|
Post by gommer on Feb 25, 2013 7:08:57 GMT
Thanks Alex, things are starting to get clearer for me now. I'm not much a an amp designer, I guess it shows.
Cheers, Marc
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 25, 2013 18:16:35 GMT
Hi Guys anyone looking for cheap but good quality transformers 240v primaries and 2X 18V secondaries should take a look here. uk.farnell.com/jsp/search/productdetail.jsp?sku=1675067&CMP=i-bf9f-00001000the what looks identical dual primaries are twice the cost and 30VA or 50VA versions are both more expensive. 80VA is just a little bit over kill for the HA/PRE but i had one already in the parts box so getting another for £10 or so seemed like a good deal and keeps my wife happy that there is less stuff spilling out of draws. so a win win nothing wrong with over spec IMHO. take care
|
|
|
Post by gommer on Feb 25, 2013 18:56:14 GMT
That's absolutely ridiculous (not your find though). If you select 2x18V then order by price, 80VA comes out cheapest of all, even 3,2VA is more expensive, lol. It's a pity these are too heavy to be sensible in the group buy. I'll sure be ordering some.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 25, 2013 22:48:26 GMT
Hi Marc Yes my thoughts exactly. I was just trawling through farnell and did a search for 18V transformers and scrolled down all seemed about the normal price and Hey what’s this £10 ish I had to rub my eyes a little. Yup a little over spec’d but for the price well I ordered one to go with the trafo that I have in hand just in case they had made a mistake. Those babies won’t even break sweat at the current required. I used the 80VA encapsulated transformers for my last build and they were waaaay more expensive than these but run coooool. Over spec’d yes But hay ho cheap as chips. Hard to work out the pricing on that trafo but who cares? Take care
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 26, 2013 13:36:19 GMT
Hurump
My £10 transformer arrived from Farnell this morning and is indeed identical to the £20 dual secondary’s one that I have already except that the cheapy has 240 secondary’s only .
So good news
Size wise I’ve placed it next to a 50VA one and it’s hard to spot the difference.
So having looked at the specs the only difference seems to be country of manufacture with the cheapy coming from China and the expensive on from somewhere else. So good to go on that front.
Hope that helps save a little cash
Take care
|
|
|
Post by gommer on Feb 26, 2013 13:42:52 GMT
Hi Shaun, were they with mounting accessories included?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 26, 2013 20:06:23 GMT
Hi Mark yes rubber pads dish clamp and bold all included. i just don't know how they do it for the price. but i can guess which takes the shine of just a little . good value transformer mad low price take care
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 27, 2013 0:34:48 GMT
Hi Marc
I’ve just had a quick look through your parts selection and noticed just one alteration that you may want to make.
68pf I’m pretty sure that we used a polystyrene cap in that location last time for improved HF response.
also that zener diode that Will mentions in his post after your list. i think that we used BZX55 3V3 in that spot.
But maybe someone can confirm the above
Good work though
Take care
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 27, 2013 0:49:58 GMT
Hi Marc I’ve just had a quick look through your parts selection and noticed just one alteration that you may want to make. 68pf I’m pretty sure that we used a polystyrene cap in that location last time for improved HF response. also that zener diode that Will mentions in his post after your list. i think that we used BZX55 3V3 in that spot. But maybe someone can confirm the above Good work though Take care Hi Shaun Not ceramic for the 68pf. Silver mica is good too for CDOM according to David2vk The BZX55C3V3 needs far less forward current and is what S.C. used originally. I have plenty, but unfortunately J.C. may not be Downunder again for a while. Regards Alex
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 27, 2013 11:04:34 GMT
