F5 Turbo Builders Thread

[Nikitas]

Hi all,
I'm building an f5t v2, and in the process of testing i managed to fry the fairchilds....Now I'm waiting for replacements. Looking to my stuff this morning i found a quad of 2SK1530 2SK201 toshibas. I read somewhere,don't remember where though, that these thingies could replace the fairchilds.

So, just out of curiocity, has anybody tried these?Any major differences in sound?
I'm thinking, since, i'm waiting and have nothing to do, try them. Any thoughts on what i should change on the boards? I've everything set for fairchilds at the moment.

I would appreciate any recommendations/ideas.

 

[Rush]

Hi all,
I'm building an f5t v2, and in the process of testing i managed to fry the fairchilds....Now I'm waiting for replacements. Looking to my stuff this morning i found a quad of 2SK1530 2SK201 toshibas. I read somewhere,don't remember where though, that these thingies could replace the fairchilds.

So, just out of curiocity, has anybody tried these?Any major differences in sound?
I'm thinking, since, i'm waiting and have nothing to do, try them. Any thoughts on what i should change on the boards? I've everything set for fairchilds at the moment.

I would appreciate any recommendations/ideas.

Nelson Pass discusses the 2SK1530/2SJ201 in the original F5T article. I used them in one of my original F5 and they sound great.
Later in the F5T thread Nelson mentioned 2SK1529/2SJ200 as having less input capacitance and is a good option as well for the F5T. Neither of these will pass the current of the Fairchild devises. All of these are no longer in production.

Rush

 

[buzzforb]

THey will work great and will plug directly in with little effect. Just look up their datasheet and try to get an idea of the VGs needed for the bias you want. Before plugging them in, set your pots below that point about 25%-50%. You have tested you FE and all is good. As long as you mount and isolate them correctly, you should be able to listen within the day.

 

[jacco vermeulen]

2SK1529/2SJ200 as having less input capacitance is a good option as well for the F5T, these are no longer in production.

Oh dear, what a shame.

 

[buzzforb]

I would love to get my hands on some. If only....

 

[dazed2]

I have the 1530/201 in mine. I tried the Fairchild's as well.
Personally I like the toshibas more than the Fairchild's. Seems more musical.

However as buzz says make sure you turn down the bias pots before turning it on. As they bias a lot lower than the Fairchild's.

 

[buzzforb]

As well as having slightly lower C, I believe it is a little more linear in nature. No different than caps. Different flavor of ice cream.

 

[Nikitas]

So, 0,2-0,25V across the 0,5 Ohm resistance I should be ok for burn in,right?

 

[buzzforb]

Please restate what you mean. You should get about .300-.400mV across the source resistors. It looks like the Vgs should be in the range of 2-2.5V

 

[Nikitas]

the rating of voltage at 300-400mV across source resistors is for the fairchilds. Having to be more conservative with the toshibas, i'm thinking of 200-250mV across the R source.
I can't find a clear enough datasheet for the toshibas to take a look at graphs.

BTW did you manage to send the package?

 

[buzzforb]

You dont have to bias them lower.

 

[Zen Mod]

let them bleed !

 

[Nikitas]

Ok, last question (for now)
While playing with the trimmer to adjust the bias, should I be observing Vgs or voltage across Rs?

 

[buzzforb]

Voltage across Rs. Bring it up to300mV and let it heat up.

 

[Renron]

"BTW did you manage to send the package? "
The Rooster crows before dawn............

Were you followed? LOL

 

[Nikitas]

"BTW did you manage to send the package? "
The Rooster crows before dawn............

Were you followed? LOL

excuse me?!

 

[Renron]

Sorry, American humor. Did not mean to offend.

 

[Nikitas]

No prob, I just have no clue what you meant.

So, I re-worked one channel and fired it up. offset at 3,5V and bias at 200mV.
I adjusted the bias to 220mV aaaaand my fuse blew. Is 2A slow blow, little? What fuses are you guys using?
I have 230V mains

 

[buzzforb]

I ran my with 1A for a while. Did you turn both post equally? Sounds like you were mainly adjusting one pot.

 

[Nikitas]

I didn't have enough time until it blew. I turn about 1/4 of a turn one pot and it blew.
I will buy tomorrow more 2A fuses and a couple at 3A to see what will happen.