Aleph J illustrated build guide

Eric · 2019-01-25 12:35 pm

I've been thinking for a while that we should collectively build a "first power on" protocol checklist and post it somewhere obvious. We seems to have had a large influx of new people showing up (which is GREAT) that could benefit from an easy and concise list without having to comb through thousands of pages of posts to gain the basics.

henryve · 2019-01-25 1:31 pm

Eric said:
I've been thinking for a while that we should collectively build a "first power on" protocol checklist and post it somewhere obvious. We seems to have had a large influx of new people showing up (which is GREAT) that could benefit from an easy and concise list without having to comb through thousands of pages of posts to gain the basics.

henryve Likes this.

Mark Johnson · 2019-01-25 2:07 pm

Make a list of volunteers. People who volunteer to read the first 1/3rd of this thread (~1100 posts) and excerpt the ones which are the most relevant. People who volunteer to read the second 1/3rd of this thread and excerpt the most relevant. People who volunteer to read last 1/3rd of this thread and excerpt the most relevant. People who volunteer to collate and edit the excerpts. People who volunteer to review and critique and finalize the checklist. And, perhaps most importantly of all, people who volunteer to maintain and update it through the next ~1100 posts or so.

Eric · 2019-01-25 4:26 pm

Ha - wise guy

. This is why I built my web page for my first real amp (my Aleph-X) - it was my distillation of thousands of pages of useful (and not so useful) commentary. Distilling the meat from the fluff takes a ton of time and the result grew larger than I thought it would and probably has a few errors in it.

My thought was for something perhaps more "universal" from amp to amp and over time that won't require constant updating. I'll post something over the next few days if there is some interest.

Mazeppa · 2019-01-25 4:31 pm

Used the dim bulb on initial PS test with 120VAC in.
Setup then for 240VAC in (configuration it will be used in), DC voltages all still correct.
Have extra fuses on hand.

I know where there's a Variac I can borrow, but unsure if it's rated for 240VAC. I think I'll wait and see if it's usable for a test, even though it will put me out a week or more.

Got a pair of cheap-o, home made speakers for initial music try.

Thanks for the tips, guys. Getting stoked about firing this baby up.

kstagger · 2019-01-25 4:45 pm

You don't need speakers plugged in to check/adjust the DC offset. Make sure you do that before hooking up any speakers.

Ditto for setting the bias.

aljordan · 2019-01-25 7:15 pm

Mark Johnson said:
Make a list of volunteers. People who volunteer to read the first 1/3rd of this thread (~1100 posts) and excerpt the ones which are the most relevant. People who volunteer to read the second 1/3rd of this thread and excerpt the most relevant. People who volunteer to read last 1/3rd of this thread and excerpt the most relevant. People who volunteer to collate and edit the excerpts. People who volunteer to review and critique and finalize the checklist. And, perhaps most importantly of all, people who volunteer to maintain and update it through the next ~1100 posts or so.

I know you are being flippant, however, a couple months back I skimmed through the entire thread in preparation to build the Aleph J, and made notes of the posts I thought might be useful:

Aleph J illustrated build guide
Post 384 and 390 - 6L6 on initial pot values

Aleph J illustrated build guide
Post 602 - note that when using single ended inputs, -in must be shorted to ground at the board. This is why 6L6 pictures seem to have a little wire connecting -in and GND. Better explanation on page 63.

Aleph J illustrated build guide
Post 680 - about which output mosfets to match.

Aleph J illustrated build guide
post 777 - interesting note about skipping input capacitor if you are using a capacitor coupled preamp.

Aleph J illustrated build guide
post 844 through 846 - regarding which way to mount the ZTX devices from the kit on the circuit board.

Aleph J illustrated build guide
Post 863 - How to wire up RCA jacks.

Aleph J illustrated build guide
Post 889 - about max bias temps.

Aleph J illustrated build guide
post 1013 - regarding where to attach purple wire from transformer.
post 1015 - how to test the trimpot resistance once on the PCB.

Aleph J illustrated build guide
Post 1042 - Tie little jfets together for thermal coupling.
Post 1043 - a good warning.

Aleph J illustrated build guide
Post 1165 - on wiring XLR jacks.
Post 1168 - further explanation.

Aleph J illustrated build guide
post 1191 - about how to wire if you have hum.

Aleph J illustrated build guide
Post 1295 - regarding eliminating hum.

Aleph J illustrated build guide
Post 1382 - about good caps to use in the amp.

Aleph J illustrated build guide
Post 1445 - schematic for testing fets.

Aleph J illustrated build guide
Post 1849 - on resistor values that important to match for balanced use.

Aleph J illustrated build guide
Post 1877 - on important cap position

Aleph J illustrated build guide
post 1970 - nice layout for 4U chassis.

Aleph J illustrated build guide
- picture of line thermistor wiring

Aleph J illustrated build guide
- more on cap choices.

Aleph J illustrated build guide
- rubber pad under transformer.

Mazeppa · 2019-01-25 7:26 pm

aljordan,

I finally started making written notes when I realized how hard it was to keep track of the more salient posts on construction.

Were you able to save them digitally as a post caught your eye, somehow?

aljordan · 2019-01-25 8:24 pm

Mazeppa said:
aljordan,

I finally started making written notes when I realized how hard it was to keep track of the more salient posts on construction.

Were you able to save them digitally as a post caught your eye, somehow?

