Amazing $50 3 Tube Preamp
- Thread starter Poultrygeist
- Start date
Poultrygeist
Lunatic Member
Sweet! :thmbsp:
Got it in.
Well, after the wait for shipping it finally came in. The box was "bruised" bent in big time on one side. The tubes were intact but there was not a one without a bent pin. One of the RCA inputs had cracked plastic. As stated there was no documentation whatsoever about the transformer. I went forward....
Bent all the tube pins back in place, secured the jacks temporarily, figured the transformer wiring as best as I could (with help from here BTW.). Crimped an AC cord on and guess what.. It works !! I was kind of surprised not to see smoke. I backed away from it before hitting the juice !! Darn thing sounds good ! For the price I could not be much more pleased. Now.. Tomorrow I will be back on to ask about a few more options. Cigar box is ready.. Thanks all ! With best regards, vsat88.
Well, after the wait for shipping it finally came in. The box was "bruised" bent in big time on one side. The tubes were intact but there was not a one without a bent pin. One of the RCA inputs had cracked plastic. As stated there was no documentation whatsoever about the transformer. I went forward....
Bent all the tube pins back in place, secured the jacks temporarily, figured the transformer wiring as best as I could (with help from here BTW.). Crimped an AC cord on and guess what.. It works !! I was kind of surprised not to see smoke. I backed away from it before hitting the juice !! Darn thing sounds good ! For the price I could not be much more pleased. Now.. Tomorrow I will be back on to ask about a few more options. Cigar box is ready.. Thanks all ! With best regards, vsat88.
68custom
Addicted Member
well I just hooked my pre up and there is no voltage on the low side! I have the 160 vac but no 6.3 vac! darn it I was all ready to post pictures and let it burn in. I did email the seller and hopefully they will send me a new tranny soon.
I gutted a satellite receiver box and am using that for my chassis I think it will turn out very nice. I am using an 18 vac laptop power supply for the amp (sure 7492 chip amp) does anyone know if I should look for a power supply with more voltage?
I gutted a satellite receiver box and am using that for my chassis I think it will turn out very nice. I am using an 18 vac laptop power supply for the amp (sure 7492 chip amp) does anyone know if I should look for a power supply with more voltage?
68, too bad about your P.S. being bad after all the wait. Mine was good but took a bit to mame realitvly certain I was hooking it up rigbt. Followed the instructions found on this thread. I have no experience with the Sure board however I have quite a bit in electronics in general and I would say that without a doubt you are correct. Without the Pre Amp you will not get much volume. Hope that hells somehow. With best regards, vsat88
Poultrygeist
Lunatic Member
Does your Sure Board have those tiny dip switches? If so they must be switched to the higher positions.
68custom
Addicted Member
well they have agreed to send me a new Tranny for a 20% discount. my pre amp/ tranny sat in a box for almost 2 months. customer service is not as good as that what you would get from some companies, moral of the story is to check it as soon as it arrives. still anxious to give it a listen!
Thanks cogitech
This may be the direction I am going. Thanks for your input. Or is that output.
The amp in my case is a tas5630. I love that thing run off a dinky 20 watt 30vdc wall wart supply. I cant wait to feed it some real juice - about 700 watts worth @ 48 v dc.
I also am putting it in a ct2121 or similar casette deck chassis with a hand wound microwave transformer to power that. The 12v DC makes it easy for me, 8 turns on my hand wound trafo. Easy.
Cool.
Srinath.
I've finally received all the parts needed for my hybrid integrated amp that I spoke of earlier in the thread. Yesterday after work, I threw it all together for a test listen. The chassis/tray is the bottom portion of a Philips DVD player that I gutted. I retrofitted some speaker terminals, inputs, and power receptacle.
I plan to make a front bezel out of wood and then mount a power switch and the volume pot in the front bezel. Then I'll cut a hole in the cover panel for the tube to stick through, and mount the 12vac transformer and the huge capacitor on top a la "retro DIY tube amp" style. Mods to the Tripath amp board include 1) replaced input electrolytic coupling caps with bipolar PIO Roedersteins, 2) removed unnecessary connectors to make room for direct soldering, and 3) (obvious) removed the stock 3300uF power cap and tied in the huge 9500uF sucker!
It sounds un-f&*$ing-believable! Way better than it has any right to sound, that is for sure. I have maybe $60 into this thing (I had a lot of the parts laying around) and it rivals the massive tube amp it is sitting on, all the while using a tiny fraction of the power of the tube amp!
I can't believe it.
This may be the direction I am going. Thanks for your input. Or is that output.
The amp in my case is a tas5630. I love that thing run off a dinky 20 watt 30vdc wall wart supply. I cant wait to feed it some real juice - about 700 watts worth @ 48 v dc.
