Restauration of Studer 169console ....in detail

[magruith]

ok thanks i testing that ...

[magruith]

it works very well dualflip

[dualflip]

Originally Posted by magruith

it works very well dualflip

Im glad it worked you can do the same thing with all the other pots in your module

[hashashan]

It won't let me leave feedback on his profile page so I'd just like to add to the praises of Roginator for this thread and also for selling me a 169 that I'm very happy with,Big up Damir!!!!!!!!

[lobit]

okay im confused..somebody mentioned you could use an acopian ld15 which is only 1amp. and someone else said you need 2.5-3amps.. which is it?

[lobit]

also someone mentioned running higher than +/- 15v to something like 16.5v anyone tried that. (on the whole console not just strips)

[dualflip]

I mentioned the 1 amp acopian as an example of how cheap you can find those psus on e-bay, however you need more than 1 amp, you can go as high as you want when it comes to current rating, not lower!

Regarding the 16.5V, i used it on a module i have, since the ICs in a module will be able to handle it, however that only applied to a single racked module, i would have to analyze the entire console to see if it can be saftely bumped to 16.5V, so for now its just better to keep it stock.

[lobit]

okay I get it. mine has the battery pack from the factory.. does that affect my choice of power supplies?

[ethyrvalve]

Originally Posted by Audioguy

Probably the most significant improvement can be had in beefing up the PSU. The DC-DC convertor version of the console will easily bottom out the supply rails on LF transients, causing very nasty instability. The only problem with a direct replacement is that there is a -8 VDC reference tap for the limiter circuit. If you are not using the limiter, no big problem. Optionally, a second regulator could be added to the -15 VDC rail to derive the needed voltage (it doesn't draw any current to speak of, it's simply a reference voltage).

If you are going to swap out opamps, I can virtually guarantee you will need to change the PSU anyway. The +/- 15V rails are only good for about .5A, which doesn't go very far with modern high-current opamps.

Hi Scott,
Are you certain, that the -8v reference will be gone? I'm finding the manual slightly confusing on this matter, but it looks to me like the -8v is derived from the -15 rail (section 7.8/2 and 7.7/11 in the manual).
The DC-DC converter on one of my two 169s gave up the ghost. I'm going to try installing a McCurdy Radio +/- 15vdc PSU (I'm not sure of its specs, but each rail has a a fast-acting 4 amp fuse).

[Audioguy]

ethyrvalve:

My bad, sorry for the mis-information. You are correct, the -8 volt reference for the limiters is derived from the -15 volt rail via a separate regulator IC in the monitor module, and fed to the master modules via pin 10 of buss board connector PP3. It also feed the limiter meters via pin 6 of the 25 pin d-sub meter bridge connector.

My apologies if I led anybody astray on this point. I have in fact experimented with different PSU to replace the DC-DC convertor, focusing mainly on the +/- 15 volt rails. So far, I have not had much success with the units I have tried.

The Studer seems to be very fussy about what it accepts as a power source. I think much of this has to do with the frequency that the DC-DC convertor operates at, which is about 50 kHz. This is a rather low switching rate for today's designs.

I haven't given up on this, though, and will report back with any success.

(Be careful about using a higher current supply with the 169/269 series. You want to make sure that you don't feed too much current to the +/- 15 volt rails in the event of a short in one of the modules, which will burn up the traces on the buss board. Given that they are totally unavailable, you do not want to have this happen!)

--S

Originally Posted by ethyrvalve

Hi Scott,
Are you certain, that the -8v reference will be gone? I'm finding the manual slightly confusing on this matter, but it looks to me like the -8v is derived from the -15 rail (section 7.8/2 and 7.7/11 in the manual).
The DC-DC converter on one of my two 169s gave up the ghost. I'm going to try installing a McCurdy Radio +/- 15vdc PSU (I'm not sure of its specs, but each rail has a a fast-acting 4 amp fuse).

[Audioguy]

If you want to maintain battery operation, you will need the DC-DC convertor power supply, as opposed to the AC supply (which has no capability for charging the batteries).

If you don't care about battery operation, you could use the AC supply, but you will need to cut a hole in the front panel to accommodate the AC input connector, remove the battery holders, and make some minor changes wiring.

Originally Posted by lobit

okay I get it. mine has the battery pack from the factory.. does that affect my choice of power supplies?

[lobit]

Im okay with losing battery capability... my main motivation is I wonder If it would sound better running with the direct ac supply rather than going through the dc converter first.

so you haven't found any supplies that work properly?

