Polytone Mini Teeny Brute

[bborzell]

Yes if you could give me the website as I am probably going to pull the trigger on this amp.

Just looking on line I see a few grills for this amp. Any thoughts as how they compare to what you did or how they compare to the originals?

Custom Speaker Grills and Covers

I opted to use the same metal grill approach as on my Roland and Genz Benz amps. I didn't want to use plastic and didn't want to have to deal with "almost" fitting round grills.

Bottom line is personal preference, I think.

[Wildcat]

Hey thanks for the great link. I getting excited about bring this old girl back to life. I'll be picking her up this weekend and will probably end up paying $100 for her.

So I will consider re-coning, I have a call into my amp guy that has a line on somebody that does it, but as to a replacement speaker, 4 ohm ....... I have a 12 " Jensen Neo in my cab which I do like.

Also my amp guy has a basement full of speakers collected over the years. If the speaker codes are visible any thoughts on those ?

[Wildcat]

Oh I also have an 10" Eminance Little Buddy at 8ohms.

[Wildcat]

Pretty much any grill cloth will work, but protecting the driver from assault will require a protective screen.

I spoke to several grill cloth suppliers who all suggested going with a metal grill, unless, of course, I wanted to have the appearance of grill cloth and then I would still need some sort of acoustically neutral hard backing for protection.

The 15" driver was too exposed, in my view, so I passed on the cloth and went straight to a metal grill. The company who did mine does custom cuts and will also do rolled edges to your spec. I needed 1/2", if I recall correctly to come flush to the cabinet edge.

Let me know if you want to check out their web site.

I looked at the website and it appears that they have 3/8" but not 1/2" unless I missed something.

[Wildcat]

IMO, get the amp. They are great.

The Mini Brutes from that era were usually rated at @80 - 100 watts into 2 or 3 ohms.

Lots of Polytone players replace the rotting foam speaker cover with circular metal mesh speaker covers bolted to the face of the speaker baffle - widely available at PA sound shops.

The original speakers from that era were typically made by Eminence.
Polytone liked to use 2 and 3 ohm speakers - it allowed them to get more juice one of the amp. Most if not all other guitar/accordian/keyboard amp makers used hight impedance speakers, I think. Schematics are readily available.

Putting in a replacement 4 ohm or even 8 ohm speaker lowers the potential volume but protects the amp, acting as a brake or choke that effectively prevents it from blowing itself up when turned up. At least that has been my experience. It will still be plenty loud.

Sound? It's a Polytone - a tiny sealed box that is full of compromises. It was designed with no regard for Thiele-Small parameters - the idea was simply to make it as small, light, clean and loud as possible. If you want SOUND, install a kill switch to the speaker and run it as a head to a speaker cab. That's why I did with my Baby Brute (with a 3 ohm 8" speaker), along with installing an 8-ohm replacement speaker when the amp blew up a few years back. It's over 30 years old, I still take it to gigs as a backup amp, and it still works great, either as a head or on its own.

This amp is showing 50 watt.

I'm bit confused as the ohm rating and the affect on the amp. I was under the impression that if you restrict the amp with a speaker at a higher ohm rating, you could damage or fry the amp. Essentially you are not allowing the amp to function the way it was designed and restrict it with a higher ohm rated speaker.

[bborzell]

I looked at the website and it appears that they have 3/8" but not 1/2" unless I missed something.

Here is what I used:

Custom Speaker Grills

The bend options are 1/2, 3/4, and 1".

[Wildcat]

Here is what I used:

Custom Speaker Grills

The bend options are 1/2, 3/4, and 1".

I'm not sure what you mean by bend options. Does that mean the ends of the grill is bent 90 degrees with a length of 1/2" so you can side it in on the outer edge of the baffle board? Do you use the foam and anchors they show ?

Thanks Rich

[bborzell]

I'm not sure what you mean by bend options. Does that mean the ends of the grill is bent 90 degrees with a length of 1/2" so you can side it in on the outer edge of the baffle board? Do you use the foam and anchors they show ?

Thanks Rich

The bend allows the grill to sit (in my case 1/2") off the baffle and flush with the cabinet edge. You could get the same effect without the bend by using the spacers and screws in their mount kit, but I prefer to have the grill edges fit flush with the baffle, hence the bend. In addition, without the bend, the edges of the grill will look much less finished.

