Polytone amps - what makes them sound so good?

thmsjordan · #1 02-09-2011, 10:03 AM

Hi all.

I recently started missing my old Polytone Mini Brute. As a jazz rig, it was a really warm sounding amp and a nice size for smaller dates. I have been thinking about just making a pre-amp from my owner's schematic that I kept after the amp went bye bye. Just trying to recapture that wonderful sound that worked so well with a P bass or an upright.

My question is this - there are several factors that may contribute to the warmth of these amps. The closed back, cabinet dimensons, the pre-amp (I hope) and the power amp. One thing i am certain of, it wasn't build quality lol.

Does anyone with history on these know if there is anything particularly that makes that signature Polytone sound before I go spending money recreating the pre-amp section of one of these amps?

I know there are wonderful alternatives out there and there are used Polytones on Ebay as well as new ones if ya can find a dealer, but I was wondering if the pre-amp alone might recreate the warmth I am looking for.

Billnc · #2 02-09-2011, 10:53 AM

Quote:

Originally Posted by thmsjordan

Hi all.

I recently started missing my old Polytone Mini Brute. As a jazz rig, it was a really warm sounding amp and a nice size for smaller dates. I have been thinking about just making a pre-amp from my owner's schematic that I kept after the amp went bye bye. Just trying to recapture that wonderful sound that worked so well with a P bass or an upright.

My question is this - there are several factors that may contribute to the warmth of these amps. The closed back, cabinet dimensons, the pre-amp (I hope) and the power amp. One thing i am certain of, it wasn't build quality lol.

Does anyone with history on these know if there is anything particularly that makes that signature Polytone sound before I go spending money recreating the pre-amp section of one of these amps?

I know there are wonderful alternatives out there and there are used Polytones on Ebay as well as new ones if ya can find a dealer, but I was wondering if the pre-amp alone might recreate the warmth I am looking for.

I'm a lover of Polytones myself, my newest one is built far better than the 70's models I've had, I think my 2000 year model actually has some solder joints rather than twist tied together! My Mini Brute II (the Jim Hall model) has a preamp out and I've recorded with it to good effect. Good luck!

cavemanbass · #3 02-09-2011, 07:51 PM

I truly loved my mini-brute, though it did not always love me back... guess I just pushed it too hard. Blown speakers several times, blown power amp section, got that repaired, then fried it again... used it as just a speaker cabinet for a while, until I blew the speaker a third time. Been sitting in my garage for 15 years.

I think the tone has a lot to do with the tiny sealed cabinet and the cheap speaker. Doesn't get much bottom, but nice mids and great definition. I knew someone that put a JBL in his, never sounded as good to me... Could be wrong about this, but if you took the same components and put them in a properly sized /vented cabinet I don't think it would have that great tone.

staccatogrowl · #4 02-09-2011, 07:59 PM

History? Polytone = Tommy Gumina. Gumina is an amazing jazz accordianist. No need for my words:

http://www.allaboutjazz.com/php/article.php?id=35987

http://www.polytoneamps.com/gpage.html

http://www.curtisbay.com/tg/abouttommy.html

http://www.tommygumina.com/

Enjoy!

staccatogrowl · #5 02-09-2011, 08:18 PM

Quote:

Originally Posted by thmsjordan

. . . My question is this - there are several factors that may contribute to the warmth of these amps. The closed back, cabinet dimensons, the pre-amp (I hope) and the power amp . . .

Factors IMO: Mini Brutes: closed back, sealed, small-dimensioned (but right) cabinet; 4-ohm speaker, 2-ohm capable with extension, analog circuit designed/voiced by a pro musician that played a full-range instrument. Portable, durable, great sounding.

Not well made or of good quality? I've had many Polytones and never had a major problem with any. One dropped down an icy flight of stairs. The amp fell and my heart sank, only to be uplifted when I plugged it in and it worked great without missing a beat. I will always have at least one Polytone in my house. What great amps!

robgrow · #6 02-09-2011, 09:49 PM

I've owned several Polytone amps over the years and have also repaired quite a few others. For starters, the older Polytone amps, which are some of the best sounding IMO, used low-performance op amps such as the 4558 and 4136 quads. The preamps were also designed to have a relatively limited bandwidth with the lowest lows and highest highs filtered out -- an anything but ruler-flat, hi-fi amp type of design. The power amp sections were pretty basic and very similar to many textbook designs such as those found in the old RCA transistor manuals. The drivers (speakers) used were fairly inexpensive units, but overall these amps were some pretty clever designs. When the Polytone amps came along, they were one of the first solid state amps to have a warm sound, when many SS amps didn't have a very good reputation for their sound.

I mentioned I like the older amps the best, and frankly I have played through some more recent vintage Polytones that I just couldn't get a sound that I was happy with. The sound of these amps can vary greatly from one era to another, or even from one amp to another. Unfortunately some of the later Polytone amps don't have that warm sound and can sound quite thin, again IMO. Lots of changes over the years and not all were improvements.

Finally I have measured the power output of several older Polytone amps and IME they rarely actually deliver the manufacture's claimed power rating.

Again just my opinions and experience. YMMV.

thmsjordan · #7 02-10-2011, 12:00 PM

Wow! So many great answers! Thank you all very much.

chadds · #8 02-10-2011, 01:43 PM

Had several Minibrutes. Kept buying them. Had one with that Texas snake looking tolex. Had the matching extension cab. Guess what? Plugged an SWR SM-400 into the cab. It sounded exactly, exactly like the Polytone.

The awesome one was the 101. Built like a vintage Fender Bassman with head in back knobs facing up. It was a 1x15. Sounded amazing and better still with a y cable and all the treble dialed up on one channel with all the bass off and the opposite on the other. Then you blended the volumes. It blew up for no reason. Then it blew up when I plugged a cable out of the line out into a PA. Great tone very portable. Later same amp had two 6"s. Didn't sound to me quite as warm.