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Cavalli Compact Tube Hybrid (CTH) Tube & Tweak thread. - Page 23

post #331 of 688
R18
post #332 of 688
thanks

Just bridged one of them, yup, that'll do necely
post #333 of 688
might want to put sockets on them, in case you use different phones.
post #334 of 688
My phones range from inefficient to extremely inefficient, but yes, sockets will be useful
post #335 of 688
The design of the CTH (those pricey CRDs) should isolate you from trips caused by power supply voltage fluctuations...
post #336 of 688
Thread Starter 
Quote:
Originally Posted by smeggy View Post
Just bridged one of them, yup, that'll do necely
Yes, with what I've heard you've driven/are driving with this little power-house, you don't need no stinkin' output resistors
As suggested, you could SIP-socket the R18s if you had SIPs. If not, if you find pot range too limited down the road w/some cans you'll know where to poke around.

BTW, be careful anytime you perform surgery on these. It's quite tight & shorts can cause bad things to happen.

From the CTH site:
post #337 of 688
heh, yeah I noticed that. 18L is easy to get to , 18R on the other hand is a bit of a squeeze like the e12 pair in there.

Sachu now has a set of the same original wharfedale isodynamics as me, even he had no idea how inefficient they really were. People think we exaggerate with these, nope, they really are that bad.

Tried the wharfeys, decent levels when bridged at 3 o'clock, 5 is max so I may actually be able to use them
post #338 of 688
Surgery over and the patient is now in stable condition, recuperating with some soothing music

Thanks guys.

I'm almost afraid to say this, but it seems to sound better without the output resistors as well as go a lot louder. Next I'll be believing in cables and cryo
post #339 of 688
nobody has any ideas of a 3 channel operation? (using TLE2426 output as GND reference for servo and input ground and the output of the ground buffer for output ground)

It gives the CTH a pseudo differential drive.
post #340 of 688
TzeYang - answer form me is, 'I don't know...' Alex could comment, I know he's been busy again lately.

My gut feeling is probably not, or it would already have been designed to do so, but that''s not the technical response.
post #341 of 688
Smeggy, any update on your e12 behavior?
post #342 of 688
Quote:
Originally Posted by wiatrob View Post
Smeggy, any update on your e12 behavior?
Not really, it's baffling the crap out of me as sometimes it'll literally run all day with zero problems, other days it'll be tripping all day. I really don't know and can't nail down any particular situation that makes it unhappy except it's more vulnerable at work.
post #343 of 688
Quote:
Originally Posted by TzeYang View Post
nobody has any ideas of a 3 channel operation? (using TLE2426 output as GND reference for servo and input ground and the output of the ground buffer for output ground)

It gives the CTH a pseudo differential drive.
I don't think it'll work very well. The input stage needs to change, IMO. The operating point of the tube in particular if you move ground up, you lose 12V and you can't maintain the circuit as is. Floating the input ground, moves the input DC to 12V above real ground. To do it easily, you would put a cap on the input, but there are other ways to handle that without a cap and would need more B+.

I'm not sure I understand the difference between your proposal and the current implementation. The current implementation has input ground to transformer ground (may be earth depending on transformer). Output ground driving the headphones is the buffered VG. The tube references real ground and since there needs to be an interstage cap anyway, the output buffer for L and R is shifted by VG allowing split rail operation of the diamond buffer and the servo shifting the output DC at the expense of output current (I think, not entirely sure right now).

The only difference is really where the input ties to. In effect, it is already 3-channel as the headphone ground is actively driven and buffered from input ground, not passively tied together. The topology is not the same as the PPA, but it is an active ground.
post #344 of 688
Quote:
Originally Posted by smeggy View Post
Not really, it's baffling the crap out of me as sometimes it'll literally run all day with zero problems, other days it'll be tripping all day. I really don't know and can't nail down any particular situation that makes it unhappy except it's more vulnerable at work.

Odd. It shouldn't be tripping so much, anywhere. I have the ****tiest power at work, and don't get trips. Does this behavior happen with the same tube in the amp in both locations?

If you're game, you might meter your power at work ( I made a plug to test lead adapter and plugged it in to see if there was a correlation between power fluctuations and e12 trips. It's a bit of work, but it seems that yours is the only one experiencing nuisance trips.

PLease, anyone else experiencing these, please speak up!
post #345 of 688
Quote:
Originally Posted by smeggy View Post
Not really, it's baffling the crap out of me as sometimes it'll literally run all day with zero problems, other days it'll be tripping all day. I really don't know and can't nail down any particular situation that makes it unhappy except it's more vulnerable at work.
Have you tried a different power supply / wall wart? I'm just a newbie, but it seems that with the discussion about dirty power, component values, etc., it would be worth trying a different power supply.
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