Personally I beefed up the heatsinks quite a lot, especially for the regulators:
20200206_1810012.jpg
As for the board, it sits on a HiFi2000 23x23cmx8.3cm case, and is elevated from two plastic "bolts"of plastic of 5mm each, which are then screwed throught the bottom place of the chassis.
I received Burson V6 vivid and it's now burning in. First 2 hours of out-of-the-box listening differ a lot from the hour 24, so I will refrain myself from giving feedback until I reach at least 150h.
20200204_151610.jpg
20200206_1810012.jpg
As for the board, it sits on a HiFi2000 23x23cmx8.3cm case, and is elevated from two plastic "bolts"of plastic of 5mm each, which are then screwed throught the bottom place of the chassis.
I received Burson V6 vivid and it's now burning in. First 2 hours of out-of-the-box listening differ a lot from the hour 24, so I will refrain myself from giving feedback until I reach at least 150h.
20200204_151610.jpg
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I guess he means is it the correct rating, would 250mA do the job?
What is your bias set at?
Ah output bias is the current you are running the output mosfets at...
so, R16/R22 - R29/R32 is 10R on the standard BOM. This will give you 60mA current (on the schematic on first page here, it gives examples of different values and bias)
I have increased my bias to 100mA using 5R resistors (lower resistor value gives higher bias) I also needed to get bigger heatsinks to be safe.
I'll guess you are using standard 10R BOM values? so you will have 60mA bias each channel. In which case your 250mA fuse should be more than fine.
Did you notice the heatsinks getting very hot before the blow out? or maybe one hotter than others?
Good job you fitted a fuse... I haven't yet but my amp is pukka, as they say in south London...
so, R16/R22 - R29/R32 is 10R on the standard BOM. This will give you 60mA current (on the schematic on first page here, it gives examples of different values and bias)
I have increased my bias to 100mA using 5R resistors (lower resistor value gives higher bias) I also needed to get bigger heatsinks to be safe.
I'll guess you are using standard 10R BOM values? so you will have 60mA bias each channel. In which case your 250mA fuse should be more than fine.
Did you notice the heatsinks getting very hot before the blow out? or maybe one hotter than others?
Good job you fitted a fuse... I haven't yet but my amp is pukka, as they say in south London...
Seriously, I'm the worst person to offer advice and it's so hard to guess what it wrong. The amp design is so simple and effective that it is hard to make a mistake. It is hard to even get a single solder bridge as the components are spaced out nicely.
But your output stage is overworking, if it blew 250mA then a ballpark guess is a faulty mosfet or optocoupler maybe. The optocouplers help with bias stability so can you check DC Voltage readings with multimeter from the optocoupler pins, I think pins 1 & 2 if someone can confirm.
But your output stage is overworking, if it blew 250mA then a ballpark guess is a faulty mosfet or optocoupler maybe. The optocouplers help with bias stability so can you check DC Voltage readings with multimeter from the optocoupler pins, I think pins 1 & 2 if someone can confirm.
Yes all standard BOM values. I will recheck the heatsinks if and when it blows out again.
Thanks for your help passive! 420 all the wayfrom LA here hehe
Also you may check the bias current by measure voltage across the 10 ohm "bias resistors". Also you can measure AC input current. If bias is correct but you draw let us say 350 mA from AC power then something is wrong another place in circuit. Also re-check the DC output from the regulators. Check DC voltage to opamp. Check if it gets very hot etc.....you can also check opamp current by measure voltage across the two 47 ohm resistors.
I do not want to turn this thread into an amp rolling discussion. If anybody feels I am doing this please say so and I will stop.
I hope this is useful for somebody (my initial choice of the op amp for Whammy was inspired by reading people's opinions here).
The direct reason for this post is a package which arrived this week from Passive420.
It contained a box with some delights. These include
1. metal cans opa627 on brown dog single to dual
2. LT1361
3. OPA604
4. LT1028
5. and metal cans LME49710
Today I made some time to do some swapping. My benchmark nowadays is Burson V6 classic (as some of you might have noticed), AD823 before.
Here are my initial imressions.
I started with opa627. Wow, very close to Burson, Burson has somewhat warmer sound a notch more live like. Then LT1361, very very good. Then I listened to opa604 which I liked less.
I could not get LT1028 working. I removed all compensation caps as Passive suggested but the amp was still oscillating.
In fact these are all very fine chips and while you can hear differences between them it is really hard to say which one is better. Might be a question of personal preferences.
After some swapping I decided that OPA627 is the one to leave in Whammy to see how I like in the longer run. As I said I prefer Burson, but I want to see how much I would miss if anything when opa627 is playing on a daily basis.
Apologies to those who would prefer blind abx tests...
I hope this is useful for somebody (my initial choice of the op amp for Whammy was inspired by reading people's opinions here).
The direct reason for this post is a package which arrived this week from Passive420.
It contained a box with some delights. These include
1. metal cans opa627 on brown dog single to dual
2. LT1361
3. OPA604
4. LT1028
5. and metal cans LME49710
Today I made some time to do some swapping. My benchmark nowadays is Burson V6 classic (as some of you might have noticed), AD823 before.
Here are my initial imressions.
I started with opa627. Wow, very close to Burson, Burson has somewhat warmer sound a notch more live like. Then LT1361, very very good. Then I listened to opa604 which I liked less.
I could not get LT1028 working. I removed all compensation caps as Passive suggested but the amp was still oscillating.
In fact these are all very fine chips and while you can hear differences between them it is really hard to say which one is better. Might be a question of personal preferences.
After some swapping I decided that OPA627 is the one to leave in Whammy to see how I like in the longer run. As I said I prefer Burson, but I want to see how much I would miss if anything when opa627 is playing on a daily basis.
Apologies to those who would prefer blind abx tests...
I am new to this forum and did some resarch, also in other Forums, because I will build the whammy headamp. Parts an PCB are already ordered.
I have two questions for which I could not find any final answer here in the Forum.
First, I want to install right away the Biurson V6 vivid. Buit there seem to be some compatibility issues. On the burson Webpage someone posted a photo with the V6 installed and did not report any Problems.
He also has installed two Mundorf MCap EVO couploing caps in the Signal path instead the generic ones. Does this make sense and can one even use a higher capacity to improve the lower cut out freqency.
Can anyone help me?
Thanks, Klaus
I have two questions for which I could not find any final answer here in the Forum.
First, I want to install right away the Biurson V6 vivid. Buit there seem to be some compatibility issues. On the burson Webpage someone posted a photo with the V6 installed and did not report any Problems.
He also has installed two Mundorf MCap EVO couploing caps in the Signal path instead the generic ones. Does this make sense and can one even use a higher capacity to improve the lower cut out freqency.
Can anyone help me?
Thanks, Klaus
