AliExpress Amorphous SE OPTs + Jean Hiraga and the SE-DHT Amp Revival

JE Labs Choke-Capacitance Coupled SE2A3 amp

Canon P + Canon 50mm f1.8 LTM 
Foma 100 in Rodinal

Inspired by my plate choke-loaded 76 line stage preamp adventures, I was curious how a similar driver circuit configuration would sound in an SE2A3 amp. So I pulled out my Radiotron Designer's Handbook, 3rd Edition to gain a better understanding of choke-capacitance coupling (aka plate choke loading) vis-à-vis resistance coupling.

Below are highlights of relevant information I gathered.

Noguchi Transformer Co. Ltd, Closing

Noguchi Transformer Co. Ltd announced that they are closing on September 29, 2018.😞😞😞

Located at the basement of Tokyo Radio Department Store in Akihabara, I was first exposed to their existence in the early 90s through their ads in MJ Audio Technology and Stereo Sound Tube Kingdom magazines. 

MJ 11-1994 

Back in the 90s they ran 2-page ads for Tamura, Tango and their in-house manufactured transformers.

Hashimoto

I was glad to see their store when I visited Tokyo in November 2015. They still had a good stock of Hashimoto, some Tamura and a comprehensive line of their house brand transformers. 

Noguchi + Tamura 

I am speculating that just like everywhere else in the world, the Japanese market for DIY/vacuum tube/single-ended triode amps is also shrinking. This explains why these manufacturers are closing shop, 😞 not to mention the fierce competition from China.

"mid-price" Finemet OPT ad in MJ 12/2015

  

The Noguchi Finemet models represented their finest quality output transformers.

Even if I stretched my budget a bit, it was a good call that I added a pair of PMF-10WS and PMF-15WS + a single Finemet FM3WS-H and a pair of Finemet FM6WS to my collection. 🙂

Sayonara!

!!UPDATE!!

As posted by "dan" in the comments section below, the entire line of Noguchi is now represented by General Transformer in the same location at Tokyo Radio Department Store in Akihabra. 

JE Labs Simple 46

I've been hoarding type 46 power tubes gathered from radio shows I attended with my buddy Chong in the late 90s. Building an SE 46 amp was in my to do list when I packed up for Manila in '08. But things got in the way. Finally, after a round trip across the Pacific, the amp has come into fruition.

Given its designation, one would think that it is just a 45 with dual grids. However, aside from the UX-5 tube socket requirement, the 46 is not quite a 45. It only puts out 1250 mWatts, 750 mWs less than the 45's 2000 mWs. Maximum plate dissipation with grid 2 tied to the plate is 5.5W compared to 10W for the 45. Although it will perform very well loaded with a 5k primary Z output transformer, the textbook recommended load is closer to 7k, due to its higher plate resistance of 2380 ohms vs. 1700 ohms for the 45.

46 tube base
diagram

chassis is punched out and ready for painting

It's been over 20 years since the Simple 45/2A3 was uploaded to the now defunct DIY section of the old Angela Instruments website. So I wanted to reprise that old-school topology with a twist. I considered retaining the octal base and using a grid capped 6F5 or a UX6 based + grid capped type 75, as a tribute to Asano-san. 🙏

However, since I am in loctal mode, I settled on the 7B4 hi-mu triode which is more in unison with the simple theme. The 7B4 is readily available NOS and can be had for less than $5 each from tube dealers. Tube rollers take note, even if loctal tubes are boxed/labelled RCA, Tung Sol, Raytheon, etc. most of them came from the Sylvannia factory in Emporium PA. 😞 

under the hood

!!!WARNING!!!

The voltages found in this circuit can be lethal! Build at your own risk!!!

