Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > uk.tech.broadcast > #70556 > unrolled thread
| Started by | "J. P. Gilliver" <G6JPG@255soft.uk> |
|---|---|
| First post | 2026-09-26 19:08 +0100 |
| Last post | 2026-09-27 13:12 +0200 |
| Articles | 20 on this page of 133 — 23 participants |
Back to article view | Back to uk.tech.broadcast
This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by
below is the oldest one visible, not the original post.
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-26 19:08 +0100
Re: OT - TV Scott <newsgroups@gefion.myzen.co.uk> - 2026-09-26 19:58 +0100
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-26 20:30 +0100
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-09-27 09:39 +0100
Re: OT - TV JMB99 <mb@nospam.net> - 2026-09-28 08:08 +0100
Re: OT - TV Frank Slootweg <this@ddress.is.invalid> - 2026-09-26 19:10 +0000
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-26 21:02 +0100
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-26 21:03 +0100
Re: OT - TV Frank Slootweg <this@ddress.is.invalid> - 2026-09-27 18:20 +0000
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-28 16:26 +0100
Re: OT - TV Frank Slootweg <this@ddress.is.invalid> - 2026-09-28 15:45 +0000
Re: OT - TV Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-09-28 16:30 +0000
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-28 17:46 +0100
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-28 22:25 +0100
Re: OT - TV NY <me@privacy.net> - 2026-09-29 16:40 +0100
OT - Lehrer (was: Re: OT - TV) "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-29 16:58 +0100
Re: OT - Lehrer (was: Re: OT - TV) Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-09-29 18:19 +0000
Re: OT - Lehrer "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-29 20:57 +0100
Re: OT - Lehrer Charles Hope <clh@candehope.me.uk> - 2026-09-29 20:00 +0000
Re: OT - Lehrer (was: Re: OT - TV) André Coutanche <acoutanche@gmx.co.uk> - 2026-09-29 21:50 +0100
Re: OT - Lehrer NY <me@privacy.net> - 2026-09-29 22:33 +0100
Re: OT - Lehrer Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-09-29 22:48 +0000
Re: OT - Lehrer "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-30 01:07 +0100
Re: OT - Lehrer John Ames <commodorejohn@gmail.com> - 2026-09-30 15:51 -0700
Re: OT - Lehrer NY <me@privacy.net> - 2026-10-01 10:57 +0100
Re: OT - Lehrer NY <me@privacy.net> - 2026-09-30 08:10 +0100
Re: OT - Lehrer "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-30 01:39 +0100
Re: OT - Lehrer Roger Blake <rogblake@iname.invalid> - 2026-09-30 00:46 +0000
Re: OT - Lehrer NY <me@privacy.net> - 2026-09-29 22:39 +0100
Re: OT - Lehrer Frank Slootweg <this@ddress.is.invalid> - 2026-09-30 12:25 +0000
Re: OT - Lehrer "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-30 13:34 +0100
Re: OT - Lehrer The Natural Philosopher <tnp@invalid.invalid> - 2026-09-30 14:31 +0100
Re: OT - Lehrer NY <me@privacy.net> - 2026-09-30 14:47 +0100
Re: OT - Lehrer John Williamson <johnwilliamson@btinternet.com> - 2026-09-30 14:58 +0100
Re: OT - Lehrer "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-10-01 02:36 +0100
Re: OT - Lehrer NY <me@privacy.net> - 2026-10-01 11:12 +0100
Re: OT - Lehrer Frank Slootweg <this@ddress.is.invalid> - 2026-10-01 14:35 +0000
Re: OT - Lehrer NY <me@privacy.net> - 2026-10-01 16:14 +0100
Re: OT - Lehrer Frank Slootweg <this@ddress.is.invalid> - 2026-10-01 17:35 +0000
Re: OT - Lehrer Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-10-01 17:53 +0000
Re: OT - Lehrer John Williamson <johnwilliamson@btinternet.com> - 2026-10-01 19:03 +0100
Re: OT - Lehrer "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-10-01 21:50 +0100
Re: OT - Lehrer The Natural Philosopher <tnp@invalid.invalid> - 2026-10-02 12:25 +0100
Re: OT - Lehrer The Natural Philosopher <tnp@invalid.invalid> - 2026-10-01 11:13 +0100
Re: OT - Lehrer NY <me@privacy.net> - 2026-10-01 11:51 +0100
Re: OT - Lehrer John Williamson <johnwilliamson@btinternet.com> - 2026-09-30 14:55 +0100
Re: OT - Lehrer Charles Hope <clh@candehope.me.uk> - 2026-09-30 14:15 +0000
Re: OT - TV Daniel70 <daniel47@nomail.afraid.org> - 2026-09-27 19:58 +1000
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-27 12:52 +0100
Re: OT - TV Daniel70 <daniel47@nomail.afraid.org> - 2026-09-27 22:13 +1000
[OT] - audio distribution, Rediffusion-style (was: Re: OT - TV) "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-28 16:43 +0100
Re: OT - TV Max Demian <max_demian@bigfoot.com> - 2026-09-27 11:44 +0100
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-27 16:12 +0100
Re: OT - TV Max Demian <max_demian@bigfoot.com> - 2026-09-27 18:12 +0100
Re: OT - TV Andy Burns <usenet@andyburns.uk> - 2026-09-27 18:23 +0100
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-27 18:34 +0100
Re: OT - TV Max Demian <max_demian@bigfoot.com> - 2026-09-28 14:03 +0100
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-09-28 15:56 +0100
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-28 16:46 +0100
