BAE PSU and 2 racks

[Steve Honest]

hi chaps

I have an 11 space BAE 500 rack and its huge PSU i notice on the psu that it has 2 power outlets does this mean i can run 2 11 space racks from it?
has anybody here tried this? and was it stable.
cheers
steve

[cabbo]

Thanks for asking this question Steve.

I got a BAE 11 space recently and noticed the same thing. There was no manual in the shipment so I called BAE. The explanation I got was yes, in theory, but if you're running a bunch of power hungry 500 units you could run into problems. The yellow, red, and green lights are specific indicators but I can't remember the details. It would be nice if BAE could include at least a paragraph of information about their rack. The fellow I talked to said information would be forthcoming on their website. I have not checked.

Since so many 500 manufacturers don't/won't publish power consumption specs, it's a bit of a crapshoot. My guess is, if you stick with VPR Alliance compatible gear you should be okay, but what fun is that? My rack is 91% full and I plan on getting another soon. I'm impressed by the size and weight of that power supply.

[TAVD]

Nope. At least not in the real world. One thing I was able to do was to run 4 channels of chip amps (ssm2019) in addition to the 11 slot rack. Two loaded 11 slot racks w/ one psu was NFG, and I had 2 or 3 empty slots. Even if you could power two racks, you'd be pushing the limits of the psu, imo.

[cabbo]

I contacted BAE and got this reply:

The PSU is rated at 2.5 amps. If you were to only use BAE 312's you could power 2 racks. Otherwise you need to calculate the current draw of every module you want to use.

Hope that helps.

cabbo

[pete]

and what for is the red and yellow led?

[Steve Honest]

they wrote to me on monday and told me i should only power a dual unit from the 2nd outlet,
no mention of what the led s denote, but i imagine its rail voltage fail lights like on my desk?
steve

[TAVD]

The led's give you a visual indication that the 3 power rails are working. If one does not light, it means there's a problem. The red or green will fail to light if the psu is overloaded, or both if you really push it. The yellow is for phantom if you have that option installed.

[cabbo]

Tom,

Do you know the current draw of the CAPI VP 26? I have had a pair since December and love them on a lot of sources. Guess I'll start contacting the other manufacturers of my 500 gear for some specs.

cabbo

[TAVD]

Not sure exactly but it's not much, like 50mA or something, depending on the DOA used. Jeff could tell you.

[cabbo]

Thanks. I will contact Jeff at some point. So 22 modules at 50 mA amounts to less than half of the available current of 2.5 Amps, leaving some headroom for start up, etc. Seems like it could work.

cabbo

[TAVD]

If you're really going to fill two racks with nothing but vp26, save the BAE psu for other 500 gear and use a 3A, 24v linear.

[cabbo]

Are you talking Group DIY 51X? Is someone building and selling these now? Last I checked, which was a while ago, it sounded like the PSU was still evolving. Admittedly, I haven't kept up with the DIY crew. I've read about the advantages of 24 volt rails, but got lost in the dust in that discussion.

I'm not a tech, Jeff built my VP 26's and did a fine job. They sound great, especially on my congas. But alas, I don't need 22 of them. A pair of 528's will be my next purchase, which will put me into that second rack. Then a pair of CAPI 312's...and then...

[TAVD]

Actually, I was thinking an off the shelf open frame linear just like you'd find inside the BAE power supply. It's a moot point though since you're mixing different modules.

[cabbo]

FWIW, here are current draw specs for some modules:

GR Harrison 32 EQ - 115 mA
Little Labs VOG - 50 mA
Classic API VP 26, 25, 312 - 51 mA
Classic API VC 528 - 78 mA
Classic API 312 DI - 90 mA
Inward Connections Step EQ - 52 mA
Rupert Neve 543 - 100mA
JLab JLA 3 - 100 mA

All the above manufacturers were happy to divulge this info. Only JLab posted the spec on their website. If anyone wants to add to this list, please do so. I'll post more when I can.

cabbo

[SRS]

Originally Posted by cabbo

FWIW, here are current draw specs for some modules:

GR Harrison 32 EQ - 115 mA
Little Labs VOG - 50 mA
Classic API VP 26, 25, 312 - 51 mA
Classic API VC 528 - 78 mA
Classic API 312 DI - 90 mA
Inward Connections Step EQ - 52 mA
Rupert Neve 543 - 100mA
JLab JLA 3 - 100 mA

All the above manufacturers were happy to divulge this info. Only JLab posted the spec on their website. If anyone wants to add to this list, please do so. I'll post more when I can.

cabbo

API 521c is 40ma (+or- 12/18 vdc)
API 527 is 130ma (+or- 15/18 vdc)
So the spec sheets say...

[cabbo]

Thanks SRS,

Here's a couple more:

SafeSound Stereo Toolbox - 230mA
SafeSound P 501 - 120mA

That mid-side compressor looks interesting.

cabbo

[cabbo]

I've calculated everything I want to run in two 11 space racks and came up with 1580 mA. That gives me 920 mA of headroom, if the BAE spec of 2.5 Amps is not overly optimistic. Might give it a go. But too bad I won't have room for these hungry modules:

1073LB - 215 mA (:~!

