Hi Everybody!
My first day in this forum, and my first post is a call for some advice.
For many years now I am proud owner of a Quad 22 / Quad II combo, mostly in the original state, very nice for its age, with NOS GEC KT66 acquired several years ago, and the aged Mullard and Valvo (mixed) EF86 replaced by wonderful matched Telefunken valves.
Now, when I bought the amp years ago, the original mains cable, as well as the Quad 22 mains terminal were missing. I improvised, listened, ... and 'forgot' about it.
Lately I found the current state more and more unsatisfying, and acquired a Bulgin mains terminal and matching plug. Looking at the 3rd pic, you can see the reason for my call for advice: on the mains terminal, one of the nuts to fix the internal cable to the pole is missing (I got the terminal for 5 Euros, so I certainly won't complain about that).
Now I'm looking for a matching nut, and as a German I have no idea about the details of British thread types. Can anybody assist and provide some detail about the nut type to look for?
The outer diameter is 3.6 mm, so my best guess from web search would be a BA 4 type.
And one more question: the original terminal and plug are two-pole ones, so no ground contact is offered. Is it recommended to ground the Quad 22 by different means, e.g. by connecting ground wire to the preamp chassis via a ring cable lug?
All the best,
duplex
(Hmmm: I wanted to include some pics to show what I mean, but found out that it's not so easy. Maybe it's because I'm under moderation as a newbie, maybe I'll learn about uploading pics later. If I learn how to include pics, I certainly will do!)
My first day in this forum, and my first post is a call for some advice.
For many years now I am proud owner of a Quad 22 / Quad II combo, mostly in the original state, very nice for its age, with NOS GEC KT66 acquired several years ago, and the aged Mullard and Valvo (mixed) EF86 replaced by wonderful matched Telefunken valves.
Now, when I bought the amp years ago, the original mains cable, as well as the Quad 22 mains terminal were missing. I improvised, listened, ... and 'forgot' about it.
Lately I found the current state more and more unsatisfying, and acquired a Bulgin mains terminal and matching plug. Looking at the 3rd pic, you can see the reason for my call for advice: on the mains terminal, one of the nuts to fix the internal cable to the pole is missing (I got the terminal for 5 Euros, so I certainly won't complain about that).
Now I'm looking for a matching nut, and as a German I have no idea about the details of British thread types. Can anybody assist and provide some detail about the nut type to look for?
The outer diameter is 3.6 mm, so my best guess from web search would be a BA 4 type.
And one more question: the original terminal and plug are two-pole ones, so no ground contact is offered. Is it recommended to ground the Quad 22 by different means, e.g. by connecting ground wire to the preamp chassis via a ring cable lug?
All the best,
duplex
(Hmmm: I wanted to include some pics to show what I mean, but found out that it's not so easy. Maybe it's because I'm under moderation as a newbie, maybe I'll learn about uploading pics later. If I learn how to include pics, I certainly will do!)
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Welcome to diyAudio 🙂 Adding pictures and files is easy, try this...
To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it forward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that.
To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it forward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that.
Thank you for your reply, Mooly! I'll give it a try ... seems to work! Didn't get this upload dialog in my first attempt ...
1st pic shows an overview, 2nd one current situation on the back of my Quad 22, and the 3rd one the Bulgin mains terminal I acquired - the missing nut can be easily identified.
Hoping that somebody can solve my problem! (I'm sure in GB you would walk in the next hardware store to look for the matching nut. Over here in Germany it's not that easy for non-metric stuff.)
Best, duplex
Attachments
Good traditional hardware stores are pretty rare these days and thread sizes can be a nightmare, there are just so many different ones.
Are there any similar nuts/bolts in the other units (out of sight) that you could 'borrow' and just fit metric in its place.
Are there any similar nuts/bolts in the other units (out of sight) that you could 'borrow' and just fit metric in its place.
Hmmm - nice idea! Re metric: M 3.5 is pretty close, but not close enough to confidently fit a 220 V mains cable to it. But looking elsewhere in the unit and maybe replacing ... that sounds like a plan. I'm going to try that and report back.