JEL Simple 46 schematic

Adjust the dropping resistor* (use at least a 10W) so that the operating point for the 46 tube is as close as possible to the tube manual specified 250V max. plate voltage x 22 ma. current draw = 5.5W.  Ideally, the 46 should see 285 volts at the plate - 35V in the cathode = 250V. As shown in the schematic, I am still running my output tubes about 8% over because I was anxious to listen and got lazy to lower the B+ further. 😎

The big surprise was, subjectively, the triode-wired 46 sounds more powerful and authoritative especially in the lower register than the 45. It sounds like the union of virtues between the dark and mythical 10/VT25  + the refreshing airiness of a 45. I've been listening to this amp for over three months and haven't had the itch to switch on my other amps. 😄

CODA

Left to Right - Globe 46, ST 46, ST 45 and 2A3

Globe tubes look really cool and usually sound more lush than their ST counterparts. I personally prefer a Globe 45 over the later ST glass bottled samples. However in the case of the 46, the difference is not as apparent and close to negligible to my ears, So save your $$s and do something less nerdy, like going out on a date. 😉

Addendum

I received this email recently from a seasoned DIYer/audio enthusiast known in various audio forums as Salectric.

"I just saw your blog post about your Simple 46 amp and I read the question someone posed in the Comment section about a suitable power transformer. I actually had Edcor build a custom PT for my 46 amps and the voltages worked out perfectly so I recommend it to anyone wanting to build a 46. I don't know if the particular unit is listed on their website but it should be available through the part number which is the Edcor XPWR 258-120.

The B+ windings have two secondary voltages. It is 345-235-0-235-345 @ 300ma. The purpose of the two voltage taps is to let the transformer function for either choke input or cap input. The lower voltage windings with a 5U4GB and cap input filter give a roughly 290v B+, and so do the higher voltage windings with a 5R4GY and choke input. With a little loss in the OPT and a 32v bias, the 46 has almost exactly 250v across it. There is also a 5V@3A and 6.3VCT.

I ordered it this way because I wanted to compare choke input and cap input with as close to exactly the same conditions as possible. (I tried a 5U4GB with the choke input as well as cap input just to be as consistent as possible.) The best sounding setup was the choke input with 5R4GY so that's how mine is set up. The Edcor is super-quiet. No mechanical buzzing at all."

Noguchi Finemet: FM-3WS-H + FM-6WS output transformers

This was the last extensive testing and listening session I did in the attic before we moved back to the states. I misplaced some data and just recovered them recently. So as promised in a previous blog entry, here's the write-up on the two entry-level SE Finemet OPTs from Noguchi.

WARNING

These are bonsai-sized output transformers. If HUGE iron + HIGH inductance and thumping bass frequencies is your idea of high-fidelity you should STOP 🛑 here!😉

However, if the finesse and realism a WE/Altec 755A can provide within its 70-13 kHz bandwidth is your idea of a GREAT time, please proceed!😊  

Noguchi FM-3WS-H

Noguchi FM-3WS-H + Tamura F7004

David vs. Goliath - indeed, the FM-3WS-H is tiny. I had to mount it on a perf board so that it wouldn't fall from the square mounting hole left by the Tamura F7004 ;)

JPY 13,910 or US $124

Noguchi FM-3WS-H
100Hz (top left), 1kHz (top right)
 and 10kHz (bottom right)

Technical and listening tests were done with the output transformer mounted in the SE10/VT25 amp, which resides in the attic mono system.

Noguchi FM-6WS

Noguchi FM-6WS + Tango U808

The FM-6WS is not that much bigger either.

JPY 16,000 or US $142

Noguchi FM-6WS
100Hz (top left), 1kHz (top right)
and 10kHz (bottom right)

Technical and listening tests were done with the output transformer mounted in the Radiotron SE2A3 stereo amp in place of a pair of Tango U808 OPTs.

