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A Very Compact Hybrid Amp - Page 117

post #1741 of 2213
bah...its an improvement over the mini3 for sure..also he didn't want an EHHA cause of space concerns...besides, the CTH does quite well with the Yamaha orthos.
post #1742 of 2213
I think my yh-3s haven't gotten enough time with it - have to try it out this week.
post #1743 of 2213
What would be a good starting point for R18 for my intended setup

Source - Zune
Cans DT770 250

Here is the twist, I am going to put in a modified Linkwitz crossfeed. I will probably just order Tangents kit unless there is something better close to the price (under ~$50). On his site he recommends a gain 2 to 3x more than normal.
post #1744 of 2213
Thread Starter 
I'm not sure what is best, but here's a way to calculate a few things that might help.

The gain of the CTH is almost identical to the mu of the triode. For 12au7 and similar this is about 17. For 6922 this is about 33. The rest of the tubes, I think, fall in between.

The output resistors are in series with the load so they reduce the gain by the ratio of R18 to Rheadphones using this formula:

Actual gain = mu * Rheadphone / (R18 + Rheadphone)

So, if you are using a 12au7 with 300R headphones:

R18 = 150R then Actual gain = 11.3
R18 = 100R then Actual gain = 12.75
R18 = 50R then Actual gain = 14.6

For 12au7 with 32R headphones:

R18 = 150R then Actual gain = 3
R18 = 100R then Actual gain = 4
R18 = 50R then Actual gain = 6.6

Highest gain is, obviously, with R18 = 0.

Does this help?
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #1745 of 2213
I finally got around to stuffing a Tung Sol 6F8G in mine last night... sounds fantastic, lots of air and space. Really nice. Sadly the E12 is still tripping more than I'd like. Other than that, very good, and very big with adapter too.

Pics later
post #1746 of 2213
Quote:
Originally Posted by blaken View Post
What would be a good starting point for R18 for my intended setup

Source - Zune
Cans DT770 250

Here is the twist, I am going to put in a modified Linkwitz crossfeed. I will probably just order Tangents kit unless there is something better close to the price (under ~$50). On his site he recommends a gain 2 to 3x more than normal.
I built a stock CTH with the kit from Spruce Canyon. When I use it with my CD/DAC combo I use the Tangent crossfeed kit. My cans are Senn HD-515, there is no lack of volume with 12au7, 12bh7a, 6fq7, or 6dj8.
Hope that helps.
post #1747 of 2213
Quote:
Originally Posted by smeggy View Post
I finally got around to stuffing a Tung Sol 6F8G in mine last night... sounds fantastic, lots of air and space. Really nice. Sadly the E12 is still tripping more than I'd like. Other than that, very good, and very big with adapter too.

Pics later
is it later yet? ..dB
post #1748 of 2213
Quote:
Originally Posted by runeight View Post

Does this help?
Absolutely. That will give me a good idea of where I need to go to maintain the default gain by the BOM resistors.

@Billyk Thanks. I assume since you use the kit you like it?

I will use sips in those sockets so I can roll them just in case but it sounds like the stock resistors will do fine.
post #1749 of 2213
Absolutely!
This is an astounding little amp for very short money. Bill put together a nice kit with everything you need and is really great to deal with. He offers magnificent support too.
I am listening to it with my laptop and a Bantam DAC as I type this. On the PC I use foobar and all the plugins like ASIO4all and crossfeed. When I use a CD player I use my crossfeed box I made from the Tangent PCB and recommended BOM. Plenty of power for my cans and a great sound with plenty of detail and sound staging. I listen to mostly live music and most of that is Grateful Dead . I can't wait to get some truly decent cans, I just can't stop building stuff!
post #1750 of 2213
Doh I don't think I made myself clear. I just meant do you like the crossfeed kit.

I do plan on buying the amp kit from Bill. He has been helping with a few questions already. In fact I think the only thing left to do is pay him and then I'll be in business

I have been interested in the crossfeed because of the closed nature of the DT770s. I like them a lot but they are really in your head and for stuff like live music, Jazz, and Folk rock I would like the sound stage to be more natural.

Thanks
post #1751 of 2213
Yes, I have become addicted to crossfeed and almost cannot listen without it. Like I said when I use the PC and my rockboxed DAPs I use software but on the CD player I use the Tangent PCB and I do like it. At first I did not quite get the effect, but now I really notice it's absence. I use it on the middle position.
post #1752 of 2213
yay, pic!



I really need to recase this thing.
Next up, replacing the coupling caps with a pair of Vitamin Q
post #1753 of 2213
Smeggy you might be taking the term test board a little too literally. That looks insanely awesome.

On another note where did you get that knob?
post #1754 of 2213
Quote:
Originally Posted by blaken View Post
Smeggy you might be taking the term test board a little too literally. That looks insanely awesome.

On another note where did you get that knob?
Cheers

these are the ones, I got a pack of four
post #1755 of 2213
Thanks that guy has a lot of knobs for sale.

OT: you might be interested in picking up this shirt before they stop making it.
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