O...yes...I forgot....in that case I have 300B's with 2,5V heater in a smaller glass envelope...?First the Sovtek 2A3 is called a 2A3 but it isn't one
SY said:The distribution of harmonics is interesting. Why do you think second is so (relatively) high?
Unequal mutual conductance in the output valves leading to imperfect cancellation of 2nd harmonic. I can reduce H2 by adjusting DC balance (which changes mutual conductance).
Konnichiwa,
No, you have a russian Valve that is broadly similar to a 2A3 electrically and was hence listed in some manuals as appropriate substitute. IIRC it is a 2C4 (would need to look up).
Sayonara
Bas Horneman said:O...yes...I forgot....in that case I have 300B's with 2,5V heater in a smaller glass envelope...?
No, you have a russian Valve that is broadly similar to a 2A3 electrically and was hence listed in some manuals as appropriate substitute. IIRC it is a 2C4 (would need to look up).
Sayonara
EC8010 said:
Unequal mutual conductance in the output valves leading to imperfect cancellation of 2nd harmonic. I can reduce H2 by adjusting DC balance (which changes mutual conductance).
What happens to that impressively low 4th when you do this?
SY said:What happens to that impressively low 4th when you do this?
Can't remember, but you wouldn't want to see the 100Hz distortion (due to the output transformer) when the currents are out of balance.
KYW:
Apologies fore the belated responses:
KYW:
“Due to the behaviour of the auditory system we can ignore the 5% 2nd HD”
I agree that the audibility of the distortion will be determined by the 3rd HD – * primarily.
But can all people ignore 2HD? - I thought this was perceived as not important/ a glow to some ~ but excess sweetness to others.
Bas
SETH PP 2A3 – but what’s the special attraction?
EC8010:
“The Sovtek 2A3 does seem to be quite good”
Thanks for the confirmation – a prime candidate!
SY
I'd need 8 of them to equal 4 7027...
So where do we get 7027s/ for how much? eBay? $?
And should we asks unless we knew there 3 HD is as good??
Apologies fore the belated responses:
KYW:
“Due to the behaviour of the auditory system we can ignore the 5% 2nd HD”
I agree that the audibility of the distortion will be determined by the 3rd HD – * primarily.
But can all people ignore 2HD? - I thought this was perceived as not important/ a glow to some ~ but excess sweetness to others.
Bas
SETH PP 2A3 – but what’s the special attraction?
EC8010:
“The Sovtek 2A3 does seem to be quite good”
Thanks for the confirmation – a prime candidate!
SY
I'd need 8 of them to equal 4 7027...
So where do we get 7027s/ for how much? eBay? $?
And should we asks unless we knew there 3 HD is as good??
Konnichiwa,
I merely suggested that in the SPECIFIC CONTEXT we could ignore 2nd HD for audibility. I do not neccesarily suggest we can ignore it completely.
Sayonara
rick57 said:KYW:
“Due to the behaviour of the auditory system we can ignore the 5% 2nd HD”
I agree that the audibility of the distortion will be determined by the 3rd HD – * primarily.
But can all people ignore 2HD?
I merely suggested that in the SPECIFIC CONTEXT we could ignore 2nd HD for audibility. I do not neccesarily suggest we can ignore it completely.
Sayonara
SETH PP 2A3 – but what’s the special attraction?
Depends on who you are
I started of with SET's..and when Lynn Olson started the PP ball rolling (for a lot of folks at least) I wanted to build an Amity (In the mean time I found out that there were quite a few who had gone before him) The price of an extra input transformer and interstage was a little steep...then came the SETH without input transformer and a center tapped choke doing the honours wrt phase splitting...I decided to do the SETH instead.
So it was a financial decision. But as it turns out, the SETH crowd are very happy with the SETH...and was rated better by one guy who had done the Lundahl interstage thing.
I haven't read the entire thread, but the EL34 when triode connected has very good linearity both in PP and SE operation.. You can get 15W easily in PP and about 5W - 6W in SE mode. They are not too expensive and I have had good results with EH, Winged C (Svet) and JJ types. In all case these tubes were matched and burned in by the vendor and gave good service out to 2000hrs in most cases. I built quite a few PP triode amplifiers commercially using these tubes in modified dyna ST-70 chassis.
The triode connected 6550 is also a great choice incidentally.
Note that some SE snobs would call these "pseudo triodes" -- curves don't lie however and they do look like triode curves and sound like triodes. The EL34 was expressly designed for good performance triode connected and to my knowledge is the only one that was.
IMHO Nothing made today will beat the old KT88 or Tungsol 6550 for reliability and good sound for the reasons SY enumerated in an earlier post. I have not heard any of the very latest versions, but some very expensive boutique tubes I heard in the not too distant past weren't up to the task.
I confess to having moved on and my amplifiers all use either 2A3, 45, 71A or 300B output tubes and almost all are SE, so hopefully I don't have any particular axe to grind..
OTOH all those beam power tetrodes and pentodes make wonderful pass elements in high performance voltage regulators..
Kevin
The triode connected 6550 is also a great choice incidentally.
Note that some SE snobs would call these "pseudo triodes" -- curves don't lie however and they do look like triode curves and sound like triodes. The EL34 was expressly designed for good performance triode connected and to my knowledge is the only one that was.
IMHO Nothing made today will beat the old KT88 or Tungsol 6550 for reliability and good sound for the reasons SY enumerated in an earlier post. I have not heard any of the very latest versions, but some very expensive boutique tubes I heard in the not too distant past weren't up to the task.
I confess to having moved on and my amplifiers all use either 2A3, 45, 71A or 300B output tubes and almost all are SE, so hopefully I don't have any particular axe to grind..
OTOH all those beam power tetrodes and pentodes make wonderful pass elements in high performance voltage regulators..
Kevin
“I never met a 2a3 I didn’t like”
As a Joe said in Sound Practices so many years ago,
“I never met a 2a3 I didn’t like”
I tend to agree here but my opinion is biased I will admit when it comes to DHT
Triodes, there just a certain something about there sound I don’t find in other valves and I tried many.
YMMV
Tony
As a Joe said in Sound Practices so many years ago,
“I never met a 2a3 I didn’t like”
I tend to agree here but my opinion is biased I will admit when it comes to DHT
Triodes, there just a certain something about there sound I don’t find in other valves and I tried many.
YMMV
Tony
Interesting thread. I just got here, but the debate earlier regarding the value of THD measurements made me think of this link: http://www.gedlee.com/distortion_perception.htm
If you give just those few examples a listen it becomes very hard to believe a simple THD % is relevant in any way to how the music will sound.
If you give just those few examples a listen it becomes very hard to believe a simple THD % is relevant in any way to how the music will sound.
rick57 said:Earl Gedlee convinced me on THD
I was convinced 25 years ago....
dave
Need help to upgrade the volume control of Sun Audio SV 2A3 stereo amp
I just purchased the Sun Audio SV 2A3 stereo amp and want to upgrade to stepped attenuators. But I do not know the impedance (Ohms) of the original volume control. The question is if the input impedance is 100K Ohms (specs) I can replace with the stepped attenuators of 100K Ohms or else? I am newly incomer so if anyone knows or has experience about this information please email me. Thanks and appreciate your help.
I just purchased the Sun Audio SV 2A3 stereo amp and want to upgrade to stepped attenuators. But I do not know the impedance (Ohms) of the original volume control. The question is if the input impedance is 100K Ohms (specs) I can replace with the stepped attenuators of 100K Ohms or else? I am newly incomer so if anyone knows or has experience about this information please email me. Thanks and appreciate your help.
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