| croft |
Hi,I recently purchased a counterpoint sa-7 pre amplifier.I have decided to change the volume pot but i am not shure of the correct value:bawling:
Any imfo or thoughts would be great:goodbad:
Also any other mods to this pre amp that could be done:att'n: Thankyou:)
Ian |
|
|
| EC8010 |
| quote: | Originally posted by croft
Hi,I recently purchased a counterpoint sa-7 pre amplifier. I have decided to change the volume pot but I am not sure of the correct value. |
Why do you want to change it? The value will probably be written on the body of the pot. Typical valve value is 100k log. You can measure it with a DVM, but you might need to desolder it first. |
|
|
| reinhard |
from my schematic the pot is a dual 100k audio
taper (logaritmic)
Reinhard |
|
|
| fdegrove |
Hi,
The SA-7 has indeed a dual 100K pot from ALPS.
A stepped L-attenuator would be a great improvement but I don't think there's all that much space to fit it inside.
If you want to upgrade this unit I would recommend trashing the Wondercraps and putting in some high-Q polyprops or styrenes instead.
MIT Multicap would be my preferred choice.
The resistors are mostly Resistas from Roederstein and Dale,these should be fine.
This preamp suffers from microphony though,so you will want to isolate it from floor and airborne vibes.
Cheers,;) |
|
|
| Bobken |
Hi Frank,
Was that a deliberate Freudian slip?:goodbad:
I fully concur with using MITs, and find the RTXs (like you, I believe) to be way better than their 'lesser' series, provided there is sufficient space to fit them in, and suitable values are available.:)
Regards, |
|
|
| fdegrove |
Hi,
| quote: | | Was that a deliberate Freudian slip? |
I can't type properly...:bawling:
| quote: | | I fully concur with using MITs, and find the RTXs (like you, I believe) |
Correct.
Fortunately there aren't all that many caps to upgrade and even the MIT popyprops would be a nice upgrade already.
From memory,I think the original ones were rated at 200-250 V so that would be O.K size-wise.
Some drilling on the PCB will be necessary to pass the thick leadout wires of the MITs though.
So careful before you short some traces on that soundboard...err...PCB.
Cheers,;) |
|
|
| Bobken |
Your typing is getting worse, Frank, you'll have the thread police onto you.:bigeyes:
Regards, |
|
|
| Sch3mat1c |
| quote: | Originally posted by Bobken
Your typing is getting worse, Frank, you'll have the thread police onto you.:bigeyes:
Regards, |
Wot's all dis den?
Tim (Deputy of the Apostrophe Police on alt.binaries.schematics.electronics :D ) |
|
|
| Bobken |
| quote: | Originally posted by Sch3mat1c
Wot's all dis den?
Tim (Deputy of the Apostrophe Police on alt.binaries.schematics.electronics :D ) |
Hi,
Not sure if your question is serious or not, but it relates to post #6 in the "Listening tests" thread. :goodbad:
Whether I bored a thousand readers or not, I did spend over 30 mins, late at night, trying to offer some helpful advice, whereas most of what this poster had already said was rather negative, and of no practical help to a 'novice', at all. It appears that the originator of the thread found my comments interesting, anyway.:nod:
Incidentally, I appreciated your post # 54 in "The Silly Question" thread, a point (one of many!) which I had also noticed amongst the efforts to discredit my comments, but, as with all the other incorrect remarks, it wasn't worth my time in referring to it.
I was interested in your own experiences about casting as I have done some of this (a long while ago), especially of the 'lost wax' variety. This was when I worked in the silver/jewellery trade, and I found it fascinating.
Am I right in assuming that this is an interest of yours, rather than your means of livelihood?
Regards,:) |
|
|
| croft |
Hi,Thankyou to all of the people who posted some great imfo regarding the counterpoint sa-7 pre amp that i have.
The value pot ratings are very usefull, Also the the cappacitor issue.;)
I had the idea of replacing the volume control after reading many hi-fi magazines articles and also noticing the differnce one made when i had an Audio research pre amp.I have seen some very cool Alps pots from Japan at £300+:cannotbe: These look awsome and apparently sound fantastick.
