1

EQ531T Tube Equalizer / Re: more bottom freq im EQ531T

« on: July 30, 2025, 03:20:14 PM »

Yes Jean-Pierre!!
You were rigth, there was another issue.

I digged into this problems more and I found that one row in my patchbay was unballanced.
Which became a problem when inserting the EQ531T or the LA502 in the patchbay.
Now I have removed that unballanced row, and inserted a ballanced patchbay instead.

I've had this unballanced patchbayrow for maybe 30 years or so, So I forgott that it sat there. 
I allways thougth that my whole patchbay was ballanced, but it was not.
So it became obvious when I inserted the EQ531T or LA502 into the unballanced patchbay.

You always learn something!!!!

Thank you for your patience for my problems.
Regards
Urban Osterman

2

EQ531T Tube Equalizer / Re: more bottom freq im EQ531T

« on: July 26, 2025, 10:38:48 AM »

I think I have found the solution of my problem of loosing bottoms from my signal.

I have some impedance problems!!
It depends on the order of 500-effects.
The last effect in the chain is very dependent on input impedance of the recording machine.

I have a chain och AB528 => EQ531T => LA502 => Alesis HD24..

And the Alesis HD24 have a ballanced 10K input Impedance, which is probably to 
low for the LA502 or if the EQ531T is the last 500-module, before
going into the HD24.

If I set the order of AB528 => LA502 => (different) Equaliser it sounds/works OK
Where the equaliser works also as a buffer for the HD24.

If i Insert a plain Ballanced buffer last in chain between the LA502 and the HD24
it also works OK.

Regards
Urban Osterman

3

EQ531T Tube Equalizer / more bottom freq im EQ531T

« on: July 24, 2025, 08:45:37 PM »

Anyone tried to replace C4 and C5 from 47uF to 100uF or 160uf to get more bottoms from This Eq?

Regards Urban Osterman

4

LA502 Optical Compressor / Re: Hissing LA502

« on: July 05, 2025, 03:24:55 PM »

I moved the LA502 to either a Bento6 or a Bento8. Works OK.
Cannot use the LA502 in a Bento10, too noisy???

Urban Osterman

5

LA502 Optical Compressor / LA502 Losing lower Freq

« on: July 05, 2025, 03:20:41 PM »

 
Hello
When I insert my LA502 into my Microphone-preamp-chain, I loose a bit of Bottom from my Sound.
Is there a way not to loose the lower frequency in the LA502? or is it part of the design?
Is this normal or did I make some error in my soldering?

My Chain is Mic/SM58 into AB528 into LA502.
Maybe it is some sort of Impedance issue?
I hear that I loose some bottoms on my voice.
I try to insert som pink noise instead of talking into the mickrophone.
But its hard to se in the spectrum analyser.

Regards
Urban Osterman

6

LA502 Optical Compressor / Re: C5 or not c5

« on: July 05, 2025, 01:25:42 PM »

Hello
When I insert my LA502 into my Microphone-preamp-chain, I loose a bit of Bottom from my Sound.
Is there a way not to loose the lower frequency in the LA502? or is it part of the design?
Is this normal or did I make some error in my soldering?

Regards
Urban Osterman

7

LA502 Optical Compressor / Re: Hissing LA502

« on: March 12, 2025, 01:23:39 PM »

Hi All
I have an LA502 installed into an Bento 10S and it is hissing a lot.
When I go beyond Gain 30 it is a lot of hiss??
When I install it into an Bento 6 I can go up to over Gain 70 before there is a sligth hiss.

Has anybody similar experience?
I have an MP AB528 in series before the LA502
But the MicPre is very silent.

Regards
Urban Osterman

8

AB528 Microphone preamplifier / Mic Noise?

« on: February 28, 2025, 04:26:42 PM »

A funny thing happend !!!

I inserted an SM58 into my AB528 Mic Preamp.
And I noticed very little background noise??

Then I realised that I had the Phantom power turned on, so I switched it off.
Then I noticed the background noise went back to normal??
The mic sounded ok both ways. No different sound??

How come it is a lot lower background noise when the
phantom power is turned on, on a mic like SM58?

/Urban

9

MU524 Vari-Mu Tube Compressor / Re: My testresult initial conditions

« on: February 27, 2023, 02:55:21 PM »

Question for Modification??

If I drive the compressor hard I cannot reduce the output volume to Unit gain.
Its pot P2 (2,2K) and R16 (220 Ohms) and the two capacitors C10 and C11, that works together.

Is it possible to lower R16 to lets say 100 Ohms or something?
To be able to turn the output volume lower.

Something you would recomend?

Regards
Urban

10

MU524 Vari-Mu Tube Compressor / Re: My testresult initial conditions

« on: February 24, 2023, 11:04:24 AM »

Hi J-P
I did a total resetup, and now I get 28,52 VDC on TP1 to ground
and 28,47VDC from TP2 to ground..... To low?

I must have forgotten to remove the JM1 before??
because I now get about 42VDC from TP1 to ground when JMP inserted (as before), and about 28,5 VDC when jmp1 reoved.

I do my setup using a SoundSkulptor 501.

Regards

11

MU524 Vari-Mu Tube Compressor / My testresult initial conditions

« on: February 21, 2023, 03:48:02 PM »

DC  Volt
      TP1 to ground = 40,46  VDC
      TP2 to ground = 40,41  VDC
AC Volt
      TP1 to ground = 0,003  VAC      ?!?
      TP2 to ground = 0,0023 VAC    ?!?

      TP3 to ground = 1,761  VAC
      TP4 to ground = 1,762  VAC

Output (Pin 2-3)    = 3,534  VAC

B+ = 42,5   (Voltage From power supply = 49VDC)


After Changed conditions

TP3 = 0,2460 VAC
TP4 = 2,753 VAC
TP5 = 2,735 VAC
TP6 = -3,280 VDC
Output = 5,53 VAC
Meter = -6dB

12

AB528 Microphone preamplifier / Re: AB528 Noisy in Bento 10S

« on: February 21, 2023, 12:09:33 PM »

Probably temporary buzz.
Works OK now!

13

First Aid / 2-slot modules such as CP554

« on: November 27, 2022, 02:04:27 PM »

Questions about Using a Two-slot 500 module.
When using a 1-slot modules in a chain of modules and passing signal from one module to next module
is normally working OK in a 500-Host (using switches on the back).

But when we are using a 2-slot module such as the CP554, as part of the signal-chain,
we are running into a problem.
Both input and output connectors are on the leftmost PCB.
Using the input and output connectors on the back of the host works OK.
So we could use short cables on the back.

How can this be solved if I want to use the Host forward-switches instead.

Regards
Urban Osterman

14

AB528 Microphone preamplifier / AB528 Noisy in Bento 10S

« on: November 26, 2022, 06:11:36 PM »

I have just finnished a kit MP AB528
It works Good in a 501 Single 500 Host
But it is very Noisy in A Fredenstein Bent 10S Host

Is there any Known problems with the power supply from a Bento 10S?

Regards
Urban Osterman