I also am putting it in a ct2121 or similar casette deck chassis with a hand wound microwave transformer to power that. The 12v DC makes it easy for me, 8 turns on my hand wound trafo. Easy.
Cool.
Srinath.
68custom
Addicted Member
It lives!
well I studied the diagram I used to wire up the tranny and figured out I had it wired incorrectly, with the help of my meter. any way gave a second shot and she fired right up! Emailed the seller and said I did not need a replacement. now its playing in the garage with my 30 gig Ipod and a set of Minumus 7s. so far it sounds good and is plenty loud! but I will give it a more critical listen after everything has burned in for a day or two of continuous use. as for my chassis I need a 2x1ft sets of interconnects and speaker jacks. I need to figure out what to do about the tubes as they will stick out the top of my chassis. only problem there is with the cover it has slots that cover one tube so I can not use a hole saw over that tube. also I have some 1/8 sheet aluminum I will sand and make a face plate from. I think the satellite receiver chassis worked out well, I even used it's switch to control the pre amp and another switch to control the sure board. I will post more pictures when it looks better, but I am pretty happy so far.
not sure why the one picture is up side down! anyone know how to fix this?
well I studied the diagram I used to wire up the tranny and figured out I had it wired incorrectly, with the help of my meter. any way gave a second shot and she fired right up! Emailed the seller and said I did not need a replacement. now its playing in the garage with my 30 gig Ipod and a set of Minumus 7s. so far it sounds good and is plenty loud! but I will give it a more critical listen after everything has burned in for a day or two of continuous use. as for my chassis I need a 2x1ft sets of interconnects and speaker jacks. I need to figure out what to do about the tubes as they will stick out the top of my chassis. only problem there is with the cover it has slots that cover one tube so I can not use a hole saw over that tube. also I have some 1/8 sheet aluminum I will sand and make a face plate from. I think the satellite receiver chassis worked out well, I even used it's switch to control the pre amp and another switch to control the sure board. I will post more pictures when it looks better, but I am pretty happy so far.
not sure why the one picture is up side down! anyone know how to fix this?
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Poultrygeist
Lunatic Member
A gutted chassis with top cover from non working gear makes a perfect donor for this project and a new front plate can be fashioned from a piece of wood. I've used a left over piece of laminate flooring for a front plate and it looked great. It's cheap, thin and easy to cut and already finished. I could envision an entire enclosure made of laminate flooring ( Pergo or whatever ).
Rat Shack sells stand offs ( metal or nylon ) or make your own to fit the drilled board holes from tiny bolt and nuts available at HD. Old chassis's are thin and easy to drill so the stand off mounting bolts can be inserted from below.
For fear of using too much force I never removed the volume control knob from the preamp. Instead I drilled a large enough hole for the knob to pass through the front plate and then used a rubber washer to conceal the hole. In the picture above I would guess that the preamp will eventually be moved to the front of the chassis.
Rat Shack sells stand offs ( metal or nylon ) or make your own to fit the drilled board holes from tiny bolt and nuts available at HD. Old chassis's are thin and easy to drill so the stand off mounting bolts can be inserted from below.
For fear of using too much force I never removed the volume control knob from the preamp. Instead I drilled a large enough hole for the knob to pass through the front plate and then used a rubber washer to conceal the hole. In the picture above I would guess that the preamp will eventually be moved to the front of the chassis.
68custom
Addicted Member
on my set up the pre amp is already mounted to the front I may give the wood front a shot maybe the top too, good idea! if you look carefully you can see the power switches are mouted to the back of the chassis so you will not see them only the volume control.
the amp is a Sure board with the 7492 chip said to be good for 25 watts x 2. this is a lot of fun!!
the amp is a Sure board with the 7492 chip said to be good for 25 watts x 2. this is a lot of fun!!
Poultrygeist
Lunatic Member
Great job 68!
I posted before I saw your pictures. You could get Lowes to cut a plexi cover for the top. Did moving the dip switches pay off?
I posted before I saw your pictures. You could get Lowes to cut a plexi cover for the top. Did moving the dip switches pay off?
68custom
Addicted Member
you know I still have not touched them seems as if the gain is right on with the pre amp. also the notes at the PE site are a little vague and the pictured amp is a slighty different style then mine. mine has two pair of switches mounted in different spots while the picture shows all 4 together. I will let it burn in for a couple of days then start to tweak!
Poultrygeist
Lunatic Member
Thanks, and yours looks pretty good as is!
Do you plan to install some rear mounted permanent RCA inputs and speaker terminals?
Do you plan to install some rear mounted permanent RCA inputs and speaker terminals?