I believe that counterpoint volume pots were pretty basic in the early desighns.
One are that i have yet to try is running a pre amp on batteries instead of the mains outlet.:rolleyes: I have seen maplin electronics sell small heavy duty motorcycle batteries that can be recharged,I believe that Unison research did a valve pre amp that had small watch batteries that heated the valve elements.:cool:
I think that this technology is not exploited enough:rolleyes:
Thanks also for the issue of michrophony in this pre amp,I have got some valve rings which i will place on the valves,Manybe there are many other options to cater for this sort of thing:idea:
Thankyou fellow audiophiles:mafioso:
Ian. |
|
|
| fdegrove |
Hi,
| quote: | | I have seen some very cool Alps pots from Japan at £300+ These look awsome and apparently sound fantastick. |
300 quid for a couple of pots??.
For that kind of money half a dozen of top notch stepped attenuators can be made/bought.
Personally I wouldn't spend too much money on a SA-7, it was a midrange product from CP and no matter how cash you care to throw at it, nothing is going to change that.
| quote: | | One are that i have yet to try is running a pre amp on batteries instead of the mains outlet. |
Be aware that batteries don't last all that long and that they constantly will discharge while you have the unit on.
The heaters consume the lion share and sonically benefit the least.
Cheers,;) |
|
|
| croft |
Hi Frank,
Thanks for the superb reply,
Will deffinatly bear this in mind for the sa-7.
I had bought it from Ebay and was intending on moddding it for my uncle who is new to high end audio and lives in the usa.
Batterys do look good on paper but i hadnt realised there shortcomings Frank,I had seen a pre amp from Nagra that has some built in.
One Counterpoint pre amp i have seen is the sa-11,ssooooo many valves:devilr:
The Alps pots are expensive,Have also seen Danish stepped ct-1 but never had one before.:rolleyes:
I suppose that the cap replacement etc will bring the most differences,:dodgy:
THX Frank;)
Ian. |
|
|
| fdegrove |
Hi,
| quote: | | One Counterpoint pre amp i have seen is the sa-11,ssooooo many valves |
And also utterly unaffordable...:bawling:
If my info is correct only a few hundred were ever sold, philosophically it is much along the same lines as the Croft Mega Micro which was sold for a fraction of the price.
Cheers,;) |
|
|
| Bobken |
Be aware that batteries don't last all that long and that they constantly will discharge while you have the unit on.
The heaters consume the lion share and sonically benefit the least.
Cheers,;) [/B][/QUOTE]
Hi Ian,
It is good to see some appreciative comments from someone, and I bet Frank is pleased with those, as it makes the effort worthwhile. There are far too many folk around who spend their time trying to argue or discredit what others have said, and most of them probably don't know much about the subject, anyway!
You can rely on what he has to say about valves, as he clearly knows his stuff here.
I had one of your pre-amps for repair once, and it wasn't bad-sounding, but like Frank said, it is doubtful if spending £300 in that way would be very cost-effective.
On the subject of batteries, I am not a valve man, and the only *audio* valve amp I ever made, I subsequently gave away, and I don't now recall the current requirements.
However, on my (remaining!) DIY valve guitar amp (only 2 watts output, so probably not too far different in current draw from a pre-amp) it draws 1.3 amps continuously for the heaters.
Going back to what you said about using watch batteries which normally range from about 30 mAh, to 100 mAh, at that rate I reckon a watch battery would last from between just over one minute to about five minutes, so you would need an awful lot of them!:goodbad:
I live quite close to you, incidentally, in Shakespeare country.:cool:
Regards, |
|
|
| croft |
Hi to everybody at Audio.com.
I have read all of the replys to my query and am very greatfull for all of the advice.;)
Please accept my appologies for not replying lately as i have managed to catch a horrible British cold and have beebn flued up for over a week.I dont normally get the flu but the weather here in England has been miserable lately.:(
Thankyou to the previous reply,Its great to hear from you in Shakespear land("BUEATIFULL COUNTRYSIDE") and many thanks for your comments.:nod: I have printed all of the imfo and will deffinatly post a thread later on today.