I have in fact experimented with different PSU to replace the DC-DC convertor, focusing mainly on the +/- 15 volt rails. So far, I have not had much success with the units I have tried.

The Studer seems to be very fussy about what it accepts as a power source. I think much of this has to do with the frequency that the DC-DC convertor operates at, which is about 50 kHz. This is a rather low switching rate for today's designs.

[Audioguy]

lobit:

A properly designed AC supply will definitely perform better than the stock DC-DC converter, which tends to bottom-out on high levels of LF program content.

I haven't experimented with any replacement AC power supplies yet. My guess is it should be much easier to find a workable substitute, as opposed to the DC-DC convertor. Whether or not it will fit in the space provided at the front of the console is another matter, though, as the height is quite limited.

I have seen a few AC supplies around which supply both +/- 15 volts and +48 phantom, but they tend to be quite large, as they are intended for large-format consoles.

I looked at some of the power supplies for smaller boards such as the Sony MXP-29 and Yamaha 01V series that might hold some promise, but have not had the time to actually try them in the Studer yet.

If you are really insanely lucky, you might find one of the original Studer AC supplies somewhere. Occasionally I see some 169 frames go up for sale, but it's pretty rare.

Once again, my caveat regarding over-current protection for the +/- 15 volt rails should be observed. Although I have only twice experienced any circuit failures which resulted in a short across the rail, it does happen, and you don't want to risk frying the buss-board backplane!

--S

Originally Posted by lobit

Im okay with losing battery capability... my main motivation is I wonder If it would sound better running with the direct ac supply rather than going through the dc converter first.

so you haven't found any supplies that work properly?

[lobit]

thanks audio, I wouldn't need to fit it inside the chassis anyway.

how much current would be too much.. more than 3 amps? what needs to be done to prevent over current? special fuses?

[dualflip]

Originally Posted by lobit

thanks audio, I wouldn't need to fit it inside the chassis anyway.

how much current would be too much.. more than 3 amps? what needs to be done to prevent over current? special fuses?

Current is determined by the load, the amp spec on a PSU is only the maximum current that the PSU can deliver, fuses can be used to prevent over current in case of a short and similar to protect both the console and the power supply, also some power supplies are equipped with a current limiting circuit, you can go higher on the PSU current rating than the one required by your console, but not lower.

I advice you to read some electroncs basics like ohms law to get a better understanding.

Hope this helps

[lobit]

well, yeah thats what I mean, if the circuit will only draw what it needs, what Is 'over current protection' and how does one implement it?

[dualflip]

Originally Posted by lobit

well, yeah thats what I mean, if the circuit will only draw what it needs, what Is 'over current protection' and how does one implement it?

When theres a short in the console, it will draw more current, thats what fuses are for, if it draws more current than the one rated on the fuse, the fuse will blow and will protect both the PSU and the console. The over current protection circuit is installed on some power supplies, and it can be adjusted (depending on the PSU).

[dualflip]

Originally Posted by Jim Williams

Something like the Power One HDD-15-5AG is ideal to power that console. Low cost, 5 amps and easy to apply. Pick off the - 15 rail and run through a LM7808 regulator to generate the - 8 volts cleanly. Or, use a LM7805 and add a 3 volt zener diode in series with the ref pin to ground.

Add a small 1/2 amp 48 volt supply for phantom and call it a very quiet day.

+1 on the Condor/Power One/International psus

[Audioguy]

Probably around 1.25 amps would be a happy tradeoff. Best to implement it using current limiting within the PSU itself, rather than with fuses (if only one rail loses power, you may risk blowing some IC's.

The optimum current cutoff will probably be a tradeoff between the current demands for best low-frequency performance vs. protection of the rails.

Note that there are also thermistors on the +/- rails for each individual module, but I wouldn't rely on these for over-current protection.

--S

.

Originally Posted by lobit

thanks audio, I wouldn't need to fit it inside the chassis anyway.

how much current would be too much.. more than 3 amps? what needs to be done to prevent over current? special fuses?

[lobit]

awesome thanks!

[lobit]

anyone here noticed any sound quality differences between using batteries vs a dc adapter? just curious, I've only ever used batteries.


hdd 15 5ag ordered! excited to hear what it will sound like with a real psu!

