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post #1891 of 2213
Okay..been monitoring the voltages on the relay input and they seem quite steady at 11.8 volts. They do, both channels vary around from 11.8 to 11.85 volts but that can't be the reason why the E12 is tripping.

Now of course if i remove the opamp in the E12 altogether the relay trips and i see the correct voltages on the output of the relays and it stays that way. Once i introduce the opamp back into the circuit the E12 starts hoping about madly.

I removed the coupling caps and put them in with the outer foil towards the input and the inner foil towards the output(buffer side). No change.
Reflowed the joints on all points which i felt might be iffy, but no change. Checked to make sure the transistors are all in their places and everything seems fine.

With the opamp in the circuit the output of the opamp in the E12 varies madly by a coupleof volts naturally triggering the E12..but what is causing this variation is something i haven't been able to work out yet.

Any theories?
post #1892 of 2213
Quote:
Originally Posted by sachu View Post
Okay..been monitoring the voltages on the relay input and they seem quite steady at 11.8 volts. They do, both channels vary around from 11.8 to 11.85 volts but that can't be the reason why the E12 is tripping.
I'd meant to measure the offset the CTH's e12 is monitoring... E.g. OG/OL & OG/OR into relay (so Vs WRT OG).
The numbers you quote sound ok, but would still be nice to know actual mVs of offset the channels have prior to & after relay kick.
post #1893 of 2213
Hey, I can comment on this amp now that I'm not selling it anymore.

The CTH is AWESOME with the entire range of Senns. I found it to have great synergy with the 600s (which I was using as my work cans with the CTH for about 8 Mnths).
post #1894 of 2213
Hoping not to get flamed for asking a question without having read the thread; but here goes:

I just purchased Wiatrob's CTH and am considering a pair of Beyer T1's. Any ideas how the CTH performs with 600 ohm headphones?

Cheers!
post #1895 of 2213
Quote:
Originally Posted by Duckman View Post
Hoping not to get flamed for asking a question without having read the thread; but here goes:

I just purchased Wiatrob's CTH and am considering a pair of Beyer T1's. Any ideas how the CTH performs with 600 ohm headphones?

Cheers!
It will do just fine. The amp is a powerhouse actually, in the time I've had it, it has been able to drive the K1000 and my ID1 (albeit not as well as an EHHA does for the latter, but impressive nonetheless).

It is a very versatile amplifier. Find a matching tube to your taste and it'll keep on surprising you.
post #1896 of 2213
Quote:
Originally Posted by Duckman View Post
Hoping not to get flamed for asking a question without having read the thread; but here goes:

I just purchased Wiatrob's CTH and am considering a pair of Beyer T1's. Any ideas how the CTH performs with 600 ohm headphones?

Cheers!

Also, Duckman's 'new' CTH is not working. I suspect the trafo - any CTH owners from Down Under have a 24V transformer suggestion?
post #1897 of 2213
oooh..seems i may have found a problem with on the CTH board. For R6R and R6L i am using 30k instead of 31k. Now that should affect only the plate voltage right? but I am reading 19.34 V on the cathode (pins 3 and 8) of the tube. That should be reading 2.4V or thereabouts.
Would using 30K for R6 affect the voltage on the cathode pins of the tube?
Edit: *facepalm* turns out i made a rookie mistake and put in 30 ohms instead of 30k. replaced R6 and now i have 2.4V on pin3 but pin8 is still reading 1.1V instaed of 2.4V. Pin 2 of that opamp is reading 3.1 volts instead of 2.3/2.4V. No idea why that is..will need to make sure other resistors are as they should be.
post #1898 of 2213
Quote:
Originally Posted by wiatrob View Post
Also, Duckman's 'new' CTH is not working. I suspect the trafo - any CTH owners from Down Under have a 24V transformer suggestion?
Best would be Jaycar, they have a 24VAC 1A https://secure4.vivid-design.com.au/...T&SUBCATID=381 , you would need to purchase a connector separately though as it just has bare wires on the lead end.

Altronics used to sell the same one but now only seem to have a 24VAC 900ma plugpackAltronics - Your One Stop Audio Visual & Electronics Supplier , haven't seen this so don't know if it comes with a connector or what size.

DSE used to sell this AC Adaptor 24Vac 1.5A (M9635) | Dick Smith Online Store, but appears it to be discontinued, you may get lucky though if you try your local store(There are a few stores in Victoria that still show stock), I managed to pick up one cheap as clearance stock a few months back, came with 1/2 a dozen different interchangeable connectors.
post #1899 of 2213
WRT A/C adapters, I now always use a fuse in series until my builds are complete. Learned the "hard way" by blowing the internal fuse in the one on left (and opening these is a battle - added fuse holder to one on left):

Must have replaced the fuse in that left adapter 4 times now across my protos & builds Once proofed I use the adapter on right. Do need to pay attention to plug size OD/ID, but while on bench I use a loose jack wired to board matching fused adapter.

Pretty sure Bill's kits ship w/fuse & holder and they should be used at least up until just before case-up. Use of an ohmmeter on A/C-in to check for shorts is also wise.

BTW I've gotten all my A/C adapters off fleabay & none have cost > $15 shipped, but might not work that way for Aussies. Look for >= 750ma.
post #1900 of 2213
While on the subject of wallwarts is there anything special I should be looking for? Some are switching while others say nothing (is this just unnecessary marketing?) I'm in the UK so need a 230v model, none of those pictured are. 24v AC and >750ma with a 2.5mm pin - is there anything else I need to look out for?

I got my kit for Christmas and am about half way through the build so will hopefully need power before new year
post #1901 of 2213
Quote:
Originally Posted by wiatrob View Post
Hey, I can comment on this amp now that I'm not selling it anymore.

The CTH is AWESOME with the entire range of Senns. I found it to have great synergy with the 600s (which I was using as my work cans with the CTH for about 8 Mnths).
How would you describe the sound signature? With what kind of valve have you matched 'em?
post #1902 of 2213
Always, ALWAYS use the fuse! I've had the same issue as CFCubed, shorted wires and the occasional reversed diode. These will save your butt every time...
post #1903 of 2213
Quote:
Originally Posted by acvtre View Post
How would you describe the sound signature? With what kind of valve have you matched 'em?

Sorry, I have tin ears so you'll have to ask someone else about sound signature.

I can only say what I like: 6H30 supertube, Amperex 8416, Raytheon 6GU7 BUT:

Please check this thread for some great info:

http://www.head-fi.org/forums/f6/cav...thread-417322/
post #1904 of 2213
Update on ε22 trips and coupling capacitor lead lengths:

I just hooked up some GIANT russian teflons, they are mounted boardside with 3-4" airwired leads.

While they sound like poop, they do not cause any extraneous trips, even when I move the caps around the board trying to get them to do so...
post #1905 of 2213
Yep, I think we've pretty much eliminated the large cap/long lead bit as a factor in CTH ε22 trips.
I've have noticed that wildly differing cap type/size influences time to relay latch... IOW, the time it takes offset to settle down. E.g. I've found big honking caps w/smaller honking caps (sonicap gen I w/gen II bypass) takes almost 2X as long to relay latch than little bitty WIMAs.
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