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Bernt Jansson
400.000-klubben
19763 Posts |
 Posted - 2004/12/14 : 19:47:22
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Transcendent har haft en ny OTL på gång ett tag nu, det rör sig om effektstarka monoblock som säljs i byggsats.
Här kommer det senaste, saxat ur Transcendents nyhetsbrev:
quote:
Super OTL Update
I have a protpotype! Unit number 1 is up and running. I actually listened to it today. Wow! There is no substitute for power. Tremendous clarity and presence. Here are some details:
I decided to use the EL519. The 6C19pi would require 32 tubes and take up too much space on the chassis. One 519 can generate more power than two of the small triodes. The amp will use 16, EL519 tubes. Continuous RMS power is a clean 175 watts into 8 ohms and 130 watts into 4 ohms. I was hoping for 200 watts into 8 ohms but didn't quite make it. (The difference is totally inaudible but I wanted the bragging rights). I may still be able to squeeze out a few more watts. I don't want to overly complicate the design or drive the cost up just to reach a certain power level.
Distortion just before clipping measures about 1%. That is super low for such a high power level. It sounds clean and precise with no breakup until it clips.
The 4 ohm power output is excellent. This amp will push more power into a 4 ohm speaker than other large, high-priced OTL amps can into 8 ohms.
Output impedance is less than 0.2 ohm. This is low enough to easily drive 4 ohm speakers. In fact, the amp should be able to drive just about any speaker available. Now I have an amp that can drive large planar speakers as well as most any low efficiency 4 ohm speaker .
Current consumption at idle is a remarkably low 3.5 amps per monoblock. That is not much more than a Transcendent T8 and less than half of any other big OTL on the market. No other manufacturer can make this clam. This is a big OTL you can live with.
The amp will look and be configured like a T16. It will be 17 inches by 17 inches and use a cage (included) like the T16 with the same or similar front panel. The transformers will be exposed behind the cage.
There is still much work to do. Creating a high power OTL is much more difficult than just adding a bunch of tubes. The circuit will be refined over the next few weeks. Much attention is required to amp/speaker protection because of the enormous amount of power that this amp can generate.
Intressant, eh? |
MVH Bernt Mitt system
"Det enda man kan vara praktiskt taget säker på är att en rak tonkurva alltid är fel." - Ingvar Öhman
Jobbar för Jorma Design och gillar bashorn
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Circlomanen
Semesterfirare
9880 Posts |
Posted - 2004/12/14 : 21:37:52
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quote:
Intressant, eh?
SMASKENS!!!!!! |
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Bernt Jansson
400.000-klubben
19763 Posts |
Posted - 2005/01/12 : 13:34:35
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Ur senaste nyhetsbrevet:
"Super OTL Update
It was a tough battle, but I finally got the sound right where I want it. I had to revisit lessons learned when I developed the T8. Those big pentodes are difficult to make sound good. It's all a matter of speed. I had to adjust the time constants of the output stage and driver stages to get the sound super smooth and musical. It took a lot of listening and adjusting. It is going to be the best sounding amp I have ever created. More power improves everything.
Initially, I used a balanced differential driver stage but it created assymetrical noise components that would not cancel out. So I ended up with something more similar to the T16, but more refined and optomized for high power.
I had forgotten, but those pentodes output a bit more current when brand new and maximum current declines slightly after about 10 hours. So the amp will be rated at 165 watts RMS into 8 ohms and 120 watts RMS into 4 ohms. That's still way more power than just about any other OTL out there.
Noise is fairly low at about 1.5 mV. When the final configuration is produced with circuit boards, that figure should go a little lower. An amp with this much power should be used with medium to low efficiency speakers. The noise will be inaudible in those applications. High efficiency speakers will be better served with the T16 or SE OTL.
Feedback has been reduced and gain increased to 30 dB. The amp will be capable of being driven with a passive preamp from a high level CD player. Output impedance is still about 0.3 ohm which is superb.
This wasn't easy to accomplish, but current consumption at idle was held to 3.5 amps. The T8 needed 3.2 amps. The number of output tubes was doubled and idle heat output only went up 10%. This means a pair of amps can be driven from a standard outlet circuit. Other big OTL amps require a dedicated 20 amp circuit and all the heat that goes with it.
Going to start working on the second edition.
With other amps, I could go from the first prototype directly to the final layout but this is just too big and complicated to do that." |
MVH Bernt Mitt system
"Det enda man kan vara praktiskt taget säker på är att en rak tonkurva alltid är fel." - Ingvar Öhman
Jobbar för Jorma Design och gillar bashorn
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