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A Very Compact Hybrid Amp - Page 131

post #1951 of 2213
Quote:
Originally Posted by devast View Post
There was. Bill stopped selling it 3-4 months ago. I'm too busy nowdays, so i did not have any free time to build mine, even though i had it for months.
For the build:
I switched c5p and c10p so my 1000uf 50V capacitor emitted some smoke and died peacefully
I'll get a new cap tuesday, and i hope nothing else died there
ouch!
And if I would to build an amp like this (or similar) where I can buy a kit under 100€?
post #1952 of 2213
I'm happy to announce that another CTH born today, she's alive and kicking hard. One word can describe her... FANTASTIC!

@netsky3
Bill is not selling CTH kits anymore, and i don't know about similar amp kits.
post #1953 of 2213
Quote:
Originally Posted by netsky3 View Post
ouch!
And if I would to build an amp like this (or similar) where I can buy a kit under 100€?
You might be able to do it for under 100 Euro, but I think the shipping costs will put you over, probably closer to 150.

There is no kit right now but the BOM for the amp is here:
The Compact Tube Hybrid Amplifier

along with a very thorough build and testing plan. The unfortunate part is that you have to buy a couple of parts from Digikey, the rest are available from Mouser, so you have to pay the extra shipping cost.

Send "runeight" a PM here, he is Cavalli Audio, and his website says that the boards are available from him (although I can't find a Contact address anywhere on his site)

I've built a couple of these babies and they are very nice.
post #1954 of 2213
Quote:
Originally Posted by devast View Post
I'm happy to announce that another CTH born today, she's alive and kicking hard. One word can describe her... FANTASTIC!
Nice to hear its up & running... So the little guy survived the cap incident.

Great too that you enjoy the sound. Now if you can resist buying too many tubes for rolling. I know I couldn't
post #1955 of 2213
Quote:
Originally Posted by devast View Post
I'm happy to announce that another CTH born today, she's alive and kicking hard. One word can describe her... FANTASTIC!
.
Nicely done....i know the feeling of resurrecting a CTH after a component failure during the build.

Enjoy her
post #1956 of 2213
Bugger, I want another one with all the tweak soup-ups.
post #1957 of 2213
Quote:
Originally Posted by smeggy View Post
Bugger, I want another one with all the tweak soup-ups.
hehe..weird, I feel the same way about a particular set of pants

Edit: You've turned to hoarding amps now considering you only had a 'lowly' mini3 about this time last year.
post #1958 of 2213
Quote:
Originally Posted by sachu View Post
Nicely done....i know the feeling of resurrecting a CTH after a component failure during the build.

Enjoy her
Was doing that. But i think i managed to fry Q1P and Q2P today. I connected the headphone out to my computers line in, pressed the power button, funny smell, and led is not glowing... No biggie, i will resurrect her again

edit: later on i realized what i have done. Basically, i shorted SG to OG

edit2: Do you think anything else could have died in the rail splitter circuit? I'm not sure about that, it should have taken "lighter" overload.
post #1959 of 2213

e12

I've been playing with caps in C4 and currently have a .33mF cap in place. I'm getting strange behavior:
- with 6dj8 no problems
- with 12au7 on cold start e12 keeps tripping
- with 12au7 on warm start (CTH warmed up with 6dj8 and then tube swapped) no problems

I'm guessing that this config is very close to the e12 trip threshold. I've searched and found several suggestions to change the e12 resistor values in this case but no details on which values to update.

Anyone solved this issue before?

Thanks in advance.
post #1960 of 2213
Quote:
Originally Posted by devast View Post
Was doing that. But i think i managed to fry Q1P and Q2P today. I connected the headphone out to my computers line in, pressed the power button, funny smell, and led is not glowing... No biggie, i will resurrect her again

edit: later on i realized what i have done. Basically, i shorted SG to OG

edit2: Do you think anything else could have died in the rail splitter circuit? I'm not sure about that, it should have taken "lighter" overload.
Go about it a step at the time.
Am guessing the buffer transistors are probably toast. you could try the simple multimeter test on the BJTs for a start but i'd recommend removing the 7824 regulator IC, turn it on and see if Q1P and/or Q2P burn out. If they do, then you have something else wrong in your power supply.
If they are are fine, then check to see if you have about 34-35V on pin1 pad of the 7824 regulator.

