked by Barney Loveland).

mylesgm wrote:Here's my 51x kit on location. From left to right, nv73x2, vp26 with JLM hybrid opamp x2 (running at 24v), VP25 with blue dot, Jensamp x2, FiveFish Audio x-12 x2, VP26 with red dot x2. For those interested, beneath that is a nite PreEq4, summit audio 2ba221 and TLA-50, 4 channel MCI mic pre (racked by me), 4 channel Neve 3415 (racked by Barney Loveland).

Neat setup there Myles!

Manning wrote:Just got an email reply from 51xaudio.com. They have plenty of rack kits in stock.

I'll be looking to order in mid-Jan or so. I'll get back to everyone on prices as soon as I can.

Put me down for one also, I have a couple of opto 5 pcbs coming from Drip so this will be a nice warm up into it!

Paul

Put me down for 1 maybe 2. This will give me something to do after I finish my drip 175. Can't wait to power that puppy up ;-)

Cheers. Jason

This thread will cause me no small grief by years end. I can feel it.

I've found a young'un who can build this stuff for me, so I'm fairly excited at getting all the benefits with none of the actual effort.

But regardless, I need to get this order happening fairly soon. Is month-end OK for people?

just polishing up a 2nd pair of 553 style api eqs. 3 band, inductor based eq with DOA/Tx output and then I've got 4 more 312 style preamps to build in the next month or so... welcome to the fun place!

Months end would be fine. I'm for just the cases and using the JLM power supplies if thats an option.

Cheers. Jason

That's the plan - we're only ordering the rack enclosures from the UK, no power supplies.

As JLM are in Brisbane it makes more sense for people to order their own power supplies, and the less-confident can order them pre-assembled.

Manning wrote:I've found a young'un who can build this stuff for me, so I'm fairly excited at getting all the benefits with none of the actual effort.

Why?
Your missing the point of DIY. The bit about "yourself" doing it.
Some of the main benefits are the effort put towards piecing projects together without the cost of labour, learning what goes into making different units work and knowing how to fix them if something goes wrong down the track.
Assuming your paying the "young'un" to build these, surely there won't be any actual financial benefit for you to do DIY? Or the reward that comes from finishing a working build if your getting someone else to do it for you (DIFY).

Oh well...up to you.

Nah, still going to do it myself. But that will be a side project for my own education, and I don't want to subject customers to my incompetence.

I currently need some stuff for the studio in the short term, and it needs to be built both competently and in a reasonable time-frame. (We actually had our first paying customer on the weekend, so we're on our way). Hence using this young'un is an acceptable compromise. He also wants to use the studio for his own projects, so everyone wins.