Question about NE5532 substitute for Green Pre v.13

[SonsOfThunder]

[quote author="microx"]Whats the best sub for a 4558?[/quote]That's going to depend on the ckt. Do you have a particular application in mind or are you looking for a single answer.

I have, btw, found ckts that use the 4558 that can be improved just by changing or removing component values in the ckt.

HTH!
Charlie

 

[microx]

Hi guys,
I picked up a Yamaha MR842 mixer on evilbay and it's full of 4558's.
I want to work on a couple of mic boards to see if I can improve them. I think I will fit sockets to one board and then I can try various chips and compare the performance to the un-modded channels. I have to say I was
surprised how quiet the mixer is as standard.
I Modded a Paia mic pre and it was for sure much better for it.
Steve

 

[microx]

Buttachunk,

That sounds like a good start. If I am going to get in any deeper with this mixer I will need a schematic so I can plan it out . The Yamaha site has a manual but no schematic. I will keep on Googlin!
This mixer has at least 50 4558's, thats a lot of stomp boxes but I never throw components away.
Steve

 

[SonsOfThunder]

[quote author="microx"]...a Yamaha MR842 mixer on evilbay and it's full of 4558's.
I want to work on a couple of mic boards to see if I can improve them.[/quote] Microx, I did some mods on a Yammy MC1602 a while back and I believe it is pretty similar, if not identical in the basic design. You can get the docs from Yamaha for something less than USD$20 and it included the owners manual, schematics, everything. Worth it!

Mine was full of 4558 and 4556, which has more drive than the '58. I replaced with LM833 (spec'd slightly quieter than 5532) on the channel strips and used OPA2134 in the summing and output amps. I measured signal-to-noise before and after and there was little improvement. As I remember, there is still a bandwidth limit that is caused by some of the surrounding component values (probably caps). I got in a hurry to use it and put it back together before i solved the problem. I need to open that back up and figure it out.

I think I will fit sockets to one board and then I can try various chips and compare the performance to the un-modded channels.

Well, IIRC, I fitted every location with gold-plated machine-pin sockets so that I could easily change my mind later. This is standard for me when I mod. That way I can easily switch back to the original part should I need to troubleshoot and I never have to heat that part of the PCB again.

I have to say I was surprised how quiet the mixer is as standard.

Except for the BW limit, I think its a great mixer really. The MC is missing some cool features but for the money (and the potential after some mods) they are hard to beat!

HTH!
Charlie

 

[microx]

Hi Charlie,

I had a look at the 1602 on the Yamaha website and you are right it is VERY similar. The only REAL difference is the 16-2 against 8-4-2 setup.
The channel boards look identical and I bet they are. I have faxed Yamaha America about a service manual. Do you know what the voltage is for the VU meter lamps?

Steve

 

[SonsOfThunder]

Microx,

I was going to look this up for you today at work, where my schem is. I got it out of its hiding place when my wife called and asked me to come home...I am still waiting...we are going to the hospital to deliver our "Ultimate DIY" as its called around here. Maybe in a few minutes...

I'll get that info as soon as I can but it might be a couple of days before I get back with you...

Send me a PM if I don't, please!
Charlie

 

[PRR]

> Do you know what the voltage is for the VU meter lamps?

If the board is working, and the lamps just blown, measure the voltage on the socket. (Could be AC or DC.) Then pick a lamp of much higher voltage, 20% to 50%, because being a little dim and long-life looks better than dead lamps after a couple months.

You could also add a resistor and use an LED for "infinite" life. They even come in white now, though I'd have a red and a yellow running lower current behind the white for that good old time incandescent mellowness.

 

[microx]

PRR,

Two of the eight are dead and this is the motive for wanting to know the exact voltage of the lamp, which is for sure higher than the fed voltage,
so as to get the same "glow".
It's a nice old mixer, almost a mini-desk, and it cost me peanuts on evilbay and has everything I need. BUT I just have to tinker with it.
Steve