Start-Up Delay for tube amp !

[thor61]

Hello Everyone ! I found this neat little circuit and/or kit ! It can be found at > A Start-Up Delay For Vintage Amplifiers Also here is a pdf from "Audio-Express 2001" that give more details ect... > http://www.nervenet.info/HT_delay/ax_aug-2001.pdf Could someone voice there thoughts about using this and/or the pro's and con's of its use ? Thank's for listening !

[Joshua_G]

Lets settle the b+ on cold tubes issue!

[Wavebourn]

I expect to see here all advocates of B+ delay myth, either directly or indirectly affiliated with sales and promotion of such obsolete superstitious devices and kits. Also, tube amp sellers who use the feature to brag may chime in soon.

[nightanole]

I always thought start up delays were for preventing blowing up rectifiers during the initial charge of the power supply caps, and blowing breakers during the same routine with larger amps

[thor61]

Will something like the above posted circuit help to get rid of turn-on thumps in a preamp or line-stage ? Also would it be better to use something like a CL90 type in-rush current limiter ? Basically just trying to understand how such things effect operation at start-up ect....

[Wavebourn]

Originally Posted by thor61

Will something like the above posted circuit help to get rid of turn-on thumps in a preamp or line-stage ?

Here you go: Lets settle the b+ on cold tubes issue!

But first of all you have to find the cause of cracking and popping and solve the main problem. I had similar problem when used some tubes out of specs for max voltage between cathode and filament. I had to select tubes that don't crack and pop.

[thor61]

The only snap crackle or pop I can think of comes from "Rice Crispies" Lets hope you don't sweep them under your rug ! I'm talking about a turn on thump heard through speakers sometimes when first turning on some amps !

[nigelwright7557]

Valve amps come on slowly so there is rarely any turn on thump.

I have built valve amps for many years and never had any problems with power on upsetting the amp or the tubes. In fact I havent ever replaced a tube that I can remember.

[thor61]

Hi Nigelwright7557 ! I'm kinda new to building tube amps ect... So time back I had built a SOHA tube HP amp, it was a very good sounding though the design had a few flaws. One of them being turn-on thumps, the current revised version takes care of such things ect... They used a relay based delay of some sort ! Its called The Super SE SOHA II and is getting rave reviews ! Its both a HP amp and Line-stage in one.

[nigelwright7557]

Originally Posted by thor61

Hi Nigelwright7557 ! I'm kinda new to building tube amps ect... So time back I had built a SOHA tube HP amp, it was a very good sounding though the design had a few flaws. One of them being turn-on thumps, the current revised version takes care of such things ect... They used a relay based delay of some sort ! Its called The Super SE SOHA II and is getting rave reviews ! Its both a HP amp and Line-stage in one.

Unless your amp has turn on thumps I wouldnt add the extra complexity of a soft start.

Having read through DIY audio threads for a number of years now soft starts are always causing problem. If something can go wrong it will eventually go wrong. KISS keep it simple !