Search found 13 matches

by ruffrecords
Sun May 30, 2021 10:34 pm
Forum: Valves
Topic: Another insane valve for phonos
Replies: 12
Views: 3764

Re: Another insane valve for phonos

Odd that you should think high gain and low output impedance is more important than noise in the first stage of a phono amp. Care to justify that?

Cheers

Ian
by ruffrecords
Sat May 29, 2021 8:24 am
Forum: Beginners
Topic: what pcb design software
Replies: 9
Views: 3476

Re: what pcb design software

I have been toying with the idea of migrating to Kicad for a long time. The up coming version 6 is said to fix many of the quirks of the old version and make it much more usable. For more than 10 years I have been using freePCB. It is a very simple and straightforward PCB layout tool. Most of the bo...
by ruffrecords
Thu May 27, 2021 10:39 pm
Forum: New Users
Topic: new user
Replies: 6
Views: 3460

Re: new user

Oops, I just realised I pooped on someone else's thread. Sorry. :shock:

Cheers

Ian
by ruffrecords
Thu May 27, 2021 10:28 pm
Forum: Headphones
Topic: New Headphone Amp
Replies: 24
Views: 14833

Re: New Headphone Amp

HD650 phones are interesting, not just for their sonic qualities, but also because their impedance is 300 ohms which makes them much easier to drive with valves. I could not find a sensitivity figure in their data sheet. All they quote is an output level of 103dB (SPL) but without specifying the con...
by ruffrecords
Thu May 27, 2021 9:53 pm
Forum: Valves
Topic: SRPP stage useing a 5670
Replies: 19
Views: 4852

Re: SRPP stage useing a 5670

OK, now I am back at a proper (Linux) computer without hard wired control key sequences, here is the long version. When I started out in electronics in the late 50s everything was valves. I built the usual power amp, a tape interface for a Brenell tape deck and various radios. By the time I left sch...
by ruffrecords
Thu May 27, 2021 5:49 pm
Forum: Valves
Topic: SRPP stage useing a 5670
Replies: 19
Views: 4852

Re: SRPP stage useing a 5670

An SRPP is a true push pull stage so it can swing plus or minus twice the quiescent current. With 6mA quiescent it can swing 12mA peak or more than 8mA rms which is 20V rms into 2500 ohms.

Cheers

Ian
by ruffrecords
Thu May 27, 2021 12:32 pm
Forum: Valves
Topic: SRPP stage useing a 5670
Replies: 19
Views: 4852

Re: SRPP stage useing a 5670

I just typed a big long reply to this and then lost the lot. I hate Chromebooks where the control key is just below the shift key! Accidentally pressing Ctrl W closes the current tab and everything you types is lost. Anyway, very short version. My interest in valves is for use in professional audio,...
by ruffrecords
Wed May 26, 2021 12:11 pm
Forum: Everyones Projects
Topic: music production
Replies: 34
Views: 5261

Re: music production

I read in the paper recently that scientists have discovered a gene that alters some people's sense of smell and taste. They can smell/taste things that many people cannot and apparently it explains why they hate brussels. I have often wondered if there may be another gene that afflicts one with gol...
by ruffrecords
Wed May 26, 2021 11:47 am
Forum: Valves
Topic: Seraphim Phonostage
Replies: 7
Views: 4283

Re: Seraphim Phonostage

TYpical audiophoolery BS.

Cheers

IAn
by ruffrecords
Wed May 26, 2021 11:30 am
Forum: Valves
Topic: SRPP stage useing a 5670
Replies: 19
Views: 4852

Re: SRPP stage useing a 5670

You need to take the opinions of TubeCAD with a healthy does of salt. His analysis is excellent but his applications (use cases -ugh what a horrible term) are equally limited. The SRPP is a very useful tool in the tube circuit designers arsenal but like all topologies, considered in isolation it has...
by ruffrecords
Tue May 25, 2021 11:16 am
Forum: Valves
Topic: SRPP stage useing a 5670
Replies: 19
Views: 4852

Re: SRPP stage useing a 5670

The SRPP is more of an output stage designed to deliver power to a load rather than an input stage. They also suffer from relatively high distortion. Using a pair of triodes in a mu follower stage would provide more gain and lower distortion. I use an ECC88 based mu follower in one of my microphone ...
by ruffrecords
Tue May 25, 2021 11:12 am
Forum: Valves
Topic: Another insane valve for phonos
Replies: 12
Views: 3764

Re: Another insane valve for phonos

Two things annoy me about articles like this. First they assume that a hghi gm automatically means lower noise - it doesn't, and they rarely if ever include actual noise measurements of the final design.

Cheers

Ian
by ruffrecords
Tue May 25, 2021 11:05 am
Forum: New Users
Topic: new user
Replies: 6
Views: 3460

Re: new user

Hello and thanks for letting me join this community. I belong to several audio groups but this is the first UK centric one I have come across. I found it by accident when looking for 6V6 cathode follower stages for a design for a version of the active DI box used at Motown studios in the 60s. My mai...