I don't know about the Jensen Neo's but I incorporated some 12" Eminence BassLite speakers into a bass amp project and was/am very impressed with the sound and you can carry the raw speaker on your little finger!
heisthl wrote:Here's another unusual phase inverter:
Thank you, but as I see it you then miss the advantages with the cathode followers. For example the low output impedance.
With the same kind of tubes (one 12AX7 and one 12AU7) I guess it's better to drive 6550's with the 12AU7 connected as cathode followers.
I'm sure you're right - I was hoping someone would tell me why they didn't do it that way on that schematic. I've never used it but it looked interesting to me.
You'll need cathode followers to drive 6550 only if you're running them in class AB2 i.e. forcing control grids positive rel cathodes. Cathode follower can do it without causing grid clipping which would happen otherwise.
The PI on Univox schematic isn't in any way unique or unusual. 1st stage is the phase splitter, the 2nd is just a differential amplifier, ok it does it's own polarity reversal on both signals but it does not split a single phase signal.
Has been used in many "old world" audio amps. Acoustic Research come to mind as one.
Aleksander Niemand
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Life's a party but you get invited only once...
affiliation:TUBEWONDER AMPS Zagray!-review
glasman wrote:...I am curious why the negative feedback around the mixer, did you find some issues here or just wanted to limit the gain of the stage.
Tonight (the time is over 11:30 PM here now) I have tested a little more with and without this negative feedback around the mixer.
As I said earlier the gig we had this weekend was a little strange. The main thing that was strange was the sound. It was a strange sound in that hall... But I also didn't recognise the sound of my amps, especially not from the Bandmaster. When I now tested with and without this feedback I could recognise that it was the choked sound it gave that I didn't like on the gig. Once again I got sure about the fact that you have to test sounds together with the band in a real situation.
I tested some other things around the mixer tonight but came back to the circuit I had before I added the feedback. None of the things seemed to change the amount of distortion at the same sound level and same sound.
Well, that feedback didn't get one week with me...
VacuumVoodoo wrote:You'll need cathode followers to drive 6550 only if you're running them in class AB2 i.e. forcing control grids positive rel cathodes. Cathode follower can do it without causing grid clipping which would happen otherwise.
The PI on Univox schematic isn't in any way unique or unusual. 1st stage is the phase splitter, the 2nd is just a differential amplifier, ok it does it's own polarity reversal on both signals but it does not split a single phase signal.
Has been used in many "old world" audio amps. Acoustic Research come to mind as one.
Thanks Aleksander, as usual a succinct summary.
The Last of the World's Great Human Beings
Seek immediate medical attention if you suddenly go either deaf or blind.
If you put the Federal Government in charge of the Sahara Desert, in five years time there would be a shortage of sand.
I've tweaked the circuit a little more. (Se the attached pdf file).
Now I like the amp to be like this on some gigs and rehearsals to see what I like it like this, but it would be really nice to get comments or criticism from you here .
I’d like to expand my answer a little on how effective the Treble Shift and Middle Shift switches are:
It depends how you see it. Compared to the Deep or Rock/Jazz switches, which I think changes the amps character rather much, they are not especially effective. But I do think that they change the voice of the respective tone controls in a useful way.
Take care,
Sven-Johan
PS: The schematic was wrong at the Bass control, but is now corrected...
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Last edited by Svempan on Sun Jun 24, 2007 5:48 pm, edited 3 times in total.
heisthl wrote:Here's another unusual phase inverter:
I can just imagine how the preamp must sound with 35 (!) volts on the plates ? yeeesh.
Well, the plate voltages is just one thing. Among other things, you also have to consider the voltage drop over the plate load resistors. In a way you can say that that's where things are happening...
Look at the voltages on the EF86 on my Clean King Amp... Looks rather strange at the first look, doesn't it? BUT, the amp sounds absolutelly tremendous!
I had hopped to get more comments, questions and maybe criticism on the circuit in my Clean King amp, but this thread seems ended...
Then I like to give credit to the person that originally gave me the idea and a circuit solution with the ECC832 (12DW7) in the reverb circuit. It's Lars Söderqvist of reVintage Amps here in Sweden. Here’s his web site: http://www.revintage.se/
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