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Magnavox 185/175 with 6l6G tubes?

B

baddog07

Active Member
C660EEF6-C310-476B-B4FD-0484DCF0E5B1.jpeg Any issues with running these amps with a 5u4G recto and 6l6G power tubes?
I have the bias separated so each channel has a 250ohm 10watt resistor in the output section.

6l6G is a 19watt tube

Plate 274vdc
Cathode 19.6vdc
250r 10watt resistor

Bias is around 10watts per tube with this setup.

Thoughts and suggestions welcome.
 
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Although the 6V6 and 6L6 have the same pinout, the Magnavox amps can not come anywhere near the plate voltages the 6L6 tubes needs on their plates unless you change out the original power transformer and tweak the power supply. That amp with the stock 6V6 tubes is only capable of about 10-12 watts per channel. a pair 6L6G's are capable of twice that.

The 6L6G will work and produce sound and will not let out the magic smoke. However, if that is an AMP185, the power transformer may not be up to the task as the AMP185 originally did not power a separate tuner/preamp like the AMP175 did so the current draw from the 6L6G's heaters may be too much for the 185.

Heater draw on a 6L6G is 0.9 A.

6V6GT is 0.45 A.
 
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SS rectifier would help with the heater current but won't really give you any more watts.

With your 6L6G's, you're still basically getting about 10-12 watts per channel so you are probably defeating the purpose of wanting/having more power except they look cool!
 
I swap in a SS rectifier sub to get 340V on the plates (175 territory), but don't think it has the current capacity for 6L6s, as mentioned... Lots of mods to 6L6s on here tho,,, do a search,,,
 
Or I could just stick with 6v6’s and be happy. Not like I’m going to reinvent the wheel here. Anything I can think up has probably already been done by someone on this forum.
 
knockbill said:
I swap in a SS rectifier sub to get 340V on the plates (175 territory), but don't think it has the current capacity for 6L6s, as mentioned... Lots of mods to 6L6s on here tho,,, do a search,,,
Click to expand...


How does the higher plate voltage affect the tone of the amp? I’m guessing you re bias it when using the SS recto.
 
I built a 175 clone using Motorola 3channel Txs and chassis,,, used a pair of the Moto Bass OPTs which are full range and much larger,,,
 
baddog07 said:
How does the higher plate voltage affect the tone of the amp? I’m guessing you re bias it when using the SS recto.
Click to expand...
Sounds about the same,,, OPTs are small on these amps... Just saying there are a few differences between the 175 and 185,
 
I noticed in your other thread which shows your listening space and I gotta give some general FYI. Those Magnavox amps which used the 6V6GT tubes used output transformers which were usually 3.4Ω's secondary.

What speakers are you using with it? Are they 8Ω? 4Ω? Wired in series or parallel?

Yes, this all has to do with getting the most out of it efficiently.
 
century tek said:
SS rectifier would help with the heater current but won't really give you any more watts.

With your 6L6G's, you're still basically getting about 10-12 watts per channel so you are probably defeating the purpose of wanting/having more power except they look cool!
Click to expand...



They do look pretty cool.
 
century tek said:
I noticed in your other thread which shows your listening space and I gotta give some general FYI. Those Magnavox amps which used the 6V6GT tubes, had output transformers which were 3.4Ω's on their secondary's.

What speakers are you using with it? Are they 8Ω? 4Ω? Wired in series or parallel?

Yes, this all has to do with getting the most out of it efficiently.
Click to expand...


They are 8 ohm speakers. I’m running the pair with the horns on top with the little SE el84 amp and the other pair I’m runnin with the 185 amp.
 
The SE amp has different output transformers with an 8 ohm secondary tap.

Transformers are from Antique Electronics
 
Member GordonW uses 6L6GC's in Magnavox amps he has supped up. Maybe send him a PM. He would give good tips on how to rebuild the power supplies and such.
 
century tek said:
Member GordonW uses 6L6GC's in Magnavox amps he has supped up. Maybe send him a PM. He would give good tips on how to rebuild the power supplies and such.
Click to expand...


Thanks for the advice. If I get to the point where I’m serious about the 6l6 mod I will send GordonW a message. He might have a schematic on hand. Hmm
 
I’ve built guitar amps and modified effects pedal for a few years. I’m probably a hack compared to you guys. I just want to let everyone know please don’t ever assume I’m giving anyone crap on this forum. I value everyone’s opinion and appreciate everything I get from this forum.

Keith aka Baddog
 
century tek said:
Although the 6V6 and 6L6 have the same pinout, the Magnavox amps can not come anywhere near the plate voltages the 6L6 tubes needs on their plates unless you change out the original power transformer and tweak the power supply. That amp with the stock 6V6 tubes is only capable of about 10-12 watts per channel. a pair 6L6G's are capable of twice that.

The 6L6G will work and produce sound and will not let out the magic smoke. However, if that is an AMP185, the power transformer may not be up to the task as the AMP185 originally did not power a separate tuner/preamp like the AMP175 did so the current draw from the 6L6G's heaters may be too much for the 185.

Heater draw on a 6L6G is 0.9 A.

6V6GT is 0.45 A.
Click to expand...


Yup. This one didn’t power a tuner it was phono only. I do have another Magnavox chassis with el84’s that did power a tuner and phono. That one must be a 175 chassis.
 
century tek said:
Those Magnavox amps which used the 6V6GT tubes used output transformers which were usually 3.4Ω's secondary..
Click to expand...

Exactly,,, My console consists of two separate speaker cabinets,,, phono in one, storage the other,,, sounds very good with the 185 they were designed for... Amp looses performance with 8R speakers,,, I never felt the need to change the OPTs!
 
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