Spirit
Been here a while!
That's where I'm gonna go when I die
Posts: 1,107
|
Post by Spirit on Feb 6, 2009 21:17:00 GMT
Reminds me of a fire engine. It's fantastic
|
|
Will
Been here a while!
Ribena abuser!
Member since 2008
Posts: 2,164
|
Post by Will on Feb 7, 2009 10:11:13 GMT
Superb case and build! Where did you find it? It doesn't look like a hammond...
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 7, 2009 22:36:21 GMT
Many thanks for the kind words! I have to admit I'm quite chuffed with it. Wilbur, 'fraid you can't buy the case, I cut and formed it myself from 1mm steel for the chassis and lid, and 3mm steel for the front and rear panels. The controls come from my musical parts bin, as do the snare lugs. I've left it running since I last posted, I'm listening now from Atrac files into AKG 280 s. Not the greatest test but still sounds very smoooooth indeed, everything is there with no nasties. Just one thing to check, I find I'm listening with the volume at between 2 and 4 o'clock (as apposed to 9-11 on xcans/ming da), is that correct? OR have I suddenly gone deaf
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 7, 2009 23:16:25 GMT
Chris As long as you are able to get maximum useable volume with the setup you are using, this is not a problem. It is an advantage, as it maximises the signal to noise ratio , because there is far less attenuation of the input signal before amplification. It also permits more available -VE feedback, which is normally a good thing. I have also been trying to explain this to Miguel. The Rudistor has a gain stated as : Inputs: 1 x Analog, RCA- Gain: 15 db This is substantially higher than the standard SC HA gain of 6dB, and would explain why the volume control setting is much lower. Manufacturers normally provide higher gain than desireable, to cover the requirements of all customers, some of whom may have relatively low level source material. Increasing the gain of the SC HA is covered in the photocopy supplied with your kit. I have not posted it due to copyright reasons. If you need this information, send me a PM. Alex As an aside, the 24 position DACT2 attenuator, when on the 12th step, has 30dB attenuation (!!!) This means that ultimate signal to noise ratio is not achievable unless system gain is reduced.
Perhaps RobertKD would care to make some comments about the highly misunderstood area of volume control settings.. ?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 7, 2009 23:30:50 GMT
I'd forgotton about that adjustment in the jaycar copies. That is a huge change tho'.
As my unit is not running with the intended kit yet, I'll hold off until it is. As you say, at the mo' no probs, just surprised.
Cheers Chris
edit for P.s. Glad it is a positive feature!
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Feb 7, 2009 23:46:18 GMT
Yes very nice Chris, I think the red and the brass look quite stunning together. The first prototype with a tile also has some attraction maybe not with the bold red statement of the case, it's also damn difficult to work with as well
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 8, 2009 1:10:36 GMT
Chris You don't need to go that far. For example : If R1 and R4 are currently 1Kohm, then a modest increase in gain (from 2 x to 3.2) will be obtained by replacing them with 2.2K ohm Metal Film resistors.
Alex
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 8, 2009 1:22:21 GMT
Chris You don't need to go that far. For example : If R1 and R4 are currently 1Kohm, then a modest increase in gain (from 2 x to 3.2) will be obtained by replacing them with 2.2K ohm Metal Film resistors. Alex Duly noted and thanks. Chris
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Feb 8, 2009 1:24:16 GMT
Alex is spot on, the position of the "volume control" is somewhat arbitrary! Indeed if you have the pot at a higher (more clockwise) position for a given listening level then all things being equal the system will have a lower noise figure. Interestingly recently I added an "el cheapo" DAC based on the PCM1793 (which I am certainly warming to!) using an ALPS 50K my preferred listening level is between 10 and 12 o'clock depending on the original material level. But that is completely relative to the drive (voltage) level from the source the impedance of the headphones and the sensitivity of the headphones, the overall gain of the system and how loud I like my music. So apart from the position the knob points, I assume there is like a heap of drive left even for the k701's if so I would leave the SCHA gain where it is and enjoy the music PS if the knob position is really messing with your psyche, undo it rotate the knob back to you preferred position and set it there Robert
|
|
Will
Been here a while!
Ribena abuser!
Member since 2008
Posts: 2,164
|
Post by Will on Feb 8, 2009 10:37:27 GMT
Wilbur, 'fraid you can't buy the case, I cut and formed it myself from 1mm steel for the chassis and lid, and 3mm steel for the front and rear panels. The controls come from my musical parts bin, as do the snare lugs. That, Sir, makes it all the more impressive! Excellent!
|
|
Spirit
Been here a while!
