Ultra Linear Push Pull Tube amp

[M Gregg]

Just a thought,

Why not do as everyone else does use a tube amp and amplify the sound with PA! Direct in via Tx.

Or use tube pre and FET output stage. Have a listen to a Krell power (SS) amp and ask yourself what you want or need.

The power loss can be quite high with tubes. Also try listening to a vellman tube power amp. OK its not the best, however you can tweek!

So all this depends on what kind of sound you are looking for is it the warmth or detail. This is again dependant on types of music you like.

And of course cost!


Regards
M. Gregg

 

[Hoej]

Hi All...

The sound I am looking for, is the soft sound, but still abel to control the bass whit out flopping around. I really want to get rid of all this Digital sound.

I really hate all the new digital once, maybe and I am saying maybe it is useable in subwoofer, but who wants that.

I am sill looking for schematic for a amp, the hashimoto look good, but i was conspicuous of the distortion.

Maybe something wet a differential input ?

Best Regards Allan

 

[Evenharmonics]

The sound I am looking for, is the soft sound, but still abel to control the bass whit out flopping around.

Then go with active crossover, use SET amp for mid and high, SS or P-P tube amp for bass as mentioned here.

 

[richwalters]

I couldn't resist tearing the robes off the Japanese Emperor.
Study this one.
http://www.drtube.com/schematics/radford/sta100.gif

This site has alot of others.

richy

PS. That THD curve I provided is for real with 20dB global nfb...no other feedback arrangement. Circuit design copyrighted but o/p transformer key element (is not cheap) from SOWTER AUDIO TRANSFORMERS.

 

[artosalo]

Circuit design copyrighted

What tubes ? UL, triode or pentode ?

Based on few decades spent on electronics industry, only patented circuit is copyrighted. One can write anything to his circuit diagrams, but it does not mean anything.

 

[mashaffer]

Just to clarify my point in posting the Hashimoto was to indicate the basic topology I was suggesting not the design details.

 

[Hoej]

Hi all..

Well…

I am searching for a amp which has following

Tube amp Ultra Linier Push Pull based on

Output Power 100 - 150 W or higer

Frequency span 10 HZ - 20 KHz with a low distortion < 2% @ full load in 8Ω @ 1KHz

Based on a mono block amp with 2 X or 3 X or 4 X KT 88 at the output state

Input state, must be low noise.

Rectifier Tube or WZ68 or silicium

The output transformer have to be a stock item.

The Power Transformer is unimportant, I will make it my self any way, however the AC Volt and Amp for all output has to be on the schematic.

The Schematic must be complete.

Best regards Allan

 

[LinuksGuru]

I would suggest you to take Citation II mod by Stew Hegeman. You can use 4xKT88 or 2xKT120.

You can download schematic from my blog.
Download Schematics & Service Manuals | MacGuru HQ

Additionally, you can take almost any PP amp with 2xKT88 and use 2xKT120 or 4xKT88 instead to increase output power. If you use quad of tubes instead of pair, you will need transformer with twice lower primary Z. As for KT120, ask other people on forum, I have no data for this tube.

IMHO, 10 Hz at full power is too low frequency will result in huge output transformer.

 

[Hoej]

Hi LinuksGuru

3 Questions.

I think it's a little strange in terms of output transformer. look at the picture, there would you see that the top turning in the winding. It does not have the same resistance as the bottom.

Which transformer would you use if you wanted to run with 4 tubes KT 88

http://www.audiomarketing.net/bart2.htm

What about the changes that are made, shall they be carried out?

Bedst Regards Allan

 

[LinuksGuru]

Hi LinuksGuru

I think it's a little strange in terms of output transformer. look at the picture, there would you see that the top turning in the winding. It does not have the same resistance as the bottom.

This is normal, winding on outer layer has larger mean winding turn length, so resistance of second part of primary is slightly higher.

