T-amp mod without pot

tuberider · 8th September 2006, 11:27 PM

Hi,
i have done the "stealth" mod but want to skip the volume pot and use as a poweramp but i´m not shure how to do it. Is it as simple as connecting the input wires with the new caps together for the left/right channel?
Happy for answers!

Aron

Puffin · 11th September 2006, 10:42 AM

Yes, how is it done ? I have done mods by using a pot, but not without.

audio1st · 12th September 2006, 10:11 AM

This is how I use my T-Amp, with a seperate pre-amp..

tuberider · 12th September 2006, 12:38 PM

Just beautiful, thanks a lot.

Aron

Puffin · 12th September 2006, 01:05 PM

Audio 1st. Thanks

Puffin · 12th September 2006, 03:13 PM

It's just occurred to me that your diagram relates to the "Stealth" mod. I have carried out the "Classic" mod. I assume that I would still need to add the 47k or 100k resistors in addition to resistors already attached to the other end of the capacitors ?

tuberider · 12th September 2006, 04:20 PM

I soldered in the 47k resistors and suddently my poor little amp was back in track again, so quiet(only a faint buzz, not audible at listening spot) even on my horns with 100db spl. I have no enclosure on this amp yet and i plan to make my speakers active and mount it inside.

The other amp with Alps pot in a wooden enclosure was suffering from very audible hum(even audible in my kitchen).
Audio1st adviced me to try grounding the pot, cover walls with foil and ground this to the negative power connection and this helped a lot - quiet as a mouse!

Puffin: you should try the resistors even if you have done the "Classic" mod.

Thanks!
Aron

Pano · 12th September 2006, 07:09 PM

Quote:

Originally posted by Puffin
I assume that I would still need to add the 47k or 100k resistors in addition to resistors already attached to the other end of the capacitors ?

That is correct. The resistors in the diagram posted by Audio 1st serve to set the input impedance. The volume pot does the same thing, as well as acting as a voltage divider. Without the resistors you run the risk of noise on the inputs. Lower input impedances generally have lower noise.

Puffin · 13th September 2006, 07:07 AM

Tuberider. I did it last night as my very small brain realised after I had asked the question, that the resisitors simply take the place of the pot. It was late last night when I got around to doing it, so I will have a listen tonight and see what it is like. I was using a 20k Alps Blue Velvet before.

Panomaniac. What difference would using 100k resistors make over the 47k I have used ? Does is lower the gain ?

tuberider · 13th September 2006, 09:46 AM

Well, i know what you are talking about. 98% of my diy time and forum time is done in the late hours after work, spending time/fighting with my 3 year old and new born daughters, renovating my house+ trying not to **** off my suspicious wife

i really should get more sleep. "The lights are on but nobody´s home" , a permanent modus that give birth to a lot of stupid questions
Aron

[QUOTE]Originally posted by Puffin
[B]Tuberider. I did it last night as my very small brain realised after I had asked the question, that the resisitors simply take the place of the pot. It was late last night when I got around to doing it, so I will have a listen tonight and see what it is like. I was using a 20k Alps Blue Velvet before.

8th September 2006, 11:27 PM	#1
tuberider diyAudio Member Join Date: Dec 2004 Location: Earth	T-amp mod without pot Hi, i have done the "stealth" mod but want to skip the volume pot and use as a poweramp but i´m not shure how to do it. Is it as simple as connecting the input wires with the new caps together for the left/right channel? Happy for answers! Aron

12th September 2006, 12:38 PM	#4
tuberider diyAudio Member Join Date: Dec 2004 Location: Earth	Superb! Just beautiful, thanks a lot. Aron

12th September 2006, 04:20 PM	#7
tuberider diyAudio Member Join Date: Dec 2004 Location: Earth	No more hum and pot! I soldered in the 47k resistors and suddently my poor little amp was back in track again, so quiet(only a faint buzz, not audible at listening spot) even on my horns with 100db spl. I have no enclosure on this amp yet and i plan to make my speakers active and mount it inside. The other amp with Alps pot in a wooden enclosure was suffering from very audible hum(even audible in my kitchen). Audio1st adviced me to try grounding the pot, cover walls with foil and ground this to the negative power connection and this helped a lot - quiet as a mouse! Puffin: you should try the resistors even if you have done the "Classic" mod. Thanks! Aron

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11th September 2006, 10:42 AM	#2
Puffin diyAudio Member Join Date: Feb 2006 Location: U.K	Yes, how is it done ? I have done mods by using a pot, but not without.

12th September 2006, 01:05 PM	#5
Puffin diyAudio Member Join Date: Feb 2006 Location: U.K	Audio 1st. Thanks

12th September 2006, 03:13 PM	#6
Puffin diyAudio Member Join Date: Feb 2006 Location: U.K	It's just occurred to me that your diagram relates to the "Stealth" mod. I have carried out the "Classic" mod. I assume that I would still need to add the 47k or 100k resistors in addition to resistors already attached to the other end of the capacitors ?

13th September 2006, 07:07 AM	#9
Puffin diyAudio Member Join Date: Feb 2006 Location: U.K	Tuberider. I did it last night as my very small brain realised after I had asked the question, that the resisitors simply take the place of the pot. It was late last night when I got around to doing it, so I will have a listen tonight and see what it is like. I was using a 20k Alps Blue Velvet before. Panomaniac. What difference would using 100k resistors make over the 47k I have used ? Does is lower the gain ?

13th September 2006, 09:46 AM	#10
tuberider diyAudio Member Join Date: Dec 2004 Location: Earth	Well, i know what you are talking about. 98% of my diy time and forum time is done in the late hours after work, spending time/fighting with my 3 year old and new born daughters, renovating my house+ trying not to **** off my suspicious wife i really should get more sleep. "The lights are on but nobody´s home" , a permanent modus that give birth to a lot of stupid questions Aron [QUOTE]Originally posted by Puffin [B]Tuberider. I did it last night as my very small brain realised after I had asked the question, that the resisitors simply take the place of the pot. It was late last night when I got around to doing it, so I will have a listen tonight and see what it is like. I was using a 20k Alps Blue Velvet before.

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