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Post by Deleted on Nov 20, 2010 9:35:12 GMT
which caps could you offer? electrolytics too? I must make a part list over all ... PSU (2x), JLH (4x) and A class HA (2x) too Which manufactures are recommend for resistors film caps electrolytic caps other BJT's (BC...) for input caps I have some WIMA MKP4 10uF 100V 20% and WIMA MKT 10uF in my stock ... I must look in my »scrabble box« too  My preferred distributors in Austria are Distrelec, RS Components, Farnell (with low delivery costs) Hi Fritzs I'm thinking of the 2 x Suntan 4700uf 10v caps which replace the 2200uf 10v on the JLH, 2 per board so you are going to need 8 of those for 4 JLH.  if you want me to order you some let me know  i was also thinking that the smoothing caps on the reg will need to have a slightly higher voltage rating due to bumping up to the 18v TX. do we need to worry about the brand, quality and ESR of that cap or will any cap of reasonable quality do  my thoughts are that because that cap is behind the JLH it will be ''hidden'' (so to speak) from the amp circuit by the JLH. so still learning and open to advice on this.  if we need suntans i can put them on the order list. what do people think? take care Shaun I am glad you brought this up. The filter caps will need to be 35V for safety reasons when using an 18-0-18V toroidal transformer.. This brings a major problem. Most 2,200uF 35V electros are too large physically, and will need additional holes drilled because of the necessity to have them side by side. The new holes will need to have the masking scraped away to give clean copper for soldering. Then there is another problem in that the larger electros are likely to block off several of the diode mounting holes. I needed to relocate several diodes to under the PCB. Some brands of 35V electros are too tall to fit in a 1U rack case ! Due to size considerations, I had to use those from RS at the attached link,as other types were too tall for my 1 unit rack case.. Alex australia.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=571-230&x=19&y=14 |
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Post by Deleted on Nov 20, 2010 9:55:41 GMT
Good evening Alex How's it going yes i was wondering about the size of those caps. looking at the simplicity of the circuit i think i may retreat to good old vero and do a rebuild. space is quite tight on that board as it is. or how about putting some board pins in and mounting the caps off board on cap clips. if we keep the wires as short as possible most of the down sides to the extra wiring should be taken out by the reg and JLH. just a thought to prevent a bodger like me from messing the board up. (it's only a bit of point to point honestly guv) I'm still rapped in the SCHA by the way it's superb. take care |
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Post by jonclancy on Nov 20, 2010 11:30:31 GMT
Good point Alex. Panasonic FCs are smaller for given values than the Suntan caps. If anyone has missed it, the JLH Ripple Eater sale has opened at DIYA and there are around 56 boeards left available at the time of writing. These will go like hot-cakes, so don't miss out!!  Cheers Jon |
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Post by jonclancy on Nov 20, 2010 11:36:36 GMT
Annnnnnd, Jaycar UK will only supply at UK prices, which on many items is a lot less, if you use an UK delivery address BUT you will probably be hit by customs. If the order is big enough it is still worth it for the saving. Anywhere else in Europe and you have to use the mail order dept. in Australia. Yup, the UK prices are SIGNIFICANTLY cheaper than the Aussie ones, due to the strength of the Aussie $ against Sterling. IIRC, you can recieve up to £18 worth of goods before customs require VAT. Bare boards do not attract Duty payments, but I don't know about component kits. HTH Jon |
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Post by jonclancy on Nov 20, 2010 11:44:34 GMT
Doh, finally caught on that you are talking about the power supply filtering caps and not C4a/b on the Ripple Eater. Been there and done that as well with my adjustable Jaycar power supply. 2200uF 35V caps from BC (light blue ones). Diodes pre-mounted under the board. Other caps rated at 35V - small values = fit fine. I also use a trimpot on each channel to adjust voltage. WRT trafos, I like the quality of these in 15, 30, 50 and 80VA ratings. How much do we need?  uk.farnell.com/multicomp/mcfe080-09/transformer-80va-2-x-9v/dp/9531815 |
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Post by Deleted on Nov 20, 2010 11:50:54 GMT
Hi Jon
One 18-0-18 30VA is more than adequate.
If you want to squeeze a little more again out of it , use 2 of those in a larger external case as Will has done..
