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Old 20th April 2008, 02:10 PM   #121
rbclark is offline rbclark  United States
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Quote:
Originally posted by rhing

I soldered the wires for the AC and the output connections to the board connectors. For mechanical integrity in the board AC connections, I snipped off spades from some insulated crimp lugs and crimped the lug over the soldered connection. It's not the most elegant solution, but it worked for me. You can do this at your own risk.

I did something similar at the outputs.
I'm pretty amateur at soldering, so I was hoping for an easy connector solution. Haven't seen anything yet. I think I'll try the soldering.

Thanks!
Bob
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Old 21st April 2008, 05:18 AM   #122
erpiii is offline erpiii  United States
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Paul,

No I haven't worked out the earphone jack... I only know that when you unplug the connector to the headphone pcb, it stops the speaker output. I think the earphone jack has a switch at the back and it must disconnect the input signal when the jack's plugged into. That kinda sucks though... I don't like the idea of the input signal making the journey through all that wire. But, as I have said before... I really don't know that much about circuits.

I see what you mean about the led's in the input path... I wanted to use the leds as a source indicator, one for each input... but I guess I could just wire back to - at the power jack and use it as an on/off indicator. I noticed that some versions of the pcb just use a resistor and some also combine it with a capacitor. Would the capacitor help keep anything out of the signal path? Just wondering...

Eddie
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Old 21st April 2008, 10:05 PM   #123
erpiii is offline erpiii  United States
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Paul,

I looked at the earphone jack wiring and this is what I figured out.

The ear phone when plugged in switches the speaker out off and routes the signal to the pcb somewhere. When the earphone is not pugged in the circuit makes a loop ... I can check continuity back to tha caps I assume these are the + signals for each channel. I made a diagram of which wires are which...

I guess if you wanted to remove the whole connector you could do so and then just jump the connections from 6 to 8 and 7 to 9. That would remove a lot of wiring from the signal path.

See attached picture

Eddie
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File Type: jpg gen2earphone.jpg (77.1 KB, 583 views)
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Old 22nd April 2008, 11:19 AM   #124
ZL2BPS is offline ZL2BPS  New Zealand
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erpii
Eddie, yes I looked at that circuit last nite & came up with the same answer as you. Accordingly I will shear off the ribbon @ the board & jumper pin's 6 & 8, 7 & 9, on the underneath of the board to keep it tidy.
You can still use your Led's as a source indicator for each input as you proposed, I would however sugest you run a seperate earth rail as distinct from using signal -.
If I had had more room I would have done the same with a rotary switch & the led's opposed by the degrees of rotation. No room in my $20 die cast case
Going to strip mine out tonite & hopefully get it off to the powder coater this week.
Trying to find a cutter I can sneak in to cut / crush R3, R02 is not so bad to get at. I will "blob" the 2 cap's.
With the 2 new Caps wired into the input, the circuit will then be identical to the Tripath evaluation board.
Hopefully I will have the case back & it up & running again in a couple of weeks.
Paul
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Old 22nd April 2008, 04:48 PM   #125
erpiii is offline erpiii  United States
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Hi Paul...

So you will be soldering the input caps right at the junction of R3 R02?
Are you going to change any of the other caps?

About the leds... the way I see the circuit for the indicator led is that it is switched through the - signal. How would running another - line from, lets say, the input DC jack, be switched? Unless I had another pole on my switch, I don't see how it could be accomplished. How can I isolate it from the signal - and also switch it, without having another switch or pole on the switch I have? I guess I could put in a dedicated on/off switch and that would leave room on the source selector for the - led switching. If this can be accomplished lemme know. I don't know much about circuitry so I'm not doubting your proposal!

Thanks,

Eddie
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Old 23rd April 2008, 02:36 AM   #126
rhing is offline rhing  United States
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Default Direct Comparison Between SI Gen 1 and Gen 2 T-Amps

I received a SI Gen 1 T-amp on loan and compared it to my SI Gen 2 T-amp.

Background:
I used Onix Reference 1 monitors (88dB efficient two-way monitors, 4Ohm nominal impedance), a modified Playstation 1 as a digital source and a Monster Interlink 200 RCA-to-3mm stereo jack adapter cable. I used each amp's respective stock power supplies (BI Switching Power Supply, 12VDC, 3A output) for the comparison. I also used a Skynet SNP-9037 switching power supply (SMPS) that used a Zu Cable Birth power cable and a DIY DC cable made of a twisted pair of 16AWG Teflon insulated Silver-plated Copper stranded conductors terminated with a Switchcraft 2.1mm/5.5mm DC connector. This happens to be an SMPS recommended by Michael Mardis. Unfortunately, for some reason, I could not power up the Gen 1 T-amp with the Skynet SMPS. I was able to swap the stock PSU's between amps (they are identical), but the Gen 1 wouldn't power up with the Skynet SMPS.