[Geoff_T]

Originally Posted by SRS

API 521c is 40ma (+or- 12/18 vdc)
API 527 is 130ma (+or- 15/18 vdc)
So the spec sheets say...

Hi

Yes but they don't mention, I presume, the in rush current at start up as any big power rail capacitors charge up.

It's this first couple of seconds that can really stuff the over current protection on the power supply and prevent it from powering up properly.

In that case, should it happen, you would have to pull a few modules out to allow it to start up then push them back in.

A pain in the ass, granted.

Solution B is for the power supply to be conservatively rated so it can handle the start up surge... That's nearer four or five amps.... Or Solution C is the power supply ramps up slowly.

This would not be an issue if the modules were designed to draw the current the racks were originally designed for.

Just my thoughts while on holiday in the UK

Posted from my iPhone

[shortstory]

Geoff makes a good point. We actually have four of the BAE 11 space racks and all four are loaded. Three of them fire up without issue, but the fourth needs to be bumped to get it to hold. By that I mean I have to plug it in (the PSUs don't have on/off switches) and then unplug it and quickly re-plug it. Usually twice. Then it settles in and all is fine. Although sometimes the phantom power LEDs on two of them don't light up even though it is present.

I've never had the problem of another poster about the signal lights lighting when over driving one of the modules although I have only two LBs and he had four.

[TAVD]

I had that ghosting signal light issue with a OSA preamp. My solution was to sell the preamp.

[cabbo]

About half the mfgr's I've contacted so far have expressed current draw as a maximum value, as in max 100 mA. I don't know if that takes into consideration startup surge.

Also, would switching all modules into bypass before powering up provide for a softer startup?

And as far as wonky light issues, I read somewhere recently of a module's pinout card being slightly out of spec. If I remeber correctly, it was a DIY discussion.

cabbo

[TAVD]

Originally Posted by cabbo

Also, would switching all modules into bypass before powering up provide for a softer startup?

No. The audio path is separate from the power rails.

[Geoff_T]

Originally Posted by TAVD

No. The audio path is separate from the power rails.

Hi

I send a long reply to this thread but the damn cell network went down and it was lost into cell neverfoundland.

Anyway, I would love to know how the +\- power rails are separate from audio. Even if the bypass was a hard link of input to output you would still have the amp circuits and psu decoupling caps drawing the start up current.

The manufacturers specs are unlikely to include the surge current as it only lasts the time constant of the charging capacitors... Maybe a second or two... But enough to stuff the overcurrent protection.

The power supply is an integral part of an amplifier circuit and the most neglected. With 500 series the buck always lands on the rack provider despite module providers have current ranges, it seems, between 50 and 250mA consumption, not including the surge current.

I gave three options in an earlier post and this will be a never ending saga until every manufacturer pulls together.

A bit like politics....

Posted from my iPhone

[TAVD]

Anyway, I would love to know how the +\- power rails are separate from audio. Even if the bypass was a hard link of input to output you would still have the amp circuits and psu decoupling caps drawing the start up current....

Umm, yeah. That's why I said bypassing the i/o will do nothing to reduce current draw. jeeze

But yes, poor phrasing on my part.

[cabbo]

Thanks Tom and Geoff for your replies. I think I'll give it a go and see what happens. I can always pick up a second power supply if needed.

Repeated bump starting to get power starved modules to run does not sound like a good idea!

By the way Geoff, I have one of your compressors and like it a lot.

cabbo

[jlaber]

Originally Posted by cabbo

FWIW, here are current draw specs for some modules:

GR Harrison 32 EQ - 115 mA
Little Labs VOG - 50 mA
Classic API VP 26, 25, 312 - 51 mA
Classic API VC 528 - 78 mA
Classic API 312 DI - 90 mA
Inward Connections Step EQ - 52 mA
Rupert Neve 543 - 100mA
JLab JLA 3 - 100 mA

All the above manufacturers were happy to divulge this info. Only JLab posted the spec on their website. If anyone wants to add to this list, please do so. I'll post more when I can.

cabbo

Retracted. Sorry for hijacking.

[cabbo]

Thanks for your input jlaber. I have not heard it yet but the JLA 3 looks awesome. Definitely on my short list of 500 series compressor modules to check out. Your website is impressive and thorough, and indicates you are passionate about your work. A good thing in my book.

cabbo

[Steve Honest]

thiis thread has been hijacked,
i remember when it was about something else
steve

[cabbo]

Steve

Sorry if I got off topic. Have you tried a second rack yet?

cabbo

[a.beck]

Originally Posted by shortstory

Although sometimes the phantom power LEDs on two of them don't light up even though it is present.

Mine does this also. (sorry to continue the hijack)

I emailed BAE about this and also running 2 racks from the one PSU, and there was a bit of back and forth, but once they found out I bought mine second hand and not from them, they didn't reply again.