Alex
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Post by jonclancy on Nov 20, 2010 13:56:56 GMT
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Post by Deleted on Nov 20, 2010 14:55:39 GMT
I have just waded through the thread and have a couple of questions. Firstly, on the JLHs, do the caps have be to uprated from eg 4700uf 10v to a higher voltage of 16v?, when the 20v PSU is used? Secondly, have the Offset Correctors been incorporated on the latest main board or are they still seperate. Thirdly, if I have this right, the main "section" count is... 18v-0v-18 30va transformer (or x2 18v 15 or 30va in dual psu) psu (jaycar) board (x2 in dual) Dual JLH (x2 in dual) A Class boards x2 (Offset corrector x2 ?) Then all your chassis mount hardware, vol pot etc. Chris I was though, are these OK as is or need beefing up? Cheers. |
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Post by jonclancy on Nov 20, 2010 15:29:34 GMT
IIRC the C4a/b in the RE only see a few volts. However, the caps on the voltage rails need to be specced accordingly as they see full voltage.
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Post by PinkFloyd on Nov 20, 2010 16:00:22 GMT
Alex,
The panasonic FK series are slightly smaller than the FC / FM, you can get them at RS.
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Post by PinkFloyd on Nov 20, 2010 16:04:42 GMT
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Post by XTRProf on Nov 20, 2010 17:03:25 GMT
O.K. thanks, I expect it to deliver around 0.28W into an HD800 through the internal 68 Ohm output. Should you replace this resistor or add values to come to 120 Ohm it will give 0.22W into 300 Ohm. with 100mA the amp will be dissipating 4W per channel and the HD800 will always be driven in class-A the maximum output voltage will be around 11Vrms for this amp. In real life it will always be lower because of the output resistor. Fran, You are God, man! Let me brushed up on my rusty electrical maths to follow your work out as model answer. Before brushing up, what's the model answer of the equivalent wattage of this class A amp into 8 ohms? Pretty close to 15W, right? Definitely class A as the current drawn is less than 100mA. You should be a part-time lecturer in a technical insitute or polytechnic or university with your experience in explaining and illustrating things very well. You reminded me of my former polytechnic lecturers. Students will love you very much for your extra mile guidance. Thank-you Professor Fran ............. |
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Post by Deleted on Nov 20, 2010 21:52:48 GMT
Alex, The panasonic FK series are slightly smaller than the FC / FM, you can get them at RS. Mike Thanks. When I got mine from RS originally, the choices were very limited. Some more general items are aoften available from U.S. or U.K. stocks, but take longer to arrive. I am an impatient old bugger ! However, the FC not only look nice, they also perform very well in the PSU too. Alex |
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Post by Deleted on Nov 20, 2010 22:01:43 GMT
IIRC the C4a/b in the RE only see a few volts. However, the caps on the voltage rails need to be specced accordingly as they see full voltage. Jon is correct. There is actually a little under 600mV across the capacitors , irrespective of supply rail voltages.I find it best to use the larger 10V types because of their superior ripple current specifications.In my original builds I used quite small types. Some of these, years later showed deterioration , having domed tops. Alex |
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Post by jeffc on Nov 20, 2010 22:11:19 GMT
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Post by Deleted on Nov 20, 2010 22:46:06 GMT
Hi Jeff The choice mainly comes down to what you would be housing the HA in. Mine fits nicely inside a 1Unit rack case. The ist one would need modification, and seems to be quite tall.It should have the size of the input caps reduced to 2,200uF unless you are using a higher VA toroidal. The 1,000uF at the output should be reduced to 100uF also. The 2nd one does look nice, but don't forget you would need 2 of them. You would need to specify +-20V Are you baulking at the thought of drilling a Jaycar PSU PCB, possibly due to lack of a suitable PCB drill ? I could assist if this is a problem by making up a couple for you. Local P and P is reasonable, so no worries there. Regards Alex P.S. I just noticed that the 2nd one also uses 4,700uF filter capacitors. I wouldn't use a Jaycar 20VA toroidal with it . (Altronics etc. are 30VA typically) |
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Post by PinkFloyd on Nov 20, 2010 23:15:48 GMT
Alex, The panasonic FK series are slightly smaller than the FC / FM, you can get them at RS. Mike Thanks. When I got mine from RS originally, the choices were very limited. Some more general items are aoften available from U.S. or U.K. stocks, but take longer to arrive. I am an impatient old bugger ! However, the FC not only look nice, they also perform very well in the PSU too. Alex FC / FM are my favourite caps, they are consistent from batch to batch and beatifully made.... saw the top off one, quality  Very low ESR and good quality electrolyte they use.... most batches I have come across are made in Malaysia.... for some strange reason only the NHG series is made in Japan.... good SOLID caps (The Panasonic) with top quality electrolyte... the cheaper caps just don't measure up in the reliability dept. IMO and most of the el cheapo cap manufacturers haven't got the correct recipe for the electrolyte Think of Panasonic as Mrs Beeton and look to the likes of Suntan and Jamicon as burger waggons trying to recreate a classic dish.... I have researched capacitors in depth over the years and the Panasonic NHG / FC / FM are safe bets and will not suffer from premature "bulging" like some lesser caps. ELNA, Nichicon, Nippon, NIC, Rubycon (to name but a few) are also good reliable caps..... One relatively unknown cap I am extremely impressed with is the "Hitano"... their non polar caps are SUPERB and they come in a 105C package..... I actually prefer the sound of these to the MUSE or Black Gate equivalents and the Hitano only cost pennies www.x-on.com.au/datasheets/p021.pdf |
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Post by Deleted on Nov 20, 2010 23:32:18 GMT
Mike
Several of us still prefer the Suntan low ESR caps in the JLH because of their more neutral sound.