Color Chart in Kanji
for wiring
transformer leads

Subjective evaluation of both OPTs

I have to admit that given the Lilliputian dimensions of these OPTs, I was predisposed to expect poor bass performance in spite of the claims from their respective spec sheets. The 100Hz square waves verified the manufacturers' claims and the quality of bass I hear more than compensates for the lack of ultimate extension which, in my experience, can only be had from OPTs the size of a Tango XE60/NY15s or Tamura F2000/F7000 series. In fact, when I invited my seasoned DIY Audio buddies for a listening session, none of them noticed significant bass deficiency.

Back in the 90s, there were two types of exotic transformer core material vying for the best - Permalloy and Amorphous. I learned then that the virtue of exotic core material shone through the mid-range, rather than at the frequency extremes. I never quite made the leap to Amorphous because I was already satisfied with the life-like mid-range abilities of Permalloy. I heard the Amorphous Tamura F5002 in a familiar circuit and system context, and thought that in spite of its edge in resolving detail, it sounded clinical compared to Permalloy. Finemet is supposed to have evolved from Amorphous. However, the mid-range performance from these two entry-level Noguchi Finemet OPTs have the warmth and lucidity of Permalloy without the antiseptic quality of Amorphous.

With such fine midrange performance I didn't expect any high frequency aberrations and the two 10kHz square wave oscillograms above confirm the smooth falling response beyond 20kHz (no ringing or phase shift), as shown in their respective spec sheets.

If I didn't already have Tamura and Tango Permalloy OPTs the bigger Finemet offerings from Noguchi are very tempting! 

!!UPDATE!!

The entire line of Noguchi is now represented by General Transformer in the same location at Tokyo Radio Department Store in Akihabra and they accept international orders.

Budget SE OPTs - Edcor and Noguchi

All output transformers were tested in the je2a3 amp using the same procedure as I did in the Hammond 125ESE many moons ago. Listening sessions were done through the same amp driving a single Altec 2-way speaker system. 

Edcor GXSE15-16-3.5K
Weight = 2.75 lbs

Primary Z = 3.5K

Secondary = fixed @ 16 ohm

Frequency Response = 40Hz - 18kHz, <1dBu 

Maximum DC current = 190 ma.

Core Material = M6, 29 ga. grain oriented steel

I ordered this Edcor OPT to get a feel on what's available to a cash-strapped US-based DIYer. It took over 3 weeks to be delivered to my doorstep at a total cost of $58.67. The nice square waves indicate quality manufacturing. Bass performance was at par with the Noguchis. But from the midrange to higher frequencies it was not quite as open and transparent. Maybe the Japanese manufacturers use higher quality laminations than the M6 steel used in this Edcor? Since the Hammond 125ESE now sells for about $60 before shipping, the GXSE15-16-3.5K would have been much better value for the money if it were offered with at least two secondary taps.  

Colors in Kanji

Noguchi PMF10WS
Weight = 3.2 lbs

Price = JPY 9,070
Approx. US$80

These two pairs of Noguchi transformers were Akihabara souvenirs from our 2015 Tokyo trip. In spite of the significant difference in price, the PMF10WS and PMF15WS are physically the same in size and weight. Based on specs, the PMF15WS has greater bandwidth and more flexibility for use with various output tubes.

Both OPTs tested well on the bench. Even if the 10khz square wave test does confirm better top end response from the PMF15WS, I could not detect its sonic superiority over the other.  Sonically, the PMF10WS is just as good if you don't need the extensive multi-tap flexibility from its more expensive sibling. In terms of tonal balance, I prefer the warmer presentation of either of the Noguchis over the leaner and more analytical Tango U808.

Noguchi PMF15WS
Weight = 3.2 lbs

Price = JPY12,560
Approx. US$112

I'm not sure if Noguchi accepts international orders. But if you're visiting Tokyo, their basement shop (closed Mondays) at Tokyo Radio Department Store is a must see!

!!UPDATE!!

The entire line of Noguchi is now represented by General Transformer in the same location at Tokyo Radio Department Store in Akihabra and they accept international orders.

Noguchi Finemet

Just a preview ;)