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ForeWatt Tube SRPP Preamplifier - Support / Update Thread
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Author:  steinkare [ 05 Nov 2017, 17:32 ]
Post subject:  Re: ForeWatt Tube SRPP Preamplifier - Support / Update Threa

Here is mine SRPP pre. I use ecc82 now, but I use to swap to other different ones. Sylvania 5814 sounds great. A 7812 are used for stab. the heaters. Great sound!

Author:  gh0st3g [ 13 Nov 2017, 21:32 ]
Post subject:  Re: ForeWatt Tube SRPP Preamplifier - Support / Update Threa

gh0st3g wrote:
Hi All,
I having building PreWatt, but I have issue to Lite VM02 Motorize Remote, I don't understand connecting, so is there someone else could be guide me how to connect them.
Thank you many much.

Hi All,
Please help me connect VM04 Remote, when I connect, no any sound pass to, just louder hum over the speaker.
I wonder should i must connect Ground Signal on VM04 Remote to Ground of Forewatt,.
I am so confuse.
Thank you.

Author:  igor04 [ 15 Nov 2017, 13:49 ]
Post subject:  Re: ForeWatt Tube SRPP Preamplifier - Support / Update Threa

Hello everybody!
I'm newby in DIY-amplifiers, this is my first project and I want to ask for help on the arrangement of the parts.
I used EasyEDA for an approximate assembly. Later I plan to gather the details on the textolit (point-to-point construction).
And another small question.
What voltage is required for the capacitor in the B + circuit?

Attachment:
SRPP_preamp_PCB-51bf529dfa724e9b9a82569ac1cb3f58.png


If this materials can't be posted on this forum, tell me and I will delete the picture.

For PSU I found a complete kit of tube stabilized regulated power supply and a diode rectifier. B+ can be put on 270 V, and the voltage for heating - by 6.3 V. (price 60 $). The manufacturer recommends it for tube amplifiers.

Author:  gofar99 [ 15 Nov 2017, 17:41 ]
Post subject:  Re: ForeWatt Tube SRPP Preamplifier - Support / Update Threa

Hi gh0st3g, Yes indeed there is a ground connection. The instructions with these units are not really all that good. I no longer have the instructions though. I usually make the ground connection to the rest of the circuitry from the MV and VO controls from any one of the negative or ground terminals at the input side near the relays. Just one wire to the rest of the preamp circuitry is needed. More than one will result in ground loops and cause hum. My preferred mathod of grounding is a bit different. I like to put a ground connection (buss) between the grounds on all the inputs that also goes to the grounds on the outputs. From this buss I attach all other grounds in the system. Still only one between the MV and VO units to the buss. If you use shielded wire between the inputs and the MV and VO units only attach one end if you use my preferred method.

Good listening
Bruce

Author:  gh0st3g [ 15 Nov 2017, 20:24 ]
Post subject:  Re: ForeWatt Tube SRPP Preamplifier - Support / Update Threa

gofar99 wrote:
Hi gh0st3g, Yes indeed there is a ground connection. The instructions with these units are not really all that good. I no longer have the instructions though. I usually make the ground connection to the rest of the circuitry from the MV and VO controls from any one of the negative or ground terminals at the input side near the relays. Just one wire to the rest of the preamp circuitry is needed. More than one will result in ground loops and cause hum. My preferred mathod of grounding is a bit different. I like to put a ground connection (buss) between the grounds on all the inputs that also goes to the grounds on the outputs. From this buss I attach all other grounds in the system. Still only one between the MV and VO units to the buss. If you use shielded wire between the inputs and the MV and VO units only attach one end if you use my preferred method.

Good listening
Bruce


Hi Bruce,
Thank you many much.
Actually, I connect ground wire from input terminal, and preamp had small sound of music, and big noise to speaker.
One things, I connect Forewat to Oddwatt (Stereo Ver.) Sometime, when I turn off Gain and direct contact, my Oddwatt (run KT77) had an issue, the KT 77 had been burn out LM317, and current go up to 200 mA. Is that problem from ground connected from Forewatt to Oddwatt.
Thank you.

Author:  gofar99 [ 16 Nov 2017, 15:52 ]
Post subject:  Re: ForeWatt Tube SRPP Preamplifier - Support / Update Threa

Hi, Not likely a ground connection issue. The Forewatt is designed to work with the Oddwatts. Power amp tube failure will frequently cause the LM317 to fail as the voltage across it because of the tube failure will exceed its ratings. I have found them rather robust and have accidently put just over 100 volts on one for a short duration and have it survive. I don't recomment trying that. They work fine with DC voltages up to about 50. (BTW tube failure can for a short while dump nearly the entire B+ voltage across one) The AC signal impressed upon the LM317s by the amp seems to have no effect. The AC swing can be as much as +/- 50 VAC and that would seem to exceed the ratings....but there are many of them out there functioning just fine. I suspect there is a wiring error somewhere. Cna you post some fairly good photos of the inside of the units.

Good listening
Bruce

Author:  Jim_O [ 16 Nov 2017, 17:09 ]
Post subject:  Re: ForeWatt Tube SRPP Preamplifier - Support / Update Threa

For what it's worth, here are the instructions and schematic for the MV-06. True, they are not the best... :)

Author:  gh0st3g [ 16 Nov 2017, 20:21 ]
Post subject:  Re: ForeWatt Tube SRPP Preamplifier - Support / Update Threa

Thank you Bruce and Jim_O.
Now I have connected the MV04 board, there is other issue that the music too small with big hum sound.
May I must be check about connect.
My forewatt, at B+ seem too high, about nearly 260V. I am using 680R at filter, and 470R at cathode is that OK or should I replace cathode resistor with 680R?
I will upload pic later.
Thank you again.

Author:  gh0st3g [ 16 Nov 2017, 21:04 ]
Post subject:  Re: ForeWatt Tube SRPP Preamplifier - Support / Update Threa

gh0st3g wrote:
Thank you Bruce and Jim_O.
Now I have connected the MV04 board, there is other issue that the music too small with big hum sound.
May I must be check about connect.
My forewatt, at B+ seem too high, about nearly 260V. I am using 680R at filter, and 470R at cathode is that OK or should I replace cathode resistor with 680R?
I will upload pic later.
Thank you again.

Hi Bruce,
Just found out the issue, may be I connect wrong all 9 pin tube socket, please confirm if I right.

Author:  gofar99 [ 16 Nov 2017, 21:57 ]
Post subject:  Re: ForeWatt Tube SRPP Preamplifier - Support / Update Threa

Hi, I can't tell from the photo...but the pins are numbered in a clockwise manner when seen from the underside of the chassis.
Good listening
Bruce

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