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-09-28 17:16 +0100
Re: OT - TV Max Demian <max_demian@bigfoot.com> - 2026-09-29 12:01 +0100
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-29 13:05 +0100
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-09-29 13:25 +0100
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-29 14:13 +0100
Re: OT - TV The Other John <nomail@here.org> - 2026-09-29 16:53 +0100
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-29 17:12 +0100
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-09-30 10:22 +0100
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-09-30 13:36 +0100
Re: OT - TV "Carlos E.R." <robin_listas@es.invalid> - 2026-09-30 11:23 +0200
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-30 11:48 +0100
Re: OT - TV Paul <nospam@needed.invalid> - 2026-09-30 07:37 -0400
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-30 14:28 +0100
Re: OT - TV "Carlos E. R." <robin_listas@es.invalid> - 2026-10-01 00:35 +0200
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-10-01 02:15 +0100
Re: OT - TV Paul <nospam@needed.invalid> - 2026-10-01 00:15 -0400
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-10-01 12:50 +0100
Re: OT - TV "Carlos E. R." <robin_listas@es.invalid> - 2026-10-01 14:24 +0200
Re: OT - TV Max Demian <max_demian@bigfoot.com> - 2026-10-01 17:17 +0100
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-10-01 12:48 +0100
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-10-01 13:10 +0100
Re: OT - TV John Williamson <johnwilliamson@btinternet.com> - 2026-10-01 13:42 +0100
Re: OT - TV John Williamson <johnwilliamson@btinternet.com> - 2026-10-01 13:32 +0100
Re: OT - TV Frank Slootweg <this@ddress.is.invalid> - 2026-10-01 14:52 +0000
Re: OT - TV Daniel70 <daniel47@nomail.afraid.org> - 2026-10-03 21:10 +1000
Re: OT - TV "Carlos E. R." <robin_listas@es.invalid> - 2026-10-03 13:39 +0200
Re: OT - TV Daniel70 <daniel47@nomail.afraid.org> - 2026-10-04 21:26 +1100
Re: OT - TV "Carlos E. R." <robin_listas@es.invalid> - 2026-10-04 13:19 +0200
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-10-03 12:47 +0100
Re: OT - TV John Williamson <johnwilliamson@btinternet.com> - 2026-10-03 12:50 +0100
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-10-03 13:09 +0100
Re: OT - TV John Williamson <johnwilliamson@btinternet.com> - 2026-10-03 15:59 +0100
Re: OT - TV Jan Panteltje <alien@comet.invalid> - 2026-10-03 15:56 +0000
Re: OT - TV John Williamson <johnwilliamson@btinternet.com> - 2026-10-03 17:19 +0100
Re: OT - TV Jan Panteltje <alien@comet.invalid> - 2026-10-04 10:54 +0000
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-10-03 18:41 +0100
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-10-03 22:52 +0100
Re: OT - TV Paul <nospam@needed.invalid> - 2026-10-03 21:24 -0400
Re: OT - TV Jan Panteltje <alien@comet.invalid> - 2026-10-04 08:08 +0000
Re: OT - TV John Williamson <johnwilliamson@btinternet.com> - 2026-10-04 09:29 +0100
Re: OT - TV Roderick Stewart <rjfs@escapetime.myzen.co.uk> - 2026-09-30 15:13 +0100
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-09-29 13:16 +0100
Re: OT - TV Jan Panteltje <alien@comet.invalid> - 2026-09-29 15:54 +0000
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-29 17:15 +0100
Re: OT - TV "Carlos E.R." <robin_listas@es.invalid> - 2026-09-30 11:27 +0200
Re: OT - TV John Williamson <johnwilliamson@btinternet.com> - 2026-09-30 11:13 +0100
Re: OT - TV John Williamson <johnwilliamson@btinternet.com> - 2026-09-30 11:19 +0100
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-30 11:57 +0100
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-09-30 13:29 +0100
Re: OT - TV John Williamson <johnwilliamson@btinternet.com> - 2026-09-30 13:54 +0100
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-30 14:34 +0100
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-09-30 18:08 +0100
Re: OT - TV "J. P. Gilliver" <G6JPG@255soft.uk> - 2026-10-01 02:22 +0100
Re: OT - TV Jan Panteltje <alien@comet.invalid> - 2026-10-01 06:37 +0000
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-10-01 10:32 +0100
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-10-01 09:41 +0100
Re: OT - TV "Carlos E. R." <robin_listas@es.invalid> - 2026-10-01 00:37 +0200
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-09-30 11:50 +0100
Re: OT - TV Jan Panteltje <alien@comet.invalid> - 2026-09-30 13:08 +0000
Re: OT - TV "Carlos E. R." <robin_listas@es.invalid> - 2026-10-01 00:50 +0200
Re: OT - TV Jan Panteltje <alien@comet.invalid> - 2026-10-01 06:12 +0000
Re: OT - TV c186282 <c186282@nnada.net> - 2026-10-01 03:29 -0400
Re: OT - TV "Carlos E. R." <robin_listas@es.invalid> - 2026-10-01 14:53 +0200
Re: OT - TV Paul <nospam@needed.invalid> - 2026-10-01 03:32 -0400
Re: OT - TV "Carlos E. R." <robin_listas@es.invalid> - 2026-10-01 14:49 +0200
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-10-01 12:57 +0100
Re: OT - TV liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-10-01 13:27 +0100
Re: OT - TV "Carlos E. R." <robin_listas@es.invalid> - 2026-10-01 15:19 +0200