No, I just copied the URLs to a separate text document. They did come in handy when I built the amp.

mkane77g · 2019-01-27 12:43 am

thanks aljordan for your post #3387

jdg123 · 2019-01-27 11:26 am

Aljordan, excellent idea! Thank you. Is there a way moderator, to put a “greatest hits” post like #3387 at or near the front of the initial post? That would make the payoff high value 😁

henryve · 2019-01-27 12:21 pm

It is a pity that don't have Wikis anymore for some of the more popular projects. A living document that summarise all the important information.

6L6 · 2019-01-27 2:28 pm

jdg123 said:
Aljordan, excellent idea! Thank you. Is there a way moderator, to put a “greatest hits” post like #3387 at or near the front of the initial post? That would make the payoff high value &#55357;&#56833;

Yes, that's a great list!!

Aljordan - your post #3387 is now living at post #3. I had an unused placeholder and put it there...

Thank you for compiling that info, it's fantastic information!

aljordan · 2019-01-27 4:16 pm

6L6 said:
Yes, that's a great list!!

Aljordan - your post #3387 is now living at post #3. I had an unused placeholder and put it there...

Thank you for compiling that info, it's fantastic information!

Thank you. I'm glad I could provide something others find useful.

Russellc · 2019-01-27 5:33 pm

aljordan said:
I know you are being flippant, however, a couple months back I skimmed through the entire thread in preparation to build the Aleph J, and made notes of the posts I thought might be useful:

Aleph J illustrated build guide
Post 384 and 390 - 6L6 on initial pot values

Aleph J illustrated build guide
Post 602 - note that when using single ended inputs, -in must be shorted to ground at the board. This is why 6L6 pictures seem to have a little wire connecting -in and GND. Better explanation on page 63.

Aleph J illustrated build guide
Post 680 - about which output mosfets to match.

Aleph J illustrated build guide
post 777 - interesting note about skipping input capacitor if you are using a capacitor coupled preamp.

Aleph J illustrated build guide
post 844 through 846 - regarding which way to mount the ZTX devices from the kit on the circuit board.

Aleph J illustrated build guide
Post 863 - How to wire up RCA jacks.

Aleph J illustrated build guide
Post 889 - about max bias temps.

Aleph J illustrated build guide
post 1013 - regarding where to attach purple wire from transformer.
post 1015 - how to test the trimpot resistance once on the PCB.

Aleph J illustrated build guide
Post 1042 - Tie little jfets together for thermal coupling.
Post 1043 - a good warning.

Aleph J illustrated build guide
Post 1165 - on wiring XLR jacks.
Post 1168 - further explanation.

Aleph J illustrated build guide
post 1191 - about how to wire if you have hum.

Aleph J illustrated build guide
Post 1295 - regarding eliminating hum.

Aleph J illustrated build guide
Post 1382 - about good caps to use in the amp.

Aleph J illustrated build guide
Post 1445 - schematic for testing fets.

Aleph J illustrated build guide
Post 1849 - on resistor values that important to match for balanced use.

Aleph J illustrated build guide
Post 1877 - on important cap position

Aleph J illustrated build guide
post 1970 - nice layout for 4U chassis.

Aleph J illustrated build guide
- picture of line thermistor wiring

Aleph J illustrated build guide
- more on cap choices.

Aleph J illustrated build guide
- rubber pad under transformer.

Same thing I do, just not as extreme. I can skim tremendous amounts of reading, just make a note about corrections, solved common problems, etc by post number. Easy to skip the banter parts.

Everyone should read all of 6L6's build guides. just be able to see complete project in mind before starting, make no assumptions and ask questions.

Works for me, (usually)

Thanks for posting your info for all,

Russellc

FengLiu · 2019-02-10 4:56 am

Why is the midpoint potential adjusting R7? Not R8? why?

Danger Mouse · 2019-02-10 10:02 am

FengLiu said:
Why is the midpoint potential adjusting R7? Not R8? why?

Because change R8, change the current trough the diff pair.
But this should be fixed. With JFET Idss >8mA (I=8.3mA=8,3V:1000Ohm)

So only way to adjust offset is R7

That`s the way i understand this.

With lower Idss say 6,4mA. Logically you have to lower the bias trough the diff pair.
This should be right :scratch1:

FengLiu · 2019-02-10 11:50 am

Danger Mouse said:
Because change R8, change the current trough the diff pair.
But this should be fixed. With JFET Idss >8mA (I=8.3mA=8,3V:1000Ohm)

So only way to adjust offset is R7

That`s the way i understand this.

With lower Idss say 6,4mA. Logically you have to lower the bias trough the diff pair.
This should be right

What is the effect of changing the total differential current on the circuit? If you change R8

FengLiu · 2019-02-10 11:52 am

Why is the total current fixed?I hope to get a reply from Nelson Pass! !Rigorous reply。。。。。。。。The Chinese people are waiting for your answer! ! ! !

Danger Mouse · 2019-02-10 6:44 pm

FengLiu said:
What is the effect of changing the total differential current on the circuit? If you change R8

Why is the total current fixed?I hope to get a reply from Nelson Pass! !Rigorous reply。。。。。。。。The Chinese people are waiting for your answer! ! ! !

No one for a Rigorous reply

Then me again :checked:

I would suggest you try to look in the www for a Explanation

Search for:

How do a Differential pair works
JFET bias
CCS for LongTailed Pair / differential amp

Some Basics that can give you a answer
Nothing Nelson Pass has invented.
So no reason to stop him from doing important work :wiz:

Aleph J illustrated build guide

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