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Old 4th April 2012, 02:27 PM   #11
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Quote:
Originally Posted by Wavebourn View Post
According to my experience it is impossible in class A or A1. At least 750V is neded, ot you need to drive them by cathode (or source) followers in AB2 region, like Ampeg did in SVT. But in any case, bass guitar amp must be built such a way so no "farting" distortions allowed, so no capacitive coupling from driver directly to grids of output tubes. So with 750-800V on anodes you can get like 360-420W from 6 tubes, with output transformer with primary like 2.5-3K P-P.
The TELEFUNKEN datasheet of the FL152, p. 9, last column, tells us that we can expect about 120 watts from a pair of those tubes, running at a plate voltage of 800 volts, at a 8 kOhms load.. This tube also is a - more sophisticated - succedessor of the TELEFUNKEN LS50 WWII tube.

You do understand the parameters? Well, let's translate it for you:

Plate voltage
Screen voltage
Plate idle current
Screen idle current
Grid 1 bias voltage
Load impedance
Input voltage for maximum drive
Plate current at full load
Screen current at full load
Output power
THD
Efficiency, related to plate DC supply

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Old 4th April 2012, 04:41 PM   #12
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Thank you Kay for the datasheet!
Yes, EL152 is repackaged LS-50, for civil usage after WW-II.

Datasheet looks like the one I saw for LS-50 of 1942, if to remove swastikas. Very useful curves.
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Old 4th April 2012, 10:19 PM   #13
es345 is offline es345  Germany
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So with 750-800V on anodes you can get like 360-420W from 6 tubes, with output transformer with primary like 2.5-3K P-P.
So we are in the same ballpark: thats the power (a little less than you predicted) what I have measured - no clipping - at 850V Ub (AB2 condition) with different Raa.
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Old 4th April 2012, 10:29 PM   #14
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Yep. plenty of clean power.

Gu-50 is the best tube for bass guirat amps, and for hi-fi P-P amps. However, for Hi-Fi some inconvenience is caused by needed hig voltage and high primary impedance of transformers.
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Old 4th April 2012, 11:44 PM   #15
AJT is offline AJT  Philippines
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perhaps these tubes might interest you, 120 watts for a pair at mere 600volts plate...

Click the image to open in full size.
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Old 5th April 2012, 02:06 AM   #16
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Nice tube, Tony!
How many of them Raytheon made, though? They are $25 on epay. Gu-50 is still 5 times cheaper.
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Old 5th April 2012, 07:10 AM   #17
AJT is offline AJT  Philippines
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thsnks, i still have to lay my hands on those GU-50's one day i will......

i am building a 4D32 pp amp.....
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Old 5th April 2012, 04:33 PM   #18
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Hi Tony,

still another question: Are there sockets for these tubes available? We know that e.g for GU50 sockets there are at least three different versions available as NOS at acceptable prices.

Best regards!
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Old 5th April 2012, 06:28 PM   #19
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Back to the FL152 datasheet, page 9, last column ;-): We see that the tubes are biased for idling at maximum plate dissipation. Is this believable, or is it more likely a mistake, same as full power plate current value in the 600 volts column?

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Old 5th April 2012, 11:41 PM   #20
AJT is offline AJT  Philippines
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Quote:
Originally Posted by Kay Pirinha View Post
Hi Tony,

still another question: Are there sockets for these tubes available? We know that e.g for GU50 sockets there are at least three different versions available as NOS at acceptable prices.

Best regards!

the 4D32 uses the same sockets as 839B, 832A, and 6C33....
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