Reel 2 Reel - bottomless pit of faff, expense and hisssssssss


#303

Have to say,i’m torn between buy that cable or this;


#304

The Mobile Fidelity (Japanese) pressing of Ziggy is supposedly an Original master recording (Half Speed) One of the additional foo factors was virgin vinyl. I’m not sure at what point things changed in the USA but certainly in the 50’s and 60’s pressing plants in the US were not allowed / able to use pure vinyl…Long story
I have a copy of this I think somewhere - I’ll dig it out. I didn’t think it was particularly astonishing though.

Nerd factoid…The UK 1st pressing of Hunky Dory has a laminated front cover and 3T//3T matrix endings. I’ve had a few in reasonable EX or above condition, they do sound punchier than later pressings and go for a reasonable lump.
https://www.popsike.com/php/detaildatar.php?itemnr=282847405345

… must now return to pyramid for nap alignment


#305

I’ve tried the Audioquest actually - bloody excellent cable if you happen to have the £££, I’d stick my neck out so far as to say transformative: streaming-haters-would-understand-what-they’re-missing-tier.

Depreciates more slowly than a Vauxhall too :+1:


#306

You’re dead to me.


#307

yeah%20right


#308

now I has a sad :frowning_face:


#309

#310

I’ve been given a couple of books that might be of interest to some of you.

Tape Recorder Servicing Mechanics - Schroder - 1967 (originally printed in German in 1961)
Tape Recorders Performance Analysis and Service Techniques P.Spring - 1961

Both hardback, in good condition and very technical.

Any use to anyone? No charge, just donation to the running of the site to cover postage.


#311

Somewhere under this lot is an r2r picked up today. So far the experience is going good - DOA


#312

Looks like you have an entire Quad valve system too. I have a collector’s interest in the serial numbers of Quad II power amps if those are what’s in the big boxes.

VB


#313

x4 Quad II’s x2 22’s, 2x tuners and a multiplex. - The II’s are all melt down material, I will send a pic of the carnage - Perhaps they were burned at the stake?


#314

Cheers :+1: (about the pic, not about the melting down).

The background to this is that the Quad IIs contain date-coded Hunts capacitors, the code for which had been lost. By collecting the serial numbers on the amps and a cross-reference from the (known) date codes on the main smoothing blocks we were able to confirm a) that the serial numbers really were serial (surprise, surprise, despite the fact that various eBay sellers with widely-spaced pairs had insisted that they had been “one owner from new”) and b) to work out the Hunts date code (it turns out that the letters from the word WHITSUNDAY map to the digits 1-0 and the 3-letter code is WkWkYr). Where we are now is that with the serial numbers and the date information we can get an indication of manufacturing volumes over the amp’s 14 year production span. I’m also curious to see if I can estimate how many of the 80,000 amps made might still be in circulation.

VB


#315



#316

Yeah, that can happen when something goes wrong. I’ve seen even worse, where a lava-flow of bitumen has oozed out of a can seam round the other side and then solidified, glueing all the large valves into their sockets. There’s a long slow afternoon’s work.

VB


#317

I haven’t poked around in one of these. Don’t they have any form of internal fusing to prevent such a meltdown?


#318

That picture makes me want to cry - son-of-a-bitumen of a job I suspect… Wonder how many thousands went to the tip back in the days before they were worth anything…


#319

No, neither in the transformer can itself nor in the HT circuitry*. There are two classic causes of mains tranny melting.

Firstly the ropey PIO coupling caps which feed the KT66s can go leaky (sooner or later they almost all do). The KT66s’ grid voltages rise and the valves go into over-current and the weakest link in the KT66/GZ32/mains tranny chain is the mains tranny. Usually one half of the HT winding fuses o/c. Whether the bitumen melts all over the place first or not depends on how hot the local surroundings are (the amps used to be hidden at the bottom of poorly ventilated cabinets).

Secondly the valves themselves just go gassy. This usually happens during long periods of disuse. At first switch-on the grid current is OK while the valves are still cool but after 5-10 minutes it rises into the several uA range, the (too high) 680k grid leak resistors can’t hold the grid volts down and we’re into thermal runaway again. This is a sad story because with a bit of care and the right kit the KT66s can quite often be de-gassed safely and runaway prevented.

Once the tranny’s gone it has to be disembowelled (dirty smelly job, needing close temperature control if the paint on the can is to survive) and the transformer itself disassembled and rewound. Then the tranny has to be potted back in the can. By the time you’re done that’s cost a three digit sum at anything like commercial rates. It’s still cheaper than a new tranny from Huntingdon though.

VB

*EDIT Quad supplied a few hundred of these amps commercially to Rediffusion, the TV relay company, for use on 24/7 duty in their audio relay networks and those ones did have an HT fuse fitted (F250mA IIRC). The fuse is worth looking out for because it indicates that the output transformer will be a 100V line version and therefore next to useless for hi-fi.


#320

The bitumen softens around 100-120C. For heaven’s sake don’t put the transformer in your oven. The smell persists for up to 6 months. Allegedly. I bought a cheap slow cooker, fitted a Variac and a thermocouple to it and lined the innards with heavy duty tinfoil. In nice weather I’ve melted the transformers out in the garden. A trick to get the transformer hotter than the paintwork is to run a few amps of DC through the heater windings which are usually still intact. The whole process is so slow though that everything tends more-or-less to thermal equilibrium so there is always a risk of the paint being darkened by the heat.

VB


#321

So they didn’t even use something similar to Leak’s ‘falling out’ resistor as seen on the ST20?


#322

Nope. There’s an F2A mains fuse which usually protects the mains transformer in the event of catastrophic circuit failure (rectifier or smoothing block or, less often, choke going short). But the KT66s are stronger than the HT winding and they will kill it before it kills them, particularly if the wire has fatigued where it turns pretty tightly round the bobbin corners. The practice of using a common cathode resistor doesn’t help as it offers less protection in the event of one KT66 going gassy.

VB