Anyone familiar with the Tandberg 3002 preamp?
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Jon_Logan
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The 3000 series was pretty fancy. I don't think you could go wrong with one of those. In those days, Tandberg was selling slew rate as a key feature. 1000V/usec. or something like that.
They definitely have that Scandanavian-Euro-metallic look about them. I believe some did have Rosewood veneer side panels. Most had black side panels, though.
They definitely have that Scandanavian-Euro-metallic look about them. I believe some did have Rosewood veneer side panels. Most had black side panels, though.
Well, it's got all the right stuff... set up with separate inputs for MM and MC, and you can select the cartridge loading on MM (three settings each for resistance and capacitance).
S/N is speced at 80dB on MM and 74dB on MC, but I've found some examples to be a little noisy. Usually a good idea to use shorting plugs on the unused input, and also to go through the internal DC offset and other alignment settings for the various circuits, which does include the phono inputs. This is a case where the later production versions of this same basic design (3002 => 3002A => 3008A) improved over time, in terms of the components used (better caps, etc.) & in circuit design.
I don't know the other pieces you're comparing it to, sorry.
John
S/N is speced at 80dB on MM and 74dB on MC, but I've found some examples to be a little noisy. Usually a good idea to use shorting plugs on the unused input, and also to go through the internal DC offset and other alignment settings for the various circuits, which does include the phono inputs. This is a case where the later production versions of this same basic design (3002 => 3002A => 3008A) improved over time, in terms of the components used (better caps, etc.) & in circuit design.
I don't know the other pieces you're comparing it to, sorry.
John
I had one of those preamps, can't remember which model. One thing that was unusual about it was that the volume knob was noisy. I cleaned and cleaned and could not get the noise to go away. Later, on a cap changing frenzy I changed a couple of large caps that went right after the volume pot in the circuit. The noise went away.
I had a Tandberg 3002A for quite a few years in my main system, first with an Adcom GFA-2 then later with a GFA-555 Pro. I found it to be a bit too bright sounding for my tastes on the line level inputs, although the phono section sounded great and it was quite flexible with selectable cartridge loading and MC/MM capability (though I never used the MC function). It's a very well built and high quality pre-amp, but I replaced mine with an Adcom GFP-555II which I find more suitable for my tastes. The control pots and switches on the Tandberg did need cleaning out from time to time. Mine was the all black version with silver knobs but I once saw one with rosewood side panels that was very nice looking indeed.
JohnMac
Addicted Member
This one is a silver with no wood sides. Maybe the rosewood came with the "A " and later versions. I'm going to try it out soon and will report back. I'll be comparing it to the not so high end pres that I mentioned earlier. One that I didn't mention is an unrefurbed solid state Dynaco PAS 4 which is not so highly regarded but I'm rather fond of for the phono section.
Keeping the internal DC offset adjustments aligned will help with the noisy controls. Tandberg did move to a much higher quality sealed pot from Germany for the 3008A. That, and better caps & some circuit improvements are the primary differences from the 3002 to the later model.
Recapping these is not a bad idea. Many of the 3002 or 3002A I have opened up were already recapped, particularly the coupling caps between the front end board and the I/O board in the rear. Pretty common to find big mylar or WIMA caps stuffed into these, replacing the originals. It's a bit ugly but probably improved the sound. I've seen enough units modified this way to suspect that Tandberg may have been doing this upgrade at their service centers. The 3008A used RIFA film caps for the coupling caps in that part of the circuit, probably a further improvement although I know some people consider them to be on the dark side sonically.
On the noisy volume control, besides keeping the DC to a minimum, I have found this is one where you want to use the best deox fluid you have. I have a small can of GC pot cleaner that smells like an old barber shop (or something old!) but a couple of drops of that stuff cures these instantly. The cleaner/lube from Fry's that works fine for me on other models tends to be a much shorter cure on these 3002/3002A volume controls, and the static will come back fast if I use that instead of the GC.
The rosewood sides were optional for all of these models. They definitely do look great on the silver ones (see pic of a 3001 tuner dressed up that way). There were also optional black acrylic sides which are much rarer. I prefer the rosewood myself but the black & silver is a nice contemporary look.
John
Recapping these is not a bad idea. Many of the 3002 or 3002A I have opened up were already recapped, particularly the coupling caps between the front end board and the I/O board in the rear. Pretty common to find big mylar or WIMA caps stuffed into these, replacing the originals. It's a bit ugly but probably improved the sound. I've seen enough units modified this way to suspect that Tandberg may have been doing this upgrade at their service centers. The 3008A used RIFA film caps for the coupling caps in that part of the circuit, probably a further improvement although I know some people consider them to be on the dark side sonically.