Have to just go and take some more medicane.......THX:mafioso: |
|
|
| analog_sa |
Hi Ian
I have somewhere an old SA7 but can't really give any values as i'm currently in Bali. Do yourself a favour and disconnect the balance pot. Firther improvements can be had if you replace the 12AY7 with something with lower Rp and get rid of the follower. 6N1P? I fully agree with Frank that putting too much effort into it is not really worthwhile.
cheers
peter |
|
|
| fdegrove |
Hi Peter,
| quote: | | Firther improvements can be had if you replace the 12AY7 |
To the best of my knowledge the SA-7 never had any of those in it,did you mean 6DJ8 perhaps?
Also keep in mind the 6N1-P requires more heater current than the 6DJ8.
I would recommend the Sovtek 6922 AKA 6N23-EB if the valves require replacement.
Cheers,;)
P.S. Enjoy your trip.:cool: |
|
|
| Bobken |
Hi Ian,
Sorry to hear of your current misfortune and hope you are soon better.:bawling:
It never ceases to amaze me that one can feel so really rotten with a simple cold, and yet although we can put a man on the moon, we don't have any effective remedies for this, nor any good preventatives.:goodbad:
You are absolutely right about how lucky I am living here out in the country. I am looking out of the window now with the sun beaming down on the open fields around us, and approx. 40 semi-tame pheasants have just been in our back garden to have their usual breakfast!:bigeyes:
It cannot get any better. :cool:
Regards, |
|
|
| croft |
Hi Bob,
Thankyou for the exellent imfo.
I think that the sa-7 does indeed use a 12axy Bob.According to the alta vista website models made in 1984 used this valve and later ones used the 6922.I was deffinately looking at some new valves Bob as the unit i bought does not have any in it and is currently sitting redundant on the hi-fi rack.
Hows the seen in Africa with hi-fi bob?Great to hear from you.;)
Thankyou,
Ian.:mafioso: |
|
|
| fdegrove |
Hi,
| quote: | | I think that the sa-7 does indeed use a 12axy |
Ian, that was my mistake actually.Not Bob's.
Cheers,;) |
|
|
| croft |
Hi Peter,
Great to hear from you,
Thanks for your thoughts;).
Wow:cool: The countryside sounds really great,I think that in this country we do have some of the most spectacular historic countryside and when the weather is ok it is brilliant:cool: I live in the west midlands and it is incredibbly industrialized with factorys galore.The neares major greenery is in a place called Kinver edge.
I always think theres something majical about the mix of hi-end hi-fi and bueatifull countryside,Especcialy in the winter when its white over outside and the valves are glowing on the pre and power amp.;) I used to have 2 leek mono block valve amps that were converted by Glen croft,Also i have a mega micro pre amp which has 2 boxes.:devily:
when the whole system was on there were over 34 valves all going at once,I didnt need to go to Blackpool to see the illuminations--i had them on the hi-fi.:bawling:
I will deffinatly look into the advice from Bob about taking out the balance control,I am not shure how to do this but i guess it cannot be that difficult.:rolleyes:
Yes,Indeed Peter the flu can be such a downer:dead: I had no sleep for 2 days and spent a fortune on medicane.It is true how they can send man to the moon but cannot eradicate the old British flu,I even used beconase hay fever treatment as this is supposed to open up the sinesis,It does actually work but only for a few hours:(
Have just bought a new croft power amplifier "series 4"and have yet to try it on my Decca kelly ribbon horn speakers.
Must dash Peter as my brain is telling me to make a cuppa,
Great to hear from you,
Stay warm,
Ian.;) |
|
|
| croft |
Hi Frank,
Thanks for the update.;)
Have just finished cleaning the sa-7 as it was covered in dust on the main pcb.
Did have an audio reserach pre amp and it was deffinately not hi-fi.
Have bought the counterpoint for my uncle in Vancouver who is new to audio etc.
Told him to go for croft but this counterpoint sold for £150:)
Thanks Frank;)
Ian.:nod: |
|
|
| Bobken |
| quote: | Originally posted by fdegrove
Hi,
Ian, that was my mistake actually.Not Bob's.