Thanks a lot so far!
Thanks a lot so far!
The folks in the UK have gone through 2 thread transitions. 🙁 The "classic" British thread is the Whitworth. The combined effort of the U.K. and U.S. in WW2 lead to the adoption of the "unified" NC and NF threads, which are basically the U.S. style thread with a tiny nod towards Whitworth of slight rounding on top. Then came the conversion to Metric.
Depending on how old the unit is, the threads will be either Whitworth or U.S. style. If the thread in question appears to be quite rounded, it's Whitworth.
I don't know anything about sourcing Whitworth thread nuts and bolts or even if it's possible. U.S. style hardware is, of course, easy to obtain.
Depending on how old the unit is, the threads will be either Whitworth or U.S. style. If the thread in question appears to be quite rounded, it's Whitworth.
I don't know anything about sourcing Whitworth thread nuts and bolts or even if it's possible. U.S. style hardware is, of course, easy to obtain.
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Hi Eli,
thanks for your advice! My amp was built around 1961, and that mains terminal in question may be several years older or younger (those amps have been built for about 2 decades, hardly undergoing any modification). I'd rather describe the thread as sharp, not rounded. Very much similar to metric 3.5, but an M 3.5 nut is a bit slacky when applied, M 3 is definitely too small.
It is not impossible that it is a BA4 thread as was mentioned.
Screw threads in England is an interesting story as there where very many of them, just to mention a few BA that was used in electronic instruments, BSC (British Standard Cycle) for bicycles and BSF (British Standard Fine) which was used in the car industry, it is very simlar to UNF but with a different top angle of 55 instead of 60 degrees, it is a common mistake to use UNF instead of BSF on a vintage car thereby destroying threads. See here British Tools & Fasteners - BA Thread Profile they sell HW also
In this case if it s a BA4 Thread it is still possible to get screws and nuts for this in well sorted HW shops in England, I can still get them here in Sweden easily.
Screw threads in England is an interesting story as there where very many of them, just to mention a few BA that was used in electronic instruments, BSC (British Standard Cycle) for bicycles and BSF (British Standard Fine) which was used in the car industry, it is very simlar to UNF but with a different top angle of 55 instead of 60 degrees, it is a common mistake to use UNF instead of BSF on a vintage car thereby destroying threads. See here British Tools & Fasteners - BA Thread Profile they sell HW also
In this case if it s a BA4 Thread it is still possible to get screws and nuts for this in well sorted HW shops in England, I can still get them here in Sweden easily.
All threads on classic UK gear is BA sized. All are still available from RS and other hardware suppliers in packs.
You require 4BA Buy 4BA screw online from RS Components
It would be best to fit the sockets again or at least use a grommet to protect the cable entry and you!
A bit of history. BA threads or British Association was used by the bicycle manufacturers originally as Whitworth was too course. The BSF threads came about but still not as fine as BA.
A 1/2" BSF spanner has a gap that fits a 1/4" Whitworth head, which is 1/2" AF (Across Flats, not American Fitting).
BSP is another standard that is still in use for plumbing. British Standard Pipe thread.
You require 4BA Buy 4BA screw online from RS Components
It would be best to fit the sockets again or at least use a grommet to protect the cable entry and you!
A bit of history. BA threads or British Association was used by the bicycle manufacturers originally as Whitworth was too course. The BSF threads came about but still not as fine as BA.
A 1/2" BSF spanner has a gap that fits a 1/4" Whitworth head, which is 1/2" AF (Across Flats, not American Fitting).
BSP is another standard that is still in use for plumbing. British Standard Pipe thread.
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You're absolutely right: inside the case there are 2 pairs of screws and nuts connecting the back panel to the chassis with exactly fitting thread. These could easily be replaced by metric 3.5 mm, freeing a matching nut for the mains connector. I'll consider this my 'Plan B' for now, following my new 'Plan A' at first regarding tubetvr's and Jon Snell's advice to really go for British 4BA types.