Re: OT - TV Jan Panteltje <alien@comet.invalid> - 2026-10-01 14:34 +0000
Re: OT - TV The Natural Philosopher <tnp@invalid.invalid> - 2026-10-01 15:51 +0100
Re: OT - TV Jan Panteltje <alien@comet.invalid> - 2026-10-02 06:52 +0000
Re: OT - TV Andy Burns <usenet@andyburns.uk> - 2026-10-04 07:52 +0100
Re: OT - TV c186282 <c186282@nnada.net> - 2026-10-04 03:15 -0400
Re: OT - TV "Carlos E.R." <robin_listas@es.invalid> - 2026-09-27 13:12 +0200
Page 6 of 7 — ← Prev page 1 2 3 4 5 [6] 7 Next page →
| From | liz@poppyrecords.invalid.invalid (Liz Tuddenham) |
|---|---|
| Date | 2026-09-29 13:16 +0100 |
| Message-ID | <1s278ix.1exku2ij8p4zkN%liz@poppyrecords.invalid.invalid> |
| In reply to | #70594 |
Max Demian <max_demian@bigfoot.com> wrote: > On 28/09/2026 16:46, The Natural Philosopher wrote: > > On 28/09/2026 14:03, Max Demian wrote: > >> Yes, I suppose there could be a matching transformer, in the same way > >> that there were boxes you connected to the "extension speaker" socket > >> of the main (valve) radio so you could listen in the kitchen. I had > >> one which had a transformer and a wander plug arrangement so you could > >> match it. Some valve radios had a high impedance output, so presumably > >> both connections would be at (more or less) HT voltage above the radio > >> chassis (which would be earth if the earth socket was connected). I > >> think there were high impedance horn extension speakers at one time. > > > Valve amps ALWAYS have an output transformer. Not least because there > > are no 'P channel ' valves. > > I think there were high impedance horn speakers, which wouldn't require > a transformer. And, of course, high impedance headphones if you don't > want a loudspeaker. The moving-iron loudspeakers were higher impedance and could be connected directly into the anode circuit of a valve but the sound quality was much poorer than a moving coil loudspeaker. Some used a large paper diaphragm, others used a small metal diaphragm with a horn for acoustic impedance matching. Some early horn loudspeakers were little more than a high-impedance earphone joined to a horn. Most post-1930s horn loudspeakers have a low impedance moving coil drive unit and some have a matching transformer built into the back of the housing. Eddystone communication receivers still had a separate high impedance headphone socket, in addition to loudspeaker connections, right up to the last valve models. -- ~ Liz Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
[toc] | [prev] | [next] | [standalone]
| From | Jan Panteltje <alien@comet.invalid> |
|---|---|
| Date | 2026-09-29 15:54 +0000 |
| Message-ID | <119gmur$3e4ln$1@dont-email.me> |
| In reply to | #70594 |
>Max Demian <max_demian@bigfoot.com>wrote: >>On 28/09/2026 16:46, The Natural Philosopher wrote: >> On 28/09/2026 14:03, Max Demian wrote: >>> Yes, I suppose there could be a matching transformer, in the same way >>> that there were boxes you connected to the "extension speaker" socket >>> of the main (valve) radio so you could listen in the kitchen. I had >>> one which had a transformer and a wander plug arrangement so you could >>> match it. Some valve radios had a high impedance output, so presumably >>> both connections would be at (more or less) HT voltage above the radio >>> chassis (which would be earth if the earth socket was connected). I >>> think there were high impedance horn extension speakers at one time. > >> Valve amps ALWAYS have an output transformer. Not least because there >> are no 'P channel ' valves. > >I think there were high impedance horn speakers, which wouldn't require >a transformer. And, of course, high impedance headphones if you don't >want a loudspeaker. Yes some tube TVs had 800 Ohm speakers without transformers. Example of a tube output stage without transformer to drive a 800 Ohm speaker: https://2.bp.blogspot.com/-GaJkZ9klfLw/VOecHjVgPuI/AAAAAAAAA4g/H2qcMWJ3tuA/s1600/Schema.png
[toc] | [prev] | [next] | [standalone]
| From | The Natural Philosopher <tnp@invalid.invalid> |
|---|---|
| Date | 2026-09-29 17:15 +0100 |
| Message-ID | <119go7i$3cdrk$3@dont-email.me> |
| In reply to | #70602 |
On 29/09/2026 16:54, Jan Panteltje wrote: >> Max Demian <max_demian@bigfoot.com>wrote: >>> On 28/09/2026 16:46, The Natural Philosopher wrote: >>> On 28/09/2026 14:03, Max Demian wrote: >>>> Yes, I suppose there could be a matching transformer, in the same way >>>> that there were boxes you connected to the "extension speaker" socket >>>> of the main (valve) radio so you could listen in the kitchen. I had >>>> one which had a transformer and a wander plug arrangement so you could >>>> match it. Some valve radios had a high impedance output, so presumably >>>> both connections would be at (more or less) HT voltage above the radio >>>> chassis (which would be earth if the earth socket was connected). I >>>> think there were high impedance horn extension speakers at one time. >> >>> Valve amps ALWAYS have an output transformer. Not least because there >>> are no 'P channel ' valves. >> >> I think there were high impedance horn speakers, which wouldn't require >> a transformer. And, of course, high impedance headphones if you don't >> want a loudspeaker. > > Yes some tube TVs had 800 Ohm speakers without transformers. > > Example of a tube output stage without transformer to drive a 800 Ohm speaker: > https://2.bp.blogspot.com/-GaJkZ9klfLw/VOecHjVgPuI/AAAAAAAAA4g/H2qcMWJ3tuA/s1600/Schema.png STAGGERINGLY inefficient circuit, but yes, it works. -- The urge to save humanity is almost always a false front for the urge to rule. – H. L. Mencken, American journalist, 1880-1956