Cheers,;) |
What a hero, Frank, but I don't mind about carrying the can.:goodbad:
My shoulders are broad, indeed they need to be on this Forum, but thanks for the consideration shown in putting the record straight!:)
Ian,
I know B'Ham well, or at least I used to some years ago.
Until the early '70s, I lived in Sutton Coldfield, and I went to Art College in Brum, and then had some jobs for some years in the Jewellery Quarter, Warstone Lane, Vittoria St., Vyse St., Frederick St., etc.
I also worked for a car firm in West Brom for a year or two, and another company in Kingstanding, as well.
The very first electronic components I ever bought were from a couple of places in Hurst St. B'hm, the whole of which was more recently knocked down and subsequently rebuilt.
Maybe about 20yrs ago I had some fantastic Saturday nights out in a place there (Hurst St. before it was re-built) called the Happy Gathering. It wasn't even licensed for drinks but it was the best Chinese Restaurant around, and was so cheap.
About 20 of us would go there and we all took our own booze with us, and the 'family' atmosphere was terrific, indeed it had to be as you were almost sitting on each other's laps, as they would never turn any business away! :goodbad:
Much to the disgust of the present Mrs. Bob, I made friends with some rather tasty girls we saw there regularly, and I have been carried down Hurst St. to the car park at the bottom more than once (and ridden in an abandoned builder's wheelbarrow!), especially near to Xmas time!!
I well recall the open fusebox on the wall of The Happy Gathering(they would be closed down as a health hazard now!) because the Chinese had simply painted the old style ceramic fuses with gold paint!!!
Frank will confirm that I am bit 'anecdotal' nowadays (what else is there left in life for an old chap, now?) :bawling: but I have done a few worthwhile things in my time, and I still have many more to try. I'll get accused of being boring again, if I keep this up, though.
Hope you are cheering up. :nod:
Regards, :) |
|
|
| fdegrove |
Hi Bob,
Maybe you haven't noticed...
Ian had all of us here mixed up in his previous posts...guess that *cuppa* was really urgent.:devilr:
(No offense Ian)
FYI,I've been to B'hm a few times too and from there to Erdington in Glen C's 911 Martini.
Cheers ,;) |
|
|
| Bobken |
Hi,
Just seen your post #21.
I'll tell you what, if only you can get to grips with these posters' names you'll be on to a winner on this Forum!;) Only joking!!!:nod: It must be the medicine!!!
Don't do anything rash with your Hi-Fi, though, as it always says "can make you drowsy, so don't operate any machinery, or whatever." on the bottle. :bigeyes:
I'm getting confused as to who I am, myself, now, after my second pre-dinner Carlsberg Special!
Cheers, |
|
|
| croft |
Hi Bob,Frank.
Many appologies for the mix up:rolleyes:
I think that all the beconase hay fever medicane i have been taking lately has started to get to me.:rolleyes:
Wow Frank,You new Glen:att'n::goodbad: |
|
|
| fdegrove |
Hi Bob,
If it is the same as the Carlsberg Elephant, I can easily understand why you're confused.:goodbad:
Cheers,:cool:
P.S.Since I've had supper already, I'm enjoying my *trappist*. |
|
|
| fdegrove |
Hi Ian,
| quote: | | Wow Frank,You new Glen |
Yes,the other one and only.:cool:
I could write a book just about the hi-fi shows we spent together already!
A brilliant designer...and quite a character too.
Tom F. from Nottingam Analogue is another brilliant chap and one of the nicest fellows I ever had the honour to meet.
Cheers,:cool: |
|
|
| croft |
Hi Bobken;)
I know west bromich very well,Also Dudley,Woverhampton,Birmingham,Sedgley,Wendsbury and Walsall.
Great post on your experiences in Brum:devilr: The good old days.
do you rememver the dome night club;)
I remember once when i was shopping in a hi-fi store called techno and the sales assistant tryed to sell me a pair of stack system speakers for £50.I wouldnt have minded but i was looking to buy a pair of bose am7 and had the cash on me,:bawling:
I also bought an old Radford ma25 monoblock from West bromich.
