Lavane
Lunatic Member
His partner Roy sells octal boards for the ST70, ST120 and one or more Dynaco mono blocks along with the M-125 as well.
A box arrived.
- Thread starter Lavane
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Legrace
Super Member
5 years and counting on your gz37 is really encouraging to hear.
Lavane
Lunatic Member
There does seem to be some demand for them. Enough?, I don't know. They seem to be popular for applications in some hifi amplifiers and even more for Guitar amps.
sKiZo
Hates received: 92644 43.20°N 85.50°W
I'm pushing it pretty hard too, running a quad of KT120s at 60mV and the 6SN7 driver ... B+ still checks out fine though, so the amp is happy. I'm also using a DIY bucker to drop the wall voltage from it's average of 123vac, so that probably helps.
(And yes ... that IS an ST120 ... more or less.) ;-}
Some quick glances at the datasheet tell me a GZ37 wouldn't likely be reliable either. Those are rated the same as a 5AR4, 250ma steady, 750ma surge with cap input supply. Only difference is the 5AR4 at 500v is rated to 200ma, the GZ37 is good for 250. At full go, 4x KT88 at 460v, ultralinear, fixed bias per the datasheet would need 560 ma. Just sitting there doing nothing its 200ma + whatever the driver wants, probably about 5ma. Honestly this should have at least a pair of rectifiers to get reasonable life from them.
Or solid state diodes are good for an amp+ for peanuts and they won't die from being thrashed to death.
Or solid state diodes are good for an amp+ for peanuts and they won't die from being thrashed to death.
Lavane
Lunatic Member
I am going to terminate the 5v winding since it isn't going to be used. I was going to use a 5K resistor. Looking through all my resistors the closest I have is 4.2K and 6.8K. How critical is the resistor value?
Legrace
Super Member
Skizo reports 5 years and still ticking in his 120, and the ones I have in my M125's are still going strong after 3 years. Whereas 5ar4 would always barf within a few weeks. Perhaps the design margin factor that was built in back in the day is far greater then current standards?
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Terminate it to what? Itself? If the 5V winding isn't being used, I'd opt to tie one end of it straight to ground and tape off and tuck away the other end. No current flows through it, and it doesn't "float" either since one end is grounded.
Lavane
Lunatic Member
Yes, to itself. Something about 120hz pulsed 500vdc into the winding?
Just looking to lower noise as much as possible. The 95db SNR stated on VTA's site I dought is realistic. That number was taken from one source and review.
Right. if one end is grounded, it will have no chance of introducing a floating static voltage between windings, i.e., it won't contribute noise to the rest of the windings.
95 dB might be a little unrealistic, but I bet you can fairly easily get 90 dB S/N ratio out of it.
95 dB might be a little unrealistic, but I bet you can fairly easily get 90 dB S/N ratio out of it.
Lavane
Lunatic Member
I thought of that John, but I hate drilling stainless steel. Just widening the hole at the back for the power switch was fun.
Lavane
Lunatic Member
Thanks Kward. I'll do that.
knockbill
Lunatic Member
Doesn't it have a pilot light on the chassis? or are you just not using one? Just curious...
Lavane
Lunatic Member
No, no pilot light with these. I guess all those tubes lighting up is enough.
sKiZo
Hates received: 92644 43.20°N 85.50°W
Pilot light? We don' need no steenking pilot lights!!
No pilot lights, but if you're serious about one, maybe put one inside the chassis and let it bleed light thru the sockets, etc ... might be a neat effect? I know McIntosh is pretty proud of their lighting. As mentioned, don't need more light - in fact, the power switch I used has an annular neon ring built in that I bypassed ...
And ya, I wouldn't worry much about noise. The Latino amps tend to be dead quiet built to spec. Only potential noise issues I'm aware of is mechanical stuff due to loose components. I know the can cap can hum some if you don't twist the mounting tabs tight. Ditto for the iron - I tapped the holes a bit larger and used tapered plumbing washers to prevent that. That and a couple wraps with black tape on the screws provides complete isolation.
No pilot lights, but if you're serious about one, maybe put one inside the chassis and let it bleed light thru the sockets, etc ... might be a neat effect? I know McIntosh is pretty proud of their lighting. As mentioned, don't need more light - in fact, the power switch I used has an annular neon ring built in that I bypassed ...
And ya, I wouldn't worry much about noise. The Latino amps tend to be dead quiet built to spec. Only potential noise issues I'm aware of is mechanical stuff due to loose components. I know the can cap can hum some if you don't twist the mounting tabs tight. Ditto for the iron - I tapped the holes a bit larger and used tapered plumbing washers to prevent that. That and a couple wraps with black tape on the screws provides complete isolation.
Lavane
Lunatic Member
This kit came with rubber washers for the power transformer at leased.Pilot light? We don' need no steenking pilot lights!!
No pilot lights, but if you're serious about one, maybe put one inside the chassis and let it bleed light thru the sockets, etc ... might be a neat effect? I know McIntosh is pretty proud of their lighting. As mentioned, don't need more light - in fact, the power switch I used has an annular neon ring built in that I bypassed ...
And ya, I wouldn't worry much about noise. The Latino amps tend to be dead quiet built to spec. Only potential noise issues I'm aware of is mechanical stuff due to loose components. I know the can cap can hum some if you don't twist the mounting tabs tight. Ditto for the iron - I tapped the holes a bit larger and used tapered plumbing washers to prevent that. That and a couple wraps with black tape on the screws provides complete isolation.
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