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Old 9th September 2011, 01:47 PM   #1191
FRUGIVO is offline FRUGIVO  Spain
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[QUOTE=regal;2703385]Frugivo, I can tell you are a speaker guy. I am willing to chip in to buy you some copper foil, Reynolds wrap has no place covering an antique classic tube
I simply experiment
True, I am sorry to wrap the tubes
but the goal is that my ears do not detect anything I do not want
the easiest way and with minimum components
I can not offer frequency response curve
try to do some measuring
I have decided to change the 27 for another 26
to get 1 watt in the 6c33
need to balance 14 vpp
with a bias of 270 mA
-13 To -16 volts grid
67 volts on the plate
on the oscilloscope can not see anything strange
got the sound is great
I'm sorry but I can hardly express myself in English
I have to give thanks to google translator

to feed the dac uses lithium batteries
a full charge for one month
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Old 9th September 2011, 01:48 PM   #1192
Gluca is offline Gluca  Italy
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all this talking about 26 makes me wonder. I never tried/listened to it. How does it compares to 801A (that I know very well)? I might modify my line stage for the 26 ...
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Old 9th September 2011, 02:31 PM   #1193
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Broadly, the 10Y is clean and dynamic and the 26 is a bit more seductive in the midrange - not exactly warm. It's hard to describe but just a little bit of magic. Euphonic, pleasant sound. I started with 10y and ended up with 26. When you go back to the 10Y you lose that special something. But the 10Y/801A is still a great tube.

Andy
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Old 9th September 2011, 03:47 PM   #1194
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Hi Gluca,

I'd say this depends on the surrounding cicuit not only on the tube. Also what you want to drive with it.

In my comparisons the 10Y/801A family of tubes beats the 26. The 10Y/801A in my favorite DHT. The 26 is more forgiving in terms of filament PSU, still critical, but it does not react as strong as the thoriated filament tubes IME.

In my universal linestage which can accept 26, UX112A, UX201A and 10Y I prefer the 10Y

Best regards

Thomas
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Old 9th September 2011, 05:23 PM   #1195
Gluca is offline Gluca  Italy
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Thanks for the replies ... If I'll find the time among all the other unfinished projects I'd love to try the 26 even if I'm pretty much a thoriated tungsted guy.

Thomas, did you try those 75THs?
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Old 9th September 2011, 05:59 PM   #1196
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Hi Gluca,

as you can see, experiences are different. Definitely worth trying out the 26 yourself.

Quote:
Originally Posted by Gluca View Post
Thomas, did you try those 75THs?
Not yet, too many other projects in the pipe.

Thomas
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Old 12th September 2011, 04:06 PM   #1197
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ok! it's time to go 26DHT for me , i have built a DIY 6n6P /AD1 amplifier and i 'll change it to a 26/AD1 soon

my plan
AZ4 tube rectifier
separate LCLC and separate RC for each tube
Capacitor all MKP
CCS filament for the AD1
CCS filament Bias for the 26 ( thanks you for the idea!!)
RC coupling interstage ( i'm a beginner ...)
automatic bias for the AD1
2.5K hashimoto output transfo
25K PEC carbon volume pot

i will post picture in few weeks and post the schematic if it sounds good, the 6N6P/AD1 combo is not so bad anyway
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Old 12th September 2011, 04:06 PM   #1198
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i forget CCS for the 26 anode..

if yo have some suggestion , your welcome!
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Old 12th September 2011, 05:19 PM   #1199
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Hello,

I love too the 26 line preamp, and work about it since many months trying to get it better !

Recently I install the Rod supply and it is really good. Superb sonic performance.
It replace a current reg with LM350 witch sounded good, but a bit too noisy (the DC should be better filtered with inductors).

I have a question to Rod : actually I connect the negative output of the filament PS on the cathode bias side, is it OK ? (this sound fine).

(Sorry if this question has already been asked...).

I tried grid bias with battery but I prefer cathode bias (not tried Duracell brand), filament bias either.
The componants are important in cathode bias : Black gate FK + Shinko resistor (or Riken).

In the HT supply I like the tube dampers (2 x 6AX4, no solid diodes) with LCLC filtering (low impedance choke like old Stancor), and low value ps cap (ASC oil polypro and Leclanché).

Actually this is a resistor load (Mills) on the plate, but choke plate will be tested, and a friend will lend me a pair of LL 1660 18mA to play

This tube is really good, very transparent, living, and with all the mods, it can sounded in pretty different ways...

Have fun !
B r u n o
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Old 12th September 2011, 08:01 PM   #1200
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Hi Bruno,

Yes, it's OK to use negative Filament terminal as the cathode.... but it is worth the time to try the positive side, and compare. Sometimes, the sound is more enjoyable! The cathode resistor should be higher value - augment by (0,75V / Ik) Ohms.

I am pleased to hear that you like the sound of the Filament Regulators!
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