Hello,
After some help sourcing parts please. Have bought the PCB from the Signal Transfer Company and require to source the parts for the switch banks. The information supplied with the PCB lists (I think) Signal Transfer Company's own part numbers and state that only they can supply. I have Emailed Douglas and he said that this would be altered. In the meantime, I need to obtain the manufacturer and their part numbers so that I can approach them directly for supply of same. Would appreciate any pointers you may be able to give on this.
Thank you
Neil
After some help sourcing parts please. Have bought the PCB from the Signal Transfer Company and require to source the parts for the switch banks. The information supplied with the PCB lists (I think) Signal Transfer Company's own part numbers and state that only they can supply. I have Emailed Douglas and he said that this would be altered. In the meantime, I need to obtain the manufacturer and their part numbers so that I can approach them directly for supply of same. Would appreciate any pointers you may be able to give on this.
Thank you
Neil
Thanks Rayma, I have since heard from from Douglas who has given me Gareth Connor's email address and stated that Gareth would be happy to supply the said switches. I have not had a reply to my Email to Gareth. I do not want to be left in a position whereby I have made a significant investment in purchasing the PCB and 737 transistors only to fin that I cannot complete it due to either (a) lack of supply of physical switches from the Signal Transfer Company or (b) the manufacturer detail necessary in order to be able to approach the manufacturer directly.
OK, my account here was suspended due to inactivity. In answer to the question regarding the switch bank, this was supplied by Gareth Connor of the Signal Transfer Company. I do not know how many units he has in stock. Prior to knowing that he could supply, I had approached the switch manufacturer and discovered that (a) these switches are no longer manufactured and (b) in order to start manufacturing they needed a purchase order for 10,000 units. I thought about that for at least 1nS and decided it was not an option. After many enquiries/searches I was able to establish that a suitable case was available from Holt Broadcast in the UK. However, this left the problem of getting the front and rear panels machined. I contemplated doing this by hand but with the limited facilities I have available came to the conclusion that I would not be able to do this sufficiently accurately to make a decent job of it. I approached two CNC companies for quotes and was given prices of over £500 Sterling. In the end I invested in a CNC machine myself, learnt how to use the appropriate SW, meticulously spent hours transferring dimension data for the panels from the published drawings into the SW, hours spent learning enough of the SW to craft the oval shaped switch bank holes, built a bench to house the CNC, learnt how to use the CNC and after many prototype cuts in blank aluminium plates have finally arrived at the point where I have cut the panels supplied with the Holt Broadcast case. I am very happy with the result. However, I hear you ask, what about the graphics for the panel? Before deciding to get a CNC, I had already approached a company who can produce acrylic panels that can be fixed to the aluminium panels.....I am visiting today to test whether this will provide an acceptable solution. However, for future projects (and now that I am able to cut the holes), I am investigating the purchase of advanced CNC SW that will allow me to design and engrave the panel graphics directly. Given all of this, you will appreciate why I have been absent from here for so long. I hope you find this of use.
Unfortunate about your account, but at least it’s great news to hear you were able to overcome the switch problems. Do you have images and measurements of the switches? I’ve read about a slightly similar situation prior.
I relearned the use of CAD after a medical emergency during the Covid-19 era, and ended up getting two front panels made. One is also for a different Doulas Self preamp. It would be great to see yours, when you are ready for the grand reveal.
I’d sought to get a CNC for woodworking. I had reached out to a local fellow that built his own (PrintNC), but he was so involved in his electric boat project that he hadn’t the time to build another. I have to admit that I was a bit overwhelmed as to how to choose parts and start such a build.
I relearned the use of CAD after a medical emergency during the Covid-19 era, and ended up getting two front panels made. One is also for a different Doulas Self preamp. It would be great to see yours, when you are ready for the grand reveal.
I’d sought to get a CNC for woodworking. I had reached out to a local fellow that built his own (PrintNC), but he was so involved in his electric boat project that he hadn’t the time to build another. I have to admit that I was a bit overwhelmed as to how to choose parts and start such a build.
Thankyou. If you look closely at the front panel, there is an error on the text of the Tone Defeat script being as it is too low in comparison to the rest of the oval switch openings. Annoyingly, this was discovered by the maker of the label just as he brought it me which will necessitate another trip to collect the final panels.
The label was made by a sign making company which, incorrectly, conjures images of hand painted shop signs etc. On the contrary, it is all very high tech. Understand what you mean by the small error but, the way I view it, if you have spent a significant amount you need to iterate until it is right.
I don't think Douglas had applied that terminology yet (please correct if wrong). The answer will come from his book 'Self On Audio' third edition. Blameless seems to apply to his later power amplifier designs. However, if the pre-amplifier works (assuming no mistakes on my part - I have already found two) as designed then I shall certainly apply the moniker 'Blameless'.
The mistakes were found as a result of initial power up testing (as described in the constructors notes) without the corresponding switches with LEDs fitted whereupon it became evident that the LEDs worked but that the power up delay was not working. The faults discovered were (i) missing resistor R205 (ii) one of the pins in the male plug in power connector from transformer to PCB had not clicked into place and was not supplying AC from one half of the transformer to the board.
The mistakes were found as a result of initial power up testing (as described in the constructors notes) without the corresponding switches with LEDs fitted whereupon it became evident that the LEDs worked but that the power up delay was not working. The faults discovered were (i) missing resistor R205 (ii) one of the pins in the male plug in power connector from transformer to PCB had not clicked into place and was not supplying AC from one half of the transformer to the board.
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Rather than reply individually to those asking about SW and whether CAD files are included note the following:-
(a) With PCB purchase, DXF files are included for both the lettering and case. Note, however, that the case for which these files are applicable is no longer available (it took me weeks to determine that fact) and so you will have to apply the dimensions to your chosen case.
(b) The CNC SW will be personal to yourself; you will have to try the free versions yourself until you find a SW that you can get on with and which is compatible with your CNC router. That process took me many weeks. Good luck.
(a) With PCB purchase, DXF files are included for both the lettering and case. Note, however, that the case for which these files are applicable is no longer available (it took me weeks to determine that fact) and so you will have to apply the dimensions to your chosen case.
(b) The CNC SW will be personal to yourself; you will have to try the free versions yourself until you find a SW that you can get on with and which is compatible with your CNC router. That process took me many weeks. Good luck.
Well, it's not boxed up yet but I have tested using first 'scope and finger input making sure there are finger outputs from all source inputs. Then (not the best source) YouTube Music from phone into CD input and on into a home built (not very good - gets too hot) amplifier with six individual amplifiers (one for each driver) fed via Lipshitz filters and.........it sounds amazing.