[toc] | [prev] | [next] | [standalone]
| From | "Carlos E.R." <robin_listas@es.invalid> |
|---|---|
| Date | 2026-09-30 11:27 +0200 |
| Message-ID | <j91vomxksl.ln2@Telcontar.valinor> |
| In reply to | #70602 |
On 2026-09-29 17:54, Jan Panteltje wrote: >> Max Demian <max_demian@bigfoot.com>wrote: >>> On 28/09/2026 16:46, The Natural Philosopher wrote: >>> On 28/09/2026 14:03, Max Demian wrote: >>>> Yes, I suppose there could be a matching transformer, in the same way >>>> that there were boxes you connected to the "extension speaker" socket >>>> of the main (valve) radio so you could listen in the kitchen. I had >>>> one which had a transformer and a wander plug arrangement so you could >>>> match it. Some valve radios had a high impedance output, so presumably >>>> both connections would be at (more or less) HT voltage above the radio >>>> chassis (which would be earth if the earth socket was connected). I >>>> think there were high impedance horn extension speakers at one time. >> >>> Valve amps ALWAYS have an output transformer. Not least because there >>> are no 'P channel ' valves. >> >> I think there were high impedance horn speakers, which wouldn't require >> a transformer. And, of course, high impedance headphones if you don't >> want a loudspeaker. > > Yes some tube TVs had 800 Ohm speakers without transformers. > > Example of a tube output stage without transformer to drive a 800 Ohm speaker: > https://2.bp.blogspot.com/-GaJkZ9klfLw/VOecHjVgPuI/AAAAAAAAA4g/H2qcMWJ3tuA/s1600/Schema.png I'm not familiar with valves EZ80 and 6CA4, I don't understand the drawings. :-? -- Cheers, Carlos. ES🇪🇸, EU🇪🇺;
[toc] | [prev] | [next] | [standalone]
| From | John Williamson <johnwilliamson@btinternet.com> |
|---|---|
| Date | 2026-09-30 11:13 +0100 |
| Message-ID | <ni45lsFdufrU1@mid.individual.net> |
| In reply to | #70621 |
On 30/09/2026 10:27, Carlos E.R. wrote: > On 2026-09-29 17:54, Jan Panteltje wrote: >> Yes some tube TVs had 800 Ohm speakers without transformers. >> >> Example of a tube output stage without transformer to drive a 800 Ohm >> speaker: >> >> https://2.bp.blogspot.com/-GaJkZ9klfLw/VOecHjVgPuI/AAAAAAAAA4g/H2qcMWJ3tuA/s1600/Schema.png >> > > I'm not familiar with valves EZ80 and 6CA4, I don't understand the > drawings. :-? > The EZZ80 and BCA4 valves are full wave rectifiers in the power supply. (Equivalent to two diodes in each valve, with a tapped transformer secondary. Back when semiconductors were expensive, I've done similar with a pair of germanium diodes, as it was cheaper than a bridge rectifier.)i The relevant stage for this thread is the output stage, which is two EL504 pentodes being driven in a sort of push-pull configuration by the input triode. The EL504s each have an independent DC supply. The circuit specifies an 800 ohm load, but I first expected to see a more standard 600 ohm load... -- Tciao for Now! John.
[toc] | [prev] | [next] | [standalone]
| From | John Williamson <johnwilliamson@btinternet.com> |
|---|---|
| Date | 2026-09-30 11:19 +0100 |
| Message-ID | <ni461gFe04aU1@mid.individual.net> |
| In reply to | #70622 |
On 30/09/2026 11:13, John Williamson wrote: > On 30/09/2026 10:27, Carlos E.R. wrote: >> On 2026-09-29 17:54, Jan Panteltje wrote: > >>> Yes some tube TVs had 800 Ohm speakers without transformers. >>> >>> Example of a tube output stage without transformer to drive a 800 Ohm >>> speaker: >>> >>> https://2.bp.blogspot.com/-GaJkZ9klfLw/VOecHjVgPuI/AAAAAAAAA4g/H2qcMWJ3tuA/s1600/Schema.png >>> >>> >> >> I'm not familiar with valves EZ80 and 6CA4, I don't understand the >> drawings. :-? >> > The EZZ80 and BCA4 valves are full wave rectifiers in the power supply. > (Equivalent to two diodes in each valve, with a tapped transformer > secondary. Back when semiconductors were expensive, I've done similar > with a pair of germanium diodes, as it was cheaper than a bridge > rectifier.)i > > The relevant stage for this thread is the output stage, which is two > EL504 pentodes being driven in a sort of push-pull configuration by the > input triode. The EL504s each have an independent DC supply. > > The circuit specifies an 800 ohm load, but I first expected to see a > more standard 600 ohm load... > Sorry, my mistake, the EL504s use the bottom one being driven to conduct more which pulls the cathode voltage of the other down, making it a class A output stage. <Note to self. Visit the optician>:-) The other supply is for the input triode. -- Tciao for Now! John.