Hi Marc I’ve just had a quick look through your parts selection and noticed just one alteration that you may want to make. 68pf I’m pretty sure that we used a polystyrene cap in that location last time for improved HF response. also that zener diode that Will mentions in his post after your list. i think that we used BZX55 3V3 in that spot. But maybe someone can confirm the above Good work though Take care Hi Shaun Not ceramic for the 68pf. Silver mica is good too for CDOM according to David2vk The BZX55C3V3 needs far less forward current and is what S.C. used originally. I have plenty, but unfortunately J.C. may not be Downunder again for a while. Regards Alex Hi Alex Yes Polystyrene or silver mica would be good in that spot with the silver mica’s possible sounding a little better. But no ceramics in audio circuits please. Just as an aside I used Suntan 100uf for the psu decoupling caps on my last build (C5/C8/C7/C11) but was thinking of trying Panasonic FC this time around. I tried Panasonic FM last time but to me the Suntans sounded a little smoother which I preferred. Any thoughts on those caps? Take care
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 27, 2013 11:21:09 GMT
Hi Shaun The Panasonic FC sound ideal. The FM have around 1/3 the impedance at 100kHz , so the FC seem a good choice. IIRC, I am using Panasonic FC for the main filter caps in the Jaycar PSU PCBs for my HA/preamp. Kind Regards Alex
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 27, 2013 11:40:04 GMT
Hi Alex Yes I have the same FC caps in my PSU and JLH OP caps and plan on using 4700uf FC bypassed by a standard (not low ESR) 4700uf for the JLH. I’m still waiting on the film caps but this should give a general idea. Take care
|
|
|
Post by gommer on Feb 27, 2013 11:54:38 GMT
Cheers Shaun and Alex, all good info. Will update parts as soon as I have a chance.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 27, 2013 22:40:40 GMT
Hi All Just a quick clarification for those about to build Greg’s lovely double JLH boards for Alex’s class A HA/PRE. The 4700UF 10V electrolytic caps mentioned earlier in the thread are replacement values for the 2200uf listed in the schematic. I’ve outlined the said caps in red Taken from Greg’s web site (hope that’s ok) The value was changed for non CL use due to a perceived increase in bass quality with the 4700uf in place. Hope that helps a little take care
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 2, 2013 11:11:38 GMT
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 2, 2013 12:19:11 GMT
Hi Alan That looks like a serious switch with nice big contacts at a great price. Well found. A few more pictures Will’s Regs Really nice boards to work with and super quality. So component t wise I have UH4004 for the bridge (saving my last two SF12 for you know what) U5/6/7/8 IN4007 C1 470pf 100V C2/3 2200UF 35V low ESR C3/8 10UF 50V Suntans . Sorry about the leaning tower of power on the photo. C4/6 100UF 50V Panasonic FC. R1/4 100R ½ W R5/6 Unpopulated R2/3 2K bourns type multi-turn trimmers Regs are LM317/337 Not the only way to do things and in no way an exclusive list. Greg’s JLH What I generally do is after HFE matching the BC550C/BC560C pairs I’ll build up as many boards as I have pairs which saves the component disappearus which can happen here. Four boards worth in this case. With current limiter fitted and 2200uf 25V Panasonic FC. I used 25V because that’s what I had in stock but 10V is good enough in that spot. So now a quick board clean up and test. Then I’ll be leaving those babies powered for the next week to help those C4A/B and C104A/104B to form. I’ll give them the old on/off cycle twice a day which helps. Then I’ll mothball them until needed. All good Take care
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 2, 2013 16:53:32 GMT
Hi All Here is my Miss Modular (Austin Healy) transformer box. As I have more building work scheduled in the spring which could leave me out of action DIY wise for 3 months maybe 4 I thought that I may as well push on a little. Here is my Transformer box with the cheap £10 jobbie on the right For the cannon sockets I’ve used female for the transformer end. That way even if it’s switched on there is very little possibility of getting a shock. With male sockets it could be ouch time. And the front just for completeness. Take care
|
|
pingu
Been here a while!
