45 SET

[IslandPink]

What gain do you need in the amp ?

[simon]

Good question. The GM70 amp is around 6W but it's rare I use most of it. The Bugle I built years ago with the 5751 driver vibrated the settee with the 208ez horns in a smallish lounge, so I think a fully driven 45 will be okay. Maybe not at Owston, but I'm not building the amp for there.

I thought I'd bias the 45s around 250V 30mA with -50 grid volts. In order to have enough sensitivity as I don't use a pre amp I was aiming to swing 50V from 1V input. The 5751 has a mu of 70 iirc, which is probably why it rocked as sources seem to output less than 2Vrms.

[Paul Barker]

I think a fully driven 45 will be okay. Maybe not at Owston, but I'm not building the amp for there.

Ok, Ill withdraw my offer too.

[simon]

Sorry Paul, which offer?

[pre65]

It would seem a shame if the 45 amps were built before Owston, but not exhibited.

[Nick]

Yep, I read Simon's comment about Owston that 2W would not be enough for that room, not that he would not think of bringing them if done in time. Transport pending, I hope to bring the OB's to Owston, so a 45 would be a good match to them.

[simon]

Yes, as Nick said.

[Greg]

Transport pending, I hope to bring the OB's to Owston, so a 45 would be a good match to them.

They should also work well with Steve C’s Heretik

[Paul Barker]

Simon, were friends thats safe! I meant my offer to breadboard a mono attempt at a mini Sukuma style in time for Owston. But as you rightly point out Owston isn’t the place for a sub 2 watt amp,the task outweighs the benefit for me also.

As a relevant stray from the electronics of it. When I came out of the Crown Spar on Sunday about 1 ish, it was typical Scarborough Sea Fret weather, the fog horn was saving lives at sea. But the resident Spa orchestra was playing beatiful music for their regular Tedy Bear show, when children bring their tedy bears and take part. Im on Esplanade, orchestra is in and out of focus according to the non linear nature of Sea Frets. But I was struck by the skill of the musicians, the composers, and the way the sounds so far away, owston would seem a matchbox compared to the journey and the distractions in the musics travel from the spar to the esplanade. But noone in our artificial world of music teproduction has ever come close the that live sound of analog music from the sheet music interpreted by the excellent and balanced musicians working beautifully as a home, playing well composed music.

Bruce Edgar’s room at vsac was the closest artificial copy ive heard, but most of our efforts pale into insignificance. Weve had a few bright moments like Jonos 45 on Hames’ Quasars. But that situation was nothing compared to music our ansestors heard before transformers onwards as electricity was harnessed to provide humans with thr facility to hear music at home. Were still nowhere near the beautiful sounds.

Not an edit, an apology. Apple nowadays have employed a moron to spell check so for instance James became Hames. I cant be bothered to go through the above with a fine toothed nit comb to correct that moron!

[simon]

Ah I see Paul, no probs.

I'd quite like to get the 45 amp built in time for Owston - I don't have any full range speakers with passive crossovers at the moment so it will be a bit risky trying them at Owston a) because of volume b) because I won't know what the bass is like. But bringing to stuff to Owston that might not sound very good has never bothered me before .

I'd really like to hear the 45 with Nick's OBs though.

And similarly I changed my Android phone recently and the autocorrect is curious. It's much much worse than my previous phone that was 8 years old. Progress eh.

[Paul Barker]

Cool

[Nick]

But that situation was nothing compared to music our ansestors heard before transformers onwards as electricity was harnessed to provide humans with thr facility to hear music at home. Were still nowhere near the beautiful sounds.

But you say that as if we cant still go and hear live music, we can if we want to, its just we ALSO have the option to hear it again in our own homes, and also the option to hear music that was performed before we were born, or was never performed live, but only existed as a creation in the studio.

I refer to https://en.wikipedia.org/wiki/Nirvana_fallacy

[simon]

I thought I'd start with a nice simple Bugle, then think about different drivers - the ECL82 with pentode CCS strangely appeals.

Anyway chassis work complete

20220824_215934.jpg (92 KiB) Viewed 1704 times

[simon]

Okay, here's the approximate layout. I don't understand how this iron has become heavier since I last lifted it... Already thinking I should have gone with a separate board for the PS, but I wanted to avoid connectors.

It's pretty much the Bugle circuit with a few part substitutions.

20220824_220141.jpg (167.62 KiB) Viewed 1704 times

[IslandPink]

I can recommend a bit of regular bouldering as good training for Owston.