Conclusion:

I couldn't tell the difference between the T-amps. They both sounded identical at equal sound levels. I was expecting to hear lighter bass with the Gen 1 since many here have said that the Gen 2 has improved bass. When I first connected droht's Gen 1, I was surprised to hear the same sound quality as my Gen 2--the same level of bass was there. Now keep in mind that I do not have a subwoofer in my system, and the Ref 1's don't go really deep (approx. 55hz). It is possible that the Ref 1's just don't allow me to hear the difference in low frequency response. I might do measurements on my Gen 2 amp later this week when I have more time. I won't do any further testing with the Gen 1, because I don't want to risk damaging the loaner T-amp.

With the Gen 1, I had to turn up the volume knob from its starting position of 6 o'clock to 11 o'clock to get an equivalent loudness to the Gen 2 (from starting position of 7 o'clock to 10 o'clock). In other words, the volume pot on the Gen 2 seems to be more responsive in adjusting volume levels.

With the Skynet SMPS, the sound quality improved. The sound was less bright, much smoother and better balanced. The bass was tighter and more defined and low level detail came through more clearly. The soundstage became deeper. With the stock PSU in either amp, there is a very thin layer of grunge in the sound that I was only able to detect once i used the Skynet SMPS and then switched back to the stock PSU. Switching back and forth, I could really pick up on that layer of grunge. Another thing that was interesting was that I could hear up close a faint hum and low level hiss coming through the speakers with the amp sitting idle. I had both the Skynet and stock PSU's plugged into my power outlet bar with the Skynet actually powering the amp. When I unplugged the stock PSU, the hum and hiss disappeared.

I don't even use the stock PSU with my Gen 2 anymore. It's really disappointing that the Gen 1 didn't power up with the Skynet SMPS, because I am curious if the same improvements I've heard with the Gen 2 amp would carry over. The Switchcraft connector is a standard DC connector and should work with either amp. At this point, I would have to assume that if I could get the Gen 1 to work with the Skynet SMPS, the same improvements would occur.

I would recommend the Gen 2 T-amp over the Gen 1 T-amp based on the following:

1. The Gen 2 looks better IMHO and the blue LED illuminated volume knob is easier to adjust
2. The Gen 2 circuit board has a better layout for modifications. Also, it is bolted into the case rather than glued in with a hot melt adhesive

Other than those minor differences, they are both very good sounding amps in my system, and I would be happy to use either one. Now that I have this comparison out of the way, I'm going to start my Gen 2 T-amp upgrade project.
Attached Images
File Type: jpg gen 1 vs. gen 2 si t-amp.jpg (21.1 KB, 1006 views)
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Rich
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Old 23rd April 2008, 02:57 AM   #127
ttan98 is offline ttan98  Australia
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Default Re: Direct Comparison Between SI Gen 1 and Gen 2 T-Amps

Quote:
Originally posted by rhing
I received a SI Gen 1 T-amp on loan and compared it to my SI Gen 2 T-amp.

Background:
I used Onix Reference 1 monitors (88dB efficient two-way monitors, 4Ohm nominal impedance), a modified Playstation 1 as a digital source and a Monster Interlink 200 RCA-to-3mm stereo jack adapter cable. I used each amp's respective stock power supplies (BI Switching Power Supply, 12VDC, 3A output) for the comparison. I also used a Skynet SNP-9037 switching power supply (SMPS) that used a Zu Cable Birth power cable and a DIY DC cable made of a twisted pair of 16AWG Teflon insulated Silver-plated Copper stranded conductors terminated with a Switchcraft 2.1mm/5.5mm DC connector. This happens to be an SMPS recommended by Michael Mardis. Unfortunately, for some reason, I could not power up the Gen 1 T-amp with the Skynet SMPS. I was able to swap the stock PSU's between amps (they are identical), but the Gen 1 wouldn't power up with the Skynet SMPS.

