1

MP566 Tube microphone preamplifier / Re: 48v Not Working

« on: January 20, 2022, 12:33:45 PM »

It turns out it is across all of my modules. Weird, I didn't have this before.

Engaging phantom power only puts out about 8 volts DC. So I guess that its something faulty in my RND R6. I will check it with them. 

Thanks!

2

MP566 Tube microphone preamplifier / 48v Not Working

« on: January 19, 2022, 07:43:36 PM »

Hi, I have been testing my new preamp which sounds lovely! I have never heard a SM57 sound this fat! 

The only thing that doesn't seem to work is the 48v. Any tips on what to check?

3

MP566 Tube microphone preamplifier / Re: signal check fail

« on: January 19, 2022, 07:38:56 PM »

Yes! I tested it with a dynamic mic and it sounds awesome, thank you for your help so far!

One minor issue I now have is, the phantom power is not working.. I'll start a new topic concerning this for future reference. 

Thanks! 

4

MP566 Tube microphone preamplifier / Re: signal check fail

« on: January 19, 2022, 01:49:52 PM »

I've bought a 'better' multimeter just to be sure. 

With a 0.5 VAC sine I get:

-  ' Set Pot IN to 10, Pot OUT to 0, Gain switch to MID:you should read 3VAC on TP1'  

I get  3.14VAC on TP 1

-  'Set Pot IN to 10, Pot OUT to 10, Gain switch to LOW:you should read 2.25VAC on TP3 and 7.2VAC on TP4.'

I get 2.32VAC on TP3 and 7.5VAC on TP4

5

MP566 Tube microphone preamplifier / Re: signal check fail

« on: January 18, 2022, 02:22:18 PM »

Check the value (by color code) and solder joints of R38 to R44.
Are you sure your meter is OK, with a fresh battery?

Checked the values, checked the joints, reflowed some of them. Checked the battery of my DDM, which is good. I still get a reading of around 13V with the gain switch set to low and the pots turned fully open. Switched to mid it reads about 15v and switched to high it reads about 10v, which seems odd. 

6

MP566 Tube microphone preamplifier / Re: signal check fail

« on: January 17, 2022, 01:01:23 PM »

So, I measured 1 VAC at pin 8 and 10 on the extender, with the preamp connected, it didn't drop at all compared to measuring just xlr pins.

Now with gain set to low I turn P1 and it turns green, I turn P2 and it turns red, but I get a reading of 13.3 volts AC instead of 7volts AC. 

7

MP566 Tube microphone preamplifier / Re: signal check fail

« on: January 14, 2022, 12:17:48 PM »

(I do have the lunchbox extender)

8

MP566 Tube microphone preamplifier / Re: signal check fail

« on: January 14, 2022, 12:12:08 PM »

no I measured the input voltage (1VAC) at the XLR pins. Where can I measure it when the source is connected to the pre?

9

MP566 Tube microphone preamplifier / Re: signal check fail

« on: January 12, 2022, 03:42:07 PM »

So I replaced Q1, the relay is clicking now when inserting the jack, so there was definitely something wrong there. 

Only thing that doesn't match up now is the ACV meting with the 1VAC sine at the input of my rack. 
With the gain set to low nd pot 1 turned to max I don't get a green light, when I turn pot 2 to max I do get a green light, but no acv reading. When switching to mid gain with both pots set to max I get a reading of3.8 ACV and when set to high I get 14.1 ACV

So I think there is still something up? Or is it okay to move ahead?

Thanks in advance

10

MP566 Tube microphone preamplifier / Re: signal check fail

« on: January 09, 2022, 10:51:33 AM »

No clicking when inserting the jack. 

11

MP566 Tube microphone preamplifier / Re: signal check fail

« on: January 08, 2022, 02:41:53 PM »

I'm sorry, I mean it reads -5.0 at 0v and tp 8, and the tube does slowly gets warm.

I just don't get any AC volts reading or led turning green/red when turning the pots.

I do get a reading of 14.1 AC volts plus leds turning green/red when inserting the signal into the DI input. 

12

MP566 Tube microphone preamplifier / signal check fail

« on: January 07, 2022, 12:23:15 PM »

Hi there,

I have been having some trouble getting my mp 566 to work. I don't seem to come past point 5 of the test guide. The manual says that the led should stay off when turned on, but in my case it flashes red green, and then green for a little bit. and then nothing happens when I turn the pots. It reads -5.08 dcv between 0v and tp 8, but I also don't see the tube light up, which I suppose should happen when powered on. 

Earlier on I made the mistake of soldering U4 directly to the pcb (stupid I know) So I figured that I might have fried it and ordered a new TCA 0372 dp1 chip, desoldered the other one and replaced it. But the outcome is the same. 

Any tips?

13

LA502 Optical Compressor / Re: irregular output level

« on: December 18, 2021, 01:13:12 PM »

I've checked the joints and reflowed quite a few of them. I am still testing, but it seemed to have worked!

Thanks!

14

LA502 Optical Compressor / irregular output level

« on: December 15, 2021, 04:06:43 PM »

Hello everybody,

I have been thinking about building some SS modules for quite some time now, in anticipation of building a unit myself, I bought a LA502 second hand from another builder. 

This unit sounds amazing! There's only one weird thing I am experiencing with it, the output level varies between two settings;


its either pretty soft (with about 9db of GR, ratio 3, I have to put the gain to full in order to get a level that's close to the source level) 

or pretty loud (with about 9db of GR, ratio 3, I have to put the gain to about 40 to get the same level as the source level)


I noticed that when it's in the softer setting it might out of the blue switch to the louder setting at some point during the session, but when its loud it won't go back to softer. So I guess the louder setting is the normal behaviour? Sometimes I can 'fix' it by turning my rack on and off a few times. 

The guy I bought it from did not recognise this behaviour. Could it have something to do with my rack? I use a RND R6 rack. Or might there be something else I am overlooking?

Any advise would be much appreciated! 

Thank you!