Well it's midrangey as hell indeed, but the real killer feature is the bright switch that brings a lot of highs back into the sound. all notes have bass in them too so they weight a lot in the mix. With the bright switch on the sound is actually very bright with mids Added. Think Kurt rosenwinkle sound on his YouTube video for lehle pedals.

But again if someone knows what gives that immadiate attack to notes I very curious of what makes it happen

At the moment I couldn't find any amp tube or solid state, with a sound as precise and immadiate as this polytone and I'm really really curious to know why as these are great features to me.

Te preamp is fairly classical so I guess it's a matter of power amp/speaker as the previous posters mentioned

Actually my polytone uses that exact power amp so I guess that solves the problem.i thought that this power amp has the bias problems.

Actually, after trying many other solid state amps from vox to aer and henriksen jazz amps, I have never found an amp with the same reactivity (attack of the notes is super fast) and dynamics as the polytone.

Do you have any idea what could be the reason for this 'directness' ?

hello,

I am thinking of starting a first amp project and i'd like to have some advices from you experienced people.

First some background: i have been building guitar effects and 1 tube amp in the last 2 years. I have a general understanding of circuits and how some parts of them work, but nothing really complicated yet.
I usually play at designing my own pcbs in eagle when i see a schematic that i like. Usually it's much simpler than an amp, but nothing seems too complicated to be done with 2 layers and a few squares inches of pcb.

I have a solid state amp project that i'd like to concretize and i would like to have your opinion and advices.
The idea behind the project is to clone my beloved polytone mini brute.
The preamp would be a clone of the preamp of the mini brute (basically an op-amp amplification device with an active bandaxall EQ).
For the power amp, I've heard the polytone power amps are really hard to bias and basically a bad design. I've also read that power amps basically do NOT change the sound at all, they just amplify the sound. So i was thinking that i could move away from the polytone power amp for a classical design with more qualities. However, i would like to be SURE that i' wouldn't be loosing some of the key features of the polytone sound by doing that.. do power amp influence the sound/dynamics/feel of the amps at all?
Power supply : linked to the power amp i suppose -> ??
Dimensions : as small and light as possible .. my polytone packs everything in a very tight package, and 9 kgs.. i'm hoping to do that, or better as components are now smaller...


Here is what i already know that i don't know...
- The practical connectivity into the amp: how to send signals/power to the boards (if there are more then one), and switches.. what physical connections should be used and how.
- heatsink!!! i don't know anything about it. my polytone has 2 power transistors glued to 2 big heatsinks, which are stuffed into the CLOSED amp, filled with fiberglass foam .... so i guess heat dissipation is not at its best, still, it doesn't seem to matter.. i guess it's possible to do better, how to manage that properly.
- power supply needed : depends of the circuit and power
- where to order a decent and not too expensive faceplate
- the actual cabinet construction . not the slightest experience but i can be helped.

So my main question at this point is : would changing the power amp fro mthe polytone power amp to a classical design change the sound?
How do i calculate the needed heatsink and power supply ?

Thanks in advance

Great, thanks!
Another question : do you have a magical solution for producting small batches of PCB for a good price? do you etch at home or do you send them for production ?

What enzo described is exactly what i found into my polytone.
i posted gutshots here :http://www.ssguitar.com/index.php?topic=2771.0

No distortion or reverb in mine, just the very simple basic preamp. the preamp pcb has a lot of free traces and spaces and i guess i could add a reverb from this, but i don't see where i would place the pot and the reverb unit

I'd be curious to know where i could buy chassis, enzo, could you share some links?
Thanks to you all for your help !

wow thanks for the great answer.
So in this case (my polytone doesn't have the drive section, nor the reverb section, only the basic amp/EQ preamp, and the exact same poweramp that is on the schematic). it is safe to assume that most of the tonal characteristics of the amp come from the bandaxall eq with flat mids, the bright switch, the speaker and cab ?

I'm curious about the heatsinking of this amp.
The 2 power transtore are mounted on 2 heatsinks, it seems ok to me, but the whole amp if filled with insulating foam, very light. i confess i worried about the heat resistance of this foam and wondered if it wouldn't start to burn if the power transistors started running too hot. is that standard practice?

Also, how do you guys make chassis? the biggest problem for me in this hobby is the hardware part :-)

that's what i read earlier and the confirmation i wanted.
So there is no hearable difference between power amps or different class and using different technologies (FET vs BJT vs chips vs ... )?

so basically, the great sound of a polytone comes from a super simple opamp preamp with a bandaxall eq, and a crappy speaker with no brand and name written onto it? could it just be the bandaxall eq with flat mids that make a big part of thatgood sound?

Hello,

I'm quite new to amplifier tweaking/building. I recently serviced a polytone i bought used for 25 euros and that got me thinking about building a polyclone.

The amp i have does follow exactly the schematics on the murchmusic site.
However, i read that this power amp was difficult to bias and was not really easy to build. Another guy that build a polyclone told that he replaced it by a FET power amp.
How much does a power amp change would change the sound of the amp?
Are there classical and good sounding power amp designs around 80 or 100 Watts that would preserve the polytone sound?

In general, are power amps transparent and does the color of the amp comes from the preamp?
Thanks in advance for your help

associated schematics :

I should mention that the preamp of my model (mini brute I) only has the very basic features : no reverb and no distortion, hence the empty parts of the preamp pcb

Hello,

New member here,
as my polytone is waiting for the post office to be opened to have the needed caps to finish the cap job, i thought i might as well post some gut pics here.

From what i gathered, the preamp and power amp correspond to the schematics posted on murchmusic's website.


Hope it helps someone.

Cheers
Arnaud