[ethyrvalve]

Originally Posted by lobit

anyone here noticed any sound quality differences between using batteries vs a dc adapter? just curious, I've only ever used batteries.


hdd 15 5ag ordered! excited to hear what it will sound like with a real psu!

I tried batteries on one of my 169s as an experiment. In all honestly, I couldn't notice a difference vs the external PSU.

Someone once told me that audiophile classical sorts (perhaps Telarc, who used Studer 169s?) would sometimes opt for batteries as a way of alleviating any possibility of AC hum. I have no evidence to prove this was so though.

Aside: I'm happy to report that the Power One PSU has been working wonderfully for me (my other 169 had its DC-DC converter board fail).

[lobit]

this might be a stupid question but, you connected the power one supply directly to the +15 /-15 connections that go to the bus bar?

Im not going to actually wire it up myself, my tech will do it, but Im trying to understand the procedure a little better.

and to clarify ethyrvalve, you haven't noticed any difference between running the mixer with the power one supply vs the dc/dc converter? I feel like I've definitely noticed the 'bottoming out' effect on low frequencies on mine. that's why Im hoping the ac power supply will remedy this.

[lobit]

another thing I was trying to make sense of is the dc voltage input on the back of the console, (near the dsub type connector on the back) Im pretty sure this was where you could plug in the outboard studer dc supply.

Im curious because my console has a spot on the front panel where you can plug in a dc adapter that seems to go into the dc/dc converter. its on a 5 pin cable, not sure if its factory or not. I'm curious as to why there would be 2 different places to plug a dc supply.

the manual does quote 3 options for powering the converter.. the external mains, batteries, and 'an external dc voltage'

[ethyrvalve]

Originally Posted by lobit

this might be a stupid question but, you connected the power one supply directly to the +15 /-15 connections that go to the bus bar?

Yeah it's pretty straightforward, there are terminals that connect to the DC-DC board that you unhook and replace with your ground and +15 /-15 output from the Power One. The manual has the connections documented very clearly, you tech should have no problem.

Originally Posted by lobit

and to clarify ethyrvalve, you haven't noticed any difference between running the mixer with the power one supply vs the dc/dc converter? I feel like I've definitely noticed the 'bottoming out' effect on low frequencies on mine. that's why Im hoping the ac power supply will remedy this.

Sorry, I meant the DC-DC converter being powered from the stock external PSU (which provides an external DC voltage) vs powering the DC-DC with batteries. I think the external mains option you're referring to is alternate built-in power supply (I don't have the manual with me).

I *did* notice higher low frequency headroom with the Power One PSU.

[lobit]

okay thanks, I get it, so you are in essence bypassing the dc/dc converter altogether? does it still serve any function or did you take yours right out?

[ethyrvalve]

Originally Posted by lobit

okay thanks, I get it, so you are in essence bypassing the dc/dc converter altogether? does it still serve any function or did you take yours right out?

Mine stopped working so I bypassed it altogether. I'm not certain if it would be advisable to only use the DC-DC converter for the +48v phantom power (leaving the +15/-15vdc outputs disconnected). Perhaps someone here who's more knowledgeable could chime in?

[Audioguy]

The DC-DC convertor will function without a load on it, but I'm not sure how it will do long term. You are better off removing it and replacing it with the new PSU so that the lead length to the backplane board is at a minimum. You can use an external supply for phantom if needed, it's not too fussy about that.

Note that you will lose the function of the power switch unless you rewire it for a PSU that has a "remote on/off" function. Unfortunately, neither the Power One or Condor supplies have this feature.

Ideally, you are best off trying to find one of the original Studer AC power supplies, which will both fit in the case, and provide the +48 phantom. Won't be cheap, of course :(

Also, you really don't need a supply any larger than 45 watts for these consoles. The original supply only put out 500 ma per rail, and is current-limited to 800 ma (for the reasons I noted previously).

--S

[Jim Williams]

That's why you get a bigger low end with a high current linear power supply, no current limiting. I would never recommend anyone use a switching psu for a console. That 5 amp Power One is only about $170. You could probably use the 3 amp version as well. Add the small 1/2 amp 48 volt linear supply for phantom and dump those Studer psu's, or better yet, sell them to someone still looking for those. It may pay for the replacements.

[pascalray]

Originally Posted by roginator

fourth 169 on work bench!! tomorrow calibration!!

AGAIN >>>> I HATE FRAKO CAPACITORS!!

hi man from wherer did you source edge card connectro i just have no luck in finding those anywhere any input will be appreciated thx in advance