There was a question posed by jwb009 in September 2005 regarding the "stealth" mod. He asked if the stealth mod could still be undertaken if R1 and R2 had been removed. I cannot see that there was an answer. I would be intersted in that I have carried out Version 1 (the classic) mod, but wonder if I am capable of doing the "stealth" mod. I have an old board with smd's on it and it tried to bridge them and they just came off the board. If R1 and R2 have been removed can you still connect up polypropylene caps (2.2uf) in the same way as shown in the picture posted on Michael Mardis's website which I think came from audio1st ?
Hello Puffin,
Unless you can replace R1 & R2 again, you cannot do the "stealth" mod. I don't think IMHO the stealth mod sounds any better than the original mod, it was just meant to be easier to carry out.
If someone knew the value of L1 & L2, you could create the same filter before the 2.2uf blocking caps.
That would be: vol pot, 100pf to ground, L1 or L2 then 2.2uf cap, followed by the 20k resistor.
Hope this makes some sense?
Barry..
Unless you can replace R1 & R2 again, you cannot do the "stealth" mod. I don't think IMHO the stealth mod sounds any better than the original mod, it was just meant to be easier to carry out.
If someone knew the value of L1 & L2, you could create the same filter before the 2.2uf blocking caps.
That would be: vol pot, 100pf to ground, L1 or L2 then 2.2uf cap, followed by the 20k resistor.
Hope this makes some sense?
Barry..
The inductors are from Autocostruire and were recommended as replacements by an article in Hi Fi World magazine. The article is the one on Michael Mardis's website (panomaniac). I used a white noise signal to test the board and as I increased the volume on the pot, the noise came from the inductors. No sound was coming out of the speakers.
Thanks for that. After some more tinkering I have got it working and it sounds fantastic. The article in Hi FI World is right when it says that the air-core inductors clean up the treble. They also give it much more air and space. I have found some Kimber Caps 0.1uf caps I used in a crossover to bypass with. I have previously not bothered with using the small caps (across the speaker terminals) that come with the stock S.I. I have fitted these to the current modded amp. I cannot find any information on the forum about using any caps across the terminals. is it worth it ? It doesn't seem to affect sound quality.
Good to hear you are up and running.
The sonic T amp already has 0.1uf smd caps across the speaker outputs on the cct board (c19 & c20).
It is all down to what sounds better, or do the extra caps make it sound worse?
PS, I have just ordered the Autocostruire 2020 amp with the air core inductors and hope I will be able to build it? The sonic T amps are costing about £30 in the UK, add on the inductors and a new pot( £35) and you are getting close to the price of the 2020 amp, about £70. So here goes
Barry..
I don't use any caps across the speaker terminals. None of the other makes of amps seem to use them either.Puffin said:
The sonic T amp already has 0.1uf smd caps across the speaker outputs on the cct board (c19 & c20).
It is all down to what sounds better, or do the extra caps make it sound worse?
PS, I have just ordered the Autocostruire 2020 amp with the air core inductors and hope I will be able to build it? The sonic T amps are costing about £30 in the UK, add on the inductors and a new pot( £35) and you are getting close to the price of the 2020 amp, about £70. So here goes
Barry..
Having done a couple of Sonic Impact's I would be interested to hear how you get on. The costs do start to rise quite rapidly when you add up the cost of a new box, pot, (I had 3 Alps 20k spare that I picked up at an audiojumble for £1.00each!)connectors and poly caps etc. I reckon each modded S.I has cost me about £55 (without the cost of an Alps pot)
Incidentally I am using 20k pots (because I am tight) which seem to be fine. What's the difference between 20k, 50k, 100k pots. Am i strangling the sound at all ?
Incidentally I am using 20k pots (because I am tight) which seem to be fine. What's the difference between 20k, 50k, 100k pots. Am i strangling the sound at all ?
audio1st said:
"Differential Output Capacitor. Differential noise decoupling for reduction of conducted emissions. Must be located near chassis exit point for maximum effectiveness." (datasheet) - Does that mean to reduce any interference with TV and/or radio?
I paid £28 delivered from Media-Zone, I see they've dropped to £27 now. Good fast service. 3.5A SMPS and lead another £19.
If you do the Stealth mod you're removing a 10k resistor R01 originally across pot wiper & ground which would give much less than 20k with the original pot...
Why is R01 there? To change the pot law?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.