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A Very Compact Hybrid Amp - Page 68

post #1006 of 2203
unless my eyes decieve me, the resistors all are correct. opamp is correct. cathode resitor is ok.

this has me slightly stumped....
post #1007 of 2203
what is the voltage @ the cathode resistor without the opamp in place?
post #1008 of 2203
cathdode, pin 3 = 2.73v, anode at 86v, no opamp. at opamp socket, V+ = 24v, V- = 0v. -

opamp back in and 101v on the anode, pin 1.
post #1009 of 2203
My CTH has now been stable for over 24 hours with every tube I have thrown at it. I am happy to have finally worked through my self-inflicted kinks. Thanks to everyone for the help.
post #1010 of 2203
Quote:
Originally Posted by tacitapproval View Post
My CTH has now been stable for over 24 hours with every tube I have thrown at it.
Great to hear!
post #1011 of 2203
Zkool, I'll post some panel pictures over on the announcement thread tomorrow. I accidentally put 24VDC on the first batch instead of 24VAC. Duh - corrected in the next batch. But you'll get the idea.
post #1012 of 2203
Hazards of buying 'lots' of tubes: I was restocking 12AU7's for the next round of kits, got a batch in today. Included in the box: Tung Sol JTL's, Sylvania 6189, USN CHS 5963, GE 5814WA - half go in to the personal box, time to look for more.

Even though I'm not tube-eloquent, the 6189 is fantastic sounding in this amp...
post #1013 of 2203
Hi gang.
I wired up the CTH and I'm getting full sound from one channel but only a faint sound from the other. Any clues what to check?
post #1014 of 2203
anymore ideas on my 'pass no current with opamp' problem. this should be entirely fixable....
post #1015 of 2203

Final thoughts on the CTH

Blutarsky picked up wiatrob's CTH review sample the other day from me, and will be comparing it to his EC-01, Zana Deux and Melos SHA Gold over the next couple of weeks or so. I loaned him my Mullard short plate which I liked so much in it as well. He has about 8 or so tubes from Bill, and a sheet telling him what voltage to set the amp at, so it should be safe.

We briefly compared the CTH to the EF1 and Amphora again, with the tube hybrids being very similar to each other as before. Then I unplugged the EF1 to move the power supply and forgot to plug it back in and power it up, so didn't have time to warm it up again. The CTH with Mullard short plate is a rich and full sounding hybrid with good power for low and high impedance phones. It was just a little less detailed, spacious and extended than the more costly ALO Amphora, which also retains a sense of tubey richness despite being a SS amp. I never did find a tube combo for the CTH that could exceed the Amphora, and it was fairly well matched by the EF1 with a Mullard tube as well (although it passed up the EF1 when EF1 had the stock RCA clear top).

We also listened to the AV123 headphone Bluto acquired from Mark Schifter which sounded nice but I think I prefer the CTH a little bit more with the Grado HP-1000. There was nothing bad about the AV123 but I simply didn't have enough time with it to get a good impression for what it can do. That will come later, and I did come away with the impression that the Av123 headphone amp sounds good to me. It seemed like the CTH had better synergy with the HP-1000's (Equinox cable) and the AV123 was really good with the SARN re-cabled ATH-A900, although the CTH did a good job with the A900 too and visa versa.

Again, I enjoyed my final visit with the CTH before it went to the next tester, only wishing for a power switch and a set of RCA input on the rear, if I was to be purchasing one. I think the CTH sounds much bigger than it's price or size, and due to the ease of finding tubes for the CTH it might be a better choice for some people than the Millett Starving Student, which I also really like a lot. And the price is more affordable than the similarly performing EF1 too, if you are capable of building it yourself (not me). I would not be surprised if Blutarsky found it to be good competition vs my old TTVJ portable Millett hybrid as well (which is a very amp too).
post #1016 of 2203
Must be why someone got dibs on my two short mullards I was selling.
post #1017 of 2203
Quote:
Originally Posted by olblueyez View Post
Must be why someone got dibs on my two short mullards I was selling.
And my Siemens arrived today but I only have the EF1 to try it in now...
post #1018 of 2203
Quote:
Originally Posted by HeadphoneAddict View Post
And my Siemens arrived today but I only have the EF1 to try it in now...
and my Siemens ECC82 is on the way too..

Its interesting to note that you found the Amphora better than the CTh. From what I remember..the CTH was a whole lot better than the Amphora..goes to show that it pays to listen to gear with your own ears, gear and music...
post #1019 of 2203
Quote:
Originally Posted by sachu View Post
and my Siemens ECC82 is on the way too..

Its interesting to note that you found the Amphora better than the CTh. From what I remember..the CTH was a whole lot better than the Amphora..goes to show that it pays to listen to gear with your own ears, gear and music...
Yeah, but there was not "a whole lot better" of anything when comparing these amps, they are all good. I do have a few hundred hours on the Amphora to burn-in the Vcaps which take a long time to settle down.

For completeness sake, I will add that this time around we used my Mac Mini > Airport Express > PS Audio Digital Link III > amps. Whereas the last time I reported my impressions of the CTH on the 16th I used my iMod with Vcaps as source to compare Amphora/CTH/EF1/Mustang. My first comparison included using RS-1, HD600, D2000, IE8 and K240M. This time we used re-cabled HP-1000 plus a pair of re-cabled and internally dampened ATH-A900.

Here are my first impressions report: http://www.head-fi.org/forums/f6/ver...ml#post5614415
post #1020 of 2203
Woohooo, after some troubleshooting with sachu, it's alive and well
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