Reallising what has been taken on with the GB
Posts: 332
|
Post by pingu on Mar 6, 2013 12:46:49 GMT
Hi Shaun, Nice pix, very shinny case. Why have you left R5 and R6 out on you PSU BTW? I am looking for the build manuals for the PSU and the HA have you any ideas? All The Best Martin
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 6, 2013 17:54:29 GMT
Hi Shaun, Nice pix, very shinny case. Why have you left R5 and R6 out on you PSU BTW? I am looking for the build manuals for the PSU and the HA have you any ideas? All The Best Martin Hi Martin the case is a cheap and shinny one from Maplino's. it won't stay shinny for long. R5/6 are for running a resistor in parallel with the trimmer so that any value (within reason) of trimmer can be used and then set to the correct value with the parallel resistor. I had 2K trimmers so no need for the set resistor. The closest we have to a build manual (apart from reading through the thread) is Will’s superb guide found here. rockgrotto.proboards.com/thread/3977?page=40#My advice would be to have a read through the SC Class A build thread as it has a wealth of useful information from people who have already build Alex’s superb HA/PRE. I still have a read through it from time to time as it’s an interesting thread. Found here rockgrotto.proboards.com/thread/3977/sc-classa?page=1#As for a build guide for the PSU REG it’s pretty similar to the Jaycar PSU we talked about but with the trimmers for voltage setting. It’s a standard dual voltage reg based on the LM317/337 three pin adjustable voltage regulators but a really nice board and layout. So no build guide as such but I’m sure that we can get you through it just ask questions on the reg or SC Class A. Take care
|
|
jonclancy
Been here a while!
Mr. Ripple Eater
Amateur EAGLEist
Posts: 1,131
|
Post by jonclancy on Mar 6, 2013 22:27:52 GMT
Shaun, that looks the Dog's... We have nearly the same approach - but I have Will's regs going in my trafo box. Nice one.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 6, 2013 23:11:14 GMT
Shaun, that looks the Dog's... We have nearly the same approach - but I have Will's regs going in my trafo box. Nice one. Hi Jon Thanks for the kind words and yes my transformers are in a box But The comparison to your precisely engineered work ends there I’m afraid. Rolls Royce to Austin Ruby again Jon Take care
|
|
pingu
Been here a while!
Reallising what has been taken on with the GB
Posts: 332
|
Post by pingu on Mar 10, 2013 14:22:22 GMT
Hi, Can anyone pls enlighten me. I have Shuan's PSU boards, can I use 4 x IN5822 diodes for the input retification. (I have some of these from a friend) They are 40v 3amp schottky diodes or must I use the uh 4004 diodes ( but I can not seem to find them at the mo). Any advise gratefuly accepted. Martin
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 10, 2013 21:34:03 GMT
Hi, Can anyone pls enlighten me. I have Shuan's PSU boards, can I use 4 x IN5822 diodes for the input retification. (I have some of these from a friend) They are 40v 3amp schottky diodes or must I use the uh 4004 diodes ( but I can not seem to find them at the mo). Any advise gratefuly accepted. Martin Martin SF11 or SF12 are good, and what I am using there in the Jaycar PSU . UF4002 to UF4004 will also be suitable. The voltage ratings of the 1N5822 are a little low here. Regards Alex
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 10, 2013 21:56:20 GMT
Hi, Can anyone pls enlighten me. I have Shuan's PSU boards, can I use 4 x IN5822 diodes for the input retification. (I have some of these from a friend) They are 40v 3amp schottky diodes or must I use the uh 4004 diodes ( but I can not seem to find them at the mo). Any advise gratefuly accepted. Martin Hi Martin While I’d just love to take credit for the PSU boards that I sent you with their slick layout and thick copper loveliness. I can’t The boards are the work of Will (board master extraordinaire) who is a member of this forum and responsible for a number of high quality boards. On the Diode front As Alex has mentioned many including myself have used the SF11/12/14 range to good effect with Alex’s design. I used UF4004 from my parts box as an OK alternative. The SF range are good but getting a little hard to find (Farnell have SF14 I think) but UF range will be ok UF4002 to 4004 will be ok . For diodes U5/U6/U7/U8 nothing special required and any of the IF4001 to 4007 is a good choice. I agree with Alex’s comments re the 5822 which may not be the best option in that spot. Take care
|
|
pingu
Been here a while!
Reallising what has been taken on with the GB
Posts: 332
|
Post by pingu on Mar 12, 2013 11:30:43 GMT
Hi Alex, Shaun,
Thanks for the help. I have now located the diodes SF11/13/14 but no SF12 so I will go with the SF14's they a cheap enough to buy a quantity @ only a few pence each.
Shaun,
Sorry didn't mean to credit you with the boards, also big apolls to Will (they are really nice piece of kit), I just meant the ones you kindly sent me .... oops Thanks both bits on order Martin
|
|