On the noisy volume control, besides keeping the DC to a minimum, I have found this is one where you want to use the best deox fluid you have. I have a small can of GC pot cleaner that smells like an old barber shop (or something old!) but a couple of drops of that stuff cures these instantly. The cleaner/lube from Fry's that works fine for me on other models tends to be a much shorter cure on these 3002/3002A volume controls, and the static will come back fast if I use that instead of the GC.
The rosewood sides were optional for all of these models. They definitely do look great on the silver ones (see pic of a 3001 tuner dressed up that way). There were also optional black acrylic sides which are much rarer. I prefer the rosewood myself but the black & silver is a nice contemporary look.
John
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I almost forgot, I actually have a 3002 here at the moment... belongs to a friend of mine that bought a complete 3001/3002/3003/3004 system. I sold the 3004 deck for him last week but haven't had a chance to get into the 3002 and 3003, much less the 3001 which needs a fair amount of work. Let me know if you need more info on the 3002 as you investigate your opportunity.
John
John
JohnMac
Addicted Member
Alrighty. I cleaned all controls and switches. Phono sounds nice. However one channel has very little output when in stereo. When I switch to mono they are equal. I switched source and amp interconnects to eliminate problems there. Any ideas?
I quess I should try aux to see if the problem is there too.
Add on: Aux is fine. I switched to the MC inputs and it works fine there but I'm using a MM cart???
I quess I should try aux to see if the problem is there too.
Add on: Aux is fine. I switched to the MC inputs and it works fine there but I'm using a MM cart???
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Low-ish output MM would work ok on the MC inputs probably.
Did you clean or try moving the switches for resistance/capacitance on the MM inputs? There's more going on in the signal path there than on the MC inputs.
Also make sure you deox the crap out of the source select switch, and physically inspect it to see if there's any distortion of the switch mounting due to impact. I've seen that cause major channel intermittencies on these preamps or the 3012 integrated amps. A little tweak makes those geared slide switches shift just enough internally to drop a channel.
John
Did you clean or try moving the switches for resistance/capacitance on the MM inputs? There's more going on in the signal path there than on the MC inputs.
Also make sure you deox the crap out of the source select switch, and physically inspect it to see if there's any distortion of the switch mounting due to impact. I've seen that cause major channel intermittencies on these preamps or the 3012 integrated amps. A little tweak makes those geared slide switches shift just enough internally to drop a channel.
John
JohnMac
Addicted Member
I did notice some noise when switching the resistance switch. But wouldn't it have the same problem in mono? I'll open it back up and pay some attention to that and deox the other controls in the signal path again. Wonder if it might be a capacitor.
I'm surprised how good the Shure V15 III sounds on the MC inputs. Not at all too much gain.
I'm surprised how good the Shure V15 III sounds on the MC inputs. Not at all too much gain.
JohnMac
Addicted Member
OK. I cleaned the capacitance/resistance switches. Not so easy to get to. Deoxed the other switches again. The symptom persists. The singnal on one channel is there and sounds good but is weak. I wonder if what I do hear from that channel is bleeding from the other. Maybe I'll put on an LP with really devided stereo channels like early Beatles.
Check the center pins on the input jacks for DC offset. Theoretically should have a loading resistor across when you do but if you see widely different values from L to R, it may mean the DC offset adjustment is way off. Could also mean someone's run a media player into it and damaged a transistor.
The service manual is here:
http://sportsbil.com/tandberg/tca-3002-circ-alignm.PDF
John
The service manual is here:
http://sportsbil.com/tandberg/tca-3002-circ-alignm.PDF
John
It doesn't have a millivolt setting? Needs to be pretty accurate as you're typically setting to zero or checking readings in the 1V range.
The toughest part of the procedure in my experience is careful connection to the correct test points in that part of the preamp. I usually attach clip leads (the little spring-loaded copper hook type) to the component leads in question while the unit is powered down, connect those leads to my meter, check the connection logic & locations three times, then power up and take the reading.
You also need some RCA jacks with resistors shorting the center to ground, two different values called for.
It wouldn't seem like a preamp would be that touchy but these things run at +/- 32VDC like a small power amp so there is some pretty decent voltage across a lot of the components. Short anything out and you can take out a transistor or resistor pretty easily.
John
The toughest part of the procedure in my experience is careful connection to the correct test points in that part of the preamp. I usually attach clip leads (the little spring-loaded copper hook type) to the component leads in question while the unit is powered down, connect those leads to my meter, check the connection logic & locations three times, then power up and take the reading.
You also need some RCA jacks with resistors shorting the center to ground, two different values called for.
It wouldn't seem like a preamp would be that touchy but these things run at +/- 32VDC like a small power amp so there is some pretty decent voltage across a lot of the components. Short anything out and you can take out a transistor or resistor pretty easily.
John
