Solid state rectifier in a DR and a SR and 6L6/6V6

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12/10/2000 1:43 PM

Bjorn

Solid state rectifier in a DR and a SR and 6L6/6V6 I did try a SS plug instead of the GZ34 in both my amps. It sounded GREAT in the DR (with Svetlanasâs 6L6) but not that great in the SR.     In the SR the sag almost disappeared and it became almost like a Twin (I owned a 70âies MV TR before the SR).     I was wondering ö is it OK to try the original RCA 6V6 and the SS rectifier in the DR ö I havnât dared to try·?         Bjorn

 

12/10/2000 2:26 PM

Trace

[QUOTE]I did try a SS plug instead of the GZ34 in both my amps. It sounded GREAT in the DR (with Svetlanasâs 6L6) but not that great in the SR.     In the SR the sag almost disappeared and it became almost like a Twin (I owned a 70âies MV TR before the SR).[/QUOTE]         Some people like the "sag" of a rectifier tube and some people do not. I think it really depends on the amp personally speaking. Also you can try different types of rectifier tubes. A 5V4 is pretty "tight" sounding but not as tight as a SS rectifier. A 5U4 get's a little bit looser and of course the 5Y3's are pretty "squishy/spoungy" sounding. Then again the newer Sovtek 5Y3's are pretty tight sounding and sound nothing like the older 5Y3's.         quote: "I was wondering ö is it OK to try the original RCA 6V6 and the SS rectifier in the DR ö I havnât dared to try·?"         Did the amp have (or does it have) 6L6's in it? What's the plate voltage?         Hollar back!!     Trace

 

12/10/2000 9:14 PM

Bjorn

Trace, thank you for responding.     Well, when I bought the DR it was dead stock. However, I thought it was too weak and too little headroom. It is carefully modded (but possible to restore to stock specs with the original parts.).     The DR now carries 2 Svetlana 6L6, biased to approx. 37 mA. The filter section is changed to SR specs. The ãvibratoä tube is removed. (Sometimes also V1).         The plate voltages (pin 3) are:     6L6/BIAS 36 mA/436V     6V6/BIAS 30 mA/444V         Bjorn

 

12/10/2000 11:24 PM

Trace

quote: "Trace, thank you for responding."         No thanks needed my friend         quote: "Well, when I bought the DR it was dead stock. However, I thought it was too weak and too little headroom. It is carefully modded (but possible to restore to stock specs with the original parts.)."         Does it sound better modded I assume? These are cool amps to tweak and there's a million mods for these! (ha, ha)         [QUOTE]The plate voltages (pin 3) are:     6L6/BIAS 36 mA/436V     6V6/BIAS 30 mA/444V[/QUOTE]         6L6's can certainly take 436V without a problem. 444V may or may not be dancing on the edge for 6V6's. What kind of 6V6's do you have in there? I know the Sovtek's can take 450V without much of a sweat at all. Many of the older 6V6's are not all that happy with that voltage (in my experience anyway). Most NOS 6V6's are pretty happy in and around 350V or so. I'm sure some other Ampager's will pop in with some advice.         Happy Holidays!     Let me know how you make out     Trace

 

12/11/2000 1:20 AM

Tremo

Wow, 444 volts and 30 mA? that's pushing things pretty hot. I'd back that current down to 25 mA or so.         It's not the voltage that kills the 6V6s, it's the power dissipation. Those Sovtek 6V6s have pretty lightweight screen grids. I've already seen an EH melt, they're not a huge improvement over the old design. If you do want to run 6V6s at those voltage and power levels, you will want to run NOS since they are far more rugged and have a substantially more robust screen grid. After all, Jim Kelly used Philips 6V6s in his amps.

 

12/11/2000 1:32 PM
OJ	Hi Tremo!     Wouldn`t it still be "pushing things pretty hot"     at 25mA ?     According the "Dissipation Method" you would end up with 16mA at 444 volts, or am I missing someting?     OJ

 

12/11/2000 11:13 AM

Bjorn

Trace and Tremo, thank you fore responding.     The 6V6 tubes the amp came with are (probably stock) RCAâs. (I compared them in my Champ to Sovtek 6V6 and JAN 6V6 ö the RCA wins without any real competition).         When reading a certain tube amp gurus book (GW·) I think he mentions a 30 mA bias value in a DR and 6V6. Is that too high? Is 25 mA a better value? Will the RCA 6V6 stand the higher voltage the SS rectifier delivers? Please understand that I am a nerd when it comes to electronics and in need of a layman explanation.         Bjorn

 

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