Eisen Audio DIY500 Compatible Microphone Input Transformers

An input transformer is necessary to unbalance the incoming signal and properly interface it with the op amp, noise-free and at the correct impedance. Since you're building a microphone premplifier, you'd pick one of the microphone input transformers from the table below. However, by using different kinds of input transformers it is possible to build a line-level or instrument-level preamplifier instead.

The designations R7, C2, and R8 refer to termination components connected across the transformer secondary, as shown in the DIY500 schematic. R8 provides loading, and R7+C2 comprise a zobel network, when necessary.

A box containing ------ means leave that component out.
A box left blank means we don't have that information yet.
When in doubt, leave the component out.

The following microphone input transformers mount directly to the DIY500 PCB

Brand Model Turns Ratio Voltage
Gain (dBu) input Z (Ω) 1% THD(+N) R7 (Ω) C2 (F) R8 (Ω) Package Included
on PCB Fully
Tested? Price (1 piece) Source(s) INFO

Altran C-3402-2 1:8.16 200 100k PCB pins v2 - present N/A (min. qty. >1) direct

beyerdynamic TR/BV 3.10.0.01.001 1:1 200 PCB pins v1 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.51.0.01.001 1:1 200 leads v3 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.10.0.03.002 1:3.16 200 PCB pins v1 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.51.0.03.002 1:3.16 200 leads v3 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.10.0.05.003 1:5 200 PCB pins v1 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.51.0.05.003 1:5 200 leads v3 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.10.0.07.004 1:7 200 PCB pins v1 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.51.0.07.004 1:7 200 leads v3 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.10.0.10.005 1:10 200 PCB pins v1 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.51.0.10.005 1:10 200 leads v3 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.10.0.15.006 1:15 200 PCB pins v1 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.51.0.15.006 1:15 200 leads v3 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.10.0.20.007 1:20 200 PCB pins v1 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.51.0.20.007 1:20 200 leads v3 - present undisclosed distributors/ dealers

beyerdynamic TR/BV 3.10.0.30.021 1:30 200 PCB pins v1 - present undisclosed distributors/ dealers

Cinemag CMMI-2CPC 1:2 +4.87 150 +8 dBu @ 20Hz ------ ------ 6k2 PCB pins v1 - present undisclosed direct

Cinemag CMMI-3.5CPC 1:3.5 +9.73 150 +7 dBu @ 20Hz ------ ------ 18k PCB pins v1 - present YES undisclosed direct

Cinemag CMMI-5CPC 1:5 +13.8 150 +10 dBu @ 20Hz 9k76 220p 39k2 PCB pins v1 - present undisclosed direct

Cinemag CMMI-7CPC 1:7 +17 200 +7 dBu @ 20Hz 30k1 22p 97k6 PCB pins v1 - present undisclosed direct

Cinemag CMMI-8B3-PC 1:8 17.8 150 -1 dBu @ 20Hz 15k 100p 100k PCB pins v1 - present undisclosed direct

Cinemag CMMI-8-PCA 1:8 +17.8 150 -2 dBu @ 20Hz 9k76 22p 100k PCB pins v1 - present undisclosed direct

Cinemag CMMI-10-PCA 1:10 +19.75 150 -2 dBu @ 20Hz ------ ------ 150k PCB pins v1 - present undisclosed direct

Cinemag CMMI-10B-PC 1:10 +19.75 150 -1 dBu @ 20Hz ------ ------ 150k PCB pins v1 - present undisclosed direct

Cinemag CMMI-10C-PC 1:10 +19.75 150 +5 dBu @ 20Hz ------ ------ 150k PCB pins v1 - present undisclosed direct

Cinemag CM-75101APC 1:10 150 -2 dBu @ 20Hz? 150k PCB pins v2 - present undisclosed direct

Cinemag CMQEE-3440APC 1:18.26 150 -2 dBu @ 20Hz? PCB pins v2 - present undisclosed direct

Jensen JT-MB-CA 1:1 -0.26 150 +2 dBu @ 20Hz ------ ------ 3k leads v1 - present $60.08 USD direct

Jensen JT-MB-CPCA 1:1 -0.26 150 +1.5 dBu @ 20Hz ------ ------ 3k PCB pins v1 - present $70 USD direct

Jensen JT-11K8-APC 1:3.5 +10.5 150 -2 dBu @ 20Hz ------ ------ 15k PCB pins v1 - present $47.06 USD direct

Jensen JT-13K6-C 1:4.8 +13.3 150 -2 dBu @ 20Hz 12k7 200p 35k7 leads v1 - present $67.72 USD direct

Jensen JT-110K-HPC 1:8 +17.8 150 -2 dBu @ 20Hz 30k1 56p 100k PCB pins v1 - present $78.51 USD direct

