| joho |
Hi Gents,
At the moment i'm working on a Aleph1.7 printboard design. My gool is a dual mono design compleet with dual supply,input relais,muting relais and the original shunt volume regulation.This all together on one dubble sided board (A4 format).
It's almost finisshed but there is a little space left for a record output buffer.
I want to use the original 60V supply because it's already avalable on the board.I did some research on the web and found two options and a variation on option 2. I build them like a "christmas tree" and did some measurement.They function well and the idle current for option 1 is 20mA and for option 2/3 5mA. I think option 1 is the best but a little overkill for a rec.out buffer so i concentrate on option 2 and 3. Also the space aspect on my printboard counts.
The problem with option 2 and 3 is the high supply voltage. Esspecialy the 2sj70(Uds 25v max) could be a problem. I try it with 60v supply voltage and it keeps working but i have a bat feeling about it. What to do ? use a pre-regulator ?(extra space on the board).
I few questions ;
Has it any sense to use the source resistors(10R)in option 3 ?
I can shift the working point by changing R11/R20 to 100k so that should be better for the 2sj70 but is it allowed for such a sourcefollower design ?
What is the output impedance of option 2/3 (5mA)?
Other idee's ?
Best regards,
Johan. |
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| joho |
Hmm. not much response for some serious questions. Maybe my Englisch is too bad.
O.k. here we go. I spoke to our local guru and he said don't use that drain resistor, it's bad for the output impedance so i use the pre-reg. to reduse the voltage to 30 volts.
See rec.out buffer rev1.
I implement this circuit on the main Aleph board and afterwards i had just enough space.
By the way , i found some image export possibility in Eagle so no screenshots anymore.
follow up.
Johan. |
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| joho |
Here is a complete Aleph 1.7 board. The most partnumbers refer to the original Pass design.The only difference is the relais supply,a unbalanced rec.out buffer and input relais on the main board.
At this moment i'm using one of the famous boards from Kristijan. The board sounds good and for a single-sided design the placing of the components is almost perfect.
Like the most bloody minded electronic-freaks, i wants to use my own choice of components and give a design my own signature. It's as the famous Dutch compagny said; Let's start(try) to make things better.
A few months ago there was also a 1.7 design made by a guy from Finland. That printboard gave me realy some serious inspiration and was the start for the final result. My gool was to make a complete all in one dual-mono board with star ground, as symetric as posible and short traces. I was thinking a long time about the use of 45 degrees curves. In the Pass designs it's usual to use only 90 degrees curves but that uses a lot of space. Maybe there was some discussion about that subject on the forum but a couldn't find it. Also the emc-suppression of my board is not optimal but this is such a specialism that i keep that for later times.
I didn't yet made this board for real so please give as much comment as possible before i turn on the etching machine.
Best regards,
Johan. |
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| Klaus |
Hi,
another idea, I did it this way in my P1.7. I have a "rec out on" switch on my front panel. It activates via one relay the connection of the passive rec out circuit w/o any buffer to the switched inputs. It can effect the sound of the P1.7 in a negitve way - but just when recording is running. Switch off means no influences at all. And for shure no buffer is affecting the quality of the rec out signal... A smart and simple solution :)
Of course I have to take care not to switch the same input as rec out destination. Bu I was not willing to create a own tape input szenario. Too seldom I do record.
regards
Klaus |
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| joho |
Hi Klaus,
I think we are on the same lime. When you look at my thirt posting there is a complete printdesign of the Aleph1.7. When you look good at the circuit around relais 19 and 20 you see the buffer circuit switched by ... I know, it's a bit a jigsaw and the partnummers of the little buffer schematics don't correspond with the printdesign. You know it's much easier(faster) to draw schematics on paper.
By the way, the first buffer i tried was a little variation on the design that you used at your D1 output.Thanks for that posting. It works very good but i didn't have enough space on my board.
What do you think of the pcb ?
Regards,
Johan. |
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| Klaus |
Hi Johan,
I talked about "no buffer" - I do not know why any buffer for this temporary rec out should be necessary. So I can not follow your ideas...
In principle I like your PCB - just the big coupling caps are IMHO not usefull. As written frequently before I prefer standard Panasonic FC electrolytic caps. They sound super and cost almost nothing... ANY big foil monster I compared against sounded tired. If interested in check again the other current treads about coupling caps.
Regards
Klaus |
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| joho |
Hi Klaus,
When you connect a record device direct on the input there is some influence. That's all clear.To use a record switch or relais makes the problem temporary. You can choose for that. Otherwise i had some small space left on the PCB and with a buffer i expect no influence and i can drive a longer cable without problems. That's the idea.
About the coupling capacitor story i spoke you before and in my actual 1.7 i use the FC's+1837's. It's much better than the standard wima 10uF mks.
I'm just like the most of us a little bloody-minded and want to have the possibility to use Mcaps.I never try them. Maybe i never use them but there is enough space and a FC always fit.
A total different question ;
I had a quick look in your personal data and found something interesting about impulse correct speakers. In Holland there is a impulse speaker factory but i have never seen a type "correct". Is it something special for the German market ?
Best regards,
Johan. |
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| Klaus |
| quote: | Originally posted by joho
Hi Klaus,
A total different question ;
I had a quick look in your personal data and found something interesting about impulse correct speakers. In Holland there is a impulse speaker factory but i have never seen a type "correct". Is it something special for the German market ?
