STC 4212 Amplifier

STC 4212 Amplifier - transformers kit!

We've been supplying quite a number of WE 212 (STC 4212) output transformers to DIY folks. This tube is really getting us curious as we have not got a chance to try it ourselves. We tested our 212 output transformers with 845 in parallel to mimic the 212 tube electrical parameters all this while and that alone, is already quite scary (845 paralleled).

212 SE is already quite massive and powerful, and now comes the extreme - 212 PSE (that is FOUR 212's in a single amp!!!!)! We have even got a 212 PPP (Parallel Push Pull, this is EIGHT 212's, how crazy (oops) is that???) quote in progress! In audio world, the sky is the limit!

The 212 replicas from PRC are getting less costly and it is getting easier to reach for most people now. We've seen more and more guys online making them and showing off to the DIY community! 

Unfortunately I'm a fan or NOS tubes, or else I would have considered making one for myself. The NOS 212, as I understood from one of my customers, is that I should forget about it due to the rarity and not being as rich as the collectors to bid for it.  

Below is a modified 212 PSE power amplifier (monoblock) for my customer. This original schematic was obtained from online / website, which I believe should be designed by Sakuma-san. This modified version is not a full blown design yet as it was just a simple conversion from 212 SE to 212 PSE, for transformer quotation use.

If I'm the one designing it, then the B+ won't be at 1KV but higher to fully utilize the power of the 212 tube, and some other J&K proprietary tweaks would be included. Since this version is not tested nor totally verified usable, use with care please. 

I did not include the minor details too since I presume users that would embark on making 212 amplifier would have enough knowledge to extrapolate from the schematic.

 

 The transformers associated with this design will be as follow:

• Input transformer - not done by J&K
• Interstage transformer for 845
• Level 3 Nanocrystalline Double C core, potted - U$1900/pair
• Level 3 EI Z11, U$1390/pair
• Level 2 Super Hi-B Double C core, U$990/pair
• Pri: 5K 80mA, Sec: 10K
• Output transformer for 212 PSE
• Level 3 Nanocrystalline Double C core, potted - U$1790/pair
• Level 2 Super Hi-B Double C core, U$1490/pair
• Level 2 EI Z11, U$1090/pair
• Primary: 5K, 300mA, Sec: 8/16
• B+ inductor
• Level 3 - not doable
• Level 2 Super Hi-B Double C core, potted - U$690/pc
• Level 1 EI Z11 - U$340/pc
• 2.5H 800mA for choke input, HV usage
• Driver stage inductor
• Level 3 Nanocrystalline Double C core, potted - U$440/pc
• Level 2 Super Hi-B Double C core, potted - U$340/pc
• Level 1 EI Z11 - U$190/pc
• 10H 150mA
• 845 filament inductor
• Level 1 EI Z11 - U$190/pc
• 0.1H 5A
• 212 filament inductor
• Level 1 EI Z11 - U$190/pc
• 0.01H 9A
• Power transformer
• Level 2 EI Z11 - U$490/pc
• Level 2 EI Z10 - U$690/pc

For those that are interested for a full blown design, please stay tuned. We might design one when we have more time on hand.

J&K Audio Design
9/13/2015


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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.

ALIS-5SE MK2 OPT Customer Feedback

A picture speaks a thousand words. What if it is a few pictures?

Below is our customer's feedback on ALIS-5SE MK2 single ended output transformer, especially made for high Rp Pentodes and Triodes.This is an amplifier built by customer himself. We supplied him the output transformers.

http://jandkaudiodesign.blogspot.com/2014/05/output-transformers-alis.html

This OPT is especially good for high Rp Pentodes due to very high primary inductance that is required to optimize the low frequency response. Do not use OPT for Triode with Pentodes! You will not realize how good it sounds unless you used the right OPT for them.

ALIS-5SE MK2 - especially built for Pentodes
ALIS-5SE Ultimate - especially built for Triodes 

 

Sweet and simple - sounds awesome!

No BS review on our output transformers.

Advertisement: If Level 1 output transformer is that good, what about Level 2, or Level 3 transformers? Thought of the day!

J&K Audio Design
9/9/2015

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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.

The Bottle Builder

I like to buy and read about anything related to tubes, even tube tabloids! I've a soft spot for it, you can say, whether I need it or not. It's interesting to read another designer's mind (be it right or wrong) and thoughts when they design their amplifiers, and that's all I've to say about this book.

A compendium of tube amplifier designs - The Bottle Builder, Volume 1.

The Bottle Builder

I have a lot of rants on this book though. Here are the things I DO NOT (an understatement, for the price I paid for this book) like about it:

1. Wastage (sand bagging?) of pages with pages after pages of BOM, and the font is so big where as the font for schematic is like ants compared to this elephant.
2. PCB drawing of multi-layer PCB - who needs that? Or who can benefit from that? We can't fabricate from the drawing.
3. Chassis drawing - another meaningless content. Front panel 3D drawing? You must be kidding me.
4. Mounting method of solid state regulator? Duh... And it occupies a full page with size as if you need that details.
5. Speaker drawings - I thought this is an amplifier builder's handbook. Hello...???
6. Incomplete BOM and tables - what's the point of publishing the BOM if you cannot complete it and be consistent. Some BOM table are just with the component label and value where as some are full table with manufacturer numbers and types. The description are even half empty for some of the tables. Come one...