@Jon: you're also right - safety first! That's why I don't want to improvise anymore with a grommet, but put the original gear in place instead. That's why I bought it.
Thank you all for your assistance so far!
Quad II monos: outer ring of fuse holder missing
And one of the matching Quad II monos also calls for action, looking at the fuse holder. One of the outer rings broke and is missing now (see 1st pic).
This damage, as well as some bent metal on both chassis, was done in summer 2000 when shipping them back and forth to Quad Service in Huntingdon. Quad original packaging didn't stand the treatment during transport. Unfortunately, the Quad guys offered no help when trying to claim the damage to the parcel service or the transport insurance.
In those days I just didn't have enough spare time for a DIY solution ... 🙁
And one of the matching Quad II monos also calls for action, looking at the fuse holder. One of the outer rings broke and is missing now (see 1st pic).
This damage, as well as some bent metal on both chassis, was done in summer 2000 when shipping them back and forth to Quad Service in Huntingdon. Quad original packaging didn't stand the treatment during transport. Unfortunately, the Quad guys offered no help when trying to claim the damage to the parcel service or the transport insurance.
In those days I just didn't have enough spare time for a DIY solution ... 🙁
Attachments
Quad 22 Finish
Let me start this post with a big fat Thank You from the River Rhine to Scotland! 405man sent me a PM, offering a broken terminal from his stock that had all the nuts needed to repair my own preamp. Since he insisted not to charge me anything, not even postage, we agreed that I would make a donation to some charity instead.
So a local project of volunteers will receive a nice donation in a few days to support their work for refugees coming to Germany those days. Thank you again, Stuart!
I installed everything now, a few 'before and after' pics are provided.
On the 3rd pic you can see, that it's a good idea to check old cablework from time to time: this is the old mains cable shown, and the damage visible on the insulation of the ground conductor was not done by my soldering iron, but by my thumbnail, without any greater effort. The whole insulation can be peeled off by hand.
I decided to provide earth contact by guiding the ground conductor outside the insulation where the mains cable enters the plug and secure everything with some shrink-on tube. Some shrink-on tube also provides solid contact between cable and plug inside the plug, serving as a cable relief (hey - is that the correct term in English?).
On pic 7, you can also see a pair of -10dB Rothwell Inline Attenuators attached between the signal cable and the preamp to adapt input levels from CD to 1960's standards.
Now that's it for the moment - a short listening test showed that the whole amp seems to be very satisfied with the new situation - much fuller and much more precise than yesterday. Or is it my own satisfaction influencing my audio perception?
CU, duplex
Let me start this post with a big fat Thank You from the River Rhine to Scotland! 405man sent me a PM, offering a broken terminal from his stock that had all the nuts needed to repair my own preamp. Since he insisted not to charge me anything, not even postage, we agreed that I would make a donation to some charity instead.
So a local project of volunteers will receive a nice donation in a few days to support their work for refugees coming to Germany those days. Thank you again, Stuart!
I installed everything now, a few 'before and after' pics are provided.
On the 3rd pic you can see, that it's a good idea to check old cablework from time to time: this is the old mains cable shown, and the damage visible on the insulation of the ground conductor was not done by my soldering iron, but by my thumbnail, without any greater effort. The whole insulation can be peeled off by hand.
I decided to provide earth contact by guiding the ground conductor outside the insulation where the mains cable enters the plug and secure everything with some shrink-on tube. Some shrink-on tube also provides solid contact between cable and plug inside the plug, serving as a cable relief (hey - is that the correct term in English?).
On pic 7, you can also see a pair of -10dB Rothwell Inline Attenuators attached between the signal cable and the preamp to adapt input levels from CD to 1960's standards.
Now that's it for the moment - a short listening test showed that the whole amp seems to be very satisfied with the new situation - much fuller and much more precise than yesterday. Or is it my own satisfaction influencing my audio perception?
CU, duplex
Attachments
That is the big question 😉 Experimenter expectation is another term for it.
Thanks for the update
Great to hear you got it all sorted.- Status
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