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Old 22nd October 2011, 08:49 AM   #241
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Mains intake filter from old SMPS unit.

I have some softstarters i designed for magnetron duty the will do the trick i think.

Click the image to open in full size.

M Gregg i agree with you that itīs a scary amount of energy stored in the caps.

Perhaps a relay and some large disharge resistors activated at power off.

On my wishlist to fit inside amp is 3 toroids, 22 caps, heater rectifier/reg for small signal, 2 fans with reg.

A remote controlled input selector/volume control perhaps.

Getting crowded !!!!
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Old 22nd October 2011, 09:38 AM   #242
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by flatheadmurre View Post
Mains intake filter from old SMPS unit.

I have some softstarters i designed for magnetron duty the will do the trick i think.

Click the image to open in full size.

M Gregg i agree with you that itīs a scary amount of energy stored in the caps.

Perhaps a relay and some large disharge resistors activated at power off.

On my wishlist to fit inside amp is 3 toroids, 22 caps, heater rectifier/reg for small signal, 2 fans with reg.

A remote controlled input selector/volume control perhaps.

Getting crowded !!!!
Sounds good,

The reason I mentioned the PSU is because I am used to working with MV/HV, however I am used to a few hunderd of uF in valve circuits and had over looked the energy in the caps. I thought you might too..LOL.

Have you thought of using TARDIS theory?
(Dr Who, little on the outside)..

Keep reaching for the volume (turn it up!)...can't LOL ! Where is me tubes..awwwww..LOL Feed the donkey give it some Caffeine..

Regards
M. Gregg
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Old 22nd October 2011, 09:57 AM   #243
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M Gregg never choose 20 mule express for delivery .

I have a good one about delivery.

I ordered 10 Omron relays USPS from Questcomp.

USPS is handled by Swedish postal service with their own custom people.

The $2/hour clerk read that it was milspec. and asked for my permission to import military equipment.

After 2 month of arguing with the Swedish foreign department the relays had to go back to Questcomp .

Lesson learned everything is from now "sample" fits in the easy dictionary.
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Old 22nd October 2011, 06:45 PM   #244
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M Gregg.....

If you are THAT desparate to hear what its gonna be like, and you have them, You could make up some adaptors and use a couple of ECC82 or any of its variants--12AU7 / 5814 / 5963 etc...

At least then electrically the voltages/gains etc will be pretty darned close, (If not the same...) to what it should be with the 6SN7....
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Old 22nd October 2011, 09:58 PM   #245
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by Alastair E View Post
M Gregg.....

If you are THAT desparate to hear what its gonna be like, and you have them, You could make up some adaptors and use a couple of ECC82 or any of its variants--12AU7 / 5814 / 5963 etc...

At least then electrically the voltages/gains etc will be pretty darned close, (If not the same...) to what it should be with the 6SN7....
LOL,

They have been on order for 2 weeks so I guess they won't be long.
Just having a laugh.....I just want to know if I need to adjust the bias level... Then again that would be impatient wouldn't it..octal relay bases ....b9a base...wires....solder. Rather pin the tail on the donkey!
Restless twitch!...fidget

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M. Gregg
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Old 23rd October 2011, 09:49 AM   #246
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by Alastair E View Post
Running 150V +- rails on O/P stages I'm using 220 ohm and get approx 180mA....

Seems a fair assumption that yours should be reasonably close to the same--even though your tubes are brand-new, and mine have several hundred (Maybe even over a thousand!) hours on them....
Alastair,

Is the 180mA with one heater or both?
So you are sinking about 20W in the valves. (40V...180ma... 220 Ohm)

With 300 ohm I'm sinking about 15W. (36V...120mA...300 Ohm)
I could change to 220 Ohm I guess..Its that cold soldering iron..

I have a box full of 12AU7....you have me thinking..

