Whoops

Re: stay at home type 69 project
« Reply #60 on: April 29, 2020, 12:00:25 PM »
Whoops to the rescue. PM me your address Whoops, so when I get PCB's done I can send you one

Thank you so much for the offer, I would love to try one of your boards out.
Thank you so much

pm sent


Whoops

Re: stay at home type 69 project
« Reply #61 on: April 29, 2020, 12:01:23 PM »
Here is a pic of it.


Can't open the image,
something wrong with the link

Rocinante

Re: stay at home type 69 project
« Reply #62 on: April 29, 2020, 12:53:58 PM »
oops.  This will work.

If there's a harder way to do this, I haven't found it yet.

Whoops

Re: stay at home type 69 project
« Reply #63 on: April 30, 2020, 12:50:35 AM »
Raindirk (Cyril Jones) has the Lutraphone Clones in their website, you can order directly from them,
here are the details:

http://www.raindirk.com/lustraphoneTransformersRaindirkAudio.php

Rocinante

Re: stay at home type 69 project
« Reply #64 on: May 01, 2020, 01:02:38 AM »
Okay guys, so how are you doing the vtb9043 and other inductors in Eagle?  Are you building them as a part?  I also suck at relays in schematics. On a pcb i am fine but via schematic i get turned around.  I like to use the Omron g5v's. A little help?
If there's a harder way to do this, I haven't found it yet.

dogears

Re: stay at home type 69 project
« Reply #65 on: May 03, 2020, 01:02:01 AM »
I realized all the high shelf cuts were missing a ground connection. All updated.   :-[

dogears

Re: stay at home type 69 project
« Reply #66 on: May 06, 2020, 04:03:32 PM »
I have a layout with just the first gain stage (preamp) using a pot for testing. It's a brand new CP pot, but it's got some scratchiness when adjusting. Is that just a consequence of the way the NFB is applied with this design? Any tricks to address that?

ruffrecords

Re: stay at home type 69 project
« Reply #67 on: May 06, 2020, 04:43:01 PM »
I have a layout with just the first gain stage (preamp) using a pot for testing. It's a brand new CP pot, but it's got some scratchiness when adjusting. Is that just a consequence of the way the NFB is applied with this design? Any tricks to address that?
Possibly place a large value resistor (1 Meg) across the pot to ensure the electrolytic always has a dc path to 0V even if the wiper lifts a little. And/Or make sure you select a very low leakage electrolytic.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

dogears

Re: stay at home type 69 project
« Reply #68 on: May 15, 2020, 06:01:20 PM »
Edit never mind. User error.
« Last Edit: May 15, 2020, 07:12:52 PM by dogears »

letterbeacon

Re: stay at home type 69 project
« Reply #69 on: Today at 03:10:14 PM »
Thanks for this project - it looks great!

I don't really need another pre-amp, but I would love the EQ! Seeing as I have some old BBC 600:600 transformers, I was thinking of using one of those as an input TX and then feed that straight into the EQ part of the circuit and the line amp. I might use another 600:600 as the output TX or maybe just leave it unbalanced.

Where would be a good place to 'inject' the output of the input TX? At the junction of Q4 pin3 and C10?


dogears

Re: stay at home type 69 project
« Reply #70 on: Today at 04:04:50 PM »
Couple of options. You could pad the input, or you could use a very large resistor for the first stage gain (~220k gives you only 1.6 dB gain) and increase the gain resistor in the second stage slightly, to around 10k.  This would bring it back to unity gain through, with a minimal loss of headroom.

Actually you could also try it without a gain resistor at all, which should turn the preamp stage into basically a unity gain buffer.


 

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