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Hi, I was wondering if anyone could tell me what year this Polytone mini brute was made? Thanks, I appreciate it. Kerry
Last edited by soybasedriffs; 07-25-2017 at 09:03 PM.
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07-25-2017 09:01 PM
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Looks like early '80s. About '83.
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I have a similar one that was made in 1982
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Diamond tolex – late '70s, early '80s.
Red distortion knob – early '80s.
(This is what I have learned... here!)
Should be one of the best Polytone eras – if You keep off the distortion knob!
(I soldered the cables off from it to avoid catastrophes in the gigs!)
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It's a good one!!!
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I agree, 82/ 83 -ish. You almost certainly realise this, but in case not, it doesn't have the original foam grille and poly badge.
Originally Posted by Greentone
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Thanks for the information. It arrives by UPS today. The grill and the badge are missing so I think I'm going to get creative with some upholstery on the front.
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The original option is that mysterious black foam. A guy sells it in Ebay: Originally Posted by soybasedriffs
POLYTONE FOAM SPEAKER GRILL or GRILLE - NEW! NOS! Factory Original
I made a grille baffle from 6mm plywood and Fender grille cloth. Thought that black grille cloth would have been a bit dull... a matter of taste of course.
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I have a trade in the works for one of these right now. Early 80s MB II, with that foam even. Very curious about these amps.
MD
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Hey, The amp just arrived. It sounds really great, and it is really loud, I think it will work at the local jazz jam here. The distortion is really funny when you turn it up, but I don't think we should knock it, that sounds pretty good when it's at one or one and a half but no more than that unless you want some kind of metal freak out of the most unpredictable and dirty kind. It's really strange, it sounds like the distortion is in its own channel, and the level for that channel is only a maybe 18% of the overall mix. One drawback though on this amp and maybe it's because it's so old I don't know but the reverb is noisy it's like I can hear a lot of noise sounding like 60 cycle hum. Is that normal? Also, on the back, are those two jacks for the effects loop? There's one for the external speaker and that is clearly marked but the other two are not marked at all, and if they are, which is which? Thanks 1 million my jazz friends
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Yeah I guess that makes sense it's two volumes so it's it's own channel. Also I might add that this thing smells like it's been in smoky bars its entire life. Let me tell you though this is the ultimate grab and go amp. It's really light and it's really loud and it doesn't sound like it's about to fall apart when you crank it so, between this and the Henricksen jazzamp, this is the one for those who are concerned about paying too much. I don't know, I'm sure that one is super awesome too, I'm just happy this came in and I'm going to get to work making it a little bit prettier. But not in a way that devalues its vintage nature of course.
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Congrats! The hum might be solved by grounding the reverb tank to the pre amps chassis. At least my Mini Brute IV became very silent after that. Originally Posted by soybasedriffs
(Be careful with that pink glass fiber inside the cabin! Causes serious itch if You don't wear gloves or something!)
I am not an expert in those output jacks so others can tell about them.
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OK! I might have to ask you later how to do that like with pictures and stuff.
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I'm getting a bit of a vibrating piece of paper noise at high volumes, is that normal? I mean it's not like this amp has a big cabinet to allow for vibration
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what is the size speaker? My old polytone is similar (minus the red knob & reverb). The foam on mine was rotten and ugly. I built a simple wooden baffle and covered it with fabric -- looks great, maybe not super tough, but oh well . . .
I think the speaker grill on your amp doesn't look 1/2 bad, but I do believe the four plastic clamps holding it down are installed upside down. Flipping them might make it look a little better . . . otoh it may produce a rattle too
Happy NAD
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The speaker measures 10 inches across. I'm going to do the same thing you did with the wooden baffle and the fabric. I just have to visit Goodwill and find something for cheap because that's kind of like my sort of upcycling philosophy. The metal grill is kicked in a little bit so I will have to figure out how to make it convex once again. Thanks for pointing out those clamping gizmos, you're right, they look like they're upside down. Also, that metal thing on the back is loose so I'm wondering if that was causing the vibration.
No matter what, I'm sure that I will make at least five trips to Lowe's because that is the unspoken law.
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Hey man thanks for the grounding solution, what do you mean by tank? Also, given the picture that I am uploading, could you point me to both the reverb tank and the preamp chassis? Your help is appreciated.
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The reverb tank is that metallic box where the two grey cables with RCA-connectors go (RED ARROW!) Originally Posted by soybasedriffs
The preamp chassis is that box in the up (BLUE ARROW!).
If soldering etc electric tinkering is not familiar for You I strongly suggest You take the amp to a tech.
(If You disconnect those grey cables, make sure You can put them back in the same way! The other is input and the other output and they say that You can break a delicate transformers in the reverb can connecting them vice versa.)
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Hey Herbie,
I grabbed a wire and touched it to both the tank and the chassis and I didn't even hear a pop or any sound like an electrical sound. Nothing. I'm thinking maybe the reverb is just noisy I don't know.
It was worth trying though
Kerry
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A quick touch does not necessarily make solid contact. You need to make sure each end is securely attached before making a final decision. It doesn't have to be soldered, but it does have to break through any surface corrosion that might be on either chassis. An ohmmeter can help.
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Ok I'll not give up on it. I need to rough up the surface with sandpaper I think
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By the way I found a staple and a tiny screw stuck to the speaker magnet. Also, when removing the back, one of the screws wasn't fully tightened so it's dome-like washer could easily rattle
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As You see, the sides of the pre amp section are not metal but tin foil plated wood (!). It is not a place to ground.
The reverb tank can be coated with some non conductive material. If so, You have to scrape it away a bit to get a contact.
If I remember correctly the RCA connectors are neither grounded but isolated from the tank's chassis. Don't ground on them.
Of course it might be some other bad grounding issue but this reverb tank thing is very common with this era Polytones.
The capasitors are already 35 years old so some of them may have started to leak and cause bad noises. But it is not tube amp, so the caps survive longer.
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I scraped away that coating on the reverb tank and used my multimeter to check and see and yes it is already electrically connected to the preamp chassis. Which leaves the only other explanation so far which is that maybe the capacitors have leaked or something. How easy is it to replace those things? Thanks again
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Are there capacitors in the reverb tank? The ones in the preamp chassis look pretty good with a visible inspection, I'm not sure how to check them electrically what I would be looking for
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