Conclusion:

I couldn't tell the difference between the T-amps. They both sounded identical at equal sound levels. I was expecting to hear lighter bass with the Gen 1 since many here have said that the Gen 2 has improved bass. When I first connected droht's Gen 1, I was surprised to hear the same sound quality as my Gen 2--the same level of bass was there. Now keep in mind that I do not have a subwoofer in my system, and the Ref 1's don't go really deep (approx. 55hz). It is possible that the Ref 1's just don't allow me to hear the difference in low frequency response. I might do measurements on my Gen 2 amp later this week when I have more time. I won't do any further testing with the Gen 1, because I don't want to risk damaging the loaner T-amp.

With the Gen 1, I had to turn up the volume knob from its starting position of 6 o'clock to 11 o'clock to get an equivalent loudness to the Gen 2 (from starting position of 7 o'clock to 10 o'clock). In other words, the volume pot on the Gen 2 seems to be more responsive in adjusting volume levels.

With the Skynet SMPS, the sound quality improved. The sound was less bright, much smoother and better balanced. The bass was tighter and more defined and low level detail came through more clearly. The soundstage became deeper. With the stock PSU in either amp, there is a very thin layer of grunge in the sound that I was only able to detect once i used the Skynet SMPS and then switched back to the stock PSU. Switching back and forth, I could really pick up on that layer of grunge. Another thing that was interesting was that I could hear up close a faint hum and low level hiss coming through the speakers with the amp sitting idle. I had both the Skynet and stock PSU's plugged into my power outlet bar with the Skynet actually powering the amp. When I unplugged the stock PSU, the hum and hiss disappeared.

I don't even use the stock PSU with my Gen 2 anymore. It's really disappointing that the Gen 1 didn't power up with the Skynet SMPS, because I am curious if the same improvements I've heard with the Gen 2 amp would carry over. The Switchcraft connector is a standard DC connector and should work with either amp. At this point, I would have to assume that if I could get the Gen 1 to work with the Skynet SMPS, the same improvements would occur.

I would recommend the Gen 2 T-amp over the Gen 1 T-amp based on the following:

1. The Gen 2 looks better IMHO and the blue LED illuminated volume knob is easier to adjust
2. The Gen 2 circuit board has a better layout for modifications. Also, it is bolted into the case rather than glued in with a hot melt adhesive

Other than those minor differences, they are both very good sounding amps in my system, and I would be happy to use either one. Now that I have this comparison out of the way, I'm going to start my Gen 2 T-amp upgrade project.

Thanks for taking the time to review both amps, it will help some potential buyers to decide. I have T-amp Gen 2, I too is quite please with it.

cheers.
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Old 23rd April 2008, 03:53 AM   #128
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Many thanks for your comparison review!

Godzilla
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Old 23rd April 2008, 07:25 AM   #129
erpiii is offline erpiii  United States
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Nice review Rich! I may have to shell out for the Skynet PS. I've looked in cyber world, but haven't been able to locate one just yet. I may have to go to your source in the Bay area to have one shipped... is it located in Santa Clara?

So, you plan to mod the G2... Since I don't know what I'm doing, I guess I'll do the wait and see thing before starting to solder. If you don't mind me asking, what are your mod plans for the G2?

Ed
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Old 23rd April 2008, 11:43 AM   #130
ZL2BPS is offline ZL2BPS  New Zealand
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erpiii
Eddie,
Re cap's, no my cap's are rather large being pp's. I will go into J2 from the Vol Pot sweeper after shielding the cap leads.
I will make up a "dummy" loom on an old Cap as the braid/heatshrink may make the wiring a bit stiff. I made a loom last nite for RCA's to Vol pot & it's OK because it's a lot longer & does not require acute bends.
The main board will be "floating" & only shielding connected to the die cast case. This worked well with my other T-Amps ( Sure & Charlize ) which are totally quiet.

Your Switch.
Had to go back to your drawing you put up a few post back. I assume you are going to use it as a power amp & bypass the Vol control. ?? as you have wired the RCA's directly to the amp input. Yes I should have looked closer at your drawing & looked at the Pot board also as the + & - pad's on the board are common for both Led's.
As you say you haven't enough poles & would need a seperate power switch & need to cut a trace on the board between the led's to do what I proposed.
Give it a go utilising a common -, after all Sonic do it that way & mine at least was very quiet, not totally but I think what noise I had was from my computer.
Are you re-casing it ??

Recd. 2 x more Sure boards today for next project. Have you tried them ?? They are very good with some basic Mod's & super cheap @ US$ 20.00 Plug & Play.


Paul
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