joehpj
-
Posts
254 -
Joined
-
Last visited
-
Days Won
1
Content Type
Profiles
Forums
Events
Posts posted by joehpj
-
-
19 minutes ago, Whitigir said:
Then we have Huawaii
It must be a counterfeit Hawaii from China. Huawei.
-
1
-
-
stax just released their new portable(?) amp.
https://mobile.twitter.com/STAX1938/status/973765646667325440
-
STN9360 ran out of stock on mouser. Can I use STN9260 or PBHV3160Z instead?
-
As a Taiwanese, I don't eat choudofu. I just can't stand that smell.
Laowei, please let me know when you visit Taiwan.
-
1
-
-
I buy insulation ceramic kits, screws, nuts, or something like that from Taobao to cut the cost. I usually buy some samples first before I buy a lot.
After I bought fake 10M90S, I've never bought high voltage silicons from China. It's indeed better not to buy form China when building high voltage amps.
IMHO, it was like gambling. When you hit the jackpot, it explodes. LOL
-
Buying from Chinese needs some more knowledge to know if the parts are genuine. I've bought from Taobao of 50 10M90S. Looked fine but turned out all fake.
If you know which vender to buy from, of course you can save a lot of money.
-
1
-
-
Whoa. Is this a power amp?
-
1
-
-
Any comperison?
-
If I am going to drive high independence headphones with this, what should I do?
1) add triple darlington stage like tubehybrid/CFA did
2) add paralleled darlington stage like dynahi
-
updated the BOM. 2K trimpot changed to 4pcs. 470R changed to 1/2w. 5W zener simply because it's slightly cheaper than 1/3w
.
-
1
-
-
Studied T2 schematic and found filament of EL34 was connected to -500V. Is there any benefit to separate -500V from AC in order to reduce AC noise? I was thinking floating the filaments just like GG and BH.
-
470R was connected direct to the tube structure so it will get hot easily. You can either lift the resistor or use higher power rating ones.
I forgot why I used 5w. and the number of the trim pots. Please follow the silk screen. I will check the BOM later.
-
Oh I was asking about the input attenuator. I used 10K for Carbon, GG which was JFET input. Should I increase to 25K or 50K for tube input?
And thanks for the information!
One more thing. Was the R65-R68 on the PS schematic used to keep the filaments grounded? I wanted to adopt the T8000 way of regulated input tubes filament power supply. So I will have to remove the two 47R of 6.3v and keep the rest two tied to 0V, right?
-
What value of pot should be used? Kevin said he always use 10k but I wonder if it should be higher because of tube input?
-
What's the max voltage of these?
-
please use imgur and post the link.
-
On 2017/12/4 at 12:37 AM, JoaMat said:
No, trimmer is replaced by a resistor long time ago. The 10m90s current source is connected to ground and set to 1mA.
Today I modified the input tubes current sources with a trimmer like T8000. Also changed the servo, using single OP tied direct from output via resistor to one of the lower tube cathode. One channel had more than 200 volts unbalance with no servo and both batteries set to 740 V. With the trimmer I managed to get outputs balanced – have been within +/- a couple of volts for half an hour now (servo disabled)….. to be continued….
Was the trimmer in series of two 240R?
-
10 hours ago, mypasswordis said:
I'm Taiwanese American, my parents are Taiwanese. Anyone interested in a meetup? I'll be there very soon.
When will you come to Taiwan? A HC Taiwan meet sounds interesting.
-
1
-
-
I am at Taipei while ang is at the other side of Taiwan.
-
1
-
-
What? Is mypasswordis also taiwanness?
-
I was thinking if I should use regulated heater for the 6922. Those tubes amplify small signals and the amp itself has very high gain.
And is there any problem to use same pair of leads for heating up the 4 front tubes?
-
Yes. Chinese often call tubes as "gall bladder". It's just one word in Chinese. As an abbreviation.
-
If low cost is the goal, JimL has a nice design SRX+. Simple and decent sound with fun of tubes.
-
@kevin gilmore once mentioned JFET input. I have some J74 and K170. Any possibility to use them? Though I think I'll still stick to BJT anyway.
.
kgst
in Do It Yourself
Posted
Stylish shoe!