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the CTH (Compact Tube Hybrid) Rev A thread... - Page 25

post #361 of 536
1/25/12 at 6:41pm

 

Quote:
Originally Posted by Forte View Post

Its on their website "The shorter lead is Shield"


Right you are.  I scanned the sonicraft site super quick in the midst of lead-bending and totally missed it!

 

BK
 

 

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post #362 of 536
1/27/12 at 2:25am


 

Quote:
Originally Posted by BK_856er View Post

....

 

Drying off from the final IPA bath now.  Might get to wire it up and function test tomorrow.

 

BK

 

 



I forgot what a ton of work the final CTH drilling/wiring is.  It's 2:19AM, but the little guy is now 100% done and passes all the startup tests!  I'll give it a listen after I get some rest.  Finally a CTH all for me.....

 

BK

 

 

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post #363 of 536
1/27/12 at 8:24am
Thread Starter 

I feel like half this project is wiring and casing up. Not my favorite part to say the least. My fav part is turning that amp on for the first time and plugging phones in. ;)

 

Enjoy the CTH!

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post #364 of 536
1/27/12 at 10:56am

Listening to the first tracks now.  Works/sounds awesome!

 

Only issue is low volumne.  Hmmm, what did use for R18?  Whoops, somehow of the 3-4 various correct values I ordered, I installed the one I mistakingly ordered with a K at the end (120k instead of 120).  Glad I socketed those things for quick changes!  Will fix that and grab some pics later today.

 

Sounding soooooo good right now.

 

BK

 

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post #365 of 536
1/27/12 at 5:10pm

Mission accomplished and sounding great!  Used 100-ohm for R18 this time and the volume is now abundant (doh!).

 

From memory, I think this CTH sounds better than the one I made last year.  Maybe C4??  Thanks Mullet for swaying my final cap decision just moments prior to install.  I look forward to comparing both units next time I meet up with my bro.

 

I went with the long case and shortened it by about 3/4" so it just barely fit the alps RK27 and AMB e27 board.  Used some solid wire for the rear power/heater connections to keep things tidy.  Regular stranded hookup wire up front.  Was going to route it under the board, but I ran into difficulty soldering from the top, so I changed plans.  One flub with a hot iron on the rear plastic hammond end piece.  Crammed in a heater switch, fuse holder, power switch and pcb input jack to the rear panel.  Still need to figure out a top piece - hopefully heavy gauge perf.

 

Thanks to CF3 for organizing the latest group buy and for the ongoing support!

 

BK

2yxrczl.jpg

 

149w4l1.jpg

 

no9bw9.jpg

 

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post #366 of 536
1/27/12 at 5:16pm

 

Quote:

Amperex Bugle Boy ECC88

Amperex Bugle Boy ECC82

Amperex USA Gold Pin JAN-6922

Pro Comm Miniwatt PCC88

Raytheon 6GU7

RCA Clear Top 6CG7

RCA Holland Gold Pin 7308

RCA 5963 Black Plate D-Getter
Siemens ECC82 Chrome Plate

Siemens ECC802S

Siemens PCC88

Sylvania Gold Brand 5814A

Telefunken ECC82 Smooth Plate

That is a sweet stash of tubes. My money is on the telefunken.

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post #367 of 536
1/27/12 at 6:18pm
Quote:
Originally Posted by drtturnip View Post

That is a sweet stash of tubes. My money is on the telefunken.

Mine is on the Siemens ECC82 Chrome Plate & Amperexs, I'm a broken record skipping CD about them:)

 

BK856er  - Looks good, really neat & compact.  Yes, C4 caps can make a diff, how much depends on your ears.  Haven't tried Auricaps yet, IIRC rds liked 'em.  If you've no use for them & don't want them laying around I'd buy 'em from you (PM).   BTW I've a couple "touched" plastic Hammond endplates in my past + associated curses:)

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post #368 of 536
1/27/12 at 6:23pm

No arguments here. They are all really fiiiiine.

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post #369 of 536
1/27/12 at 6:30pm

Nice work BK.

 

Of course, that is now expected. wink_face.gif

 

Somewhat surprised to see the alps vice a TKD. Gotta be a story lurking on that one.

