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Old 22nd May 2006, 11:10 PM   #531
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Here is some of the stuff, I'm getting closer to Quasi time.
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Old 22nd May 2006, 11:32 PM   #532
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Quote:
Originally posted by TomWaits
Here is some of the stuff, I'm getting closer to Quasi time.
Shawn,

Thanks for the pic of caps and heatsinks with toroids. The caps are what value/voltage? Darn how many of those caps did you get for $40.00? From Sayal as well?

I am going to have to improve my parts hunting skills

How many quasi amps do you intend to build? Number of modules per toroid?


Regards,

John L. Males
Willowdale, Ontario
Canada
22 May 2006 19:39
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P.S. My appologies in advance for any typo errors. If you cannot "decode" the typo or feel there is a typo (some typos are correctly typed spelling, but can be mix of wrong/omitted words) speak up and ask me to clarify. jlm
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Old 23rd May 2006, 03:21 AM   #533
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Hi Shawn,

My appologies, I must of been brain dead. I did not see your post for some reason prior to your pic post of heatsinks, toroids, and caps that I asked questions you already answered.

I am assuming you are using one cap per rail, hence 4 caps for two toroids.

I will likely first build a pair of quasi amps based on the 25-0-25V toroid I have. Once I have that down, I will decide if I will do two or 4 modules per the 44-0-44V toroids. I think with the 1127VA versions I will be ok for my listening needs.

Shawn, sorry you had panic over the VA ratings I mentioned. All you may have found was that you might of had some higher than 927VA. These were either 927VA or 1127VA. I am sure you would be more than happy to have 1127VA versions.

Gosh, what load are you thinking of driving to want to mono one module to a one 44-0-44V 927VA toroid? Planning to shake some foundations were you?

I like to go active crossover. I just feel the 44-0-44V would be overkill for tweeters for sure, and likley midranges as well. If that is case then I will only use two modules per 44-0-44V. These toroids were a great price for their specs. I just wish I could find 30-0-30V ones instead as that better suits my power requirements. I decided I had been waiting long enough for some toroids so I dove in with the same toroids you have.

Then like magic quasi's design came along. I had fretted about some other n-channel designs which all seemed to have various issues in terms of stability or part requirements. The beauty of quasi's design is it is simple (I like simple designs from a sonic perspective.), low in the electrolytic count, flexible to alternate transistors (output devices aside, as there are lots of choices for most designs), easy to build (no SMD stuff), and believe it or not the reasoning for many of the parts selection quasi made (do not fall of your chair quasi).

From all the reading I had done prior to seeing quasi's design and since there are many excellent elements of the design well done in my opinion makes quasi's design exceptional. (quasi - you can send donations anytime for my glowing compliments to my numbered Swiss Bank Account )

If I use the 44-0-44V toroids for midrange, I will likley figure out a protection circuit to limit RMS output voltage to about 24-30V RMS. If I do so I should be able to run 6 modules off one 926/1127VA toroid and still have excellent headroom current wise. Each module is intended to have its own PSU board with a bridge on each side of the supply rail so PSU seperation should be very good. If that works well then I will build another set of 6 to change to bi-amp. I will then decide if tri-amping will be worth the move.

I intend to go seperate enclosures for each toroid and PSU module so I will have various options and flexibility, especially going the seperate enclosure for each toroid and each PSU module. This allows me flexibility for special suitations if I wish, or to experiment. This seperate enclosure approach avoids having to have one very large case to house 2/4/6 modules, the 44-0-44V toroid and PSU modules, and the other supporting circuits I wish to add in.

Am I itiching to build? YES. I still need to sort out case and heatsink parts or solutions mostly. If Supremetronic/Honson gets stock again of a 2U case with heatsinks already part of case, I will get one, was about $50.00, and build a stereo unit so I can give the design a listen. I am sort of committed in what parts I have bought to build more. I believe my instincts will be very happy once I have built the first one. I still have some caps to source/buy, but for the first one I will be ok and have various choices. I am also still trying to figure out where I can find a 12-18V relay that will fit quasi's board. Even for the 25-0-25V 225VA toroid I like to use an inrush circuit. I just need to sort how I can implement an inrush circuit in module dedicated manner.

I hope you had a good Long Weekend Shawn and the visiting family is enjoying their visit as well.