, turn the amp off, If that is fine then remove all the splitter transistors, leave the ground splitter IC in,
plug in the regulator IC and turn the amp on..check to see if you are seeing 12V on pin 3 of IC1S.
If that is fine, then go ahead and turn off the amp, plug in the splitter BJTs and see what happens.
If you aren't getting 12V on pin 3 of IC1S opamp then replace the splitter TO-92 part and check for voltage level at pin 3 of the opamp again.
If you are getting 12V then plug in the splitter ICs and turn on the amp.
if things are still blowing, you will again have to do the whole thing again and also replace the buffer transistors.
post #1961 of 2213
Quote:
Originally Posted by stringgz301 View Post
I've been playing with caps in C4 and currently have a .33mF cap in place. I'm getting strange behavior:<snip>
My *guess* is since you passing more signal (below audible?) using more-than-spec capacitance (> 0.22uF), this introduces the CTH e12 latch sensitivity. IIRC, I had similar symptoms when I tried big, honking Sonicap Gen I 1.0uF caps in the C4 positions.

Anyway, as far as de-sensitizing CTH's e12 I can only say that I *know* we posted the CTH component #s & recommended values for doing that... Either in this thread OR the Tube & tweak one.
post #1962 of 2213
Quote:
Originally Posted by sachu View Post
Go about it a step at the time.
Am guessing the buffer transistors are probably toast. you could try the simple multimeter test on the BJTs for a start but i'd recommend removing the 7824 regulator IC, turn it on and see if Q1P and/or Q2P burn out. If they do, then you have something else wrong in your power supply.
Q1P and Q2p are 100% toast. I turned it on and measured no voltage at the 24v regs input leg. I'm trying to figure out if anything else has died as well or not, unfortunately i don't have my spare transistors with me I don't think i can do the multimeter test on transistors that are soldered in the circuit already, or i'm getting some weird reading on them (some i tried to measure randomly).


Edit: Replaced Q1P and Q2P, and it's working again. Thanks for the support tho
post #1963 of 2213
Quote:
Originally Posted by devast View Post
Edit: Replaced Q1P and Q2P, and it's working again. Thanks for the support tho
It's not perfect yet. Somehow, my E12 trips at specific points of a track, over a specific volume level. I have found only one track that trips, this never happened before on that track. I've got my VG at +12V(11,94V according to my budget multimeter), and E12 behaves like it did before for example at startup. Maybe i've damaged ICE? I have no clue. High power (white noise and pink noise) tracks play without a trip at high volume.

edit: I replaced basically the whole rail splitter. E12 still tripping Tried replacing ICE too, still the same. I think something died there maybe... any clues? Also, it's tripping when there's no phone plugged in (lol).
post #1964 of 2213
Quick bump. It's still tripping. Can anyone do the following: do not plug headphones into the cth, set the volume pot to max, and start playing something. It immediately trips for me, and i wonder if it does the same to others. I replaced some stuff in e12 yesterday, and came to a conclusion that e12 is fine Now i'm suspecting the output buffer... Already tried an opa2134 at IC1 position, no change.
post #1965 of 2213
Yes, we should have suggested to see if your CTH's e12 is "doing its job" when its tripping. One way to do this is by measuring DC offset (in mV) from OG to each "input" pin of the relay. Looking at PCB the relay "line input" pins are 2nd ones over from OR/OL side of relay.

When I'd a problem I'd solder wires to those relay pins & use 2 meters to watch offset during the trips... To confirm e12 or OB. IIRC, when there was trouble it was more often in OB parts. I took the fastest sure route to repair - replaced all OB transistors + OPA. But some were successful at targeting & replacing specific parts.
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