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Post by Deleted on Oct 9, 2010 3:54:10 GMT
Pete I have sent you an email with the Square wave response photos of the modified version. Alex
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Post by Deleted on Nov 4, 2012 12:31:37 GMT
Well, I just set up the SCHA, which I have not used for a couple of months. I had forgotten how GREAT it sounds! I do not have a Senn HD650 but I do have a Senn HD580 with a set of stock cables from an HD650 and I used it for these impressions. BTW, the source was a Meridian 506.20 cd-player and the I used the December 1976 recording of "Jazz At The Pawnshop". For those who do not know I personally do not care much for the HD650 sound and much prefer the HD580/600 presentation. I also listen at very low levels and even though my SCHA has a low gain of around 2-3 I do not go higher than 9 o'clock on the volume pot of the SCHA. BTW, zero volume is at 6 o'clock and I use an stepped attenuator, that is about 5 to 7 clicks to go from 6 o'clock to no more than 9 o'clock. The sound is fast, very fast with excellent micro-detail and it renders the note to note transition with crispness and smoothness. The hi-hat notes on the end of Limehouse Blues are so detailed/realistic it feels like you have a drummer playing next to you. The overall presentation is dynamic and very articulate with no harshness to speak off. The clarinet at the beginning of I'm Confessin' is so mellow yet the notes cut right through that if I closed my eyes I feel like I am in an small jazz club listening to live music. Hope this short impressions help. Miguel Thanks. That should help. BTW, if you want a little more oomph at the very low end, then you should replace those 4 x 2,200uF electros in the SC HA JLH with low ESR 4,700uF 10V types , and give 48 hours for the electros to fully form. Regards Alex By replacing those 4 x 2,200uF with low ESR 4,700uF 10V types, will that subtract at 'something' else? I do tend to like my music with some punchy bass. Especially since my headphones can supposedly go down to 5Hz.
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Post by Deleted on Nov 4, 2012 19:30:51 GMT
Hi Vince. All recent JLHs used for analogue , except for those that need to use the Current Limiter section, use a 4,700uF 10V low ESR in parallel with a normal 4,700uF 16V It increases the simulated PSU capacitance from about .5 FARAD, to 1 FARAD. JLHs used purely for digital areas can use 2 x 4,700uF 10V low ESR in parallel. If you use 2 x 4,700uF 10V low ESR in parallel for analogue, the sound can be a little too etched sounding and ultimately fatigueing. Alex
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Post by Deleted on Nov 5, 2012 1:06:16 GMT
So you'd recommend to sticking with the recommended 4x2,200uF caps instead?
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Post by Deleted on Nov 5, 2012 1:35:25 GMT
So you'd recommend to sticking with the recommended 4x2,200uF caps instead? No. The SC HA uses the JLH with the Current Limiter section at the LHS of the schematic bypassed. I would recommend using a 4,700uF 10V low ESR capacitor in parallel with a normal 4,700uF 16V capacitor on both supply rails, although the 2,200uF 10V low ESR in parallel with a 2,200uF 16V will sound almost as good. Using 2 x 2,200uF 16V in parallel will likely result in a smidgin less HF detail, and perhaps a slight loss of very LF punch.You can vary these things to fine tune the result you want.
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Post by Deleted on Nov 5, 2012 12:50:34 GMT
So you'd recommend to sticking with the recommended 4x2,200uF caps instead? No. The SC HA uses the JLH with the Current Limiter section at the LHS of the schematic bypassed. I would recommend using a 4,700uF 10V low ESR capacitor in parallel with a normal 4,700uF 16V capacitor on both supply rails, although the 2,200uF 10V low ESR in parallel with a 2,200uF 16V will sound almost as good. Using 2 x 2,200uF 16V in parallel will likely result in a smidgin less HF detail, and perhaps a slight loss of very LF punch.You can vary these things to fine tune the result you want. Ah okay. Your post in the tweaks thread suggests to use 2200uf caps and so does Greg's websites suggests the same too. Okay i'll hunt for 4,700uf 10v low ESR caps. And when you say normal 4,700uF 16v Capacitors do they replace C5 and C105?
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Post by Deleted on Nov 5, 2012 16:52:40 GMT
Vince It's called progress. The original published design only gave details for up to 100mA of current. The original design always used the Current Limiter section with Q6 and Q106.The SC HA is able to use the internal current limiting of the voltage regulators in the PSU PCB ,thus permitting bypassing/removal of Q6 and Q106.This permits us to improve the JLH current capability to as high as 2A, and double it's simulated capacitance to around 1 FARAD. ONLY C4a,C4B, C104A and C104b are altered. C5 and C105 remain 100uF 25V. To recap. For the SC (Jaycar) HA, my suggestion is to use 1 x 4.700uF 10V low ESR and 1 x 4,700uF 16V for C4a and C4b, and 1 x 4.700uF 10V low ESR and 1 x 4,700uF 16V for C104a and C104b.
Alex
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Post by Deleted on Nov 5, 2012 21:18:03 GMT
Vince Your completed JLH should look like similar to the attached photo, as the Current Limiter section is not used with this HA . Wire links should be soldered between the points highlighted. Alex Attachments:
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Post by Deleted on Nov 6, 2012 3:34:06 GMT
Thank you very much for making things more clearer for me. I really appreciate Should be expecting the parts to arrive by late next week.
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Post by Deleted on Nov 8, 2012 13:52:46 GMT
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Post by Deleted on Nov 8, 2012 20:54:47 GMT
Vince They should be O.K. However, why are you going to all that trouble when you could pop into a local Jaycar store in Melbourne and get suitable caps and most of the other bits including the terminal blocks at the same time ? The only harder to get bits should be the BC550c,BC560C, 2SA1930,2SC5171 and 4 x 2.2uF. Even with the 2.2uF, they can be replaced by these. www.jaycar.com.au/productView.asp?ID=RM7170&form=CAT2&SUBCATID=967#1Regards Alex
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Post by Deleted on Nov 8, 2012 23:26:10 GMT
I'm not fussed waiting for the items to arrive in the mail. I also combined my order with my friend to take the sting out of $39 flat rate shipping.
Pretty much ordered every specified component for the JLH, PSU diodes, and mods for the SCHA. Except the for the 68ohm 1 watt output resistor. Mouser didn't have any metal film types on hand, so i'll have to go to Jaycar for that.
Cheers, Vince.
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