Regards,

John L. Males
Willowdale, Ontario
Canada
22 May 2006 23:27
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P.S. My appologies in advance for any typo errors. If you cannot "decode" the typo or feel there is a typo (some typos are correctly typed spelling, but can be mix of wrong/omitted words) speak up and ask me to clarify. jlm
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Old 23rd May 2006, 07:13 AM   #534
AndrewT is offline AndrewT  Scotland
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Hi Tomwaits,
the thyristor protection is fitted to two makes of amplifiers that I have. Crimson fit it around the VAS stage and use the triggered pair to disable the CCS of the LTP. I think they have set it up to monitor very high frequency and thus cuts input if the circuit oscillates or it gets fed with Hi Freq. Their implimentation never sees the zero voltage and so the thyristor circuit needs to be manually reset, mains off or a switch added to the trigger. Crimson also have conventional single slope current limiting to augment the thyristor.

Cyrus have fitted it to the Cyrus One amp and I think it is on my Cyrus Two as well.
Their implementation is completely different; monitor the output current through the Re and then disable the CCS of the LTP. Look up the Cyrus One (1) schematic on this forum.

I have never "heard" either of these limit and the only time I have been aware of a trigger was when feeding 50kHz into the Crimson at highish level.
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Old 23rd May 2006, 11:28 PM   #535
anatech is offline anatech  Canada
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Hi Andrew,
Cyrus kills the current sources still, don't know about the new Power because I haven't had any in yet. Very civil way of damage control if you ask me.

-Chris
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Old 24th May 2006, 05:12 AM   #536
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Quote:
Originally posted by AndrewT
Look up the Cyrus One (1) schematic on this forum.

You know it better than we do, so give us a link, I find searching the forums still difficult and awkward. Just as bone, give a dog a bone. Cheers, Shawn.
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Old 24th May 2006, 05:22 AM   #537
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Quote:
Originally posted by anatech
Hi Andrew,
Cyrus kills the current sources still, don't know about the new Power because I haven't had any in yet. Very civil way of damage control if you ask me.
-Chris
Now two guys are speaking in a foreign language and one of 'em is a moderator! Donít tease us Please explain more of your experience. Abrupt comments are just that. Why not turn them into gold? Or do we have to beg for your knowlege? Get the can opener on yer key board and start typing, wild goose chases are not fun unless I am alowed to shoot!

Just two cents worth,

Shawn.
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Old 24th May 2006, 07:11 AM   #538
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Default Best option

Hi quasi ... i am back

Now i make my high power amp !

Well, what you consider the best option of speaker and amp:

speaker amp
1- 2x (400rms@4hom speaker) with 2x (440rms@4hom) amp
2- 2x (400rms@4hom speaker in paralel) with 1x (800rms @ 2hom) amp ?
3- 2x (400rms with double 4hom bobine) that totalize 800rms@ 4hom load with 1x 800rms @ 4hom amp ?

i wait your opinion to order the speaker.

Thanks ...and sorry for my bad english jejej
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Old 24th May 2006, 08:23 AM   #539
AndrewT is offline AndrewT  Scotland
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Hi,
the Cyrus One power amp schematic is here.
http://www.tcaas.btinternet.co.uk/cyrus1pwr.gif

Q35 & Q37 form the thyristor. The ratio of R101 & R103 allow the trigger point to monitor output current level and to set the trigger point/output current.
Voltage across Re (R107A&B) triggers the pair on and then connects R67 to an effective ground.
This disables Q11 and stops the CCS pulling current through the LTP and so removes signal from the output.

Another poster pointed out that his amp still failed when output was shorted to ground. I cannot see if the thyristor protection was inadequate for this failure mode or if something else caused the failure problem.

A thyristor once triggered holds on until the current through it collapses to zero. i.e. it is latching.

With the Cyrus circuit it unlatches each time the current waveform crosses the ground reference. It appears that Cyrus have engineered in an automatic unlatching.

Anatech or others,
have I explained this correctly? or can you teach me more?
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Old 25th May 2006, 02:14 PM   #540
quasi is offline quasi  Australia
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Default Hi Aggresiva

-
The amp should not be run in parallel so option 2 is out. I think option 3 means a dual voice coil speaker and this would work ok.

My preference is option 1. You can take advantage of slightly more efficiency from the larger cone area from 2 speakers.

If the amp is for musical instrument use, you should use the 10 FET boards.

Cheers
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