[toc] | [prev] | [next] | [standalone]
| From | The Natural Philosopher <tnp@invalid.invalid> |
|---|---|
| Date | 2026-09-30 11:57 +0100 |
| Message-ID | <119ipu1$4i1s$7@dont-email.me> |
| In reply to | #70623 |
On 30/09/2026 11:19, John Williamson wrote: > the EL504s use the bottom one being driven to conduct more which pulls > the cathode voltage of the other down, making it a class A output stage. Yes, the use of the top one is something I hadn't seen before, but it certainly works. Lot of heat for not much power, and You would get more out of e.g. a single EL34 with a transformer. Or a pair. Back in the day transformers were cheap. Today they are sadly not. The output transformer is probably at least half the component cost of a valve amplifier... -- I was brought up to believe that you should never give offence if you can avoid it; the new culture tells us you should always take offence if you can. There are now experts in the art of taking offence, indeed whole academic subjects, such as 'gender studies', devoted to it. Sir Roger Scruton
[toc] | [prev] | [next] | [standalone]
| From | liz@poppyrecords.invalid.invalid (Liz Tuddenham) |
|---|---|
| Date | 2026-09-30 13:29 +0100 |
| Message-ID | <1s293ju.13joq5r1awzwqkN%liz@poppyrecords.invalid.invalid> |
| In reply to | #70626 |
The Natural Philosopher <tnp@invalid.invalid> wrote: > On 30/09/2026 11:19, John Williamson wrote: > > the EL504s use the bottom one being driven to conduct more which pulls > > the cathode voltage of the other down, making it a class A output stage. > > Yes, the use of the top one is something I hadn't seen before, but it > certainly works. > > Lot of heat for not much power, and You would get more out of e.g. a > single EL34 with a transformer. > > Or a pair. > > Back in the day transformers were cheap. Today they are sadly not. The > output transformer is probably at least half the component cost of a > valve amplifier... It was the second-most-expensive component 'back in the day', that is why they were often skimped. When valves with lowish anode voltages and high peak emissions were developed for television receivers, that opened the way for totem-pole valve output stages capable of driving a loudspeaker directly. In some cases it was no more complex than the equivalent push-pull cicuit with its signal-inverter stage - it didn't even need a separate heater winding for the top valve because telelvision valves were designed for use in heater chains with high heater-cathode voltages. With no output transformer there were more-benign overall phase shifts in the amplifier, so more feedback could be used, giving better linearity and lower noise. It also gave worse behaviour under overload conditions, as designers of transformerless transistor amplifiers with large amounts of feedback were to discover later. -- ~ Liz Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
[toc] | [prev] | [next] | [standalone]
| From | John Williamson <johnwilliamson@btinternet.com> |
|---|---|
| Date | 2026-09-30 13:54 +0100 |
| Message-ID | <ni4f4cFfdl0U1@mid.individual.net> |
| In reply to | #70626 |
On 30/09/2026 11:57, The Natural Philosopher wrote: > On 30/09/2026 11:19, John Williamson wrote: >> the EL504s use the bottom one being driven to conduct more which pulls >> the cathode voltage of the other down, making it a class A output stage. > > Yes, the use of the top one is something I hadn't seen before, but it > certainly works. > > Lot of heat for not much power, and You would get more out of e.g. a > single EL34 with a transformer. > Assuming the transformer could handle the bandwidth. The output from the circuit given would be flatter and less distorted, even across the audio bandwidth, assuming a resistive load. As the designer saw fit to use smoothed DC for the heater of the input valve, avoiding noise and hum were obviously a priority. -- Tciao for Now! John.
[toc] | [prev] | [next] | [standalone]
| From | The Natural Philosopher <tnp@invalid.invalid> |
|---|---|
| Date | 2026-09-30 14:34 +0100 |
| Message-ID | <119j35i$8pgq$4@dont-email.me> |
| In reply to | #70632 |
On 30/09/2026 13:54, John Williamson wrote: > On 30/09/2026 11:57, The Natural Philosopher wrote: >> On 30/09/2026 11:19, John Williamson wrote: >>> the EL504s use the bottom one being driven to conduct more which pulls >>> the cathode voltage of the other down, making it a class A output stage. >> >> Yes, the use of the top one is something I hadn't seen before, but it >> certainly works. >> >> Lot of heat for not much power, and You would get more out of e.g. a >> single EL34 with a transformer. >> > Assuming the transformer could handle the bandwidth. The output from the > circuit given would be flatter and less distorted, even across the audio > bandwidth, assuming a resistive load. > Not hard to do a 50-30Khz transformer . > As the designer saw fit to use smoothed DC for the heater of the input > valve, avoiding noise and hum were obviously a priority. > > Any mains powered amplifier hums a bit. And even ones that are not. mains hum fields are all pervasive The best one I have has an SMPS power supply feeding a class D amplifier. Feels way too light for the power -- For every complex problem there is an answer that is clear, simple, and wrong. H.L.Mencken
[toc] | [prev] | [next] | [standalone]
| From | liz@poppyrecords.invalid.invalid (Liz Tuddenham) |
|---|---|
| Date | 2026-09-30 18:08 +0100 |
| Message-ID | <1s29g8x.1vtoj2z9nbyyuN%liz@poppyrecords.invalid.invalid> |
| In reply to | #70636 |
The Natural Philosopher <tnp@invalid.invalid> wrote: > On 30/09/2026 13:54, John Williamson wrote: > > On 30/09/2026 11:57, The Natural Philosopher wrote: > >> On 30/09/2026 11:19, John Williamson wrote: > >>> the EL504s use the bottom one being driven to conduct more which pulls > >>> the cathode voltage of the other down, making it a class A output stage. > >> > >> Yes, the use of the top one is something I hadn't seen before, but it > >> certainly works. > >> > >> Lot of heat for not much power, and You would get more out of e.g. a > >> single EL34 with a transformer. > >> > > Assuming the transformer could handle the bandwidth. The output from the > > circuit given would be flatter and less distorted, even across the audio > > bandwidth, assuming a resistive load. > > > Not hard to do a 50-30Khz transformer . Tell that to the researchers who have spent their entire lifetimes designing broadband audio transformers for valves. Have you ever tried? I have. I wouldn't normally worry about minor misunderstandings but you have been putting forward a whole string of misconceptions as extablished truths.and then subtlely backing down when presented with the historical facts that prove them false. It concerns me that these erroneous ideas are so commonly believed and propagated, so I will continue to challenge them. -- ~ Liz Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
[toc] | [prev] | [next] | [standalone]
| From | "J. P. Gilliver" <G6JPG@255soft.uk> |
|---|---|
| Date | 2026-10-01 02:22 +0100 |
| Message-ID | <119kcl0$ok4n$1@dont-email.me> |
| In reply to | #70636 |
On 2026/9/30 14:34:42, The Natural Philosopher wrote: [] > Any mains powered amplifier hums a bit. And even ones that are not. > mains hum fields are all pervasive > > > The best one I have has an SMPS power supply feeding a class D > amplifier. Feels way too light for the power > > Yes, I have one of those - came with an external supply, similar to (probably identical to) the sort that comes with laptops (or did a few years ago: modern laptop ones are tiny). Yes, far too small and light for the power - because with modern transistors, class D dissipates hardly any (waste, heating) power in the output transistors, so needs hardly any heatsinking, which is much of the weight in a transistor amplifier. I think mine is rated something like 50W (might be per channel!), and is about fag-packet size - really just big enough to support the connectors and volume knob. -- J. P. Gilliver. UMRA: 1960/<1985 MB++G()ALIS-Ch++(p)Ar++T+H+Sh0!:`)DNAf "Bother," said the Borg, "we assimilated a Pooh."
