Transformerless Tube Input Discussion

[bcarso]

The 1/f corner on the 6C45 was probably accounting for a lot of the 3nV I saw too, so PRR's estimate is probably closer to reality (happily).

 

[bcarso]

Tek really went south when they fired a lot of their old engineers and the newbies started doing these ugly menu-driven monstrosities.

I remember one budget scope H*rm*n bought that actually didn't allow you to view one channel while being triggered by the other!! Amazingly stupid!

I still like my 2236 although it has developed problems. I do miss the beautiful fine dots/traces of the old 500-series tube scopes though.

 

[clintrubber]

Thanks all for the info.

Even though I still use Tek scopes, they kind of lost me about the time the 465 scopes came out.

At work we try to avoid buying Tek when we can - we've had a few nasty surprises with expensive Tek-stuff that suddenly was no longer servicable.
Bye bye investment...

 

[clintrubber]

Tek really went south when they fired a lot of their old engineers and the newbies started doing these ugly menu-driven monstrosities.

Same for HP - we'd love to buy another spectrum analyser at work with comparable performance to their old, say HP3585, but HP/Agilent can't make them anymore... Perhaps we should try refurbished.

I remember on budget scope H*rm*n bought that actually didn't allow you to view one channel while being triggered by the other!! Amazingly stupid!

:shock:

I still like my 2236 although it has developed problems. I do miss the beautiful fine dots/traces of the old 500-series tube scopes though.

I have a 535A and I like that 6cm vertical ! :wink:

 

[NewYorkDave]

I have an RM35A and a 543B :thumb:

 

[analag]

A transformerless tube pre might not be as good as a transformer input type at certain things, but for a hot output condenser mic it's hard to beat. I am updating the input section to the schematic posted at the beginning of this thread. I'm hooked to the sound of these things, I have a number 1 song on the local stations featuring this device, so what can I say. Reggae.

Analag

 

[CJ]

The last time I looked, there were two transformers in your typical tube mic pre. Consider a circuit with maybe only one chunk of iron missing? Take your pick. I say ditch the input iron and run a nice warm parafeed output stage. Hopefully, your lack of cmr and any grounding issues from using a common mode input won't screw things up.

 

[analag]

Look at my FETCODED design the CMRR is way up there, frequency response is flat from 10 to 100khz the only thing it's lacking is saturation distortion....oh I forgot that's the magic isn't it. My intention is to build one of each I have more than one of each and so far the transformerless tube input is a unique animal it's got me by the balls?

Analag