I wish I had seen that 200VA before you went on vacation Steve.
As is I am very happy with the heat sink and chips ,ect I purchased from you.

Thanks JM
I will try it with out that buffer(Q2) and see about getting some sound clips.
I also want to try some other line in source (FX, another pre-amp)directly to the PA.
So I can better tell how much clipping is coming from the PA vs the preamp.
Alot of the clean channel overdrive(if not all) is coming from the 386 chip clipping.
A regular NJM386B would probably be better suited as well.
I also left the gain pots the abilty to overdrive the opamp if desired.
I got the master volume idea from you in another thread  :tu:

Here is the schematic of how it sits now-
http://i419.photobucket.com/albums/pp276/Bry928/SolidState%20Amps/12Watt-TDA1519B%20build/12WattTDA1519B_schematic.jpg
It has a fair amount of clipping going on it emulates an old tube amp fairly well IMO
It has a smooth overdrive going on,in the clean channel the louder you get.
The OD channel sounds good from a little diode clipping mixed in,(low gain)
to all out clipping from all the components.
The idea was to get some light clipping from the FETs as well,I think that is happening IDK for sure.
And to compensate for the loss of the tonestack,which helps tame the signal out of the op amp.
If I could change it it would be to get the clean channel -cleaner, maybe not possible with the 386 and this chip amp?
It evolved from this 2 channel Ruby build here http://i419.photobucket.com/albums/pp276/Bry928/Pedals%20and%20effects/SSamps/3862channelamp-small.jpg
I apologize for the hand drawn schematics the first one should be pretty legible though.

Any suggestions? Thoughts? Ways to improve?
Any critisisms welcome.

Also I plan to use two transformers so the pre and power amp have different supplies.
I will draw that out later.

Thanx Mensur, how about a cathode follower instead? using a small triode? one half for each phase?
Also do you have a recomendation what to use for the voltage follower instead?

Quote from: phatt on August 18, 2009, 10:44:42 AM
Hi posegate,
                Would be better if you just explain the symtoms you have noticed
and then you might get closer to fixing the problems you are having.
Cheers Phil.

Hi phatt sorry to hijack thread but are you ZP? zaphoid phil from Canada?
If so you have helped me in other forums 

I dont find the EH tubes all that great.IMO unless they are NOS
I like for pre amp the JJ long plate gold pin 12AX7
or the Chinese Tung Sol from MusiciansFiend  suprised me as well.
Does your amp get hot and start to distort? Only reason heat sink would help.
To improve tone otherwise you can replace any carbon film resistors with metal film ones
for less noise.(proly wont notice the difference though unless amp is hissy)
And replace the smaller electrolitics with Nichicon brand UKW pre-fix (UKW line only)
I did this in my little Crate  (all SS not Hybrid) and the difference was so good even the drummer noticed  when I demo it for him :lmao:
I did the same to My multi FX proccesor and now the sound has no HISS and is much more clean and pleasing.Better than when it was new many years ago.

OK I now have a better understanding of rated Mah and ,
The fact that batteries have an internal resistance.
And the discharge curves that are used to give the rated Mah are often based on an average or a 20 hour rate.
Also the rating drops as the charge is depleted,
And that the AA size cannot supply the full rated Amps for more than a millisecond if that.
So more realisticly I think the D cell in a Nimh rechargable rated at 12,000 Mah Or 12amps(in theory)would be better to get a draw of 2-3 amps for one hour (maybe depending on internal resistance and heat)
Also (as I understand now) since as less amps is needed to produce more watts as current increases then raising the V to +/- 18 or 24 would yield far more volume for a longer period of time per the same Mah rating Vs +/- 12V.
I tried this with my amp and at 16V the volume was comparible with rechargables as to 12V with MUCH more current available from transfromer.
So for car chip amps maybe 15 rechargable D cells for several hours use, the LM3886 would need 30 D cells to work as a decent 40 watt amp.

I dont know if any of you remember the Music Man amp that took 40 D cells to get a 60V supply? (from 1970s)
The batteries lined the bottom and both sides of the inside of the amp (must of weighed a ton.

I think it looks AWESOME Serg!
AND this thread helped me alot too,good info.

I think you misunderstood my fault.
The idea was to go from the phase inverter in the Marshall to 2 X 3886 in bridged mode.
But instead of inverting one chip to get the inverted phase for BTL mode.
I would take it from the phase inverter of the Marshall 18 watt.
This ways both chips would be non-inverting.

Maybe better to use the signal before the PI and use the 3886 X 2 in normal BTL form?

Would the 3886 chips work?

And would the signal be TOO much for use as a pre amp to the 3886s as the plates are at
high V?

Thanks JM  :tu:
Again another  explanation I find very useful.

Thanx JM
I searched the Mouser cataloge (I have hard copy)
And T0-220 largest size I could find.
Where do you order your insulators from?
And do you know of a supplier of just a small sheet of Mica?

I was thinking of cutting two small strips off of another TO220 mica insulator,...
But was afraid the cuts would distort the edges so as to make the thermal transfer less efficient and negate the benifits. any thoughts?

Also the thermal compound I have from Radio Shack says it has a dielectric rating of 300V
isnt that sufficiant for the small area where the insulator isnt covering? given the small gap and no actual contact?

I know 4 more questions
But I do appreciate the advice JM its has been very helpful as always.

WOW thats a really nice sounding amp indeed then.
Very nice job.
I was thinking of trying a hybrid too.
DId you still go with 4 gain stages -2 triodes?
I have 4 stage SE amp it is a Trainwreck Francesca pre with a Marshall stage .68uf 2k7 bypass in front of that,Very high gain I was considering using that in front of my LM3886 chip but read here 12ax7s not so good for use with the SS power amp.
After hearing yours I think the tone is incredible, exactly what I am after for the dirty channel.
I was also considering using my Marshall 18 watt pre-amp all the way to include the phase inverter -
Into two 3886 chips both non-inverting BTL,wouldnt this work as well?
That way the signal is already 180 off so both chips would be non-inverting.
Or is that too much?
The normal channel is both halves of triod in parallel the other is tremelo channel.
I would just have to adjust the power rail a little to keep the V down with  the PA not being used.Or just use a different transformer.

I swore it said 35VA transformer but I looked again and didnt see it.I must been confused,
looking at to many schematics.

EDIT- Look at page 8 of the owners manual under power requirements.
Power supply 120VAC 60HZ 35VA
thats where I saw it at along with the THD and wattage ratings.
Is that a misprint ? or maybe the watts RMS is wrong instead ?

Wow JM thats an excellent tip using your "Greenbox" to compare spkrs.
Especially using the V30 as a reference point really shows how those little dips and peaks will affect the sound.
I am curious you mentioned the Italian made Jensens.
I own some Electric Lightnings and love em.
Have you any experience with the Sica brand spkrs made in same factory?
The specs on them are impressive 100.3 spl 100watt rms
But the "Greenbox " on them is very erratic but seems close to the V30.
They are very inexpensive compared to thier siblings from the same factory.
Also do you know of any suppliers of the Sica line?
I can only find one in USA but no longer stocking the Sica guitar spkrs only PA and bass ones.

Hey Joe looking good!
Thanks for sharing ,I am looking forward to seeing the finished build.