[toc] | [prev] | [next] | [standalone]
| From | Jan Panteltje <alien@comet.invalid> |
|---|---|
| Date | 2026-10-01 06:37 +0000 |
| Message-ID | <119kv3u$u11m$1@dont-email.me> |
| In reply to | #70649 |
>"J. P. Gilliver" <G6JPG@255soft.uk>wrote: >>On 2026/9/30 14:34:42, The Natural Philosopher wrote: >[] >> Any mains powered amplifier hums a bit. And even ones that are not. >> mains hum fields are all pervasive >> >> >> The best one I have has an SMPS power supply feeding a class D >> amplifier. Feels way too light for the power >> >> >Yes, I have one of those - came with an external supply, similar to >(probably identical to) the sort that comes with laptops (or did a few >years ago: modern laptop ones are tiny). Yes, far too small and light >for the power - because with modern transistors, class D dissipates >hardly any (waste, heating) power in the output transistors, so needs >hardly any heatsinking, which is much of the weight in a transistor >amplifier. I think mine is rated something like 50W (might be per >channel!), and is about fag-packet size - really just big enough to >support the connectors and volume knob. Build this in year 2000, on 24/7 here ever since, never a problem https://panteltje.nl/panteltje/amplifier/index.html single chip 75W Even used it to drive an old power transformer to make 120V 60Hz to drive my cryo cooler that works with a 60 Hz mechanical resonance: https://panteltje.nl/pub/cryo/ Note the Asus 701 controlling it Can make rocket fuel, nic for doing superconducting anti-gravity drive experiments... For a bit more load audio I have a Mc Crypt 2x 180W amp and speakers.
[toc] | [prev] | [next] | [standalone]
| From | liz@poppyrecords.invalid.invalid (Liz Tuddenham) |
|---|---|
| Date | 2026-10-01 10:32 +0100 |
| Message-ID | <1s2aqjb.5ujmgh12vfll6N%liz@poppyrecords.invalid.invalid> |
| In reply to | #70649 |
J. P. Gilliver <G6JPG@255soft.uk> wrote: > On 2026/9/30 14:34:42, The Natural Philosopher wrote: > [] > > Any mains powered amplifier hums a bit. And even ones that are not. > > mains hum fields are all pervasive > > > > > > The best one I have has an SMPS power supply feeding a class D > > amplifier. Feels way too light for the power > > > > > Yes, I have one of those - came with an external supply, similar to > (probably identical to) the sort that comes with laptops (or did a few > years ago: modern laptop ones are tiny). Yes, far too small and light > for the power - because with modern transistors, class D dissipates > hardly any (waste, heating) power in the output transistors, so needs > hardly any heatsinking, which is much of the weight in a transistor > amplifier. I think mine is rated something like 50W (might be per > channel!), and is about fag-packet size - really just big enough to > support the connectors and volume knob. Has anyone ever thought of modulating the power supply so that it became the amplifier? -- ~ Liz Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
[toc] | [prev] | [next] | [standalone]
| From | liz@poppyrecords.invalid.invalid (Liz Tuddenham) |
|---|---|
| Date | 2026-10-01 09:41 +0100 |
| Message-ID | <1s2ani4.999mzm11dx9jkN%liz@poppyrecords.invalid.invalid> |
| In reply to | #70636 |
The Natural Philosopher <tnp@invalid.invalid> wrote: > On 30/09/2026 13:54, John Williamson wrote: [...] > > As the designer saw fit to use smoothed DC for the heater of the input > > valve, avoiding noise and hum were obviously a priority. > > > > > Any mains powered amplifier hums a bit. And even ones that are not. > mains hum fields are all pervasive Only two weeks ago I had to design a valve pre-amp to go with an historic radio transmitter. It uses a UCF80 with D.C. heaters (fed from the 30v relay supply) and the hum level is not detectable below the hiss (which is about 10dB above 'perfect' Johnson noise). The biggest problem was microphony, which was overcome by using a resiliently-mounted valveholder and soldering a strip of roofing lead around the screening can. A similar design from about 7 years ago was a three-channel pre-amp for a 25-watt P.A. amplifier; with all three faders at maximum, the hiss level is only just audible and there is no detectable hum. With long mic leads and inputs grounded to different circuits, hum can be a real problem - but this isn't attributable to the amplifier. -- ~ Liz Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
[toc] | [prev] | [next] | [standalone]
| From | "Carlos E. R." <robin_listas@es.invalid> |
|---|---|
| Date | 2026-10-01 00:37 +0200 |
| Message-ID | <ni5h9jFjmjfU2@mid.individual.net> |
| In reply to | #70622 |
On 2026-09-30 12:13, John Williamson wrote:
> On 30/09/2026 10:27, Carlos E.R. wrote:
>> On 2026-09-29 17:54, Jan Panteltje wrote:
>
>>> Yes some tube TVs had 800 Ohm speakers without transformers.