I paid £30 for it:confused:
Am just enjoying some tea(vegetables and steak and kidney pye):rolleyes: and watching the holiday program on the tv.
Must get my brain into gear and remember proper names on the forum.So much good imfo,amazing.:devily: |
|
|
| croft |
Hi Fred,
Amazing that you new Glen Croft.:bigeyes:
Totally amazing desighner,one of the best ever.
I never met Glen but heard about him.
Have got a series 4 power amp and also a mega micro pre amp.:goodbad:
I hear that Amar is now doing the majority of the buissness in the uk.(IRONBRIDGE).
The new vitalle pre amp is doing really weel,although i hear that Glen does not actually manufacture them himself.:cannotbe:
i hear that Glen used to build his superb desighns through the night and he didnt like hi-fi shows beacuse of all the falsness in the industry.:rolleyes: My freind also knows Glen(rod whitehouse).
He has a one of a kind power amp from Glen(over 200 watts).
Also know Don swayne,he told me when Glen built a huge pre amp in a basement and it nearly took all the mains out of the house fews box,the sound was "EXILLERATING".
I beleive that Glen used rs components in the early days.
Amazing small world:nod: |
|
|
| fdegrove |
Hi Ian,
I'm not sure if Glen still builds all of the gear himself but he sure does all the circuit designs.
| quote: | | I hear that Amar is now doing the majority of the buissness in the uk.( |
Since 1988 or thereabout already.
Amar is more of a poet but he takes a lot of the burden from Glen.
| quote: | | i hear that Glen used to build his superb desighns through the night |
Glen always worked at night...
| quote: | | Also know Don swayne,he told me when Glen built a huge pre amp in a basement and it nearly took all the mains out of the house fews box,the sound was "EXILLERATING". |
The predecessor of the Mega Micro...a real gas factory that one.
| quote: | | I beleive that Glen used rs components in the early days. |
Even the ugly boxes for the Micro range of preamp came straight out the RS catalogue.
Some parts,like the coupling caps from Roederstein were brought in by his wife, Marianne, from Germany.
She works (or worked) there, I never met here though...Glen must have known why.:mafioso:
Cheers,;) |
|
|
| croft |
Hi Frank,Simply an enthraling reply;)
I really appreciate all of the imfo,Its great to hear how the early days of hi-fi desighn came about.
I look at other companys and they seem to be very profit orientated from the outset.:(
I think that Glen must be one of the true originators of hi-end audio.
It amazes me just how many people have never bought or heard his equipment,instead buying what the current trend suggests.
The mega micro is an ideal example,i have heard many pre-amps and they are good but the micro has a nack of making things sound "REAL"and less hi-fi.
I had an audio reserach sp9 and it was a complete joke compared to the croft.I heard a vt100 power amp and it was even worse.I always thought that Glens desighns would do well in the far eat as they seem to appreciate these desighns more than other countrys.
I think that in many years to come his desighns will be fully recindled much like the early leeks and radfords.
Untill then we can but just enjoy the labours of an extra ordinary person in hi-fi.
Amazing how Glens wife used to work in audio aswell,superb.;) |
|
|
| Bobken |
Hi Fred, Ian,Peter and old uncle Tom Cobly,
In fact anyone who simply doesn't just wish to argue the toss!!:goodbad:
Frank,
Yes I had also met Glenn, but only on a couple of occasions and I knew his place in Erdington.
The present Mrs. Bob comes from near there in Wylde Green, and I used to pass thro Erdington on the way to work each day, and then on thro Gravelly Hill (where spaghetti junction is now).
Don't mention Carlsberg Elephants to me, its now a dirty word at Bob's.:bawling:
They were the only beers I really liked, and we always had a good stock in at home for many a year. Then about two years ago, supplies dried up everywhere, and after not getting any sense out of the usual suppliers, I contacted Carlsberg in the UK, and their Customer Services told me that there was no longer sufficient demand for them in the UK. Massive Bummer!!!
The last one I had was a single bottle at Xmas, which a kindly neighbour brought around for me. I had been notorious for my consumption of that golden nectar, and he had saved it for about two years, but as I had just fixed his wife's car radio, he knew it would be the best reward possible. I made the small bottle last for ages, it was so nice.