That is not normally a problem in the PSU itself where all the types you mentioned are more than suitable, dimensions permitting.They do however add to the cost of a project if you have to source them in addition to what is supplied in the kit. In this case, the 25V types supplied are inadequate when using an 18-0-18 toroidal, so it is definitely an advantage to use something better if ordering from RS etc.
Alex.
P.S.
I also have some lower value Hitano NPs in my stocks.
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Post by Deleted on Nov 20, 2010 23:37:37 GMT
IIRC the C4a/b in the RE only see a few volts. However, the caps on the voltage rails need to be specced accordingly as they see full voltage. Jon is correct. There is actually a little under 600mV across the capacitors , irrespective of supply rail voltages.I find it best to use the larger 10V types because of their superior ripple current specifications.In my original builds I used quite small types. Some of these, years later showed deterioration , having domed tops. Alex OK, Cheers guys. Chris |
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Post by jeffc on Nov 21, 2010 3:48:42 GMT
Will/Alex, I'm a bit confused here  . I note in Alex's amp picture, that there are PCBs supplied by 2 +/-V Jaycar PSUs feeding 2 dual JLHs. Each PSU could be supplied from a separate transformer, thus affording independent supplies for each channel I guess. So are 4 PCBs required for balanced input, 2 for single ended, or what am I missing. Please excuse my ignorance  cheers.. jeffc |
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Post by Deleted on Nov 21, 2010 4:46:07 GMT
Will/Alex, I'm a bit confused here . I note in Alex's amp picture, that there are PCBs supplied by 2 +/-V Jaycar PSUs feeding 2 dual JLHs. Each PSU could be supplied from a separate transformer, thus affording independent supplies for each channel I guess. So are 4 PCBs required for balanced input, 2 for single ended, or what am I missing. Please excuse my ignorance cheers.. jeffc Jeff Perhaps Will (?) is talking about the JLH PCBs ? There are 2 KC5418 type PSU PCBs required , and either 4 x Will & Jon/Alan JLH PCBs, or 2 x Greg Erskine type dual JLH PCBs that Aussie members still have access to F.O.C. (limited numbers) Like many others,(including well qualified people) I do not believe in balanced operation for normal domestic use. Alex |
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Post by Will on Nov 21, 2010 10:36:19 GMT
I think that Jeff is talking about JLH's in that quote. To make things simple (like wot I am ) here's a layout diagram, indicating traffo's, PSU, JLH's and amp boards, all for normal headphone use. I don't think anyone has gone 'balanced' with four amp boards. |
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Post by Will on Nov 21, 2010 10:45:08 GMT
Hi Chris,
Yes, the dc offset correctors are incorporated into the main pcb (bottom right section of the pcb in the picture.
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Post by Will on Nov 21, 2010 10:51:12 GMT
SC HA/Preamp - Background.Just to clarify a possible misapprehension : The original Class A amplifier.......*snip* Thanks for the background on your amp, very interesting |
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Post by Deleted on Nov 21, 2010 12:52:54 GMT
Hi Chris, Yes, the dc offset correctors are incorporated into the main pcb (bottom right section of the pcb in the picture.  |
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if you want me to order you some let me know 
. I note in Alex's amp picture, that there are PCBs supplied by 2 +/-V Jaycar PSUs feeding 2 dual JLHs. Each PSU could be supplied from a separate transformer, thus affording independent supplies for each channel I guess. So are 4 PCBs required for balanced input, 2 for single ended, or what am I missing.
