2N3053 is a no no! I have tried them before, they heat up tremendously!,
even at low power.
TY!
My approach on plain Circlophone
Hello all,
I want to share my plain Circlophone layout tryout. I tried hard for this time. It's output transistor and driver arrangement based on Dx amp (by Carlos). I thought that such kind of layout is best to use TO3 metal case output transistors. Still can be easily converted to plastic case only layout but this is not the main purpose.
Any opinion appreciated.
Hello all,
I want to share my plain Circlophone layout tryout. I tried hard for this time. It's output transistor and driver arrangement based on Dx amp (by Carlos). I thought that such kind of layout is best to use TO3 metal case output transistors. Still can be easily converted to plastic case only layout but this is not the main purpose.
Any opinion appreciated.
Attachments
My pcb status
I think I'm close to final but not sure. Grounding scheme is in question. Due to different requirements of TO3 metal transistor construction, I decided to offer plastic transistor version separately. Bord size is 100*60 mm even with those fuses and bigger bypass capacitors.
This time I have spend a time for presentation..
I think I'm close to final but not sure. Grounding scheme is in question. Due to different requirements of TO3 metal transistor construction, I decided to offer plastic transistor version separately. Bord size is 100*60 mm even with those fuses and bigger bypass capacitors.
This time I have spend a time for presentation..
Attachments
Last edited:
Hi jerryo,
In current revision, I merged the input ground track (the one you mentioned I think) in to the main track. At first, i supposed to establish a star ground effect but later decided to avoid it due to short track length. There is going to be 2 different boards but same layout. One is metal transistor and plastic transistor version which is 10*9cm, other one is only plastic transistor version which is 10*6cm.
Regards.
Final versions so far..
Hello All,
I think that my layout is ready for an actual build, though haven't build one yet.
I have exported two versions with same layout. Hybrid (Metal + plastic) version is constructed best with L-shaped aluminum profile. Suggested minimum profile size is 40x40x6 mm. Board sizes are 100x90mm and 100x60mm respectively.
Hope they will be useful for prospective builders of this extraordinary amp.
Regards.
Hello All,
I think that my layout is ready for an actual build, though haven't build one yet.
I have exported two versions with same layout. Hybrid (Metal + plastic) version is constructed best with L-shaped aluminum profile. Suggested minimum profile size is 40x40x6 mm. Board sizes are 100x90mm and 100x60mm respectively.
Hope they will be useful for prospective builders of this extraordinary amp.
Regards.
Attachments
Last edited:
Apparently, the information superhighway is clear full of pot-holes covered by band-aids.
And we needed some more band-aids.
A recent forum update broke most of the store-search type ebay links in post#1. After the forum update (to ebay rover), it quit finding parts from reliable vendors.
That had to be fixed!
So, as a repair, I have written a huge number of html redirectors and posted them to startfetch.com (my handmade, homepage project, which has superior safety due to the absence of trackers). Next, I sent the problem links to the redirectors. All of the links work now. The parts finding function has been restored to post#1.
And we needed some more band-aids.
A recent forum update broke most of the store-search type ebay links in post#1. After the forum update (to ebay rover), it quit finding parts from reliable vendors.
That had to be fixed!
So, as a repair, I have written a huge number of html redirectors and posted them to startfetch.com (my handmade, homepage project, which has superior safety due to the absence of trackers). Next, I sent the problem links to the redirectors. All of the links work now. The parts finding function has been restored to post#1.
Links to posts within the same thread don't work reliably in all conditions (except that links direct to attachments always work). They're working on the problem; however, functionality tends to come and go. So that's the problem. Here are three possible solutions:
1).
I can link to posts in Other threads, such as the http://www.diyaudio.com/forums/solid-state/189599-my-little-cheap-circlophone.html so, "the other thread" is a great spot for technical materials, directions and expansive information. This is how we started and the functionality has been reliable.
2).
