Wednesday, July 1, 2015

Rollei 35 repair


I found this on the internet reasonably priced to be worth a gamble. It had a couple of dents but no serious signs of abuse. I've been hankering for this camera as a college kid in the early 80s. Instead, I chose a Pentax K1000 SLR which I could upgrade with a zoom lens ;)

This particular sample was made in Singapore in the early 70s. Not the more collectible '66-'70 or post '81 manufactured in Germany.

When it arrived, the 40mm f3.5 Tessar lens was clean and clear but shutter speeds below 1/30 functioned like B and the lens retraction mechanism was erratic. So I consulted my friend, Google.


This excellent time lapse video shows the top cover disassembly in detail.


1. Green arrow - dried up lubricant in the slow escapement gear train causes all slow speeds to function like B. A few drops of lighter fluid in this area will loosen dried lubricant. Cycle the slow speeds. You should start hearing gears whirring. Keep cycling the slow speeds until the fluid is dry and then add a tiny drop (or two) of gun oil.

2. Yellow arrow - the circular brass plunger actuates the lens retraction latch. Make sure this is properly inserted to the latch upon reassembly. Note: The lens will retract ONLY IF the shutter is cocked.

3. I did not bother to check the light-meter since it requires an obsolete PX625 mercury battery. Anyway I have an iPhone app and Sunny 16.

When this was introduced in Photokina '66, it was the smallest full frame camera in the world. Due to its diminutive size the controls defy common logic. So it's best to consult the manual before use.

Rollei 35 + Prazisa RF
Test shots

Kodak TX400
Kodak TX400
Kodak TX400

More pics

Thursday, June 25, 2015

6F8G


I recently discovered a few of these cool-looking ST glass equivalent of a 6SN7 in my tube stash. This tube plugs into an octal socket but has different pin outs (vis a vis 6SN7) and requires a 1/4" grid cap for the second triode section. So I rewired the line stage section of my JEL mono preamp to use it.

JE Labs Mono Preamp
6SL7 + 6F8G

Not sure if it sounds better,
but it certainly looks a lot better ;)

Tuesday, June 16, 2015

Altec 605B Duplex


After years of storage the Altec 605B is recommissioned in the mono system. The plywood open baffle is painted in gray primer as an homage to Altec utility cabinets. I am using the stock Altec XO N1600C circuit but built using paper in oil caps and a low DCR choke. 

video

Short iPhone clip 
"Benny Rides Again" Chess Records, mono LP

Thursday, May 14, 2015

Asano, MJ and Stereo Sound Tube Kingdom


The Bookshelf
In the past, I've posted pictures of books and magazines which shaped my audio DIY journey like Sound Practices, Radiotron 3rd edition and RCA tube manuals. The following publications were also significant influences, despite my not being able to understand Japanese. The schematics and high quality pictures speak for themselves.

Asano -- Volume 1 and 2
Isamu Asano (1914-1981) was a banker who built amplifiers as a hobby. His projects were compiled in these two volumes.


A 3 stage RC coupled 27>27>45 SE amp.



A single-ended Western Electric 205D triode driven by two stages of type 56 triode.

Mr. Asano also contributed articles to MJ.

MJ - Audio Technology

MJ articles cover vacuum tubes all the way to the latest in digital technology.


Some issues may feature a listening room or two...



or even a recording session


technical graphs


Stereo Sound Tube Kingdom
A quarterly vacuum tube(centric) publication + special issues devoted to classic equipment and components.


Issue No. 3, 1996


This was the source of inspiration for my Open Baffle project.


The Altec 618  2 cubic foot sealed cabinet for the 755A


A Japanese DIYer's take on a Western Electric SE104 amp


Western Electric 753C speaker system: Jensen 15" woofer and WE32 horn + WE713A compression driver

A couple of featured listening rooms


Speaker system: Jensen EP807 bass reflex cabinets loaded by WE TA4194A woofers, KS6373 horns with WE555 drivers with tungar PS for the field coils
Amp: WE91B
Preamp: WE129
Turntable: EMT 927st


Speaker system: 2x755A in flat baffles with auxilliary Jensen cone tweeters driven by Altec 127 amps fed by 2 x Altec 1567A preamps. Sources: Thorens TD521s turntable and Accuphase DP70 CD player


Field coil speaker system powered by Tungar PS: Altec VOT 825 bass bins loaded by Magnavox 15" woofers, WE555 + WE3 horns and Kanno 597 (WE clone) horn super tweeters
Ampifier: Western Electric 118A (PPP 6L6)
Preamp: Western Electric RA1214
Turntable: Rek O Kut 16" turntable with Ortofon RMG309 + Gray 108 tonearms

This level of quality does not come cheap and depending on the exchange rate, an issue can cost anywhere between US$30-$50.  But it's invigorating to sense the innate passion of Japanese culture by thumbing through the pages.