6j4+6p6 hifi preamplifier kit! - Page 2

siliconray · 23rd December 2011, 02:11 PM

Hi Sled

It seems the one in your link is similar to the tube in the kit.

Do you have trouble in tracking your package? what did you order? If it's tube amplifier kit don't anticipate to receive them in less than 1 month for surface shipping. Surface shipping has very poor tracking system.

I got a dispute on paypal because the shipping is too slow. But there's no $50 way to throw 10kg to 5000km away in one week.

jazzy939 · 16th March 2012, 01:49 AM

siliconray,
I bought this amp and it is very good indeed!
The gain is a bit too high, which feedback resistors should I change and what are the values/ratings?
A value vs gain figures would be nice.
Thanks!

siliconray · 16th March 2012, 02:05 AM

Hi Jazzy, good to know that. Just change the 24k resistor to a lower value the gain will be reduced.

jazzy939 · 16th March 2012, 02:08 AM

Thanks siliconray.
Keep up the good work!

siliconray · 16th March 2012, 02:20 AM

Hi Jazz, It would be nice if you can post some pics of your work, both inside and outside. Some beginners are struggling with the hum problem of the preamplifier. Your experience will be very helpful. Thanks!

jazzy939 · 16th March 2012, 03:48 PM

Ok, I will do that soon. I am currently experimenting with the resistor's values to get the right gain. In the original configuration (24K resistors) if assuming 0 volume is at 7 o'clock position, just under 9 o'clock position it is already too loud for me!
FYI, I am using ROTEL RB-980BX as the power amplifier.
Sonically it is fantastic, the gain which in my opinion is too much at 10dB is making me losing 'proper' volume control.
How much lower resistance can I use? Right now I am at 10K, slightly better but I want to cut down further, possible to use 2k or 3K?
Thanks .

siliconray · 16th March 2012, 04:08 PM

what is your sound source? you may not need a preamp if using CD as source. Usually CD has 1.5Vp-p, high enough for most power amplifier. If you are using low level digital players (such as ipod) the preamplifier is usful.

You may reduce the feedback to 5.1k or even lower, until you get the comfortable gain. lower value is no harm to the performance.

jazzy939 · 16th March 2012, 04:18 PM

Yes, that may be the reason as I an using a CDP.
I somehow found the sweet spot at 1.5K, since the CDP is my main source I shall stick to this for the time being.. have not tried other sources like tape deck, minidisc deck and a turntable(with separate phono preamp).
Thanks for the responses. Will upload few pics of the built.
Right now need to enjoy the music

sled108 · 17th March 2012, 09:32 PM

Here's Mine...The PreAmp Sounds Great, right from the first Turn On. But, the Kit has some Real Issues...

An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this.

bobrown14 · 17th March 2012, 11:03 PM

Quote:

Originally Posted by sled108

Here's Mine...The PreAmp Sounds Great, right from the first Turn On. But, the Kit has some Real Issues...

An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this.

Hey Sled - nice build looks perfessioinal, what "real issues" do you see need to be addressed?

Cheers,
Bob

23rd December 2011, 02:11 PM	#11
siliconray diyAudio Member Join Date: Sep 2011	Hi Sled It seems the one in your link is similar to the tube in the kit. Do you have trouble in tracking your package? what did you order? If it's tube amplifier kit don't anticipate to receive them in less than 1 month for surface shipping. Surface shipping has very poor tracking system. I got a dispute on paypal because the shipping is too slow. But there's no $50 way to throw 10kg to 5000km away in one week. __________________ www.siliconray.com High Quality Audio Enclosures, Amp Kits, Amplifiers, PCB Fab Services Chat with me

16th March 2012, 02:05 AM	#13
siliconray diyAudio Member Join Date: Sep 2011	Hi Jazzy, good to know that. Just change the 24k resistor to a lower value the gain will be reduced. __________________ www.siliconray.com High Quality Audio Enclosures, Amp Kits, Amplifiers, PCB Fab Services Chat with me

16th March 2012, 02:20 AM	#15
siliconray diyAudio Member Join Date: Sep 2011	Hi Jazz, It would be nice if you can post some pics of your work, both inside and outside. Some beginners are struggling with the hum problem of the preamplifier. Your experience will be very helpful. Thanks! __________________ www.siliconray.com High Quality Audio Enclosures, Amp Kits, Amplifiers, PCB Fab Services Chat with me

16th March 2012, 04:08 PM	#17
siliconray diyAudio Member Join Date: Sep 2011	what is your sound source? you may not need a preamp if using CD as source. Usually CD has 1.5Vp-p, high enough for most power amplifier. If you are using low level digital players (such as ipod) the preamplifier is usful. You may reduce the feedback to 5.1k or even lower, until you get the comfortable gain. lower value is no harm to the performance. __________________ www.siliconray.com High Quality Audio Enclosures, Amp Kits, Amplifiers, PCB Fab Services Chat with me

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16th March 2012, 01:49 AM	#12
jazzy939 diyAudio Member Join Date: Nov 2007 Location: Petaling Jaya, Malaysia.	siliconray, I bought this amp and it is very good indeed! The gain is a bit too high, which feedback resistors should I change and what are the values/ratings? A value vs gain figures would be nice. Thanks!

16th March 2012, 02:08 AM	#14
jazzy939 diyAudio Member Join Date: Nov 2007 Location: Petaling Jaya, Malaysia.	Thanks siliconray. Keep up the good work!

16th March 2012, 03:48 PM	#16
jazzy939 diyAudio Member Join Date: Nov 2007 Location: Petaling Jaya, Malaysia.	Ok, I will do that soon. I am currently experimenting with the resistor's values to get the right gain. In the original configuration (24K resistors) if assuming 0 volume is at 7 o'clock position, just under 9 o'clock position it is already too loud for me! FYI, I am using ROTEL RB-980BX as the power amplifier. Sonically it is fantastic, the gain which in my opinion is too much at 10dB is making me losing 'proper' volume control. How much lower resistance can I use? Right now I am at 10K, slightly better but I want to cut down further, possible to use 2k or 3K? Thanks .

16th March 2012, 04:18 PM	#18
jazzy939 diyAudio Member Join Date: Nov 2007 Location: Petaling Jaya, Malaysia.	Yes, that may be the reason as I an using a CDP. I somehow found the sweet spot at 1.5K, since the CDP is my main source I shall stick to this for the time being.. have not tried other sources like tape deck, minidisc deck and a turntable(with separate phono preamp). Thanks for the responses. Will upload few pics of the built. Right now need to enjoy the music

17th March 2012, 09:32 PM	#19
sled108 diyAudio Member Join Date: May 2008 Location: Deep in the Heart of North Jersey	Here's Mine...The PreAmp Sounds Great, right from the first Turn On. But, the Kit has some Real Issues... An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this.

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