If you PM me with a specific need, I can write redirectors to serve up a "boomerang" function, first to startfetch.com and then right back here to the correct post within the same thread. The lease is paid up on startfetch for the next 4-1/2 years, so the functionality should work for at least that long and probably much longer.
3).
You can put relevant materials AND a text file within one zip file and attach the collection anywhere you like and I can link to that from anywhere. The user of this will receive the zip file collection along with the text file that contains what you'd like to say about it.
Hello Daniel,
I wasn't aware of that situation regarding to the referring other posts in same thread. Btw, Option-1 would be the best shortcut as workaround for this issue. I thought that it would be good to not bloat the main thread with pcb design experiments but at this point, it seems it is best to post at least final pcb revisions at another thread rather this one.
I will try to collect my contributions at another thread (or page) and contact with you via PM.
Regards.
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I recently converted my current darlington builds to mosfet and replaced high voltage/wattage 2sa1546 servos via 2n2905A small signal transistors on both channels as what like you did above. So, difference of attained sonic behavior is remarkable, as like as plugging a totally different amplifier.
Now, amp sounds more bright but seems well defined compared to earlier setup. Some little details at familiar songs also distinguishable. Bass is not boomy as like as darlingtons. I think I really liked the bass of darlingtons. Low freq is not weak but different.. I heard similar bass behavior impressions from other people with different amps regarding to mosfet-bjt comparisons.
I think I should install 2n2905A's first and then mosfets later. Although it is not clear for me that which part caused the sonic difference mostly but I can barely state that 2n3019, 2N2905A(pnp) type small signal transistors would be the best bet on choosing servo transistors depending on my listening expressions so far.
Regards.
I think it is early for a conclusion until experimenting more and seeing the things within the designer point of view.
Maybe mosfets require a strict way to implement properly in my setup. Paralleling may be one of possible options.
My amps run on 190mA quiescent current. I see some designers tend to bias mosfet amps rather higher, example 200mA per mosfet. In total of 400mA bias, we may question that "high efficient class A" concept of Circlophone. Btw, it is not that hard to do that by decreasing values of current sensing resistors each side.
Ok, I reinstalled darlingtons on one channel. I listened couple of tracks by regularly swapping channels and I couldn't manage big difference on overall presentation but.. mosfet one seems pushing woofer more powerful on some tracks. I don't know why.. maybe while getting hotter, my mosfets (IRFP250N) shows their real capabilities afterwards.
So, I don't want to generalize overall performance at all and both versions deliver delicate listening experience.
So, I don't want to generalize overall performance at all and both versions deliver delicate listening experience.
Paralleling would be possible, but only if a strict matching is enforced otherwise it could have unpredictable effects
Theoretically ±47V is possible, but I don't know any builder here used such high rails. For example, I've never go over 32V rails due to my limitations but I'm planning to build a high voltage version with 2SC2922's.
With such high rails, you should strictly select transistors depending on their SOA and Vce ratings. My Japanese Darlington&Mosfet version at post#227 is a good example.
I'm using 2SA1698's as PNP Servo transistors now and I'm quite happy with them. I'm using ST TIP142C darlingtons as outputs. I think I gone too quick with doing listening comparisons with UNMATCHED mosfets. Mosfets require much more strict matching.
The current flows over R21 should be 1-1.5ma. I've made some simulations depending on this purpose and I posted values at post#228.
So, what about darlingtons? Are base resistors necessary?
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Elvee's Single Rail Circlophone has joined the long list of circlophone varieties cataloged at post#1.
P.S.
Also, the headline schema at post#1 was suffering 2n5551's, few of which do work on-spec; however, there's many imitation transistors that won't do. So, I had to swap those with sc1845 and post a replacement schema (for linkup to post#1).
P.S.
Also, the headline schema at post#1 was suffering 2n5551's, few of which do work on-spec; however, there's many imitation transistors that won't do. So, I had to swap those with sc1845 and post a replacement schema (for linkup to post#1).
