Tuesday, December 27, 2016
We occasionally take in some damaged HIFI equipment to repair, as a good will to get the gears alive again, or helping friends and customers, as a favor. This, however, has led us to discover some unhealthy trend that the after sales and service of certain manufacturers and distributors are as good as none.
Some HIFI equipment requires special parts and PCB to be replaced in order to get them alive again, such as the controller board for smart power management system for a battery backed power supply regulator, label masked off parts, special custom made integrated circuits (IC), and such. These parts are not available outside, except the creator/manufacturer themselves.
To our dismay, multiple mails and phone calls are often, not successful to get their responses to entertain our requests, or even our customers' queries! What kind of customer service is that?
The most recent one, is to ask for just a replacement power transformer (willing to pay!) since the specifications is not made known to us, and the owner wanted the original part. Nadah... distributor is wiling to entertain for a few mails but at the end, nothing. Manufacturer just kept quiet since day one. Bravo service, really! Oh ya, your design sucks too, cramping all the parts in a small chassis, including a big hot power transformers, with very minimal venting. No wonder it failed, and failed twice - the unit has got the original power transformer replaced once, with a badly done job. I guess the repair guy could not get replacement part and just substituted with anything he can find on hand.
It is not that we are asking for free parts and free service! Our friends and customers are paying a hefty price tag for the HIFI equipment they purchased! It is their right to get replacement parts at least, if sending in for repair is not an option. Nadah... not even a reply of email sometimes, or sometimes a wait of eternity is presented to us, on the requests.
Gosh... even a little entity like us, provides better service than them! Shame on you!
Now you guys have 1 more thing to consider before buying any HIFI equipment - ask around first on the after sales service, the durability of the equipment, and how helpful is the seller/distributor!
Just venting out... thank you for listening, and share your good or bad experiences with us, in the comments section!
J&K Audio Design
Friday, December 23, 2016
One of the benefits of offering transformer repairing service is, you get to analyze all the various exotic, excellent sounding, conservatively built, extraordinary designs in the past! Then, those knowledge and know-how can be applied to our products, combining the old school engineering with modern technology = best of both worlds.
Below is the WE 618B Input Transformer that our Thailand customers ordered, to compare with another WE 618B clone from Japan.
|Permalloy EI Core|
|Cloth Wire are used|
We can make ANY transformers! We can contract manufacture too (ODM), building the transformers you need for your on the shelf products.
Contact us for more details!
J&K Audio Design
Friday, December 16, 2016
Nanocrystalline 6C33C Double C Core Single Ended Output Transformer – for 6C33C tube, custom made for Melquiades 6C33C SE amplifier.
We have made this pair last year but didn't have the time to post it at our blog. Since there's a recent request to make 6C33 OPT, we took the opportunity to publish the specifications here. The user was concerned that there might not be sufficient bass if he chose Nanocrystalline (aka Finemet) core for better mid-high resolution.
Worry not, friend. People often have that misconception as many of the amorphous core they used in their amplifiers are not optimized. Amorphous core output transformers require different design method compared to ordinary orient Hi-B / Z11 cores. Using the same formula for both will just end up with emphasized / tilting towards the mid-high frequency response, giving the amorphous core a bad / false reputation - of being detailed but lack of low frequency extension and mid-bass impact.
For those that have used our NanoC output transformers, they would have find that our OPT are balanced in low-mid-high (no BS, just look at the measurement below), and yet rich with harmonics and flavor instead of being overly colorless and flat. That's how a properly design amorphous based OPT should sound. Switching to Permalloy / nickel core adds more silkiness in the highs, and produces a golden tone to the mid-range.
Optimize your 6C33C SE amplifier now by getting a pair of J&K 6C33C OPT home! Let your creation shine like a star!
- Power: 40W(20Hz）
- Actual in circuit frequency response (360mA)
- 20Hz（-0.36dB）—1KHz（0db）—20KHz（-0.19dB）（12 Ohm tap, 1W）
- Note: measurement conditions, 6C33C, plate voltage 150V, plate current 360mA, fixed bias, secondary load with resistor, at 1W.
- Full bandwidth:
- 7Hz – 70kHz +/- 3dB @ 360mA
- 5Hz – 100kHz +/-3dB @ 280mA
- Primary impedance: 650 Ohm (can be 1K-1.2K too)
- Secondary impedance: 0-6-12 Ohm (or 4/8, 8/16)
- Core: Nanocrystalline Cut Core (aka Finemet)
- Primary DCR: 18.1(18.3) Ohm (B-P, measured at 29degC)
- Secondary DCR: 0-6 Ohm (0.28 Ohm), 0-12 Ohm (0.4 Ohm)
- Primary inductance: 3.26(3.4)H @ DC bias of 360mA, 20Hz, 5Vrms
- Primary inductance can be increased if the air-gap, primary inductance, core size are varied, tailored according to applications.
- Primary current (absolute max): 600mA (recommended <= 360mA)
- Efficiency: 0-6 Ohm (>92%), 0-12 Ohm (>93%)
- Matching results:
- DCR <2% (actual <0.2 Ohm)
- Primary inductance <5% (actual <0.14H)
|Measured at 360mA|
|Measured at 280mA primary current|
|Measured at 280mA primary current|
J&K Audio Design
Thursday, December 15, 2016
For those that are unaware of what it is, you can refer to the links below:
As you can see from the measured data, bandwidth is RULER FLAT from 20Hz - 20kHz, and low frequency -3dB point is at 10Hz, more than most speakers can reproduce. Channel matching is spot on. Most importantly, it sounds absolutely terrific! Do not hear it from us, try it yourself.
We'd like to THANK Lasse for sharing the pictures and providing a review for us!
I like the TVC's. They are made with tight tolarenaces regarding channel balance and frequency response from each step.