That's where I'm gonna go when I die
Posts: 1,107
|
Post by Spirit on Feb 8, 2009 12:08:03 GMT
PS if the knob position is really messing with your psyche, undo it rotate the knob back to you preferred position and set it there Robert Sound advice
|
|
|
Post by corky on Mar 6, 2009 14:06:47 GMT
Hi all, long time lurker, first time poster. I've had my HA for some years now. I did things a little different, namely using MJE15030/31’s for output transistors and LM4562. But after thinking about it for ages i finally got around to building a JLH. That along with getting rid of the RLC, fuses etc. To be honest i have't really noticed too much difference, maybe a little more clarity? Doesn't matter, i enjoyed it and it has laid the obsessive compulsive beast within me ...well for now anyway. Am i crazy in thinking about making a balanced SCHA?!? The cases are 2 external CDROM units and yes i do realise i wired up the channels wrong Edit: OK maybe you can't see that i have hooked up channels wrong, and the LM4562 isn't different, joust the OP transistors.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 6, 2009 20:49:26 GMT
corky Very interesting build. I think your JLH may be holding you back a little . Why the big filter caps in place of the 100uF 25V ? Normal Jaycar electros are ideal there. Elna Starget 100uF 35V also work well there. These caps,and their value, will influence the SQ. Also, if your differential pair transistors are fairly well matched, try fitting the added 2K7 resistor as discussed in the Tweaks thread. Not an earthshattering difference, but worthwhile on all the JLHs I have constructed. I have since retrofitted these resistors to earlier JLHs that I have in other audio gear, with improved results on all occasions. (I have been playing with JLHs for >10 years) Are the 2,200uf caps you are using Jaycar's Suntan CD286 caps ? They look a blue colour in the photo,instead of black. The reason for using the Toshiba devices in the HA, was that they typically have an HFE close to 200, which presents a much reduced load to the LM4562. Also the 2SA1930/2SC5171 have an Ft of around 200MHZ compared to 30MHZ for the MJE devices. What happened to the 100nF bypass capacitors for the I.C. ? Do you have an alternative bypassing scheme under the PCB ? Alex P.S. The importance of component types in the JLH is discussed in the attached link starting at post 77. See also,post 99. www.diyaudio.com/forums/showthread.php?s=&postid=1559279#post1559279
|
|
|
Post by PinkFloyd on Mar 6, 2009 22:16:33 GMT
Look like 100uF ELNA Cerafine to me ;D
|
|
|
Post by corky on Mar 7, 2009 3:19:18 GMT
I love the dual case build! Do not understand why two umbilical cables between them? Heh, yeah the other is for the LED. I didn't really plan well enough, only 4 core in the main one (+15, -15, gnd, earth for the enclosure). the caps on the JLH are WES low ESR ones. The big arsed 100uF ones are elna cerafine (well picked pink floyd!!). The cerafines again are from WES, i had them lying around so i thought why not, even if they are 100V They do get in the way of the bc639/40's. Had to get a little creative.
|
|
|
Post by nickyboyo on Mar 7, 2009 22:49:49 GMT
|
|
Spirit
Been here a while!
That's where I'm gonna go when I die
Posts: 1,107
|
Post by Spirit on Mar 8, 2009 8:57:35 GMT
Looking good Nick Blank PCB arrived yesterday. Just waiting on the photo paper I've ordered from the States. Should be here by mid week, so should have a JLH for you by the end of Sat.
|
|
|
Post by nickyboyo on Mar 8, 2009 10:02:19 GMT
Great news Phil, keep me informed mate of how much i owe you and i will fix you up
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 8, 2009 14:55:44 GMT
meh still a work in progress Robert
|
|
|
Post by rossman on Mar 9, 2009 11:24:21 GMT
My rebox of the SCHA from SandyK which was given to me while I was in Aus last year for those that haven't already seen it in the main SCHA thread. [img src=" i474.photobucket.com/albums/rr101/rossman1965/Picture131-1.jpg"][/img] This is my own build from scratch. All enclosure parts are recycled from other bits of kit. Wiring and layout is a bit messy because I messed up and drilled the holes for the pot and switch the wrong sides of the front panel.
|
|
|
Post by rbrook on Mar 15, 2009 13:03:15 GMT
Finally got the camera out. Not the final layout still need to fit in the JLH when it arrives and finish off the front panel.
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 15, 2009 13:08:32 GMT
Finally got the camera out. Not the final layout still need to fit in the JLH when it arrives and finish off the front panel. Hi Richard, well very frelling nice like the LCD VU meter excellent Robert
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 15, 2009 13:46:49 GMT
pfft mmm
|
|
|
Post by rbrook on Mar 15, 2009 14:15:44 GMT
Ha Ha !
Is that one you prepared earlier?
If you want to mount the LCD away from the board i found an old Floppy drive cable did the trick just fine.
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 15, 2009 14:29:22 GMT
Ha Ha ! Is that one you prepared earlier? If you want to mount the LCD away from the board i found an old Floppy drive cable did the trick just fine. well I was thinking of it as well ha also I like the magnetic shielding, you have put some thought into this haven't you the only other "extra" thing I could think of is a DAC, have a look at Jeff's or other DAC modules out there. ;D Robert
|
|