Now I suffer with the Carlsberg Special Brew, a bit stronger (9% as opposed to about 7%), but it is thicker and darker, more like barley wine, and I don't like it as much. After a few of those I can really walk on water, though, so they must be religious or something! :scratch:
Ian,
The original Crofts were real Heath Robinson looking affairs, as Fred said full of RS bits, and by sight, you wouldn't think they could sound any good at all. Just goes to show you shouldn't ever judge anything by its appearance! :goodbad:
I nearly got ostracized when I first joined the Forum, and mentioned that a Threshold I once had (super looking affair with loads of aluminium everywhere, weighed a ton!) sounded rather bland to me! I knew that Nelson was responsible, but he seems good humoured (you have got to be looking like Albert Einstein!), but I don't think I made any friends in his camp of followers.:eek:
I continually get into bouts of jousting with others here because I make the mistake of telling the truth, and that can be heretical to some!
It doesn't deter me though.
I don't recall the Dome, but my memory of those alcoholic days is not so good sometimes, but I well recall many good nights out at the Opposite Lock Club, in Gas Street I seem to recall (somewhere off at the back of Broad St. anyway)
Strangely, I've never really taken to valves, myself, but I am just about familiar with 12 AX7s and 6005s:eek:
Regards, |
|
|
| fdegrove |
Hi,
For all you Croftians here's a link where Amar dishes up the story behind our little genius:
EMINENT AUDIO
Mind you,I could add a chapter or two to that as well.
Hi Bob,
Come to think of it...it's been ages since I had an Elephant...apart from the occasional pink one, that is.;)
Hmmm...need to check if those are still on the menu in Belgium...if not, I'll just have to introduce you to are own brews then.:dead:
Hi Ian,
Please...don't call me Fred...it's a long story, but let's just say any other name would be O.K....while you're on that funny medicine that is.
You even don't remember that Penta show story I told you about a few months ago???:bigeyes:
Cheers folk,;) |
|
|
| Bobken |
Hi Frank,
I had better watch this name bit myself if you are a bit sensitive about it.:nod:
I was taken back in time when I read the reference you posted here about Glenn's beginnings. Who on earth was it who said there is no future in nostalgia!!!:goodbad: Must have been me.:nod:
I was at Himley Hall for that famous very first Croft demo, and if I remember rightly, it was Midland Hi-Fi who organised (at least partly) the show there.
I also went straight out and bought the Opus 3 record mentioned in the demo, with "Tiden Bara Gar" on it, I was so impressed with all that I heard! It is still a very good 'reference' recording, and I use it to this day.:cool:
The only other comment I would make on that story is that the name is not spelled correctly, and it does rather imply some ill-doings, which I will not comment upon here!
In fact the guy's nickname was "Norty" not "Naughty", which came from his real name, Mike Norton, who I got to know quite well about that time as he was interested in an amplifier of my own design which I was developing, possibly with some commercial interest in mind.:eek:
On the subject of Glenn's car, I loved the Martini colours on white 911's, and my best mate had one about that time too.
He bought it at about the time I also bought a new Lotus, and for several years we would go on annual holiday to various parts of France with our respective wives.
It used to really p*ss him off (but really boosted my ego!) because in France, the Porsches were quite plentiful, but hardly anyone had seen a Lotus, so everywhere we parked the locals were crawling all over my car, and ignoring his!:goodbad:
In one place where we spent ten days, I used to park on the seafront, overlooking the sands each day while we sunbathed, and one enthusiatic young local lad asked me all about the Lotus.
I showed him the works etc., and took him for a ride in it, whereafter he spent the remaining days whilst we were there, giving guided tours around it and spilling the beans to all the others who would crowd around with admiration. I couldn't hear what he was saying, but he was probably telling them all that it was his.:cool:
It was amazing and I reckon I could have sold tickets!!!
Those were the days alright, but I still have the car in the garage under wraps (it is still immaculate) but it hasn't (officially!) been out on the road since 1990.
Regards,:) |
|
|
| croft |
Hi Bob,:eek: Wow what a small world.
