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#82
Good morning
I am an old (63YO) audio enthusiast with very little soldering skills (acquiring some).
My sound system consists of Class D amps (Samwu TPA3118, Weiner, and lately a 3255EVM which I swap on whim outputing to a pair of Tannoy bookshelves.
My sources are a TV, DVD player and a Digital Box which plays FLAC, WAV and MP3s
For volume control, I route the input signal to a cheap 2-tube buffer. I was able to buy an external switch to select sources but it is flakey.

I would like to assemble a pre-amp with minimum work, hopefully forgiving in the soldering area. And if possible the minimum number of components and cost.
Would anyone please advise me whether the Bi or the Mesmerize (or other circuti) would fit my requirements.
I have very little info about these circuits except that they have a selectable input and very good reputation for sound output.
Thank you.
 
#83
paugie said:
Would anyone please advise me whether the Bi or the Mesmerize (or other circuti) would fit my requirements.
Click to expand...

The B1 would work for you. Boards and Jfets are available at PassDiy. It's not a complicated build, you can easily handle it.

Unless the fact that the B1 board from Pass only has two switchable inputs creates a problem for you.
 
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#86
The B1 feeds the power amplifier.
For phono you use:
phono > RIAA pre-amp > B1 > power amp
or
phono > RIAA pre-amp > tube buffer > B1 > power amp
You would need the tube buffer only if your RIAA pre-amp cannot adequately drive the cables to the next stage.

The B1 accepts two inputs, whereas the DCB1 based Mezmerise has upto six inputs.
 
#87
Dear 6L6,

I saw some members connect their speaker negative back to the board GND at first and then to the power GND (star point). Also some members connect the speaker negative directly to the power supply GND (start point).

I thought in the first case, a big wire is needed, big current from speaker and small signal go in the same wire. And in the second case, a small GND wire is sufficient, because only small signal is going thru the wire.

What difference could they have? And which way could be better under which conditions?
 
#89
Hi 6L6, do you know the part number for the diode bridge you use in power supply of some Firstwatt you have built? Also the 4 terminal white screw-in thing used to hold in thermistors. What type of IEC inlet you used?

If not part number then what are these 3 things called? Thanks!

Edit: I saw the BOM for power supply and didn't see these parts.

I'm complete noob to SS. I've built countless tube amps.
 
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#90
imnewbie said:
Hi 6L6, do you know the part number for the diode bridge you use in power supply of some Firstwatt you have built? Also the 4 terminal white screw-in thing used to hold in thermistors. What type of IEC inlet you used?

If not part number then what are these 3 things called? Thanks!

Edit: I saw the BOM for power supply and didn't see these parts.

I'm complete noob to SS. I've built countless tube amps.
Click to expand...

I used this terminal part: 1546670-4 TE Connectivity / AMP | Mouser
and here's the link for GBPC3502 bridges: https://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/GBPC3502
 
#92
Diode help

I am planning to use the diode section of the board. I noted that on the first page of the build guide 30A, 200V minimum diodes are recommended. I was not sure if this referred to forward or reverse voltage and current. Looking at Mouser's parameters listed for TO220 devices it looks like this is forward current and reverse voltage. Can anyone confirm this?

Based on Jeff Young's advice about "fast" and "soft" diodes I came up with the diodes linked below. They exceed the suggested minimums and the data sheet for them touts them as fast and soft. Will these diodes work well for the PSU?

https://www.mouser.com/datasheet/2/427/vs-hfa30ta60c-m3-1351050.pdf
 
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#95
Just purchased a couple tubes of IRFP9140 and IRFP140 MOSFETs.
Need to match them. This instructional article says to bias to .2V across the MOSFET source resistor.

Is the actual parallel Source resistance actually .235 Ohm?
What's the actual current each mosfet sees?
What's the total bias for a push-pull F4 channel?

Thanks,

Vince
 
#98
Another very successful build, Aleph J!

Thanks to 6L6 for the guide which I always follow exactly. I can't stop listening to it every night. My favorite amp for 1-2 months now. The F5 is taking a rest 😉

Hoping, a guide will come out for a heavy class AB.

Many thanks again to Jim☺☺☺
 
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