Which transformer would you use if you wanted to run with 4 tubes KT 88
BARTOLUCCI TRANSFORMERSÒ

Better to ask Bertoluchi himself, he knows his own products much better. I think 100W 2.5K should be fine.

What about the changes that are made, shall they be carried out?

Hmmm, I'm not sure. Better to sticj with stock schematic for the first time.

_______________________________________________________

Here is the link to 100W KT88 PP amplifier.
Hashimoto KT-88 UL Push Pull
Actually schematic is not very original, its design is based upon simplified (stripped down) Sansui AU-111.

PS. Citation II has 30dB NFB (sorry, forgot source), so it is very sensitive to phase shift. 100W transformer is quite large, thus, even if it will have low leakage inductance, distributed capacitance will be high for sure. Resonant frequency of original Citation II transformer is over 200KHz, and this is not done just for fun, but to make amplifier stable at HF.

 

[Hoej]

Hmm ...
I thought it was wrapped with two parllelle threads started in ground point so that you got the same impedance and inductance of the transformer and ligedes the same ohm value. This would mean that it the same AC and DC rata for each tube.

But there is probably a reason which I do not know about for not doing it

Thanks again

 

[Matt BH]

Hey Hoej,
Sorry I am so late in my reply Been working real hard.

We used to have a pretty big 1MW ABB DC motor and drive at my old work. It drove a rubber mixer that was pretty bloody hairy. It had its own 11KV-415V transformer and the line iductor to filter out noise from the drive used to sing like crazy under load(500Kg of raw rubber and various addatives) Good times

Cheers Matt.

 

[BHD]

Here's a 300 watt tube amp:

Monobloc300

Good luck!

 

[Hoej]

Hi Matt

I can imagine that it requires hearing protection has never seen such a large DC motor, the largest I have seen and heard was a 200KW that I repareted for current leakage in the armature it was for an extruder, and as you say choke coils in the outputs do really make a lot of noise

It must have been quite an experience to hear such a large DC motor running

Bedst Regards Allan

 

[Hoej]

Hello everyone ...

Thanks to everyone who helps me in my search for tube amplifiers.

I'm close to have decided myself, I have looked at the various amplifier,
but always ends up with a schematic with too many lurking feedback loop

so it ends with me looking at kit .... I like the kit from Bob Latino
I look for responds curves (square 1KHz & 10 KHz) but have only found
something from the little brother M120.

Picasa Web Albums - Arnold Matthews - Steps in buil...


Prototype 125 watt monoblock tube amplifier KIT - Page 3

# 35

Prototype 125 watt monoblock tube amplifier KIT - Page 7

#102

Does anyone have a kommentat for this amplifier?

I must emphasize that I am not for either expensive gold or silver cable
but a good general quality throughout. So when I look at the tube
amplifier is the same that apply again.

I would like to build Bob's amp, and fine trim it slightly (if possible),
with a slightly higher voltage to the output tubes and 2 x GZ33. But I
have some questions in this context, it is possible to parallel connecting
2 pcs. GZ33 if yes. should the chokes be replaced. I know the heater needs
5V 3A no problem and I've seen an amplifier that was drives with two
tubes in parallel, I just cannot remember where

I would like to optimize it into to run with KT120 not so much that the
output transformer cannot keep up.
But what about the drives step? can it provide a voltage swing and which
is big enough? Is it possible to decrease the resistors which voltage
swings over? or it will run in current limit?

Well ... If there is positive mood for the amplifier, then it will be the
one I build.
The idea was to begin with the Original Plan. And hear it play here after
optimize (if possible).

I will start to change the solid state rectifier in to 2 X GZ33 instead.
I am aware that there is a higher voltage drop across the GZ33 tube than
solid state rectifier, again if I increase the B + voltage.

I would like if there is anyone which has knowledge of the M125 or any
ideas, or commentators, and especially on the basic structure of the M125,
then please say so. I have never heard the M125 play.

In advance thank you