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Cavalli Compact Tube Hybrid (CTH) Tube & Tweak thread. - Page 26

post #376 of 688
Just out of curiosity, what has the average build been running people? $100-120 range?
post #377 of 688
The kit prices are on the Spuce Canyon page:
Options

I'd plan on about $200ish total for a build with transformer, perf'd top, a couple cheaper tubes to roll and maybe a cap upgrade. I built mine with the longer hammond 1602 case, perf'd top and cheap Ebay stepped attenuator. I'd recommend the 1602 case and perf'd top option for sure. A beefier transformer than the Spruce Canyon offering is nice if you intend on trying power hungry tubes. If you start rolling expensive tubes, the sky$ the limit. I've settled on a 6DJ8 Bugle Boy and a Siemens E88cc as my two "go to" tubes lately, which are currently about $20ish apiece. I like either of them better than spendy telefunkens, "PQ" 6922's and RCA variants.

It's a very nice amp project that ought to be more popular than it is. I probably have 500 listening hours on mine with 20 or 30 tube swaps and not a moments grief.
post #378 of 688
Thread Starter 
Quote:
Originally Posted by bada bing View Post
< snip >
It's a very nice amp project that ought to be more popular than it is.
I probably have 500 listening hours on mine with 20 or 30 tube swaps and not a moments grief.
Great to hear feedback like this.

Quote:
Originally Posted by barleyguy View Post
Isn't there a trade off on noise versus power with the output resistor? That's why I haven't wanted to go that direction.
I'd hate to underpower the orthos in order to make the IEM's quiet.

Would the C3H change help the noise without changing the power output?
Going beyond the recommended 330uF for C3H did not yield improvement in my testing (330uf C3H equaled use of battery heater using my most sensitive cans - D2000s). Someone w/more sensitive phones could confirm my findings by moving to 470uf & above and seeing if it makes any difference. Note fitment would become tough.
Most of the related posts are in the "A Very.." thread.

Yes, the ideal R18s are jumpers, but its a good place for resistance to cope w/higher gain tubes WRT volume pot range. R18s also mask any very low level hiss or hum that may be heard between tracks w/very sensitive earphones. I'm not sure every last minuscule trace of hum possibly heard between tracks using very sensitive cans can be eliminated. We do have A/C & other things in close proximity to input stages on the 3" x 5" PCB.
post #379 of 688
Thread Starter 

Favorable impressions over on NYC meet thread...

Just a heads-up that CTHs w/Amperex PQ 8416, Siemens "Chrome Plate" ECC82(12au7) & RCA clear-top were well received @ last weekend's last weekend's Fall NY meet (see mostly around pg 6 or so).

Now we know CTHs don't need $30->$40 PQs & chrome plates to sound very good, any early 60's ones will do. OTOH we know the design is great @ extracting each tube's inherent characteristics so don't think the nuance such tubes have to offer is lost either. Same may go for coupling caps, resistors, etc as well.
post #380 of 688
Quote:
Originally Posted by cfcubed View Post
Just a heads-up...
Thanks for the link. I'm sure Erik will love his new amp, especially starting out with an 8416.

Quote:
Originally Posted by cfcubed View Post
Now we know CTHs don't need $30->$40 PQs & chrome plates to sound very good, any early 60's ones will do. OTOH we know the design is great @ extracting each tube's inherent characteristics so don't think the nuance such tubes have to offer is lost either.
I agree with this based on my own experiments. The circuit does seem to be pretty transparent with respect to the tube. It's just as fun trying out a $3 tube as it is a $25 tube. Whatever the tube is capable of doing, you'll hear it. I have a new batch of tubes coming, with some complete unknowns to me, so it will be interesting to see if there are any surprises to be had. This time I picked up some 7 and 8 volt tubes as well, just to see.
post #381 of 688
Quote:
Originally Posted by TimJo View Post
Thanks for the link. I'm sure Erik will love his new amp, especially starting out with an 8416.