Jensen JT-115K-EPC 1:10 +19.75 150 -2.5 dBu @ 20Hz ------ ------ 150k PCB pins v1 - present $76.36 USD direct

Jensen JT-115K-E 1:10 +19.75 150 -2.5 dBu @ 20Hz ------ ------ 150k leads v1 - present $73.32 USD direct

Jensen JT-DB-EPC 1:12 PCB pins v1 - present $73.08 USD direct in reverse

JLM Audio JLM 1:4 1:4 +9.3 150 -7.6 dBu @ 20Hz ------ ------ 10k leads v1 - present YES $30 USD direct

Lundahl LL1532 1:1 600 +10 dBu @ 50Hz 2k 1600p ------ PCB pins v1 - present £25.88 GBP (Canford) distributors or direct

Lundahl LL1538 1:5 200 +10 dBu @ 50Hz ------ ------ ------ PCB pins v1 - present $62 USD (K&K) distributors or direct

Lundahl LL1538XL 1:5 200 +13 dBu @ 50Hz ------ ------ ------ PCB pins v1 - present $73 USD (K&K) distributors or direct

Lundahl LL1576 1:7 200 ------ ------ ------ PCB pins v1 - present distributors or direct

Lundahl LL1576 1:7 50 +12 dBu @ 50Hz 30k 200p ------ PCB pins v1 - present distributors or direct

Lundahl LL1577 1:14 50 +6 dBu @ 50Hz 80k 100p ------ PCB pins v1 - present distributors or direct

Lundahl LL1578 1:10 50 +4 dBu @ 50Hz 40k 200p ------ PCB pins v1 - present distributors or direct

Lundahl LL1578XL 1:10 50 +12 dBu @ 50Hz 50k 200p ------ PCB pins v1 - present $73 USD (K&K) distributors or direct

Lundahl LL1587 1:2 PCB pins v1 - present £25.88 GBP (Canford) distributors or direct

Neutrik NTM1 1:1 200 PCB pins v1 - present £27.98 GBP Canford

Neutrik NTM4 1:4 200 PCB pins v1 - present £27.98 GBP Canford

OEP A262A2E 1:2 150 6k04 PCB pins v1 - present £9.60 GBP (Canford) Canford, Farnell, RS

OEP A262A3E 1:6.45 150 62k PCB pins v1 - present £9.60 GBP (Canford) Canford, Farnell, RS

OEP A262A6E 1:1 150 1k5 PCB pins v1 - present £10.10 GBP RS

Pico Electronics 23xxx entire range several to choose from various leaded, M8 bushing v1 - present ~$55 USD direct

Pikatron ÜP 3093 M 1:2 200 PCB pins v1 - present €21.40 EUR Bürklin (part # 80 C 780)

Pikatron ÜP 3094 M 1:5 200 PCB pins v1 - present €21 EUR Bürklin (part # 80 C 782)

Pikatron ÜP 3095 M 1:10 200 PCB pins v1 - present €21.40 EUR Bürklin (part # 80 C 784)

Pikatron ÜP 3096 M 1:15 200 PCB pins v1 - present €21.40 EUR Bürklin (part # 80 C 786)

Sowter 3195-C 1:7 16.37 200 25k PCB pins v1 - present £29.30 GBP distributors or direct

Sowter 4935-C 1:7 16.23 200 30k PCB pins v1 - present £33.76 GBP distributors or direct

Sowter 9540-C 1:1 -1.85 200 200 PCB pins v1 - present £33.76 GBP distributors or direct

Sowter 9610-C 1:10 19.23 200 30k PCB pins v1 - present £35.12 GBP distributors or direct

Brand Model Turns Ratio Voltage
Gain (dBu) input Z (Ω) 1% THD R7 (Ω) C2 (F) R8 (Ω) Package Included
on PCB Fully
Tested? Price (1 piece) Source(s) INFO

Please Note: The above listed transformers are stock items, available new. Some of these same manufacturers produce OEM, custom, and other non-stock items sharing the same footprints. Granted, there are even more options than we're aware of.

Other microphone input transformers can be mounted through more creative means, such as laying sideways and held down with a cable tie. Below are some examples.

Brand Model Turns Ratio Voltage
Gain (dBu) input Z (Ω) 1% THD(+N) R7 (Ω) C2 (F) R8 (Ω) Package Included
on PCB Fully
Tested? Source(s) INFO

API AP2622 1:8.16 150 leads v1 - present used market

Tamura (OEM?) GA80071 leads v1 - present used market Yamaha PM1000 mic i/p

UTC 0-1 1:15.81 200 solder lugs v1 - present used or Magnetika

UTC 0-2 1:15.81 200 solder lugs v1 - present used or Magnetika

UTC 0-12 1:1.58 ~3.5 200 solder lugs v1 - present used or Magnetika

UTC 0-16 1:14.14 250 leads v1 - present used or Magnetika

Specifications subject to change without notice. GMT