Magnavox 8802-00 amp lacking adequte output...

[cableguy]

or is it..?
I don't know so I am posing the question to the forum. This amp sounds good but I can turn the volume pot on the preamp all the way up without distortion or clipping. The output reaches somewhere around medium listening levels. My other two Maggies (169 BB mono's and a 6BQ5 stereo) both have a lot more output....:scratch2: As I said the 8802-00 amp sounds good, just does not have the output I would think it capable of...
It is the same amp as Gordon is selling here
http://www.audiokarma.org/forums/showthread.php?t=160166...
any ideas? Is it functioning as it should or is there something off...
BTW, I have tried swapping the output tubes, preamp tubes and as of today the rectifier...there was no increase or decrease in output.
Pics of the Belly....

http://inlinethumb38.webshots.com/42789/2823129650103324012S600x600Q85.jpg (http://good-times.webshots.com/photo/2823129650103324012lNhJQM)

http://inlinethumb29.webshots.com/39900/2445426060103324012S600x600Q85.jpg (http://good-times.webshots.com/photo/2445426060103324012rXtGEU)

http://inlinethumb39.webshots.com/41702/2014032890103324012S600x600Q85.jpg (http://good-times.webshots.com/photo/2014032890103324012oLriPI)

http://inlinethumb15.webshots.com/42638/2551136510103324012S600x600Q85.jpg (http://good-times.webshots.com/photo/2551136510103324012XFOWHA)

http://inlinethumb26.webshots.com/35545/2054757860103324012S600x600Q85.jpg (http://good-times.webshots.com/photo/2054757860103324012lBfdth)

http://inlinethumb35.webshots.com/36130/2095169360103324012S600x600Q85.jpg (http://good-times.webshots.com/photo/2095169360103324012vNnGLe)

as always any and all help is appreciated....

Thanks,

Bill

[GordonW]

You appear to be having a classic, known problem with these... there's a couple of resistors that have to be added in, to replace some circuitry from the preamp/tuner which interacted with the amp (balance control).

On each input tube- where the cathode resistor connects to the feedback-loop wire (coming from the terminal strip for the output transformers), there needs to be a 390 ohm resistor to ground, one for each channel. Looks like there's nothing there, from what I see. I edited your picture, to show where they would be:

http://www.audiokarma.org/forums/attachment.php?attachmentid=88632&stc=1&d=1208987020

Install these, and I'll bet things are a lot better. Now, the 8802 does have slightly less gain than an AMP185, but it's not MUCH different... they'll usually work with the same preamps and speakers...

Regards,
Gordon.

[cableguy]

Thanks Gordon...I was just doing a little Internet research and it appears you are the most publicized author on said missing 390 ohm resistor and these restorations right now(that's pretty sweet actually). add another one to that list....
I was going to contact you next, but as it worked out I won't need to now...:thmbsp:
As I said the amp sounds great, just is IMO lacking a certain amount of output. I also figured the fix would be a relatively simple one as well.


Thanks again,

Bill

[cableguy]

OK...where do I get a couple of these???
Are they something you can get locally, or is there a preferred vendor out there?




Thanks,

Bill

[Tube Radio]

Check Mouser Electronics. Get 390 ohm metal film resistors. I use metal film whenever possible in restorations, because most are 1% tolerance and they are relatively inexpensive.

[cableguy]

Check Mouser Electronics. Get 390 ohm metal film resistors. I use metal film whenever possible in restorations, because most are 1% tolerance and they are relatively inexpensive.
Thank you sir....:thmbsp:


Bill

[cableguy]

Here is the skinny with pictures regarding this mod.

http://www.audiokarma.org/forums/showthread.php?t=103122&highlight=maggotbox

Also I ordered the resistors today and they came in a 100 count package so if anyone needs a few PM me and and I send them to you...no charge. they are cheap, so I figure for all of the free help and advise I get round here this is the least I can do...
(Kegger if this is inappropriate or is out of line with AK reg's I will remove the last bit of this reply...)


Thanks again folks,


Bill

[avguytx]

I got the resistors I needed at Radio Shack. They actually had them in stock which was a lot cheaper than ordering them from somewhere and having to pay shipping, wait, etc. Heck, I may have a few dozen in the garage from back in my car alarm days when we had to use resistors on tons of stuff. I'd be glad to check and drop them in the mail if so.



Edit: Found the unopened package of tons of resistors. I have the 390-ohm 1/4 watt 5% tolerance resistors if you want them. I'd be glad to drop them in the mail if you PM me your address.

Edit: Oops....didn't read the rest of your above post where you already ordered a bunch of them! :D

[cruisaire]

Hmmmm....looks familiar.

[cableguy]

Well, got the 390 ohm resistors today. Soldered them in and she's a runner...:banana:....took about 5 minutes.
Awesome.:thmbsp:


Thanks,


Bill

[Urizen]

Soldered them in and she's a runner...

Schweet!:thmbsp:

[mhardy6647]

we'll send a bill for our consulting services :-)

[cableguy]

Schweet!
Thanks bud...:thmbsp:
we'll send a bill for our consulting services :-)
Tell you what, I'll grab the KLH 7's for you...:naughty:
But seriously, the help we get round here is amazing....thanks again..




Bill

[mhardy6647]

In all seriousness, the way I look at is... "one less amplifier in the landfill, being put to better use for someone's enjoyment of music"!

[analog addict]

How's it sound now? Have you compared it to it's big brother, the 9302?

I love my 8802. Currently it's running my K-horns via a modded BH FPII...(Gee, where did I get that from????....:D)

http://audiokarma.org/forums/attachment.php?attachmentid=89553&d=1209605149

[mhardy6647]

K-horns and a Maggotbox; gotta love that! :-)

[analog addict]

K-horns and a Maggotbox; gotta love that! :-)

Nothing like running your K-horns with a $40 console pull. You'd be amazed at how good it sounds after it's restore. If you think little output tubes can't put out room shaking bass, you're wrong....:thmbsp:

[analog addict]

...I'm also kinda regretting selling that pair of Dynaco Z-565 OPT's a little while ago, especially after pricing them while looking at a ST-35 clone kit....:tears:

Jay, you wind up with them? I can't remember.....:stupid: