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Old 13th August 2012, 03:00 AM   #1251
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A rating of 200mA is enough for 2 channels.
4 EL84 (2 per channel) idling at around 35 to 40 mA each = 160mA. A bit of overhead to handle the peaks.

ASIDE: After months of intermittent listening/tweaking I finally screwed the bass plate on the 6SL7/6V6 version, this weekend just passed.
To get the last "drop" of performance out of it I added 10 Ohm + 2u2 zobels across the 4 Ohm speaker taps to correct the speaker impedance vs frequency characteristic. That makes the amps's job a little easier.

Cheers,
Ian

Last edited by gingertube; 13th August 2012 at 03:08 AM.
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Old 13th August 2012, 05:04 AM   #1252
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Default RE:post number 800

Quote:
Originally Posted by rhone View Post
I'm working out exactly what I need for the build (fixed bias version) and have a few basic questions. I've built a few valve circuits but don't have much experience with the SS stuff. I mean, all the bits are so SMALL
Anyway, the pots: 100R and 50k. Single or multi turn? Cermet?
The 12AX7 gridstoppers (1k5): I've got plenty of 1k, do they need to be that bit bigger?
The 2u2 cap. between the 50k pots: An 'audiophile' 400v polyprop type? A mylar?
Rod

Hi Ian, I am slightly confused, having been trawling through this very tnformative thread for a while now. I cannot see which components the poster of this message is refering to. (the pots: 100R and 50k. Single or multi turn? Cermet?
The 12AX7 gridstoppers (1k5), 2u2 cap. between the 50k pots).

He is making reference to a fixed bias layout, what would be the advantage of this and could you point me towards the schematic?



By the way I have just finished constructing the 2 CCS's for the ecc83's but only had green LED,s to hand. Does green make any difference, what current should it provide?

cheers. Ian.
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Old 13th August 2012, 05:38 AM   #1253
rhone is offline rhone  Australia
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Quote:
Originally Posted by sharkey22 View Post
Hi Ian, I am slightly confused, having been trawling through this very tnformative thread for a while now. I cannot see which components the poster of this message is refering to. (the pots: 100R and 50k. Single or multi turn? Cermet?
The 12AX7 gridstoppers (1k5), 2u2 cap. between the 50k pots).

He is making reference to a fixed bias layout, what would be the advantage of this and could you point me towards the schematic?



By the way I have just finished constructing the 2 CCS's for the ecc83's but only had green LED,s to hand. Does green make any difference, what current should it provide?

cheers. Ian.
Hi Ian,
That was my post you quoted and, yes, it's the fixed bias version which has some extra components. That amp is currently doing good service in my system. Circuit is at post 431 page 44 of this thread. Somewhere in the thread are some comments Gingertube made comparing the two versions. IIRC the fixed bias version sounds slightly better, but I'm sure you'd be happy with the simpler to build original version.
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Old 13th August 2012, 07:14 AM   #1254
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Guys,
Something has happened to my notifications and I'm not getting emails when someone posts to this thread anymore. I need to look through the last few pages to catch up with what you've been doing.

The 100 Ohm pot is in the cathodes of the 12AX7 diffamp. It allows balancing of the diffamp. Adjust it for equal anode voltages on the 2 12AX7 triodes. A simple single turn job will do.

The 50K are the bias set pots. I always like to use 10 or even 20 turn pots for these.

If using Green LED for the current source reference (on the bottom transistor of the cascode current source) then there will be about +1.8V at the transitor base and about 1.2V at the emitter. Try a 820 Ohms resistor from the transistor emitter to negative supply. That should give you 1.2 / 820 = 1.5 mA current source.

Cheers,
Ian also (gingertube)

Last edited by gingertube; 13th August 2012 at 07:16 AM.
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Old 13th August 2012, 10:36 AM   #1255
Siberia is offline Siberia  Lithuania
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Sorry, cat post

Last edited by Siberia; 13th August 2012 at 10:38 AM. Reason: Cat post
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Old 13th August 2012, 01:08 PM   #1256
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Quote:
Originally Posted by 6L6 View Post
I only have Macs, so I can't run PSUDII, and am slightly in the dark about how this will play out...
I can run PSUD2 just fine with wine under Linux, and I think Wine is available for OSX as well. So you should be able to do the same.
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Old 13th August 2012, 01:17 PM   #1257
6L6 is offline 6L6  United States
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Quote:
Originally Posted by mace1337
I can run PSUD2 just fine with wine
Interesting! I will look into that!
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Old 18th August 2012, 12:40 PM   #1258
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Help required for tube rectified Power Supply.
Does anyone have a suitable schematic including transformer voltages/current requirements, rectifier type, choke, resistor and cap values. I intend having a transformer constructed that will provide for both Solid State and have an option for a valve rectifier. I'm afraid my knowledge / ability isn't up to all the workings out.
Any info will be much appreciated.

Ian
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Old 20th August 2012, 09:15 PM   #1259
fmena is offline fmena  Canada
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Speaking of Power Supplies.... has anyone implemented the Salas Shunt High Voltage Regulator in their build of the Baby Huey? Would it even be beneficial to even implement the Salas SSHV2 regulator for the Baby Huey power supply?

Link is here: GB for Salas SSHV2 regulator

Thanks
Frank M
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Cheers
FM
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Old 20th August 2012, 09:20 PM   #1260
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Default Transformer ratings.

Quote:
Originally Posted by gingertube View Post
A rating of 200mA is enough for 2 channels.
4 EL84 (2 per channel) idling at around 35 to 40 mA each = 160mA. A bit of overhead to handle the peaks.

Cheers,
Ian
So using the original schematic a 375-0-375 transformer @ 160mA will give approx 340v @ 250mA.DC ?
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