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Magnavox 175-67 Tube Amp

T

tube-a-lou

Addicted Member
Magnavox 175-67 Tube Amp Upgrades

Hi All,
I'm new to this so here goes. I received a Maggie 175-67 ( 2 weeks ago).
That I'm in the process of restoring. it was partial stand alone job, I just
added a fuse and Speaker terminal's, and to my surprise it sounded good,
as I've been changing parts it been getting better and better, I added
matching Caps .1's and .047's for increased bass and added .022 to
replace the input ceramic's that were in there for smoother sound, Added
new resistors and some wiring upgrades and a grounded 3 way cord, it's
very quiet with no hum or other noises and to my surprise pretty loud,
considering that I'm using pretty inefficient speakers Celestion 100 or
SL6's with the Copper domes So is there any other upgrades I can do
for this amp, by the way how many watts is this amp. I did look at the other
threads and got great info from them which is great, but want to know if there's
anything new to know and watch out for.

Thanks

P.S. Tubes are two 12AX7's, Four 6V6'es and one 5U4.

Thanks
Tube
 
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Hi the amp is about 12 watts a channel , you should change the ceramics to polly caps , they will sound better .Use the cap value from Gordons schematic fot the audio circuits

maggie206l620conversion20ss20pow-1.gif

Schematic By GordonW

8417001-1.jpg


Photo of my 185 .
http://www.justradios.com/safetytips.html
 
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Hi,
Thanks for the help, so should I change to same value or improve with other value type also
why do these sound so good, my 100watt C.J. 2100 didn't sound this good kind of flat, great bass
but mid and high's lacking in something I can't put my finger on and did mag ever make a 20 or
25 watt amp?
 
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Depending on the condition of the current tubes, a newer matched quad and pair of driver tubes could change and improve the sound.

I rebuilt my 185 as a 175 with all new caps and resistors as well as brand new set of tubes with a vintage rectifier so I can't compare directly to the old stuff.
 
If the output tubes use cathode bias with shared resistors it might be a good idea to change it to separate bias resistors (and caps). Of course there is always SY's "Red Light District" approach. ;)

http://syclotron.com/

mike
 
Hi,
Thank you all for the help! I did want do change the 6V6's for a matching set
are JJ's good or should I go the Electro harmonix route
Thanks
tube-a-lou
 
tube-a-lou said:
Hi,
Thanks for the help, so should I change to same value or improve with other value type also
why do these sound so good, my 100watt C.J. 2100 didn't sound this good kind of flat, great bass
but mid and high's lacking in something I can't put my finger on and did mag ever make a 20 or
25 watt amp?
Click to expand...

AMP142 20 watt monoblocks
Picture087.jpg

The concert grand had a pair of bi-amp monoblocks with 6 6v6's for bass and 2 6v6 for highs...
 
That schematic doesn't show 8 tubes, it only shows 6. That schematic shows the two halfs of the 6EU7/12AX7. On the schematic it looks like two individual tubes.

You will notice it says, "1A & 1B", "2A & 2B". This indicates the two halves of a single tube.
 
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The power output tubes are the 6V6/6L6's. If your talking about the 5U4 rectifier tube, that schematic shows solid state diodes in the place of where the rectifier tube would normally be.
 
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