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Old 2nd June 2011, 09:30 PM   #11
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by murphythecat8 View Post
okay, well THATS encouraging!!!!!! I didnt get the pre-amp, only the tube amp.

The sensitivity is for both mono blocks. If I touch either one, the "problem" is there.

I dont have a schematic, now, so for now, I'll put this at hold.

I really hope I can get one, but bit scared that I wont, if I cant have a schematic, is it dramatic.

The thing is, the technician had a inondation (flood?) so for the moment, is really unavailable...

Thanks guys, this gives me hope! Really

BTW, I use some good old dynaco A-25's
Just an idea,

Get a large piece of paper,

Put circles on it with tube numbers in them, plus all components (screwed to the chassis) on the paper in the same place as on the amp draw the circuit as a wiring diagram then transfer it to a schematic. There are only a few components from the look of it you only need to draw the one if they are mono block! Post your schematic if its wrong some one will say!

You can look up the tube connections.

Take care of stored charge in capacitors! Test before you touch.

Regards
M. Gregg
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Last edited by M Gregg; 2nd June 2011 at 09:39 PM.
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Old 6th June 2011, 03:01 AM   #12
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hi everyone, I still dont have a schematic, however I talk to one user, and I decided to swap my jenson caps for russian ft-3.

Now, there's something weird, one channel seems to slightly sound louder then the other. I dont even know if I'm imaginating stuff, but I dont think anymore. Just a slightly more clear from the left channel. This surprise me, I would have thought that if I had a problem from one channel, well it would be clearly audible, but the problem is just mild. What can cause this? I swapped all the tubes from one side to the other side block, and the problem is still there. Bear in mind that the problem is subtle, not huge... the problem also comes from the monoblock which the buzzing sound. I'm not even sure theirs a problem, anyway thought I pitch this in.

Also, now that I swap the caps for russian in the audio signal, what else obvious thing I should upgrade?

thanks a lot folks for your help, I dont know what I could do without you, and this really pushes me to dimyself something. I'll probably make a phono stage as a beginner project.

thanks...
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Old 6th June 2011, 03:09 AM   #13
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hi everyone, I still dont have a schematic, however I talk to one user, and I decided to swap my jenson caps for russian ft-3.

Now, there's something weird, one channel seems to slightly sound louder then the other. I dont even know if I'm imaginating stuff, but I dont think anymore. Just a slightly more clear from the left channel. This surprise me, I would have thought that if I had a problem from one channel, well it would be clearly audible, but the problem is just mild. What can cause this? I swapped all the tubes from one side to the other side block, and the problem is still there. Bear in mind that the problem is subtle, not huge... the problem also comes from the monoblock which the buzzing sound. I'm not even sure theirs a problem, anyway thought I pitch this in.

Also, now that I swap the caps for russian in the audio signal, what else obvious thing I should upgrade?

thanks a lot folks for your help, I dont know what I could do without you, and this really pushes me to dimyself something. I'll probably make a phono stage as a beginner project.

thanks...
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Old 9th June 2011, 05:46 PM   #14
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hi everyone, I still dont have a schematics, will come eventually.


however, I have bought the russion teflon fl-3 caps to change my jensen caps.


Now that this is done, what other thing I should swap?



ps: the little buzzing sounds are gone, I placed my amps differently (appart), and since then, the microphonic sound is gone.
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Old 9th June 2011, 06:16 PM   #15
tomchr is online now tomchr  United States
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Jason - If you're not happy with the sound, I seriously doubt you'll be happier by performing random component swaps. It would be far more likely that you can obtain happiness by changing the amplifier architecture (i.e. rebuilding it) or at the very least change the bias point. However, to advise you on this, a schematic is really needed.
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Old 9th June 2011, 08:57 PM   #16
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hi tom, no I'm happy with the sound, just not completely in love, not freaking out, but it stils kicks any SS amp I've tried, and I tried a lot. There's a lot of things I like actually. It wasn't even clear for me at first, but I'm starting to really like the sound of it. Sorry if I didnt edit my opinion on the amp. When I tried the amp, my system wasnt like it is now, but with my system right now, I like the sound of the amp, now I just want to make it even better. should I start a new thread?

Swapping the jensen signal cap is not a "random" swap right, its suppose to change a bit my sound isn't it?

All I want to do is swap the critical components (not all of them, but like caps) and go from there...?

Last edited by jasonthegreat; 9th June 2011 at 09:08 PM.
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Old 9th June 2011, 09:10 PM   #17
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Quote:
Originally Posted by jasonthegreat View Post
hi tom, no I'm happy with the sound, just not completely in love, not freaking out, but it stils kicks any SS amp I've tried, and I tried a lot. There's a lot of things I like actually. It wasn't even clear for me at first, but I'm starting to really like the sound of it.

Swapping the jensen signal cap is not a "random" swap right, its suppose to change a bit my sound isn't it?

All I want to do is swap the critical components (not all of them, but like caps) and go from there...?
In general, your amp looks like something my dad (retired TV repairman) would put together, with any parts he had on hand.

Anyway, many knowledgeable people have stated that carbon comp resistors (the brown ones with the stripes) have no place in a hifi amp (except as grid stoppers maybe). They tend to "go high" in value over the years and also are noisy. Now, lots of people here would advise you to go for costly exotic resistors, but i daresay that replacing them with normal carbon films will go a long way. Just swap them with equal wattage ones, in one channel only, and verify for yourself. Then, you can decide on the other channel.

Last edited by costis_n; 9th June 2011 at 09:17 PM.
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Old 9th June 2011, 09:21 PM   #18
Sheldon is offline Sheldon  United States
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Quote:
Originally Posted by jasonthegreat View Post
Swapping the jensen signal cap is not a "random" swap right, its suppose to change a bit my sound isn't it?

All I want to do is swap the critical components (not all of them, but like caps) and go from there...?
First things first.

You've described what could be basic issues (buzzing and other noises). So, get a schematic (Or draw one up yourself. It will be good experience and it is DIY). Then measure all the voltages and calculate current across all components.

Next, track down any issues of hum or noise, until you have determined that it falls within expectations for the design.

Then, and only then, consider circuit or part changes. Otherwise it is random.

Sheldon
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Old 9th June 2011, 09:22 PM   #19
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Also agree with the above.
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Old 10th June 2011, 03:31 AM   #20
tomchr is online now tomchr  United States
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Quote:
Originally Posted by jasonthegreat View Post
hi tom, no I'm happy with the sound, just not completely in love, not freaking out, but it stils kicks any SS amp I've tried, and I tried a lot. There's a lot of things I like actually. It wasn't even clear for me at first, but I'm starting to really like the sound of it.
Sorry. I must have missed something. I thought there was a serious issue with the amp that you were trying to fix. Now I understand that you like the amp but wouldn't mind if a few improvements could be made to the sound quality.

Quote:
Originally Posted by jasonthegreat View Post
Swapping the jensen signal cap is not a "random" swap right, its suppose to change a bit my sound isn't it?

All I want to do is swap the critical components (not all of them, but like caps) and go from there...?
I wouldn't know one boutique capacitor brand from another. I tend to select capacitors based on which dielectric material is used, its parasitic components (like ESL, ESR), etc. I've had good results with polypropylene caps even when used in the direct signal path. Polypro caps that can handle the voltage may be a bit hard to find at regular electronic component distis, but places like Antique Electronic Supply has a nice selection of polypro caps. I like the Solen caps. They're well spec'ed (and I've confirmed some of their specs) and relatively inexpensive.

~Tom
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