audio-talk

Aye, I did say, probably loading the trafo to prevent the LF instability / oscillation like wot you've been experiencing. Only as you've found, looks like value needs to be smaller. Don't forget the actual trafos used aren't necessarily the same ones the original designer was expecting. Ah! Thanks ...

No more thoughts on what R21 is doing/there for anyone? We've been listening to the one (!) channel of this amp for a couple of hours now, a couple of observations. 1) Its sensitive. Not overly so but the volume pot is back off a fair bit compared to every amp I've built so far. Spec says 200mV (for...

Thank you David - 'smy intended result. Actually even at a distance I'm getting sick of the Dub - back to Prodigy and then something else. We are going for the whole week here. Now go on, tell me that's not enough - then they are crap speakers and I'm still sulking about not going to Owston. Meanwh...

That's not a Zobel network, Zobels are R and C in series, not in parallel. C2 gives more HF feedback to roll it off going into the supersonic band. "Whats the purpose of R21?" Not a lot at the moment! Can only suppose it's to prevent the LF instability thing, but as you've proved the valu...

Why not in-phase wired? I'll have a go at answering this one Mike. In anti-phase you get a lot of same-channel frequencies cancelling one another out with the speakers facing one another, that way the external SPL is relatively low but cone excursion is relatively big (remember the aim here is to b...

I've been studying the cct diagram. Sure enough there's a Zobel network (C2/R4) that provides feedback to the first stage via the secondary of the o/p TX. There's also a 1K resistor across the secondary too wired across the speaker terminals in the amp. Because of the way Tony's built it I can work ...

JM programmes on tonight, those want to know probably do already but for those that want to find out about one of the best singer-songwriters ever... Tune into BBC4 10PM-11PM for the documentary 'Johnny Too Bad' and then stay tuned as there's a compilation programme made up of some of his BBC sessi...

JM programmes on tonight, those want to know probably do already but for those that want to find out about one of the best singer-songwriters ever... Tune into BBC4 10PM-11PM for the documentary 'Johnny Too Bad' and then stay tuned as there's a compilation programme made up of some of his BBC sessio...

Don't get it with push pull either unless they use feedback. Maybe a zobel network across the output will help? Yes, this does one does Nick. I'll read up on the desctructions tonight, thank you. :idea: Ding (another!). Thats what that 100R is across the speaker terminals inside the amp. I've remov...

Well done that man http://livinginthepast-audioweb.co.uk/images/misc/th_thumbsup.gif ...almost................. :cry: So i bring home the now resplendent left hand channel amp and connect it up to my set-up and lo and behold....crazy oscillations, sounds like an outtake of Hawkwinds 1st LP. Hurrump...

Stayed a bit later this evening so I could hum chase some more. On this amp the heater volts were floating. I've referenced them to a +30V point by fitting a potential divider across the HT and tying one of the AC heater legs to that tapped point. I remembered doing this on BOBA and his hum level dr...

Its' looking good Tony, I've got the '100Hz special' up to the workshop in Lundun. I've removed one of the chassis from the big casing and powered it up on it's own. Away from it's mate it doesn't motorboat on start up BUT there is approx 6mV of hum on the o/p. I'll see if I can reduce that but I'll...

Nick wrote:

mids fine but the top! yikes - ragged harsh painful.

Err, were these the drivers you poked a hole on one of them?

Minor detail I'm sure Nick

DTB

I put the needle in the groove.

That sounds pretty good too

DTB

Oooo Andy didn't diss 'em then?

Dub m'lad. Thats what y'need to thrash 'em. Its the LAW I tell you


DTB