DC power rails;

Across both +/-……………………………..…334.3V DC

Minus rail…………………………………….-165V DC

Plus rail………………………………………+168.8V DC

I was looking at the thread re: 6C41C

Just for fun a comparison re heaters:

6C41C........6.3V...2.8A=17.6W

Full 6c33c.....12.6....3.3A=41.6W/2=20.79W=half 6c33c.

Only 3W difference?

Regards
M. Gregg
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Old 23rd October 2011, 06:07 PM   #247
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Thats with both heaters running, = 220 ohm cathode-resistors, 180mA at 150V plus/minus, 300V across the rails.

My rails are within half a volt of 150V--both the plus and the minus, Wonder why yours are a couple of volts apart...?

The 6C41C does work quite happily in this circuit, and has an O/P around the same as one half of 6C33C
--For some reason though--the 6C41C sounds utterly horrible for a couple of hours, then comes alive--NO idea why there is such a huge change after burn in though....

You're gonna do it aint ya!--Youre gonna bung some 12AU7 in adaptors in there till you get your SN7 aint ya!
--Go on,--You might as well.....Boring Sunday night, nothing else to do!
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Old 24th October 2011, 12:18 PM   #248
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by Alastair E View Post
Thats with both heaters running, = 220 ohm cathode-resistors, 180mA at 150V plus/minus, 300V across the rails.

My rails are within half a volt of 150V--both the plus and the minus, Wonder why yours are a couple of volts apart...?

The 6C41C does work quite happily in this circuit, and has an O/P around the same as one half of 6C33C
--For some reason though--the 6C41C sounds utterly horrible for a couple of hours, then comes alive--NO idea why there is such a huge change after burn in though....

You're gonna do it aint ya!--Youre gonna bung some 12AU7 in adaptors in there till you get your SN7 aint ya!
--Go on,--You might as well.....Boring Sunday night, nothing else to do!
Well here is a story to tell:

I made these:
As I finished the last joint and cleaned the base up, These arrived (6H8C). I thought I can't believe it chaos theory reigns supreme. Honest I had not taken my hand off the base of adapter last one in the socket!!!!!

So I put the 6H8C's in ......a strange buzzzzz from one channel. I thought it must be one of my earths are not correct, however I put the music on WOW.....then my DC heater protection cut in...

Thoughts are that it did not cut in with the SL's so I put in the adapters and WOW.....no cut out!....The tubes are stuffed....so the adaptors are in at the moment the Mullards sound nice! So me thinks, I have had some more on order for 2 weeks should be matched.....I think A couple of Tung sol are on the cards....I still haven't changed the bias...running 300 Ohm. Yes it is running my Alpair 7's...sounds very nice. I will let it warm up and have a play let you know more....
Regards
M. Gregg
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What is the sound of one hand clapping?

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Old 24th October 2011, 03:56 PM   #249
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Still no transformers and lot of promisses from supplier

Good to see youīre almost there M Gregg.

Looking forward to your impressions when itīs up and running full throttle.
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Old 24th October 2011, 04:17 PM   #250
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Hmm--What a shame the 6H8C is causing probs...

-Nothing worse than waiting for something and finding when it arrives its broken, or not as expected!

One thing I have noticed with the 6H8C, the heater-current is quoted as 600+-50mA but always appears to be higher--although Ive never measured it. Sounds like you have a H-C leak or short in one of the 6H8C....

--Whats your protection scheme for the DC heaters...?

Have you 'biassed' up the heaters 30-50V Positive with respect cathodes? Ive found this helps with hum injection from heaters with various amps Ive made in the past....

Knew you would end up making some adaptors, The ECC82 is basically the B9A equiv of 6SN7 anyway, so at least you'll run right with those (Its Just a personal thing, I'm not too keen on the B9a twin-triodes, but that doesn't mean they are bad!)....

Glad its working and sounding good so far for you...
--Let us know how it sounds, You may find it better with the higher bias on the O/P stage though....
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