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Building Elvee's Circlophone:  Documentation, Parts, Accessories, & beginner friendly
Building Elvee's Circlophone:  Documentation, Parts, Accessories, & beginner friendly
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Old 18th April 2018, 05:42 PM   #371
Gouthama is offline Gouthama  India
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Quote:
Originally Posted by danielwritesbac View Post
Ouput device data from Elvee:
Higher quality score = more suitable
2SD1047_____Quality Score:__1.76
MJ(L)21194__Quality_Score:__1.60
MJ(W)21196__Quality_Score:__1.45
MJ15022,4___Quality_Score:__1.20

BD249C______Quality_Score:__1.04
MJ15003_____Quality_Score:__0.94
MJ802_______Quality_Score:__0.71

MJ15015_____Quality_Score:__0.55
MJE3055_____Quality_Score:__0.46
TIP41_______Quality_Score:__0.43
2N3055______Quality_Score:__0.35
TIP33_______Quality_Score:__0.34

BD911_______Quality_Score:__0.29
TIP3055_____Quality_Score:__0.16

Lower quality score = less suitable


So, good devices from this table include: 2SD1047, MJ21194, MJL21194, MJW21194, NJ21194, NJL21194, NJW21194, MJ21196, MJL21196, MJW21196, NJ21196, NJL21196, NJW21196, MJ15022, NJ15022, MJ15024, NJ15024, BD249C, MJ15003, NJ15003, MJ802, NJ802. Can you find any of these?
I am little puzzled here. 2SD1047 is ranked on top which has ft of 20Mhz, but overall circlophone design principle suggests to use slower devices (<4Mhz)..
Yup.. Building circlophone again with only the best components suggested by Elvee.
Regards ll
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Old 18th April 2018, 09:16 PM   #372
Elvee is offline Elvee  Belgium
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To be honest, I do not exactly remember the precise details of the equation leading to these scores, but I certainly didn't work it out lightly, and I don't disavow it in anyway.

There might be some misunderstanding here: the Circlophone was designed with slow devices in mind, typically the 2N3055, scoring ~0.35.
This means that it won't oscillate or misbehave with these devices, and it will even tolerate slower devices, but of course, in our real material world you cannot change lead into gold (well, in fact you can, but it is impossibly costly), and whilst using slower devices is possible, they will reduce the amount of GNFB available at higher frequencies, meaning a higher 20k THD figure.
Is it problematic? That's for you to judge: how well can you hear the 20k harmonics? How important for you is the HF performance?
I take no sides, but I attributed a better score to better devices in this respect, as I did for SOA for example.

In summary, the score takes into account a number of factors, including today's builders preferences, but it is certainly not an index of the final audible qualities of the amp: robustness and other factors are also included.

What I certainly never meant is that slower devices will lead to better performances: slower devices will work, and the difference with faster ones will not be extreme, except perhaps for extremely slow devices (Ft<100kHz), but even then, the difference doesn't seem to be overwhelming, since a member (terranigma) built a C based on these devices and liked it.

If you use faster devices, the C's topology will accept them, but the amplifier will become more sensitive to local problems: long, loose wires to the OP devices may lead to local instabilities, but that's certainly not something unusual or unexpected.

Transistors like BD249 or MJ15003 have a score of ~1, meaning perfectly OK, but they are slow enough to be almost instability-proof: they look like an ideal compromise.
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Old 18th April 2018, 10:18 PM   #373
terranigma is offline terranigma
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I built C's with those 2SD1047's because they were cheap and have good specs. They were just fine, at least I couldn't observe something catastrophic. The only problematic ones that I remember was 2SC5200's. You probably know that what "C" means in Japanese transistors.

I didn't hesitate to build with 200khz devices and also with HEXFETS. They were just fine too, differences were subtle if used same small transistors on remaning sections. According to my experience, Circlophone builders should have concentrate on small signal transistors, especially those ones at bias servo. These are the ones defining sound character in my opinion.
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Old 19th April 2018, 03:43 AM   #374
Gouthama is offline Gouthama  India
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Thank you very much for the detailed explanation Elvee.
Thanks for your inputs Terranigma.

Since I will be using circlophone for high frequency also (in a biamped set up with linkwitz active crossover) decided to go with Njw21194. And Bc556b for inputs and ksa1845 for sensors . This time I will be supplying with 35V rails. All the active devices will be procured from RS component so that authenticity is guaranteed. My last setup which had tip35c(st) was procured locally and failed authenticity test suggested by Eva. Which may be the reason for failure of my earlier circlophone set up(extreme load dumping event explained by Elvee few pages back).
But even with the fake devices circlophone performed exceptionally well. As per my friends who had listened to circlophone set up (one of them is a Indian classical musician who performs in small concerts) had told me music reproduction is very close to live performances without a hint of listening fatigue.
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Old 19th April 2018, 05:27 PM   #375
terranigma is offline terranigma
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Quote:
Originally Posted by Gouthama View Post
and ksa1845 for sensors
Sensor transistors are running in Class-A, thus power and heat dissipation requirements probably will be higher than what ksa1845 can provide.
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Old 20th April 2018, 02:23 AM   #376
Gouthama is offline Gouthama  India
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Quote:
Originally Posted by terranigma View Post
Sensor transistors are running in Class-A, thus power and heat dissipation requirements probably will be higher than what ksa1845 can provide.
Thanks Terranigma, then what is your recommendation for Q12, Q13 on 35v rail. I modified Alexmm pcb to take ksa1845 and my pcb are shipped. Please note that mine is original circlophone as Elvee published. Only difference is rail voltage.

Last edited by Gouthama; 20th April 2018 at 02:26 AM.
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Old 20th April 2018, 02:27 AM   #377
Gouthama is offline Gouthama  India
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Quote:
Originally Posted by terranigma View Post
Sensor transistors are running in Class-A, thus power and heat dissipation requirements probably will be higher than what ksa1845 can provide.
Thanks Terranigma, then what is your recommendation for Q12, Q13 on 35v rail. I modified Alexmm pcb to take ksa1845 and my pcb are shipped. Please note that mine is original circlophone as Elvee published. Only difference is rail voltage.
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Old 20th April 2018, 08:10 AM   #378
Elvee is offline Elvee  Belgium
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Don't worry: all the transistors of the Circlo engine, including the sensors can be any ordinary low power signal ones, like the BC547/557 etc.
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