ECP Torpedo III [indexed in first post]

Would you gents be interested in group buying Telefunken 12AZ7s? I found a place with some, and I figure that way we can manage matching uncertainty to an extent.

 

Please count me in, if they ship internationally that is....

 

I would be interested as well.

As an aside, I'm finishing up my build, and just installed the Cinemag's. I noticed, however that they are slightly different from one another.
The difference is in the base that rests on the PCB. One of them sits flush, while the other has two molded in standoffs on each side.
It doesn't affect the installed height much; the one with the standoff sits a bit taller, but you have to look closely to tell. Just wondering if
anyone else has seen this.

 

I'll pick them up personally and bring them with me to the States. Thing is you guys will have to wait till January for when I get back. They do ship internationally, but that will preclude any haggling on the price on my part. Throw me a PM so I can keep track. Listed price at the time was about $77 a piece, but I can negotiate with the store owner, especially if a few more of us get in on it.

He also has Mullard 12AZ7s for like, $33 a piece at listed price.

 

Yeah ... we've seen it.

EDIT: Angry smiley is for Cinemag, not TheloniuSnoop.

 

I hope to get most of the heat sinks out tomorrow. I've tried to send a standard response to everyone who requested them, but if you think I missed you, please let me know.

 

Finally finished my build. First, a huge 'thank you' to Doug for this fantastic design, and his extra work on the mod's, and of course to Tom who brought
it to reality. You guys rock. Seriously. Another tip of the hat to MortenB, bazelio, MisterRogers, et al for their added mod's and reports.

Here are some highlights of my build:

Uses all the mod's from Tom
To address Doug's concern about heat to C5, it and the adjacent output CCS were tilted away from each other
The resistors and transistors near the output CCS were installed under the PCB
For added clearance, I used the 3/8" screws for the output devices, eliminated the washers, and used blue Loctite on the nuts
I installed the same heatsinks that Mr.Sneis used in his build (silver ones) directly to the reg's
Resistors in signal path are Takman metal film except plate load's are carbon (I have metals to try also)
TKD pot (perfect fit; barely)
Cardas Rhodium RCA's
Cardas 2x21.5 shielded cable for input
Since the TKD pot covers the input/output eyelets, I used the same cabling from the pot directly to the input resistors
Vishay nude input resistors
Rike cap's with Soundcoat damping sheeting
Output resistors mounted under PCB to help with cap clearance
MEC 100 choke

 

You forgot the most important part: how does it sound?!

 

Pix are up. Also added a couple of pix to my post 1263 above.

 

Has anyone here added the CCS upgrades, while having the stock EPCOS caps (and Cinemags), or equivalent fit box caps? I might build one of these again in the future (even if I have to source my own parts), but fitting those Mundorfs in was a huge pain for me. I made it work, but I don't think it would be worth doing again for me if it's a very small difference. The CCS was more than worth it though, and would be much easier on a fresh build. Worst part of that upgrade was just desoldering the old parts out cleanly.

Alternatively, I did some more digging and found Doug has been doing some other bespoke designs, on a case by case basis. (Copenhagen, DSHA-2/4)

My question for @dsavitsk

Is there a future possibility of PCB's being offered for sale for any of those, even if at a higher premium for your design efforts? And is the Copenhagen compatible with the same spec'd Cinemag OPT's as the T3?

 

I've added the CCS upgrades while using the (now stock) Solen caps, which are far superior to the EPCOS box caps, and a fairly easy fit. It should be a good solution, as the most significant tweak is easily the output CCS boards (barring transformers).

 

We should comparo the snoopertrick model 2 vs my standard specs one

 

The "bespoke" amps have been largely the development of new things. I am waiting for metal to come back from the finishers, and for a few back ordered parts to arrive, and I should be able to finalize and announce those new things. But at least in the immediate future, there are no plans for any of these to be available as PCBs.

No. The Copenhagen is a transformer loaded push-pull amp while the T3 transformers are not designed for a high voltage differential between the windings, or for DC current (hence the coupling caps).

 

Wait! I'm supposed to listen to it?

Still burning it in.

 

Thanks for the clarification, Doug. That's definitely understandable. You have to make returns on your efforts as well. I look at the offering of the T III as more as a service to the community. I'm now a big fan of your design philosophy from my subjective experience with the T III. I'm going back to school in January full time for electrical engineering, so I'm also looking at the DIY aspect as a learning supplement. Of course, If I ever build off of your designs in the future, I'll ask and credit you first and foremost.

 

It's done burning in. Get to listening and enjoying! Looking at your clean build makes me want to go back and and finally finish my cap and CCS installs properly.

I'd originally planned to use the larger TKD pot also, but backed off that plan. Nice to know it worked out. Did the front panel need any modification?

 

I had to slightly enlarge the pot hole on the front panel for mine

 

Ditto. Just a slightly bigger hole, but everything lines up perfectly.

 

I decided that the top of the case desperately needed more air flow, so ........





Haven't decided yet how to blacken the holes.

I've been listening to the amp with SD HD800's, but kept getting the feeling that it sounded veiled compared to my first build, which only had the
tube CCS mod. I decided to change the plate load resistors from Takman 1W carbon's to the same resistor in metal to see if it made a change.

MortenB, you hit the nail on the head! The plate load's have a very noticeable effect on the sound, at least to my ears. The change to the metal
film's opened things up, and not by a slim margin. The difference was apparent in the first few seconds of play. The veil is gone and the amp is
now more dynamic.

 

Yes, the plate load resistors do change the sound signature, and I'm also not a fan of Takman carbons there. I'm also not entirely sure I'm going to keep the output CCS boards. I had a nice dynamic punch with good attack and tonality using AMRG resistors, but less of the forward/aggressive signature the CCS boards produce.