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Old 18th October 2013, 02:03 PM   #61
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Default TTC 5200

I haven't been around for a while due to work commitments, nor have I had a chance to read the preceeding few posts. I have just purchased 4 pair of MJL3281/1320 and some A970/C2240 and some BC546/56 for my L20.

I might have been better to buy the pair of pcb, If there were one available!

Here is the SOA of the TTC5200's and I see that they have very low current capacity for the voltages that I want to run, i.e. 50 each way.

Cheers.
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Old 18th October 2013, 05:40 PM   #62
AndrewT is online now AndrewT  Scotland
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At 50Vce they have good current capability, about 2.4Adc
It's @ >60Vce that they collapse. Down to just 1A @ 70Vce and 1.6Apk for 100ms single shot.
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Old 18th October 2013, 10:52 PM   #63
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Default 5200

The black line on the graph says 400mA @tc25degC.
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Old 19th October 2013, 09:32 AM   #64
AndrewT is online now AndrewT  Scotland
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@~97Vce

But your output device can only have this Vce (from +-50Vdc) if it is driving a very reactive load with a very out of phase signal. This necessarily reduces the duration from DC to maybe around 10us to 10ms, not DC.
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Old 20th October 2013, 05:15 PM   #65
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Thumbs up Cheers

Quote:
Originally Posted by AndrewT View Post
@~97Vce

But your output device can only have this Vce (from +-50Vdc) if it is driving a very reactive load with a very out of phase signal. This necessarily reduces the duration from DC to maybe around 10us to 10ms, not DC.
I get it, the speaker is only a few ohms and not a piece of fencing wire!

This can only be a good thing; as I have always looked at the 'DC' line of the graph and tried to stay within it's boundary, meaning that my output transistors are usually under-stressed. [provided I use a 'speaker' on the output terminals!].

On the other hand: When I come to think of it, the 25 degree transistor-case scenario is an ideal. The size limitation of my heat-sink (if it 'is' to fit within a case inside my lounge room!) will substantially reduce the SOA once again.

If the L20V9 I ordered last month doesn't turn up this week, I intend to use my MJL's for a 100W amp based on Mr.Self's Blameless.
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Old 20th October 2013, 05:26 PM   #66
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Quote:
Originally Posted by AndrewT View Post
did you read posts 5 & 7?
Yes, and particularly enjoyed # 7
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Old 17th November 2013, 11:42 AM   #67
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Quote:
Originally Posted by farmerjack61 View Post
I get it, the speaker is only a few ohms and not a piece of fencing wire!

This can only be a good thing; as I have always looked at the 'DC' line of the graph and tried to stay within it's boundary, meaning that my output transistors are usually under-stressed. [provided I use a 'speaker' on the output terminals!].

On the other hand: When I come to think of it, the 25 degree transistor-case scenario is an ideal. The size limitation of my heat-sink (if it 'is' to fit within a case inside my lounge room!) will substantially reduce the SOA once again.

If the L20V9 I ordered last month doesn't turn up this week, I intend to use my MJL's for a 100W amp based on Mr.Self's Blameless.
I am going to give it a miss, There are no instructions with the kit and the pcb does not match the components shown.
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Old 10th December 2013, 08:55 AM   #68
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Hi I emailed Jimjim to ask him about tranformer size. Would it be very stupid with a 1000 w 34 VAc trafo for each channel or should it be enough with 500 W for each channel. I have four 500 w 33 vac transformers.

Anybody know if it will be 3 ohm stable with 48 vdc supply ?

Jimjim answered on a completly other question then i asked I think
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Old 10th December 2013, 03:30 PM   #69
AndrewT is online now AndrewT  Scotland
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Quote:
Originally Posted by Erlend Sæterdal View Post
..........Anybody know if it will be 3 ohm stable with 48 vdc supply ?..........
You are asking the wrong question.

If you plan to use 4ohms speaker then the question is:
Will it be stable with a reactive 4ohms load?

A follow up question would be:
Will it be able to deliver enough current from the PSU to the Speaker to allow a 4ohms reactive speaker to be driven properly? This last has little to do with amplifier stability.
A test that you can do is to measure the maximum unclipped voltage into 8ro and 4r0 and 2r0 and 1r0

Then graph the Voltage results as dBV and see where they suddenly drop off.
That drop off which could be at -1dBV or -2dBV relative to 8r0 dBV
The load for this lower output voltage will give you a clue to how well the amplifier delivers current into lower loads.
A 4ohms capable amplifier should easily drive a 2r0 load and very good 4ohms capable amplifiers will drive a 1r0 to high output voltages for a few seconds until the heatsink begins it's fairly fast warm up towards output stage destruction.
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Last edited by AndrewT; 10th December 2013 at 03:56 PM.
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Old 16th December 2013, 10:06 PM   #70
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Well I do not need that kind off answer.

Funny that one channel is getting hot and the other not without any load at all. Leads are indentical in both channels.
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