Raleigh Audio Line Stage Impedance and Gain
(version 1 Combo Input and version 2 Active Output)

The Line Stage has options for different gains, input impedances and output impedances.  The transformers are wired so traces can be cut and jumpers can be installed to change the transformer ratios, and thus the gain. Changes to the transformer ratios will give changes to the gain in 6dB steps. Linear changes to the gain within a 6dB step may be achieved by adjusting the ratio of the value of the series resistors (R1-R4) to the value of the potentiometer. Increasing the size of the series resistors decreases the gain. The value of the series resistors should not exceed one-half the value of the volume control, and the smaller the series resistor, the better.  Where it can be used, 5KΩ (+/- 10%) is a good value to use for the series resistors (R1-R4.) The “standard” version of the Line Stage has 8dB of gain, an input impedance of 50KΩ and an output impedance of 400 Ohms.

  

Combo Input Options

Option

Gain *

Transformer

Ratio

Volume Control

R1-R4
(max)

Input Impedance

Note

1

0dB

LL1676

1:1

K&K

5KΩ

10KΩ

1

2

-1.6dB

LL1676

1:1

50KΩ

5KΩ

10KΩ

 

3a

-6dB

LL1676

1:1

50KΩ

25KΩ

50KΩ

 Standard

3b

-6dB

LL1676

1:1

10KΩ

5KΩ

10KΩ

3c

-6dB

LL1676

2:1

K&K

5KΩ

40KΩ

1

4

-7.6dB

LL1676

2:1

50KΩ

5KΩ

40KΩ

 

5a

-12dB

LL1676

2:1

50KΩ

25KΩ

200KΩ

 

5b

-12dB

LL1676

2:1

10KΩ

5KΩ

40KΩ

 

* The gain numbers above are in addition to a base of +26dB.
* The gain assumes that R1-R4 = max
Note 1: K&K refers to the custom RAKK dac stepped attenuator available from K&K Audio.

  

Extreme Output Options 

Option

Gain *

Transformer

Ratio

Output
Impedance

Note

7

-12dB

LL1674

4:1

400Ω

Standard

8

-18dB

LL1674

8:1

100Ω

 

* The gain numbers above are in addition to a base of +26dB.

 

Recommended Option Combinations
 

Total Gain

Volume Control

Options

Input Impedance

Output Impedance

Note

14dB

K&K

1 & 7

10KΩ

400Ω

 

12.4dB

50KΩ

2 & 7

10KΩ

400Ω

 

8dB

10KΩ 3b & 7 10KΩ 400Ω  

50KΩ

3a & 7

50KΩ

400Ω

Standard

K&K

1 & 8

10KΩ

100Ω

Wiring change 1                        Preferred

6.4dB

50KΩ

2 & 8

10KΩ

100Ω

Wiring change 1

2dB

10KΩ

3b & 8

10KΩ

100Ω

Wiring change 1

K&K

3c & 8

40KΩ

100Ω

Wiring change 1 & 2

0.4dB

50KΩ

4 & 8

40KΩ

100Ω

Wiring change 1 & 2

-4dB

10KΩ

5b & 8

40KΩ

100Ω

Wiring change 1 & 2

Note: The RAKK dac custom stepped attenuator is the preferred option for all gain choices where it is listed.

 

Wiring Changes

These wiring changes are for version 2.x Extreme Active Output boards and version 1.x Combo Input boards.

The transformers have been provided with wiring pads to facilitate manual wiring. The pads immediately adjacent to, on one or both sides, of each transformer pin are connected to the pin. I will call these pads “transformer pads.  An external trace is connected to another pad adjacent to the transformer pad. I will call these pads “external pads.” A transformer pad is connected to its external pad by a short trace that may be cut to separate an external trace from its transformer pin. Once this short trace is cut, the transformer pad and external pad may be connected to other transformer pads and external pads with jumper wires. In some cases on the Combo Input board, two transformer pads are directly connected together with a trace.

 All wiring changes should be performed on both channel’s transformers.

  

Wiring Change 1

 This wiring change is performed on the LL1674 transformers on the Extreme Active Output board. It will change the output transformer ratios from 4:1 to 8:1, thereby providing an additional 6dB of attenuation. 

  1. Cut the trace between the transformer pad and external pad at pin 1.
  2. Cut the trace between the transformer pad and external pad at pin 4.
  3. Add a jumper wire between the transformer pad at pin 2 and the transformer pad at pin 4.
  4. Add a jumper wire between the transformer pad at pin 1 and the transformer pad at pin 5.

  

Wiring Change 2

This wiring change is performed on the LL1676 transformers on the Combo Input board. It will change the input transformer ratios from 1:1 to 2:1, thereby providing an additional 6dB of attenuation.

  1. Cut the trace between transformer pad 6 and transformer pad 10.
  2. Cut the trace between transformer pad 7 and transformer pad 9.  
  3. Cut the trace between the transformer pad and external pad at pin 1.
  4. Cut the trace between the transformer pad and external pad at pin 2.
  5. Cut the trace between the transformer pad and external pad at pin 5.
  6. Cut the trace between the transformer pad and external pad at pin 6.
  7. Cut the trace between the transformer pad and external pad at pin 7.
  8. Add a jumper wire between the transformer pad at pin 2 and the external pad at pin 7.
  9. Add a jumper wire between the transformer pad at pin 7 and the external pad at pin 2.
  10. Add a jumper wire between the transformer pad at pin 5 and the external pad at pin 6.
  11. Add a jumper wire between the transformer pad at pin 10 and the external pad at pin 5.
  12. Add a jumper wire between the transformer pad at pin 6 and the external pad at pin 1.
  13. Add a jumper wire between the transformer pad at pin 6 and the transformer pad at pin 9.