I suggest calling them for measuring/fitting instructions. The fit on my grill was exact.

I did use their anchor kit, but I don't recall the anything about foam.

[Wildcat]

The bend allows the grill to sit (in my case 1/2") off the baffle and flush with the cabinet edge. You could get the same effect without the bend by using the spacers and screws in their mount kit, but I prefer to have the grill edges fit flush with the baffle, hence the bend. In addition, without the bend, the edges of the grill will look much less finished.

I suggest calling them for measuring/fitting instructions. The fit on my grill was exact.

I did use their anchor kit, but I don't recall the anything about foam.

Okay now I understand. Thank you. I'll try to post some before and after pictures.

[Wildcat]

So I finally got a chance to pick up the amp this weekend. When I saw it in person it was in really good shape for the age. However, it smelled like smoke really bad when I got it home. The owner was a smoker.

Since the speaker was trashed I took it to the only reconning guy in the area after paying $100 for it. Ray is well known in the area and does a lot of warranty work for major speaker companies.

Several items for the amp. The speaker is 12" instead of 10" from what I have read. Also the amp wattage is 90 watts.

After dropping it off at the recon shop I took it to my local old school tube radio, amp repair guy. I walked in the door and he groaned when he saw it was a Polytone amp. He told me I should have called him before I bought it. I guess he hates to work on them. Did I mention he's a tube guy? He hates the insulation and the limited area to reach your hands into the amp cab.

So he put it on the bench and ran it through its paces. Then I went to the basement and got a 12" 4 ohms speaker that he pulled out of an organ. He repairs Hammond organs also.

I took her home cleaned her up and then fired her up. I notice a vibration noise immediately. After listening it was the circuit board vibrating because the foam under it has deteriorated. So I got some foam and placed it under the board. That took care of the vibration. I noticed that there was documentation in the chassis from December of 1982 that indicated that chips were replaced.

I am still playing around with the setting, but overall I really like the sound. So much that I plan to play it for a while over my tube amp. It nails that bottom end jazz sound without having to use the tone on my guitar. I never like the base tone from my neck pickup. I just couldn’t dial in what I was looking for. With the Polytone is natural sounding.

I put the dials on the amp at 3 for the bass and 7-8 for the treble and fool around with it there on the low input and with the 3 way switch at the high setting.

The internal of the amp must get a pounding with the closed back system. My concern is that I am going to start to really like this guy and it blows up on me.

[FONT='Calibri','sans-serif']BTW I did order a custom metal grill for it as the original must have fell apart sometime ago. [/font]

[alexage]

Just saw this:

POLYTONE FOAM Speaker Cover, Grill, NEW! ORIGINAL STOCK! | eBay

Foam for 15" Mini-Brutes, maybe others.

[Wildcat]

Just saw this:

POLYTONE FOAM Speaker Cover, Grill, NEW! ORIGINAL STOCK! | eBay

Foam for 15" Mini-Brutes, maybe others.

Thank you!!

[Gertrude Moser]

The original speaker was likely 4 ohms, if you replace that with an 8ohm, you will do no harm (to any SS amp, not so with tubes) to the amp, but doing so will cut the amps power by half, so your 90 watts will be 45 watts.

[Hammertone]

....[ ]...I'm bit confused as the ohm rating and the affect on the amp. I was under the impression that if you restrict the amp with a speaker at a higher ohm rating, you could damage or fry the amp. Essentially you are not allowing the amp to function the way it was designed and restrict it with a higher ohm rated speaker.

I always thought that it was the other way around. The HIGHER ohm rating prevents the amp from working as hard as it would usually work, so it should be a happy little amp-camper. If you put a LOWER ohm-rated speaker into an amp, you lower the resistance and essentially force the amp to put out more effort that it is designed for, making it unhappy. Ask a real toaster tech - he'll have the answer.

The original Eminence-built speaker in your Teeny-Brute was probably rated at or 2 or 3 ohms. Putting in a 4 ohm speaker is really not a big deal - the volume drop won't be that audible. Heck, maybe it had a 4-ohm speaker to begin with - I don't have a spec sheet for that model.

My limited understanding is that SS amps are more sensitive to these changes than tube amps. My guess is that Polytone used (uses?) low-ohmage designs as way to get maximum volume out of little amps.