 

Let us know what you think of the genII once you compare notes with your brother's rig. I was leaning towards the genI for this build if not only for the bang for the buck, but, the advertised neutrality. Most interested in your subjective opinion of the two builds.

 

 

 

 

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post #370 of 536
1/27/12 at 6:41pm
Thread Starter 

That Telefunken is one of the best tubes depending on what headphones are in use. I have to agree the Siemens ECC82 Chrome is awesome too! Since that posting, I've pretty much collected every desirable or notable 12AU7/6DJ8 type tube and even some of the better ones don't "work" with certain phones. It seems the TP1s really reveal the tube more so than any other phones I own.

 

BK~ your build looks great as usual. I'll take pics this time. I'm not going the e27 route, I'll be doing something very similar in terms of longer case, RK27, etc. I think I'm going to try Sonicap Gen 2 .15uF 600v for the C4 position because the lack of availability of .22uF Gen 2s. I'm not so much a fan of the Auricap with this amp. I think I'd rather use Wima MKP instead or the lower rated Sonicaps. I am curious about the Gen 1s too though. I would think they would be best to let the tube shine without coloring anything.

 

I'm not going to lie, I've tapped the plastic ends with an iron on a few CTHs as well. It goes with the territory. It's like a rite of passage.

 

For the top, I'll be using some silver colored perf metal I found on an old broken space heater. I stripped the parts and used a tin cutter to make a few pieces. The only thing I don't like about it is that it's thinner than the previous perf metal I used, but it will work fine when in the case.

 

I'm starting the build on Sunday, so let the games begin!

 

 


Edited by Mullet - 1/27/12 at 6:47pm
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post #371 of 536
1/29/12 at 2:01am

Try the amp ohm PIO copper foil caps. My favorite coupling caps.

 

The 6CG7 clear top will always be a favorite of mine in this big punching little amp. Wish I had kept one of the CTHs i built..


Edited by sachu - 1/29/12 at 2:03am
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post #372 of 536
1/29/12 at 2:17am

A new batch of boards would be nice....

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post #373 of 536
1/29/12 at 5:49am

>  A new batch of boards would be nice....

 

That may be in the works by a different member, stay tuned.

 

So I've posted about the eliminate-power-off-click mod a few times & have been asked about it. 

The CTH e12 implementation does a good job of protecting your cans against harmful DC offset at anytime, not just during pwr up & pwr off.  But there is the annoyance of an audible click during pwr off.

A pretty easy brute-force way to completely eliminate the pwr-off click is to use a DPDT power switch for your CTH, using one set of poles for 24AC in latch & the other set to make/break the pwr to the relay.

 

Using words I'd said "Re: relay interrupt:  IIRC, I just used a dremel w/small bit or X-acto knife & cut away one of the under side traces to the relay coil... Probably the Q3E/D3E junction to coil negative trace.". 

Here's a pic of this for the Rev A PCB:

 

CTH_relay_trace.jpg

 

On CTHs w/o the mod I simply remove the cans from my head prior to power down (always leaving cans plugged in, pwr off click is harmless).  No need for that w/this mod.


Edited by cfcubed - 1/29/12 at 5:53am
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post #374 of 536
1/31/12 at 6:50am

Which ones did you use in CTH? Also, I just posted an IC on CTH Board GB. Here's your chance to get one back :-)
 

Quote:
Originally Posted by sachu View Post

Try the amp ohm PIO copper foil caps. My favorite coupling caps.

 

The 6CG7 clear top will always be a favorite of mine in this big punching little amp. Wish I had kept one of the CTHs i built..



 

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post #375 of 536
1/31/12 at 7:21am

Though some of our tweak/caps posts belong in the Tube & Tweak thread, wanted to give a heads-up not to use these silly expensive V-Caps in a CTH:

http://www.v-cap.com/teflon-capacitors.php

I've found out the hard way that CTH e12 relay lock is temperamental using them (e.g. locks w/some tube/can combos not others), even using the new BoM. 

So I'll be listing a minty pair of those for use in some other amp design.  When they work they are joy though, well if you manage to forget what you paid for 'em:)

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