as i always say. build it right the first time
I don't think anyone starts building an amp with an objective not to build it right ;-) Errors do creep up in different forms including component failures and spurious copies.
Audiosan,
Thank you so much. Your observations are always so astute. I on the other hand have screwed up on construction projects everyway possible. It has helped me learn how to fix things. Try this, unhook the board from the heatsink, using a variac bring the power up slowly and carefully, to around 8 or 10 volts output on the power supply. Feel the output transistors. If only one side +/-, gets warm, you can test the transistors on the other side. If they test fine start looking at the resistors.
Thank you so much. Your observations are always so astute. I on the other hand have screwed up on construction projects everyway possible. It has helped me learn how to fix things. Try this, unhook the board from the heatsink, using a variac bring the power up slowly and carefully, to around 8 or 10 volts output on the power supply. Feel the output transistors. If only one side +/-, gets warm, you can test the transistors on the other side. If they test fine start looking at the resistors.
Wired up a new PCB and component set for the bad channel. Works perfectly well now. Biases nicely and stable. Took it upto 350mV bias. The heatsinks are massive and very effective. Originally over engineered for Turbo V3. They get to be mildly hot.
Checked the audio. Works perfectly. Did not listen enough to find the differences between my existing F5 builds and this. Looks like I have completed the build of F5 Turbo V2. Will post pictures once I tidy up the wiring in a day or so.
Thanks to everyone for their help.
Cheers.
Thanks. I will compare both and post my impressions. BTW the mosfets and the diodes are from you ;-) Thanks for the help to the DIY community. My next one in a identical chassis is the V3. But for the screw-up w.r.t to mounting holes on the heatsink for the mosfets, I would have gone into the testing phase of V3 as well.
Pictures of completed F5 Turbo V2
As mentioned in an earlier post, completed the build including setting up the biases, monitoring heat and stability etc.
Also did few hours of sound testing with my Fostex back loaded horns, which are currently used with a standard F5.
As far as impressions of the sound are concerned, the amp is simply outstanding. It has F5 like detail and clarity and has very strong dynamics and a solid bass support. Each and every instrument can be felt and heard. The amp does not attract attention and one instantly starts enjoying the music rather than hearing the amp. There is no fatigue. The difference between a regular F5 and F5 Turbo V2 as far as my build comparison is concerned, is that the Turbo is bit more warmer and more in control. It has stronger dynamics and support for stronger bass. These needs to be taken as a relative comparison and in no way a comment on standard F5's sound. While the sound signatures are almost similar, I should be able to tell a Turbo in a blind test due to stronger dynamics and bass.
Definitely a keep in my collection. Have a minor non-instrusive hum problem to be resolved in terms of double ground from my preamp. Also have a suspicion that 8 x 10000 uF per power supply rail is not sufficient enough. It probably needs to be 8 x 22000 uF. With higher bias, the capacitors are adding leakage current.
The heatsinks are warm and not hot enough. The Toroid is a 1KVA model. Both these are a overkill for a V2. Will use the trafo for V3 soon and swap it with a 600VA model.
Here are the pictures:
As mentioned in an earlier post, completed the build including setting up the biases, monitoring heat and stability etc.
Also did few hours of sound testing with my Fostex back loaded horns, which are currently used with a standard F5.
As far as impressions of the sound are concerned, the amp is simply outstanding. It has F5 like detail and clarity and has very strong dynamics and a solid bass support. Each and every instrument can be felt and heard. The amp does not attract attention and one instantly starts enjoying the music rather than hearing the amp. There is no fatigue. The difference between a regular F5 and F5 Turbo V2 as far as my build comparison is concerned, is that the Turbo is bit more warmer and more in control. It has stronger dynamics and support for stronger bass. These needs to be taken as a relative comparison and in no way a comment on standard F5's sound. While the sound signatures are almost similar, I should be able to tell a Turbo in a blind test due to stronger dynamics and bass.
Definitely a keep in my collection. Have a minor non-instrusive hum problem to be resolved in terms of double ground from my preamp. Also have a suspicion that 8 x 10000 uF per power supply rail is not sufficient enough. It probably needs to be 8 x 22000 uF. With higher bias, the capacitors are adding leakage current.
The heatsinks are warm and not hot enough. The Toroid is a 1KVA model. Both these are a overkill for a V2. Will use the trafo for V3 soon and swap it with a 600VA model.
Here are the pictures:
Attachments
Anivila, great job!
Thank you for the review of your impressions against the F5. What you said is exactly the reason I am about to embark on building the V3
BTW how did you go about tuning harmonics using P3?
I did not tune the harmonics yet. The wiper of 200 ohms preset is set in the middle. I don't have the means to measure distortion nor do I have access to scope. Will attempt one of these days, if I can do it with a borrowed scope.
The secondary voltage of the toroid is 24v per winding.
I completely missed this fact. I agree. I might get higher current capability with more number of output devices but there will be no higher voltage swing. Looks like I need to order a 35V secondary trafo for V3.
I do have decent sound cards including an external USB M-Audio device. I need to check on the software.
Just did some quick calculation. Please tell me if I'm wrong.
at 100W into 8 ohm you will need 26.83VDC at the speakers. Since we need to calculate it in ACV then we multiply by root 2 or 1.414 thus giving us about 40V rails.
Using NP's approximation 40V rails would require about 30V secondaries at the transformer.
Is this correct?
at 100W into 8 ohm you will need 26.83VDC at the speakers. Since we need to calculate it in ACV then we multiply by root 2 or 1.414 thus giving us about 40V rails.
Using NP's approximation 40V rails would require about 30V secondaries at the transformer.
Is this correct?