I also have done deakings with Midland hi fi studio in Wolverhampton.I know the 2 Micheals pretty well.
I am still trying to convince Mike to start advertising on the internet.The back of the shop is like an alladins cave of hi fi bits.
I had a demo of a perpetual technologies dac last week and it was very good.
I also know Himley hall in Dudley aswell (great day out for familys).
One thing i forgot to mention on the forum is that with the counterpoint sa-7 that i bought on the plug for the mains the earth plug has ben taken out.I was wondering if it is still ok to power up.I thought it may be a mod of some kind.:rolleyes:
Cheers:nod: Ian. |
|
|
| croft |
Sorry bob that should have been "dealings"instead of deakings.
Must be this cheap keyboard i got from poundland:rolleyes: |
|
|
| Bobken |
| quote: | Originally posted by croft
Hi Bob,:eek: Wow what a small world.
I also have done deakings with Midland hi fi studio in Wolverhampton.I know the 2 Micheals pretty well.
I am still trying to convince Mike to start advertising on the internet.The back of the shop is like an alladins cave of hi fi bits.
I had a demo of a perpetual technologies dac last week and it was very good.
I also know Himley hall in Dudley aswell (great day out for familys).
One thing i forgot to mention on the forum is that with the counterpoint sa-7 that i bought on the plug for the mains the earth plug has ben taken out.I was wondering if it is still ok to power up.I thought it may be a mod of some kind.:rolleyes:
Cheers:nod: Ian. |
Hi Ian,
Yes it sure is a small world alright!
:nod:
With regard to the earth you mentioned, I would be very wary of operating any gear (unless it was designed to be operated without any earth, of course) without an earth, especially if as you suggest here, it is the result of some modification.
You don't say exactly how this mod was done, but is it not possible to re-connect the earth in question, or if I correctly grasp what has happened here, perhaps use another lead or possibly change the mains plug?
I am always cautious here, also bearing in mind the usually very high voltages associated with valve gear, and generally, if the manufacturer has used an earth, it is good idea to retain it.
Maybe that's how I have survived for some 60 years. :goodbad:
What I would guess has happened here, is that it has been disconnected to overcome a 'hum' caused by an earth loop. This action may be fine all the while there is another piece of gear attached via cables and the other gear is already earthed, as it is likely (NOT for certain, if say 'ground lifts' are used) that the cable's shields will complete the ground circuit to the 'modified' gear.
However, it is not a practice which I agree with, since in a situation such as you have now where it has changed hands, or even if the cables in the system are temporarily disconnected, there is no earth at all, and this can be very dangerous with equipment which is intended to run with an earth.
If you have absolutuly no alternative but to try it like it is, be very wary of touching the case and operating any controls, until you are absolutely certain it is safe!!!!!!:bawling:
Take care.:)
Regards, |
|
|
| fdegrove |
Hi,
| quote: | | You don't say exactly how this mod was done, but is it not possible to re-connect the earth in question, or if I correctly grasp what has happened here, perhaps use another lead or possibly change the mains plug? |
The CP units that were exported left the US with the US powercord and were set to 220VAC at the distributor/dealer.
So,instead of changing the US plug for the corresponding local one often an adapter was fitted.
Maybe your SA-7 sports just a UK plug with the eart prong snapped of?
I never suffered from earth loops with the CP gear so for safety reasons it seems wise to replace your plug with a proper one.
Note that US colourcoding for live,neutral and earth is different.
Better to jot down the colourcoding.
Simply changing for another lead is not practical as the lead is intergrated and clamped at the case side.
Cheers,;) |
|
|
| EC8010 |
Refit that earth ASAP!
Disconnecting the earth at the plug is highly dangerous, whether the equipment is valve or transistor!
The purpose of the earth connection is that in the event of a fault connecting mains to the chassis, a sufficently high current will flow to blow the mains fuse quickly. Audio leads etc may well provide an earth path, but it will not be sufficiently low resistance to allow the current required to blow the fuse.
In the event of a hum loop, the correct connection to break is the bond from the signal ground to the chassis. Never break the mains safety bond.:forbiddn: |
|
|
|