Best regards,
Johan. |
Hi,
now I got you regarding caps... Regarding rec out buffer I hope that my source device buffer is capable to drive in between the P1.7 and the cable to the higher impedance rec in. When I see e.g. the NE5534 input buffer in my DAT recorder I do no longer think about losses of sound performance...
"Impulse correct" speakers means no brand. It means speakers designed to reproduce as well as possible a step response. Like electrostatic/-magnetic speakers or width range speakers are doing. Many guys and my ears tell me that those speakers sound so much more realistic. The company Audio Int´l in Germany created DIY kits with ESS AMT-speakers and 18´´ Excel Mg chassis which follow this ideal. Currently nothing is online about it because the main dealer reworks his homepage.
Regards
Klaus |
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| joho |
Hi Klaus,
Probably you're right. The most record devices are not really hi-end. Otherwise a good buffer does no harm.
The impulse correct story sounds very interesting , maybe you can start a threat at the speaker builder part of this forum.
Anyway, thanks for the info and the serious response.
Regards,
Johan. |
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| AuroraB |
Very nice PCB, Joho...............
Any files?? ;) |
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| joho |
Hi Aurora,
To design a complete board means a lot of work. I put a image on this forum to get FEEDBACK. I'm not a pcb-guru so probably there are some points to make better.
First i want wait a few days for that feedback.
Afterwards i want to make a prototype and compare that with my actual Aleph 1.7 .
If the working and sound is ok then i have no problems to sent it to everybody who has serious interest.
Regards,
Johan. |
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| mwmkravchenko |
You did a great job on your layout. If you don't mind I would like to try making a copy. Did you use eagle?
If so I have a copy to.
MArk |
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| joho |
Hi Mark,
Thank you for the complements.
Yes the layout is made with Eagle. Great software by the way.
I used thick lines so everybody with an old aquarium and some chemicals can make this printboard.
I didn't make it in real yet so maybe there are a few mistakes in the design !!!
What do you mean with "i have a copy to" ?
You have also a own design ?
Best regards,
Johan. |
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| mwmkravchenko |
It is amazing how leaving out a word will completely destroy an idea. I wanted to say make a copy to of your design. It is a well thought out layout and one that I would find hard to improve upon. So if you would be willing I would be very gratefull to use your file to make a copy of your board design.
Mark |
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| highbias |
YES! I would also be very interested in using your file to make PCB's. Could you post the Eagle file here or could you e-mail it to me. I would be most grateful if you could.
Mark Gulbrandsen
cinerama84106@yahoo.com |
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| joho |
Hi Mark and Mark,
Sorry for my late reaction. I was a few day's on hollyday so...
As said before i want first make a prototype myself so please have a little patience.
I have not much time but i expect to have a bare pcb at the end of next week. There are a lot of holes to drill, placing components etc. so maybe at the end of oktober i have something real.
Follow the postings on this part of the forum and when you see a nice picture of a naked Aleph 1.7 amp, sent me an email for the Eagle-files.
Best regards,
Johan. |
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| mwmkravchenko |
Just checking on on how things are going.
Mark |
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| joho |
Hi Mark,
The problem is time, time, time...
I have i little son of 7 months old and he is a really time spender.
At the moment he's trying to hit my keyboard so...
My only progress was a 3d presentation of the pcb but i used so much special(not standaard) components that it was no great succes.
Have a little more patience.
Best regards,
Johan. |
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| mwmkravchenko |
It's good to hear you put your family ahead of your self and personal pursuits. I have two little boys and completely understand how much time they need. Please do not think I am rushing you. Family first. Hobbies later.
Mark |
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| pamaz |
yeah family first!
unless your baby is going to be something like 2 years old and starts to talk so much , you would like to dedicate some time to hobbies just for resting your ears! ( my personal experience!!!!)
BTW family first
Ciao a tutti
Paolo |
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| joho |
| ...and there is finally some progres |
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| joho |
Hi Gents,
The 1.7 is still experimental.I will compare it with a other PCBdesign and select the best to build it in a beautiful case.
B.t.w. don't look too good at the bmp-file of the pcbdesign earlier in this threat. There are some bloopers in it.
Regards,
Johan. |
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| TheJudge |
Looks really impressive. Nice work. :)
Let us know how is sounds. |
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| joho |
Hi judge,
It sound not bad but is stil running in.
I build a A1.7 before(not my pcbdesign) and after some modifications in the volume control and grounding it sounded marvelous. Very 3d.
The casework was very hopeless and i decided to renovate that amp but i never made it complete.
Now i need it again for reference but look at the picture, i have lots of work to do.
wordt vervolgt...
B.t.w. Also a happy 1.7 owner? |
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| TheJudge |
Not yet. :)
Working on my Aleph-X PCB's now, then I will go for the 1.7.
But it's not going very fast, working with Eagle for the first time. :smash:
Your PCB's are pretty big. I hope I can make them a little smaller so I can fit a DAC in the same case as well. |
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| joho |
Hi Judge,
Yes the board is almost the maximum you can print with a A4 printer. But it's a all in board.
In the definitife version i will put the trafo's and bridges in a separate case.
You say that you what a dac in the same case. Be careful with all the digital **** produced by the converter. Keep it separate or use a shield between the boards !
Eagle is a wonderful program, it's very easy to use and there are good cracks ...oeps.
I worked with ultiboard and orcad but i became crazy of that software. Everytime when you made a little mistake or forgot something, you had a problem.
B.t.w. I'm also working on Aleph X amps. All the boards are ready and i expect some heavy case parts this weekend.
Another serious loss of money.
Regards,
Johan. |
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