Marantz 8B Output Transformers

One of the issues of cloning legendary designs like Dynaco ST70, Marantz 7/8/8B and so forth, are the difficulties in getting the original output transformers to go with the design. Due to age, the originals output transformers are hard to come by, and most of them time, in very bad condition or damaged. 

On top of that, buying replacement output transformers from other makers, that do not follow the original design, the tone, quality and taste of the original design is lost, or deviated further away. Worse is that some of the original designs / schematics do not specify the primary/secondary winding in detail where it is impossible to remake.

Well, we have good news for you. We've repaired many famous and legendary output transformers in the past. We've reverse engineered it for our customers, kept the design data so that we could reproduce the same exact copy if future customers that want to restore or rebuild their classic machines, using the original cores, or with modern cores.

A few of them are Marantz 8B output transformers with the feedback secondaries, or WE 543A input transformers and etc. 

Let us know what you need and we shall check if we have it for you.

Do note that we do not support piracy. We do not clone modern designs for profit. These are just for restoration/repair purposes only, or for extinct and out of print designs only.

1/29/2016
J&K Audio Design

Product Lists  
Level 0

Level 1: link 1, link 2, link 3

Level 2: link 1, link 2, link 3, link 4, link 5, link 6 

Level 3: depends on type, size and complexity. Email us for details.

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* Finished amplifiers, DACs, audio gadgets, upgrades and repairs - this is not our core business and we do it out of passion. We do not have fixed models, fixed price and we customize for each individuals. The sky is limit of creativity.  

* Our product lines are always improving and increasing. If you do not see what you want, contact us!  

* Please email for volume discounts, distributor and OEM pricing.

 

Balanced Preamp Output Transformer

Are these requirements what you are looking for in a preamp output transformer? 

• Sounded as good as measured or specified in datasheet?
• Balanced or single ended configurable preamp / linestage output transformer? 
• For medium high current driver tubes like 5842, 6C45, 5687, 6900, E182CC? 
• Flat frequency response from 20Hz to 20KHZ?
• Install and forget? Worry free reputable source? 

We have the answers to above all. Here's our Level 3 Nanocrystalline Double C 6K medium current balanced preamp / linestage output transformer.

Frequency response (in circuit measurement, standard 20Hz - 20KHz)

(150Ω+150Ω balanced out)： 20Hz（-0.66dB）—1KHz（0db）—20KHz（-0.23dB）

(150Ω single ended OUT1)：  20Hz（-0.65dB）—1KHz（0db）—20KHz（-0.2dB）

(150Ω single ended OUT2)：  20Hz（-0.65dB）—1KHz（0db）—20KHz（-0.16dB）

(600Ω single ended OUT1)：  20Hz（-0.62dB）—1KHz（0db）—20KHz（-0.31dB）

(600Ω single ended OUT2)：  20Hz（-0.62dB）—1KHz（0db）—20KHz（-0.31dB）

Core: Nanocrystalline SiFe Cut Core

Primary DCR: 359.9Ω（360.2） （B-P，9℃）

Secondary DCR, E-OUT1: 17.6（17.6）Ω

Secondary DCR, E-OUT2: 18.4（18.4）Ω

Primary inductance: 51.6H （51.1H）（DC bias at 25mA，20Hz，5Vrms）
Primary DC (absolute max)：50mA （recommended≤30mA）

Notes & tips

* P & OUT1 is in phase

* Suitable for tubes with Rp ~<2K

* Higher current version is available for tubes like 45, 2A3, 300B as drivers 

* Play with different configurations to tune it to your likings

* Measurement is done with 10K load, results will be better with higher loads but still very good with lower loads like 1K or 5K.

Here are the measured results with single 5687 tube. 

7Hz - 75kHz -3dB

7Hz - 65kHz -3dB

7Hz - 90kHz -3dB

7Hz - 65kHz -3dB

7Hz - 80kHz -3dB

If you do not find what you need at our website, contact us. We are expert in customized transformers for various applications. Tell us your desires and we will make it happen.

J&K Audio Design

1/21/2016

Product Lists  
Level 0

Level 1: link 1, link 2, link 3

Level 2: link 1, link 2, link 3, link 4, link 5, link 6 

Level 3: depends on type, size and complexity. Email us for details.

Iso-trans: link 1, link 2

* Finished amplifiers, DACs, audio gadgets, upgrades and repairs - this is not our core business and we do it out of passion. We do not have fixed models, fixed price and we customize for each individuals. The sky is limit of creativity.  

* Our product lines are always improving and increasing. If you do not see what you want, contact us!  

* Please email for volume discounts, distributor and OEM pricing.