>>>
>>> Example of a tube output stage without transformer to drive a 800 Ohm
>>> speaker:
>>>
>>> https://2.bp.blogspot.com/-GaJkZ9klfLw/VOecHjVgPuI/AAAAAAAAA4g/
>>> H2qcMWJ3tuA/s1600/Schema.png
>>>
>>
>> I'm not familiar with valves EZ80 and 6CA4, I don't understand the
>> drawings. :-?
>>
> The EZZ80 and BCA4 valves are full wave rectifiers in the power supply.
> (Equivalent to two diodes in each valve, with a tapped transformer
> secondary. Back when semiconductors were expensive, I've done similar
> with a pair of germanium diodes, as it was cheaper than a bridge
> rectifier.)i
The drawing with two anodes of different sizes confuses me.
>
> The relevant stage for this thread is the output stage, which is two
> EL504 pentodes being driven in a sort of push-pull configuration by the
> input triode. The EL504s each have an independent DC supply.
>
> The circuit specifies an 800 ohm load, but I first expected to see a
> more standard 600 ohm load...
>
--
Cheers,
Carlos E.R.
ES🇪🇸, EU🇪🇺.
[toc] | [prev] | [next] | [standalone]
| From | The Natural Philosopher <tnp@invalid.invalid> |
|---|---|
| Date | 2026-09-30 11:50 +0100 |
| Message-ID | <119iph7$4i1s$6@dont-email.me> |
| In reply to | #70621 |
On 30/09/2026 10:27, Carlos E.R. wrote: > On 2026-09-29 17:54, Jan Panteltje wrote: >>> Max Demian <max_demian@bigfoot.com>wrote: >>>> On 28/09/2026 16:46, The Natural Philosopher wrote: >>>> On 28/09/2026 14:03, Max Demian wrote: >>>>> Yes, I suppose there could be a matching transformer, in the same way >>>>> that there were boxes you connected to the "extension speaker" socket >>>>> of the main (valve) radio so you could listen in the kitchen. I had >>>>> one which had a transformer and a wander plug arrangement so you could >>>>> match it. Some valve radios had a high impedance output, so presumably >>>>> both connections would be at (more or less) HT voltage above the radio >>>>> chassis (which would be earth if the earth socket was connected). I >>>>> think there were high impedance horn extension speakers at one time. >>> >>>> Valve amps ALWAYS have an output transformer. Not least because there >>>> are no 'P channel ' valves. >>> >>> I think there were high impedance horn speakers, which wouldn't require >>> a transformer. And, of course, high impedance headphones if you don't >>> want a loudspeaker. >> >> Yes some tube TVs had 800 Ohm speakers without transformers. >> >> Example of a tube output stage without transformer to drive a 800 Ohm >> speaker: >> >> https://2.bp.blogspot.com/-GaJkZ9klfLw/VOecHjVgPuI/AAAAAAAAA4g/H2qcMWJ3tuA/s1600/Schema.png > > I'm not familiar with valves EZ80 and 6CA4, I don't understand the > drawings. :-? > I'm not familiar either, but I do understand the drawings. It's quite clever, but pretty wasteful of power. -- How fortunate for governments that the people they administer don't think. Adolf Hitler
[toc] | [prev] | [next] | [standalone]
| From | Jan Panteltje <alien@comet.invalid> |
|---|---|
| Date | 2026-09-30 13:08 +0000 |
| Message-ID | <119j1jv$8f2g$1@dont-email.me> |
| In reply to | #70621 |
>"Carlos E.R." <robin_listas@es.invalid>wrote:
>>On 2026-09-29 17:54, Jan Panteltje wrote:
>>> Max Demian <max_demian@bigfoot.com>wrote:
>>>> On 28/09/2026 16:46, The Natural Philosopher wrote:
>>>> On 28/09/2026 14:03, Max Demian wrote:
>>>>> Yes, I suppose there could be a matching transformer, in the same way
>>>>> that there were boxes you connected to the "extension speaker" socket
>>>>> of the main (valve) radio so you could listen in the kitchen. I had
>>>>> one which had a transformer and a wander plug arrangement so you could
>>>>> match it. Some valve radios had a high impedance output, so presumably
>>>>> both connections would be at (more or less) HT voltage above the radio
>>>>> chassis (which would be earth if the earth socket was connected). I
>>>>> think there were high impedance horn extension speakers at one time.
>>>
>>>> Valve amps ALWAYS have an output transformer. Not least because there
>>>> are no 'P channel ' valves.
>>>
>>> I think there were high impedance horn speakers, which wouldn't require
>>> a transformer. And, of course, high impedance headphones if you don't
>>> want a loudspeaker.
>>
>> Yes some tube TVs had 800 Ohm speakers without transformers.
