Is a typo or this LTPI using 1/2 6aq8 + 1/2 12ax7 in an ELK amp is correct ???

[kagliostro]

What do you think ?

is a typo or really the ELK ES-30 Japan guitar amp uses such mixed architecture for his LTPI  

K

[kagliostro]

Yes, is commonly published, but the send of the reverb is an ecc85 and the return is labeled 12ax7

the LTPI has 1/2 ecc85 and 1/2 12ax7  that is very odd

the same ELK brand but model Twin 50 has the same odd architecture

http://www.drtube.com/schematics/elk/twinamp50.gif

I can understand that may be there is a necessity to have the 12ax7 tube in the recovery of the reverb

but don't you think that an LTPI using different triods is really odd ??

K

[HotBluePlates]

It's probably an error, as the ECC85 has half the mu of the 12AX7 so the inverter is less likely to be balanced.

Then again, the tail resistor may force balance close-enough.

[kagliostro]

Hi HotBluePlates

I've seen only this two schematics and both has the same odd architecture

looking to the first I was thinking that it was a typo, but when I've seen the second schematic a doubt come to me

may be they do this thing (using the tailor resistor as to balance the signal) for "special effect" in the sound ?

sometimes I've read about people using resistors or also trimmer to balance near perfectly the PI (I think guitar guy borrowed this from HiFi guy) but there was people that say that they prefers a non perfectly balanced PI who gives a "pleasant tone" to the amp

Which is your personal opinion about ?

Thanks

Franco

[HotBluePlates]

Which is your personal opinion about ?

I don't know. I've never seen an Elk amp in person, much less inspected the actual amp or played through one. So I really couldn't say...

[kagliostro]

I haven't put my question in a clearly way

I mean, which is your opinion mixing different triodes in an LTPI and balancing the signal with resistors

do you think that a sort of mojo sound may come out doing that ?

Franco

[HotBluePlates]

If my memory and tube charts serve me correctly isn't there  a 12__7 with mixed triodes that would someone to test mixed mu tubes in a LTPI circuit, without having to have two heaters.

Agreed; I think this would be the best way to find out.

The 12DW7/7247 is the American part number for 1/2-12AX7, 1/2-12AU7. The European part number is ECC832.

[kagliostro]

12DW7 is claimed to be a good tube for reverb circuits and for FXLoop too, I think

to try it in a LTPI is a good idea 

within 15 days here there is an electronics fair, I'll look for a pair of those tubes 

K

[tubeswell]

JJ makes them in 2 pin configurations:

the ECC832 with the 12AU7 triode on pins 1, 2 and 3 and the 12AX7 triode on pins 6, 7 and 8

and the ECC823 with the triodes on the opposite sets of pins

[kagliostro]

I've find this odd PI that uses a Pentode and a Triode one for each branch

New Phase Splitter
A R Bailey MSc(Eng) AMIEE, Bradford Institute of Technology. Wireless World, September, 1962.   
Improved high-frequency response.
Circuit of complete EF86 pentode amplifier and ECF82 phase-splitter for use in a high-fidelity amplifier with a large amount of negative feedback.

http://www.amplimos.it/phase%20splitter.htm


May be this give more sense to an "apparently" unbalanced PI like the 1/2 ecc85 + 1/2 12ax7 ?

K

[sluckey]

You've been finding a lot of oddball circuits lately. Maybe you need to update your search engine. 

[kagliostro]

YES !

I was looking about documentation for the paraphase PI

in reference to this tread and PRR post

http://www.el34world.com/Forum/index.php?topic=15485.0

and I've find this strange thing

Ciao Steve

K

[DummyLoad]

he does come up with the weirdest stuff...  

attached is how i think elk ES-30 is built.

--pete

[DummyLoad]

You've been finding a lot of oddball circuits lately. Maybe you need to update your search engine. 

italian search engine... like italian cars & motorcycles... they have a mind of their own... 

ps. i can confirm this; i own a guzzi le-mans. 

[kagliostro]

Nice Toy Pete



Some year ago there was an article on MotoTecnica of a modded Le Mans with a volumetric compressor from a Lancia HPE Volumex car



unfortunately (for you) I do not have anymore the magazine with the construction plans  

K

[DummyLoad]

nice scooter k, but not the 850, the V11 tenni

this one:

[kagliostro]

Oh, yours is a newer model

NICE  

---



K

[Custom_Amp_30]

What do you think ?

is a typo or really the ELK ES-30 Japan guitar amp uses such mixed architecture for his LTPI  

K

Its not a typo, I can assure you. half of the 6AQ8 is used in the reverb circuit while the other is used in the in the PI shared with half a section of a 12AX7. It works out.

[PRR]

> odd PI that uses a Pentode and a Triode

I think it would work the same with a twin-triode.

You guys with your supercharged scooters! Do they mow the lawn as well as a 1972 Craftsman GT-18? (OK, today my GT wanted to leak fuel, so I turned to my newest motor: a 2.3HP $119 WalMart push-mower.)

[kagliostro]

PRR if you like the Craftsman

give a look to what is building a friend of an italian forum (he is a carpenter) 

starting from this



at the begin of the job



this is the result (still not ultimated)



K

[kagliostro]

The friend required a small multi function small tractor and decided to build it by himself using a cultivator decommissioned

Where's the intermediate result?

are you looking for this ?

http://www.cncitalia.net/forum/viewtopic.php?f=89&t=41896

http://www.cncitalia.net/forum/viewtopic.php?f=89&t=41896&start=30

http://www.cncitalia.net/forum/viewtopic.php?f=89&t=41896&start=45

http://www.cncitalia.net/forum/viewtopic.php?f=89&t=41896&start=60

http://www.cncitalia.net/forum/viewtopic.php?f=89&t=41896&start=90

http://www.cncitalia.net/forum/viewtopic.php?f=89&t=41896&start=120

http://www.cncitalia.net/forum/viewtopic.php?f=89&t=41896&start=135

http://www.cncitalia.net/forum/viewtopic.php?f=89&t=41896&start=150

http://www.cncitalia.net/forum/viewtopic.php?f=89&t=41896&start=195

http://www.cncitalia.net/forum/viewtopic.php?f=89&t=41896&start=240

K