Some more amplifiers with EL34's (EL60's) at high anode voltages (900 V in the Siemens ELA 2796). Ofcourse the anode and screengrid voltages sag with signal.
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yes, Mullard had one in Mitcham with up to a dozen EL34 in parallel push pull.
The thing was hopelessly unreliable.
Not a week would go by without at least a couple of them dying and melting.
EL34 have a design which simply cannot avoid going into serious secondary grid emission.
The higher anode voltages just push it rapidly into break down, and death.
Trying to run them anything over 500V was well recognised at Mullard as being suicidal, which is why they put people off attempting it.
It's also why people like Reeves at Hiwatt/Hylight, (who used to work there) immediately said they were a hopelessly unreliable POS, and went to GEC instead fitting a quad or more of KT88.
Reeves and his amps were made like military precision and went for the very best transformers (Partridge).
It put the British "sound" on the world market, and those amps can last almost for ever.
EL60? EL37? EL34.
Forget it! That's power for pussies, not for serious stuff.
I want to see any EL34 that can stand up to the punishment of a good solid 807 (or even better Thomson - CSF French 5933), never mind my good old KT8C wartime stuff still going strong 70-80 yrs later.
You MUST be right, SEVEN authorities back what you say: sarcastic, sarcastic, sarcastic, sarcastic, sarcastic, sarcastic and sarcastic (besides you)
Since they are the World Authority on EL34, it MUST be so.
RE-AL-LLY?
So the 500000 or more Marshall, Laney, VOX, Selmer, Sound City, Hi Watt, etc EL34 amps are known bu NOBODY and the 1000 (if that many) KT88 Hiwatt, Orange and even Marshall are THE ones which defined Rock Sound worldwide?
Nice to know.
Please send me an autographed copy of your book when you publish it, I have a special shelf in my Library for such literature.
At clipping the HF power developed increases rapidly. Some Crossoveer Networks design in tungsten lamps in the HF end to control the degree of HF going to the tweeters. A commonly used device is the PX bulb.🙂
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It's a pitty for 'sarcastic1' that '6vheater' and 'mullered' were banned from this forum. Their dads also worked for Mullard Mitcham and also thought EL34's were rubbish. If they would still be active on this forum they could support sarcastic1 in his crusade against the EL34 and Mullard-Philips.
https://www.diyaudio.com/forums/tubes-valves/371054-using-807s-mullard-5-20-circuit-8.html#post6630947
https://www.diyaudio.com/forums/tubes-valves/348071-tubes-actually-sound-47.html#post6058022
https://www.diyaudio.com/forums/tubes-valves/346458-optimal-gain-distribution-2.html#post6005018
https://www.diyaudio.com/forums/tubes-valves/273028-bogen-beasts-5.html#post4350104
https://www.diyaudio.com/forums/tubes-valves/273028-bogen-beasts-5.html#post4349282
https://www.diyaudio.com/forums/tubes-valves/371054-using-807s-mullard-5-20-circuit-8.html#post6630947
https://www.diyaudio.com/forums/tubes-valves/348071-tubes-actually-sound-47.html#post6058022
https://www.diyaudio.com/forums/tubes-valves/346458-optimal-gain-distribution-2.html#post6005018
https://www.diyaudio.com/forums/tubes-valves/273028-bogen-beasts-5.html#post4350104
https://www.diyaudio.com/forums/tubes-valves/273028-bogen-beasts-5.html#post4349282
Thank you PFL200, as far as I know some tried to fit modern EL34 to this kind of old designs, and got fireworks. Apparently the quality of the EL34 went down to usual requirements in most amps (400-450V B+). NOS tubes are out of my budget and also out of my desires TBH.
That tab is great jhstewart9, I remember I found those bulbs in a David Eden 4x10" bass cabinet years ago that was flashing when abused by the bass player.
I always suggest to buy the power tubes from the vendors who normally test them for guitar amp; there are some of them that can supply EL34/6CA7 with a strictly selection
I would like to know the brand of loudspeaker for Hifi with a lamp in series to the tweeter.
It is an ancient ( and bad) solution never seen in the last 20-30 years.
Walter
I would like to know the brand of loudspeaker for Hifi with a lamp in series to the tweeter.
It is an ancient ( and bad) solution never seen in the last 20-30 years.
Walter
Stupid question maybe, but why not tie a bidirectional TVS diode across the tweeter to prevent destruction? The TVS will eat the (excessive) clipping energy?
(sorry it's messy, it was drawn freehand with a very sensitive mouse)
(sorry it's messy, it was drawn freehand with a very sensitive mouse)
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Gross distortion when those kick in, and produces more load on the amplifier, not less. With PTC thermistors, it turns the tweeter down instead of just clipping.
I've paid my university playing in a band and I have to say that the so called "C logo", that is an "S" indeed, were claimed as being the most british sounding EL34 on the market, but never noticed (nor read on guitar amp forums) differencies in reliability with other major brands. I remember Electro Harmonix has been weak for a certain period.
People at Marshall switched to 5881 on early JCM900 series, then back to EL34 on late JCM900 and the 2000 series. Rumors said it was due to weak production of EL34 in that period.
People at Marshall switched to 5881 on early JCM900 series, then back to EL34 on late JCM900 and the 2000 series. Rumors said it was due to weak production of EL34 in that period.
I know the story of Svetlana from beginning.
The last russian production of 34 are more safe.
When well selected they are fine
Walter
The last russian production of 34 are more safe.
When well selected they are fine
Walter
It has been done, professionally, and by none less than Electrovoice.
They do protect tweeters, no doubt, but sound horrible, so were dropped like hot potatoes:
OT posts removed.
Ok.
That's not what I meant though.
I was thinking simpler like this.
That's not what I meant though.
I was thinking simpler like this.
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There has got to be a better way of testing a circuit. Why exceed ratings so badly? Build the test amp lower voltage.
cheers,
Douglas
cheers,
Douglas