>>
>> Example of a tube output stage without transformer to drive a 800 Ohm speaker:
>> https://2.bp.blogspot.com/-GaJkZ9klfLw/VOecHjVgPuI/AAAAAAAAA4g/H2qcMWJ3tuA/s1600/Schema.png
>
>I'm not familiar with valves EZ80 and 6CA4,
Google
https://www.radiomuseum.org/tubes/tube_ez80.html
Both those tube you mention have 2 anodes and one cathode,
each are used as 2 diodes to make 347 V from two opposite phase transformer
outputs, to give a power line with less ripple (100 Hz versus a 50 Hz ripple
or 120 Hz versus 60 Hz in 'merryca, as in case of one diode,
that way needing less supply filtering, allows smaller filter capacitors to be
used,
anode1
0----->|----
|--0 -cathode
0----->|----
anode2
>I don't understand the drawings. :-?
It is a schematic diagram shows how the 'tubes' are connected.
You need some electronics expericne to understand thsoe circuit.
>--
>Cheers, Carlos.
>ES🇪🇸, EU🇪🇺;
>
[toc] | [prev] | [next] | [standalone]
| From | "Carlos E. R." <robin_listas@es.invalid> |
|---|---|
| Date | 2026-10-01 00:50 +0200 |
| Message-ID | <ni5i22FjmjfU3@mid.individual.net> |
| In reply to | #70633 |
On 2026-09-30 15:08, Jan Panteltje wrote:
>> "Carlos E.R." <robin_listas@es.invalid>wrote:
>>> On 2026-09-29 17:54, Jan Panteltje wrote:
>>>> Max Demian <max_demian@bigfoot.com>wrote:
>>>>> On 28/09/2026 16:46, The Natural Philosopher wrote:
>>>>> On 28/09/2026 14:03, Max Demian wrote:
>>>>>> Yes, I suppose there could be a matching transformer, in the same way
>>>>>> that there were boxes you connected to the "extension speaker" socket
>>>>>> of the main (valve) radio so you could listen in the kitchen. I had
>>>>>> one which had a transformer and a wander plug arrangement so you could
>>>>>> match it. Some valve radios had a high impedance output, so presumably
>>>>>> both connections would be at (more or less) HT voltage above the radio
>>>>>> chassis (which would be earth if the earth socket was connected). I
>>>>>> think there were high impedance horn extension speakers at one time.
>>>>
>>>>> Valve amps ALWAYS have an output transformer. Not least because there
>>>>> are no 'P channel ' valves.
>>>>
>>>> I think there were high impedance horn speakers, which wouldn't require
>>>> a transformer. And, of course, high impedance headphones if you don't
>>>> want a loudspeaker.
>>>
>>> Yes some tube TVs had 800 Ohm speakers without transformers.
>>>
>>> Example of a tube output stage without transformer to drive a 800 Ohm speaker:
>>> https://2.bp.blogspot.com/-GaJkZ9klfLw/VOecHjVgPuI/AAAAAAAAA4g/H2qcMWJ3tuA/s1600/Schema.png
>>
>> I'm not familiar with valves EZ80 and 6CA4,
>
> Google
> https://www.radiomuseum.org/tubes/tube_ez80.html
>
> Both those tube you mention have 2 anodes and one cathode,
> each are used as 2 diodes to make 347 V from two opposite phase transformer
> outputs, to give a power line with less ripple (100 Hz versus a 50 Hz ripple
> or 120 Hz versus 60 Hz in 'merryca, as in case of one diode,
> that way needing less supply filtering, allows smaller filter capacitors to be
> used,
>
> anode1
> 0----->|----
> |--0 -cathode
> 0----->|----
> anode2
>
>
>> I don't understand the drawings. :-?
>
> It is a schematic diagram shows how the 'tubes' are connected.
>
> You need some electronics expericne to understand thsoe circuit.
I am an electronics engineer :-)
What I don't understand is why the two anodes have different sizes.
--
Cheers,
Carlos E.R.
ES🇪🇸, EU🇪🇺.
[toc] | [prev] | [next] | [standalone]
| From | Jan Panteltje <alien@comet.invalid> |
|---|---|
| Date | 2026-10-01 06:12 +0000 |
| Message-ID | <119ktkd$tgdj$1@dont-email.me> |
| In reply to | #70646 |
>"Carlos E. R." <robin_listas@es.invalid>wrote: >>> >>> I'm not familiar with valves EZ80 and 6CA4, >> >> Google >> https://www.radiomuseum.org/tubes/tube_ez80.html >> >> Both those tube you mention have 2 anodes and one cathode, >> each are used as 2 diodes to make 347 V from two opposite phase transformer >> outputs, to give a power line with less ripple (100 Hz versus a 50 Hz ripple >> or 120 Hz versus 60 Hz in 'merryca, as in case of one diode, >> that way needing less supply filtering, allows smaller filter capacitors to be >> used, >> >> anode1 >> 0----->|---- >> |--0 -cathode >> 0----->|---- >> anode2 >> >> >>> I don't understand the drawings. :-? >> >> It is a schematic diagram shows how the 'tubes' are connected. >> >> You need some electronics expericne to understand thsoe circuit. > >I am an electronics engineer :-) Practical experience with tubes? >What I don't understand is why the two anodes have different sizes. In the drawing? Maybe just a drawing error / constraint. https://www.radiomuseum.org/tubes/tube_ez80.html Both anodes look the same size to me! IIRC I have used that tube in the long ago past.
[toc] | [prev] | [next] | [standalone]
Page 6 of 7 — ← Prev page 1 2 3 4 5 [6] 7 Next page →
Back to top | Article view | uk.tech.broadcast
csiph-web