A lot of blank spaces, or small pictures occupying a full page. This is a big book! It's a lot of price to pay for all the above content, don't you think so? If you ask for my opinion on whether to buy it, you know my answer.

Share your thoughts, for those who has bought this book, or even if you have not bought it. 

J&K Audio Design
9/8/2015

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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.

Transformer Repair

Transformer burnt? 

Transformer malfunctioned? 

Transformer does not work for no reasons, apparent reasons? 

Transformer has issues - fever, flu, diarrhea, and any diseases at all?

Transformer has gone missing on your newly acquired amplifier from eBay, Audiogon, online seller, or anyone? 

Purchase damaged high value, vintage transformers (such as WE transformers for example) cheaply and restore it to original conditions for resale, or personal usage, we can help with that too!

We can help!

Send us the pictures, dimensions and weight and we shall provide you a quotation to make / repair it to be as close as the original conditions. We can reverse engineer it and clone it to the original conditions. We have repaired so many transformers that if you need any vintage transformers to clone a machine, we might be able to help too. 

Let us know!

J&K Audio Design
8/29/2015

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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.

EL84 Push Pull Tube Amplifier

This is an EL84 Push Pull Tube Amplifier that we had made many months ago (sorry, we were too busy to update our blog) for one of our local customers that will use it to power his center channel as well as main speakers, depending on this mood.

EL84 Push Pull Tube Amplifier
* Triode + Pentode mode - convertible
* Stereo and mono-modes
* Active auto-biased, with external pots for balancing tubes
* Level 2 Z11 Precision Wind Output Transformer
* Full Z11 power transformer and chokes
* High end - audiophile components used all over
* Tube rectified, pseudo-choke-input power supply 
* 5U4G / 5X4G rectifier, EL84 x 4 power tubes, E288CC x 1 driver tube
* High quality ceramic tube sockets with gold plated copper pins 
* Full aluminum chassis with 5mm thick top plate 

Enough with the chatter, here goes more pictures! 

J&K Audio Design

8/16/2015

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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.

Transformer User Guide

We are on a 3 months trip to USA as some of our close friends / customers know, and therefore it is a perfectly good time to discuss with them in on "paper" on their feel of our products. Production is slower than usual but we've got no choice - thousand apologies for the longer wait (it's totally worth it!).

We have some sharing after quite extensive and exhaustive discussions with a few of our usual suspects - our frequent buyers/users. They've used from Level 1 till level 3 quite frequently for their products and also for own use, and finally we came up with these BKMs (best known methods).

We feel that it is something worth sharing - our transformers user guide, so here it goes. We start with the best of course.

*  Level 3 transformers
- The best! Best apply on truly balanced systems. They will reveal any Gremlins in your systems.The -3dB low frequency response could be as low as 5Hz! The highs are adequate and usually extends above 65kHz and above.
- Focus on over all balanced, with excellent low frequency response and weight. Due to this, if your room or speakers have issues on bass, it will be revealed and it will not sound good until you rectify these problems.
- Sometimes one may feel that it is slower and heavier but this IS the true nature of full un-distorted reproduction of the low frequencies. They were missing all the low frequencies all this while! It is best to re-tune the system after the transformer run-in.
- If you have low power amplifiers, it is best not to use these transformers as the true low frequency response will suck more power out of the tube to the transformers/speakers, causing earlier distortion than what it used to have than other transformers. Not many speakers and rooms can handle <30Hz frequencies. Poorly designed amp may distort, speakers may boom or distort, and your room may create problems as such abundance of low frequencies.
- If you have big speakers, perfect room, perfectly designed amplifier, high power tube amplifiers, or aren't afraid of problems on re-tuning your system, this is the perfect output transformer to have! You have to re-tune your system for the new found low frequencies though, this is a must to capture the full potential of your new found system. 
- For some that feels that their system low frequency response is inadequate and they want to dig more out of them, this is something to try too if they have some power to spare. 
- Character - steady, warm, weighty, extended and thick.

* Level 2 transformers
- 2nd in line top quality for wider coverage of systems. This is our best seller too where it is not so finicky on system matching. The -3db or -2dB low frequency response is usually tuned to 20Hz. The high frequency response usually can go up to as high as 100kHz or more!
- Focus general purpose use, with excellent mid to high frequency response. Bass is not overly done so that is more friendly to the overall system. Since not much music are present below 20Hz, not many speakers can produce 20Hz faithfully, and not many tube amplifiers are capable of delivering full power at 20Hz, no energy is wasted at that region and your overall system may sound more power than it is. 
- If you love mid-highs more, have small speakers, have low power amplifiers, have smaller rooms, have room problems or others, this is definitely your ideal choice. It will create lesser issues for you. 
- Character - lively, fast, taut, with good PRAT.

* Level 1 & 0 transformers
- This is the budget but good output transformers. It is good for entry to mid level systems and 1st time builders. They can test out their systems first and later upgrade to Level 2 or Level 3 after they get to know their systems more.
- The standard models are quite decent actually especially the ALIS or ALOS version where it has been proven many times to excel and do better than branded transformers a few times the price. 
- These are something that users can buy/use everyday due to friendly price for excellent results.
- Character - very balanced, typical tube sound, slightly on the warm side.

That's all for now. Hope you enjoy the read!

J&K Audio Design
8/16/2015

Product Lists  
Level 0

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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.