I agree with this based on my own experiments. The circuit does seem to be pretty transparent with respect to the tube. It's just as fun trying out a $3 tube as it is a $25 tube. Whatever the tube is capable of doing, you'll hear it. I have a new batch of tubes coming, with some complete unknowns to me, so it will be interesting to see if there are any surprises to be had. This time I picked up some 7 and 8 volt tubes as well, just to see.
I am greatly enjoying my new amp, indeed! The Amperex PQ tube sounds fantastic even with the Denons. I'm finding the bass isn't too much on all but the most low end heavy recordings. With classical, jazz and acoustic music everything sounds full and dynamic. Even though I'm sure the "cleartop" is no slouch, I'm not sure I'm going to be able to pull that Amperex out.

Well, that's not really the case. I subscribed to this thread for more tube rolling ideas and I hope to be able to contribute to the community's experience with tubes for this amp.

There is a small group of us in the New York area that wants to start having regular DIY mini-meets, primarily SiBurning. We had one meet in the spring with SiBurning, Kerry and one of SiBurnings friends from outside of Head-Fi. I have very little DIY experience myself but I'm trying to learn. I was thinking the CTH could be a good group project for us.
post #382 of 688
Thread Starter 
Quote:
Originally Posted by erikzen View Post
I am greatly enjoying my new amp, indeed! The Amperex PQ tube sounds fantastic even with the Denons. <snip >
I subscribed to this thread for more tube rolling ideas and I hope to be able to contribute to the community's experience with tubes for this amp.
Great to hear. There are a lot of 8416 fans in this thread. Even with its bass presence think it does very well w/the rest of the range too.
Its been expressed that other Amperexs exhibit similar traits (e.g. 6922, their 6dj8 Bugle Boys).

Think most around here have a Seimens around they like (bada bings post above). Seems my tube tastes run like keyid, adamus, timjo AFAIR.
Quote:
Originally Posted by erikzen View Post
There is a small group of us in the New York area that wants to start having regular DIY mini-meets, primarily SiBurning. We had one meet in the spring with SiBurning, Kerry and one of SiBurnings friends from outside of Head-Fi. I have very little DIY experience myself but I'm trying to learn. I was thinking the CTH could be a good group project for us.
I'm bringing this part over to the original CTH thread "A Very...".
post #383 of 688
Quote:
Originally Posted by cfcubed View Post
Think most around here have a Seimens around they like
I'd like to get my hands on one of those chrome plates you had at the meet. I found some Seimans at Tube Depot but the prices are ridiculous.

https://www.tubeworld.com/index_high.htm
post #384 of 688
Thread Starter 
Got my New-Old-Stock (NOS) one for $35 or so shipped off the bay (like the NOS PQ 8416 you now have). There's one for $48 shipped... Its tests look good (we look for reasonably matched triodes, e.g. within 5%), but that's pricey. This thing is there too.
I just set a search & waited. It took weeks to get those deals AFAIR.

Again, don't really need PQs & chrome plates but those things do indicate the makers' premium tubes. If you can snag NOS for little more I would.

Some more reading for you
post #385 of 688
Thanks Chris!
post #386 of 688
It works very nicely with my Tung sol 6f8g tubes, my fave ever for the CTH.
post #387 of 688
Smeggy, does the CTH need any modification to use the 6f8g (if I am not mistaken its 6.3v) or could you just buy one of those adapters to 12au7 on ebay?
post #388 of 688
mine was upgraded (*caugh) in various ways, but yes, the 6f8g works fine with an adapter from ebay
post #389 of 688
Sweet! Looks like there is another tube to get and try.
post #390 of 688
Quote:
Originally Posted by smeggy View Post
mine was upgraded (*caugh) in various ways, but yes, the 6f8g works fine with an adapter from ebay
ahem..i believe just one (*cough ) doesn't describe the upgrades fully
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