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Scott 299C, low volume, help!

Jenkster

Jenkster

When I had talent
Subscriber
We are getting extremely low volume, both sides, out of the Scott. All the tubes test great, replaced the selinium rectifier, all caps except the 30/30 @ 500V cans. Please tell me it's not the output transformers! Tested the secondaries and primaries which tested correct. The voltages tested good as well. Any suggestions would be appreciated!
 
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Check the voltages coming out of the can transformers under load. The schematic is here, you will see voltages coming out of different points on the schematic. You will see 255v, 270v, 300v, and 430v on the schematic where you need to measure. If these voltages are low it may be these caps.

http://hhscott.com/database/vhhs_00011.html
 
Were you using it and it suddenly went low, or did you receive it in this condition? Check for open hi-watt resistors in the power supply and power filter capacitor areas.
 
cademan said:
Were you using it and it suddenly went low, or did you receive it in this condition? Check for open hi-watt resistors in the power supply and power filter capacitor areas.
Click to expand...

Voltages seem to be OK so we will check the power supply resistors etc. Thanks for the tip. Oh, it was this way when I bought it.
 
With the those Scotts, you must have all of the 12AX7s installed.

Both the phono inputs, tuner, tape in etc pass thru the 12AX7s in the tone control.

The GZ34 is sommon to both channels.

My MP3 with the volume turned up and tuners provide enough voltage so that I can't turn the volume past 11-12 O'clock. A few times, the volume drops in my Scott 222A; I panic! Then I discover that the volume on my MPS3 is down.

Once you get it running, if your unit uses the 6U8, 6BL8, E80CF family, switching to E80CF will make a dramatic improvement.

Best from Tucson
Bob
 
Plus.

I love my Scott 222A!

I use K40Y Russian PIO as coupling caps; Mullard GZ34 withe dual getters, Brimar long plate 12AX7-Cv4004, Mullard E80CF, and Siemens E84L, simple 12gauge mil surplus stranded, silver coated copped, teflon insulation and a HomeDepot AC plug.

Best from Tucson
Bob
 
Hey, my buddy figured it out. Apparently there are several versions of this amp. Some have 6U8 driver tubes and some, wait for it, use 7199's! This particular amp uses 7199's which have a different pin configuration that the 6U8, which is the tubes that were in it when I bought it.:scratch2: My friend believes it would be better to re-configure the amp to use 6U8's as opposed to 7199's. The 6U8's are certainly much cheaper and more readily available than the 7199's. I would appreciate any input on this issue.

Thanks!
 
wire it for the 6U8 family of tubes and then use a E80CF-7643. It will have tighter control, more harmonics from the midrange, more accurate top end, and percussion instruments, like a piano sound like a percussion instrument and guitars are actually plucked.

Best
Bob
 
Thanks for the info Bob. Are the E80CF's readily available and reasonably priced? I know you can pick up 6U8's for under $10.
 
Last time I checked, Jim McShane had some Mullard made E80CF, my favorite, for $21 each--course tested!

By scanning eBay constantly, I found Valvo made ones for 10-15 each. I bought some Siemens labeled ones thinking the were made by Valvo, but they turned out to be Mullard made.

It seems as if Mullard, TFKN<>, and Valvo were the only ones to make ones with gold pins.

I have quite a variety of the 6U8 family of tubes. This is a situation where the E80CF just run circles around any of the 6U8 types I tried. Most times I try out different tubes its a matter of getting something while having to give up something--not so with these E80CF--gain tremendous amount and loose nothing.

Best from Tucson
Bob
 
becketma said:
I have quite a variety of the 6U8 family of tubes. This is a situation where the E80CF just run circles around any of the 6U8 types I tried. Most times I try out different tubes its a matter of getting something while having to give up something--not so with these E80CF--gain tremendous amount and loose nothing.
Click to expand...


I just switched to the E80CF's in place of the 6U8's in my 222c and I totally agree. I didn't know that the phase inverter tubes could make such a difference.

Now, I do.
 
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