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In Reply to: RE: Fusion Power Multiplier posted by bcherry on May 12, 2010 at 01:26:04
Is this module a buffer, similar in general concept to the First Watt F4? A different concept entirely? Something in between? Neither? Both?
If it is a buffer would it be possible to create an EML 20A spud amp (could use an output transformer with suitable 2ndary impedance) and add the buffer for some single-stage DHT goodness into moderately efficent speakers?
Also, if it can be used as a buffer, what would be preferred 2ndary impedance be? 16 Ohm is mentioned; what would be the optimum? Up to what impeadance is workable?
Cheers
R
“Take your mask off when you're talkin' to me." Band of Horses
Follow Ups:
Hi,> Is this module a buffer, similar in general concept to the
> First Watt F4?Somewhat - Yes. But there is an extra trick that works specifically with amplifiers that already put out some power of their own.
> If it is a buffer would it be possible to create an EML 20A
> spud amp (could use an output transformer with suitable 2ndary
> impedance) and add the buffer for some single-stage DHT goodness
> into moderately efficent speakers?Yes, this could be done. I think the EML20B would a better choice.
> Also, if it can be used as a buffer, what would be preferred
> 2ndary impedance be? 16 Ohm is mentioned; what would be the
> optimum? Up to what impeadance is workable?Optimum is something that produces 16V at nominal full power (or 32V is using a bridged output for more power).
If we use Child's law that the maximum output power of a triode is 1/4 of anode dissipation we are likely safe.
Using the 20B at what EML calls medium bias we get 18W Anode dissipation and thus around 4.5 Watt power. Call it 4 Watt to be safe.
Ohms law gives us that with 16V at 4Watt we have 0.25A and thus an impedance of 64 Ohm.
So a custom Transformer with around 5 Watt at 25Hz (20W at 50Hz) would be needed, 10K:64R.
This is 12.5:1, so with the gain of the EML 20B at 20, we need around 10V Input Voltage to make this work at full power. One might use a 1:5 Stepup transformer on the input of the EML 20B to get the needed overall gain for full power at 2V input or an extra tube stage or a Tube Preamp with significant gain (14 - 20dB).
It strikes me that this would probably a better job for a 2A3 with a 3K: 64 Ohm output transformer. Use this with a "normal" 2-Stage DC coupled Amp like the old 1940's DC coupled Amplifier from "101 Radio Hookups" Book (6SF5, 2A3 DC) which in turn has been used in a range of famous Amplifiers out there. This kind of Amplifier would need 0.5V for full output so ideal for use with passive preamplifiers etc.
In fact, I have been thinking about building something like that myself (not too serious), with two chassis, one with the 2A3 DHT Amplifer, the other with the Fusion Modules and matching powersupply.
So far the lack of suitable output transformers has limited this, but, for arguments sake, one might use some Autoformers with a 1:2 stepup from a 16 Ohm Tap (2A3 Amp) or 1:4 from an 8Ohm Tap (2A3 Amp) and the fusion module to make a near "universal" DHT Booster Amplifier that could be used to to give most DHT Amp's major Cojones.
TBH, I have so far not really put major work into this as I am unsure if there is significant interest for this "Solid State Booster Amp after SE Amp" concept.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 06/28/10 06/28/10
hi thorston. i would totally be interested in a unvirsal DHT booster that would fit between the amp and speaker. did you ever look further into this?
Thanks very much Thorsten. I will digest this over the next few nights...
Thankfully, we have some great custom winders over here Oz, so transformers should not be a problem. Will certainly give this some thought.
Also, are you able to briefly share how the buffer affects the sonics?
Cheers
R
“Take your mask off when you're talkin' to me." Band of Horses
Hi,
> Thankfully, we have some great custom winders over here Oz,
> so transformers should not be a problem. Will certainly give
> this some thought.
Great. Do download the Fusion Manual and read that too, it has more detail on the whole range of implementations.
> Also, are you able to briefly share how the buffer affects the sonics?
To be honest, I have major issues telling if it is in or not, the 300B Fusion Amp, which is so far our only application, unless I turn up the volume past what the 300B Amp handles on it's own.
I think it is the little extra circuit trick described in the whitepaper on page 3 that makes all the difference to conventional buffers, as I have heard a few of these.
I am thinking making the next complete Fusion Amp a Monoblock that can can use either 2A3 or 45 with a DC coupled frontend and permanent Fusion plus 8/16 Ohm outputs.
Or maybe a 45/2A3 Amp with the full bore 160W/8Ohm & 260W/4Ohm Quad Pack of outputs? I think a 260W 45 Amp would be quite a fun thing to have.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
.
“Take your mask off when you're talkin' to me." Band of Horses
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