I used Sommercable Carbocab 225 (6N copper in compressed carbonized plastic layer and polypropylen insulation) to wire all the taps, which I find very good cable especially compared to it's price. I use Oyaide Tunami cabling otherwise almost everywhere.
Please find a picture of the installed units attached. I did not take other pictures than that, I'm sorry and now I have put on the stainless steel covers which block the view of the transformers. The freq response of each step has now "normalized" and is identical in each step. Funny how that changed slightly in the burn in process also.
Thank you for the (snipped - our little secret)!
Do note the measurement is made by Room EQ Wizard software. It is limited to 48kHz sampling frequency only and therefore the accuracy for such sampling rate is <= half of the sampling frequency before Nyquist effect kicks in. So, everything after 24kHz is not faithfully measured. The TVC bandwidth is definitely much much more than 20kHz.
Suppose the highest frequency component, in Hertz, for a given analog signal is fmax. According to the Nyquist Theorem, the sampling rate must be at least 2fmax, or twice the highest analog frequency component. If the sampling rate is less than 2fmax, some of the highest frequency components in the analog input signal will not be correctly represented in the digitized output.
|TVC measurement - left channel|
|TVC measurement - right channel|
|Screen capture of email sent to us|
|Coincident Statement Line Stage|
Update on 12/21/2016 (thanks to Lasse that provided the supplementary information).
* The measurements are from the whole modified Coincident Statement Line Stage preamp. The preamp has been modified with J&K TVC and Noguchi FM-10K-600CT output transformer. Very simple & great sound, zero feedback.
* Also the sound-card's input/output is not DC connected and the loop back measurement has attenuation at the bass (-3dB @ 7,5Hz).
J&K Audio Design
Sunday, December 11, 2016
In a blink, we're almost at the end of 2016! We would like to take this opportunity to thank our customers, friends and family for their support on our journey along the way. We would like to apologize if we have offended anyone or have a long lead time for our products.
Highlights for 2016
- MADE NEW FRIENDS! Especially a few folks from Bangkok, Thailand; Silicon Valley, USA; Hong Kong, Singapore, Malaysia, Taiwan, and from Russia with love! We enjoyed your company, and also your sharing of your projects, knowledge and ideas! Long live friendship!
- EXPANSION - we've gone a bit to aggressive due to the rise in orders and made the wrong step to hire technician and that regrettably screwed up on a few power transformers projects due to new hires mistakes and miscommunications.
- We were deeply very sorry about those cases. Please let us know how to make up to you.
- After much consideration, we have reverted back to our business model, limited experienced engineers and practice: good stuff have to wait! We apologize in advance for the long lead time - that's how good stuff are made.
- PROGRESSION and MATURITY in winding technology - for those that notice, our product specifications and outlook have changed over time. We've been improving (and increasing the varieties) our products in the background and keep on exceeding our own expectations. Things just keep getting better, such as OPT winding methodology, isolation transformer improvement, materials/equipment upgrade, and such!
- We've built quite some massive OPTs again this year, such as 212 SE OPT, 212 PP OPT, 212 PPP OPT, GM70 OPT, GM100 OPT and such that had gone into several very, very high end amplifiers.
- MATERIALS TECHNOLOGY - previously we were mostly limited to various SiFE, amorphous and Nanocrystalline (aka Finemet) cores. Now, we have added some Permalloy (nickel + iron) cores to our product line, with some 1 time-of special cores that come and go, such as Cobalt or Western Electric cores, for connoisseurs with special unique tastes.
Thank you again!
J&K Audio Design
We used to get alerts from Blogspot whenever there are new comments posted at our blog. It's funny that some time ago, Blogspot stopped doing so and we could not keep track of what have been posted in our blog, if there are questions or not pertaining to the topic of interest.
If you've any questions, comments or help needed on our posts, please drop us an email and we will attend to it at the shortest time possible. For those that have posted comments at our blog, if you do not see any response, we apologize and urge you to resend those comments to us at our "contact us" form.
Apologies for mistakenly being "arrogant".
J&K Audio Design
Friday, December 9, 2016
Western Electric 618B Input Transformer
One day, we've been chatting casually with one of our customers about Western Electric sound, and transformers. They're interested in the WE 618B, that is sky high in price for an original pair - U$6,500 - U$7,000/pair (wow... that's crazy!).
We dug our repair logs years ago and found that we have actually repaired them before, and we have recorded down all the winding details, plus the core physical dimensions too. With that, we will be able to recreate a WE 618B faithfully with modern EI Permalloy cores. If one can supply us the WE Permalloy core, that would be even better, closer to the original.
* Clone with new EI-35 Permalloy core, or you supply original WE 618B / similar WE cores
* Recreate following exactly the original WE 618B winding method (we repaired before)
* Potted in square case, bare or framed in standard end bells.
* U$890 / pair (compared to U$6,500 a pair the original)
* Lead time ~4 weeks
J&K Audio Design
Hacker alert!We have been alerted that a hacker (or more) with the name of Aleksandar Tsankov has access to our email database and has been phishing data and/or money from our customers.
Please take note that there is only one official email account for J&K Audio Design. Any other emails pretending to be J&K are fakes! If the reply does not sound right, it is not right!
We suspect that he might have either hacked our email account (unlikely), or hacked our blog "Contact Us" form. Or perhaps our customer has malware on his/her computer that the data got sent to the hacker while he fills up the Contact Us form?
We are investigating all these possibilities now. Meanwhile, just be extra careful. If you have gotten funny emails from us, please use the Contat Us form to resend it for reverification, just to be safe.
Many thanks to our customer to alert us about this very unfortunate incident.
Level 0: link 1
Level 3: depends on type, size and complexity. Email us for details.
Power-trans: link 1
* 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.