Search found 16677 matches

by pre65
Fri Nov 17, 2017 8:17 pm
Forum: Beginners
Topic: Dual rail +/- 80v power supply.
Replies: 9
Views: 75

Re: Dual rail +/- 80v power supply.

Semi naked in front of an 833a amp no less. :shock: :shock:

Yes, Powerdrive it is, and I've wanted to try it for a while.
by pre65
Fri Nov 17, 2017 2:37 pm
Forum: Everyones Projects
Topic: 811a SET amp.
Replies: 274
Views: 20501

Re: 811a SET amp.

Nick wrote:
Fri Nov 17, 2017 2:04 pm


Though TBH, 5ma looks like a good op point. Maybe a little less to preserve the thing a bit more.

and I dont think a 76 needs a grid stopper. Its a relatively docile valve.
I'll try a 680R instead of a 600R as the 10M45s setting resistor.

Thanks for all the useful tips, much appreciated.
by pre65
Fri Nov 17, 2017 1:53 pm
Forum: Assorted Stuff
Topic: Nothing In Particular
Replies: 8778
Views: 387812

Re: Nothing In Particular

It made me laugh. :lol:
by pre65
Fri Nov 17, 2017 1:49 pm
Forum: Everyones Projects
Topic: 811a SET amp.
Replies: 274
Views: 20501

Re: 811a SET amp.

According to the data sheet for a 76 max current is 5ma.
by pre65
Fri Nov 17, 2017 12:25 pm
Forum: Beginners
Topic: Dual rail +/- 80v power supply.
Replies: 9
Views: 75

Re: Dual rail +/- 80v power supply.

Thanks Nick, although I can't see from the circuit where those numbers came from ? Regarding the PSU I found these PCBs on Ebay, and as space is a consideration I'll get a couple to try. https://www.ebay.co.uk/itm/Dual-Polarity-Symmetrical-Power-Supply-PCB-Only-DIY-For-Audio-Amp/112020371980?_trkpar...
by pre65
Fri Nov 17, 2017 11:58 am
Forum: Beginners
Topic: Dual rail +/- 80v power supply.
Replies: 9
Views: 75

Re: Dual rail +/- 80v power supply.

Thanks Ed.

I was more thinking of the mosfet follower likely current draw.
by pre65
Fri Nov 17, 2017 9:58 am
Forum: Solid State
Topic: P6 AMP REVIEW
Replies: 11
Views: 95

Re: P6 AMP REVIEW

Well done Nick, excellent review. :)
by pre65
Fri Nov 17, 2017 9:56 am
Forum: Beginners
Topic: Dual rail +/- 80v power supply.
Replies: 9
Views: 75

Dual rail +/- 80v power supply.

On the new 811A amp I need a +/- 80v power supply for the mosfet follower part. I'm not sure where to start. :( If I use PSU designer to design a 160v power supply can I then use the transformer secondary centre tap to create an 0v rail and connect to the other two with capacitors ? I have a transfo...
by pre65
Thu Nov 16, 2017 9:12 pm
Forum: Everyones Projects
Topic: 811a SET amp.
Replies: 274
Views: 20501

Re: 811a SET amp.

As the 76 is 6.3v and indirectly heated I'll use AC heating to start with.

I can't remember why I purchased the 76 but I'm glad to find a use for them.

The amp PSU will be my dual mono supply, so that is already taken care of. :)
by pre65
Thu Nov 16, 2017 5:43 pm
Forum: Everyones Projects
Topic: 811a SET amp.
Replies: 274
Views: 20501

Re: 811a SET amp.

See if this works. If you click on the second image it should show up the right way round.
Scan.jpg
by pre65
Thu Nov 16, 2017 5:11 pm
Forum: Everyones Projects
Topic: 811a SET amp.
Replies: 274
Views: 20501

Re: 811a SET amp.

Thanks Paul, I value your thoughts.
by pre65
Thu Nov 16, 2017 12:52 pm
Forum: Computer Audio
Topic: laptop upgrade
Replies: 9
Views: 91

Re: laptop upgrade

It escapes me for know what it's called but you can download a bit of software that tells you what your key is. Then you can download a fresh copy of the OS if you wish and stick in the key. Done it a few times. This may help if you really need the COA number. http://www.techadvisor.co.uk/how-to/wi...
by pre65
Thu Nov 16, 2017 12:23 pm
Forum: Computer Audio
Topic: laptop upgrade
Replies: 9
Views: 91

Re: laptop upgrade

As far as I know the BIOS remembers the W10 code number so you just do a download from the Microsoft web site and authentication is automatic.

Good luck with all the updates. :lol:

PS My laptop came with a wiped disc and the above worked for me.
by pre65
Thu Nov 16, 2017 9:05 am
Forum: Everyones Projects
Topic: 811a SET amp.
Replies: 274
Views: 20501

Re: 811a SET amp.

Yes Steve, should have read "top plate". :) On this new amp there is grid bias, which is new to me on a power valve. The circuit shows the 811a with a 50R 5W hum pot across the filament, and also two 30R 3W resistors to the hum pot output to ground (via 1R sensing resistor). As I'm using Tent Lab he...
by pre65
Wed Nov 15, 2017 3:22 pm
Forum: Everyones Projects
Topic: 811a SET amp.
Replies: 274
Views: 20501

Re: 811a SET amp.

I've officially started to collect the bits I need for the 811A rebuild.

Now got two UX5 Amphenol British made bases on the way.(for the 76 triode)

I'm hoping to gut the old version and start again, it will need a new aluminium to plate at the very least.