want to build a pentode driven drd 2a3!

tubo · 2nd September 2007, 04:12 PM

hi folks,

i would like to build a pentode driven drd 2a3 or 300b, just like the one thorsten have but with e180f as the driver, as i have a quad given to me. im wondering if there is a schematic laying around on some of the threads. im fairly a newbie in ellectronics and tubes but i have built quite a few amps from schematics with parts list up until 400v.

will you guys be able to also specify the ps transformer and chokes if possible hammonds?
i would also like to use elctraprints for the plate chokes.

i already have some parts which are listed below.

transcendar 3k or 5k opts at 150ma
tj 2a3
tj 300b
e180f

thanks in advance!
ivan

Klimon · 2nd September 2007, 08:30 PM

I'ld be interested to hear about pentode driven drd's too. How do pentodes behave with a choke load btw; not such a natural combination as triode + choke or am I completely missing things?

Simon

jane · 2nd September 2007, 08:41 PM

Pentodes have quite high internal resistance which, together with a reactive load, might affect the low frequency response.

Jan E Veiset

Geek · 2nd September 2007, 10:17 PM

E180F is a great tube, but even better in triode mode. Would take care of the pentode high plate-Z issues Jane speaks of.

dave slagle · 3rd September 2007, 01:28 AM

i would expect that you would need to resistively load the pentode and not inductively load it as typically done. Inductive loads and pentodes typically lead to very odd results.

the simple tasks is to find a pentode that is happy with the load it gets when you divide current by the needed bias. (10ma of current and a 45V bias would require a load resistor of 4K5)

dave

2nd September 2007, 04:12 PM	#1
tubo diyAudio Member Join Date: Apr 2007	want to build a pentode driven drd 2a3! hi folks, i would like to build a pentode driven drd 2a3 or 300b, just like the one thorsten have but with e180f as the driver, as i have a quad given to me. im wondering if there is a schematic laying around on some of the threads. im fairly a newbie in ellectronics and tubes but i have built quite a few amps from schematics with parts list up until 400v. will you guys be able to also specify the ps transformer and chokes if possible hammonds? i would also like to use elctraprints for the plate chokes. i already have some parts which are listed below. transcendar 3k or 5k opts at 150ma tj 2a3 tj 300b e180f thanks in advance! ivan

2nd September 2007, 08:41 PM	#3
jane diyAudio Member Join Date: Jul 2004 Location: Norway	Pentodes have quite high internal resistance which, together with a reactive load, might affect the low frequency response. Jan E Veiset __________________ Life is hard - Then you die.

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2nd September 2007, 08:30 PM	#2
Klimon diyAudio Member Join Date: Apr 2005 Location: Leuven	I'ld be interested to hear about pentode driven drd's too. How do pentodes behave with a choke load btw; not such a natural combination as triode + choke or am I completely missing things? Simon

2nd September 2007, 10:17 PM	#4
Geek diyAudio Member Join Date: Sep 2004	E180F is a great tube, but even better in triode mode. Would take care of the pentode high plate-Z issues Jane speaks of.

3rd September 2007, 01:28 AM	#5
dave slagle diyAudio Member Join Date: Mar 2003 Location: NYC	i would expect that you would need to resistively load the pentode and not inductively load it as typically done. Inductive loads and pentodes typically lead to very odd results. the simple tasks is to find a pentode that is happy with the load it gets when you divide current by the needed bias. (10ma of current and a 45V bias would require a load resistor of 4K5) dave

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