• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

7236 vs 6AS7 ?

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It's more expensive than the 6AS7, but it can be had for reasonable prices on eBay. The Tungsol version is a triode connected two-grid tube and can stand higher plate voltages than the 6AS7 or the 5998. The 7236 is a computer rated 5998.

I can't comment on the sound compared to the 6AS7, but my little 7236 stereo amp seems to have low distortion, although I've never measured it.

John
 
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One thing to beware of: the 7236 does not have very good heater-to-cathode insulation, unlike most of the regulator tubes (6AS7, 6080, 5998, 6528). I've had some break down at 150V.

Parametrically the 7236 is very much like the 5998. It was actually designed to drive the spindle motors of computer tape drives!

Pete
 
Thanks for the heads up, I've no doubt we don't want arc-over, it sounds like a bad thing !

It's my first project and I want to keep thins relatively simple but for all the effort of building this I want it to sound good enough to keep around for a few years.

I'll be using cathode bias and tube rectifier so that the HT comes up after the output tube has had some chance to suck a good 2.5 amps. With low mu tubes I understand that fixed bias isn't always advised [http://www.diyaudio.com/forums/tubes-valves/167872-my-cellini-triode-amp.html]
 
This amp would also be improved by using SY's CCS on the plates of the 12AT7.

Not necessarily: I believe it was designed by Tim de P who deliberately chose the driver tube, plate resistor value and operating point to provide a degree of 2H* cancellation. A ccs induced flat driver loadline would not produce the same result.


*which the 5998 produces in abundance
 
Not necessarily: I believe it was designed by Tim de P who deliberately chose the driver tube, plate resistor value and operating point to provide a degree of 2H* cancellation. A ccs induced flat driver loadline would not produce the same result.

Are you sure it was designed by Tim DeParavicini? I was under the impression it was designed by an Italian DIYer. And besides, distortion cancellation in a single ended amp is a bit of a canard, don't you think?

John
 
Are you sure it was designed by Tim DeParavicini? I was under the impression it was designed by an Italian DIYer. And besides, distortion cancellation in a single ended amp is a bit of a canard, don't you think?

1. No. However the information source is usually correct.
2. Depends. In instances where very high levels of H2 are being generated I think it can be justified. I have built two amps where it was definitely beneficial.
 
1. No. However the information source is usually correct.
2. Depends. In instances where very high levels of H2 are being generated I think it can be justified. I have built two amps where it was definitely beneficial.

I believe the amp was designed by Cristiano Jelasi and Ciro Marzio. There is nothing remarkable about the design other than it was meant as a simple exercise for the beginner. As for carefully chosen component values, the resistors used are of common values and are repeated as often as possible. There are four 100kΩ, and two each of 1kΩ, 1.5kΩ, 4.7kΩ and 220kΩ, which could have easily been 100kΩ as well. All of the capacitors are 100µF except the coupling cap which can be anything from .1µF to .47µF. I wired mine up in a couple of hours and was able to use components I already had on hand.

John
 
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