Tube Amp with the "Good Kind of Distortion"

[mhardy6647]

The only tube gear I've owned was a Sherwood. It sounded very tuby but the tubes where old and soft sounding. It was great eye candy and attracted a lot of attention.
View attachment 167465

So the tubes are not the final gain stage? Oh I see it's FETs. Interesting. I like!
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Her cousin lives at my house.

 

[Doodski]

Her cousin lives at my house.

Yes, I know. I see it every time that you post pics of your racks.

 

[mhardy6647]

Yes, I know. I see it every time that you post pics of your racks.

Yeah... but I actually didn't even remember that I had a cropped closeup until this morning.
Sorry about that.

 

[MakeMineVinyl]

I thought you could at least turn them off?

I'm sure you can, but the mere existence of such obvious pandering to the flashing lights/colored gizmo crowd is insulting. Seriously though, I think Mcintosh, under their new overlords, has cheapened their brand by including such obvious fluffery.

 

[watchnerd]

I'm ready for my service call.

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BTW, where did you get the tube caddy?

 

[MakeMineVinyl]

BTW, where did you get the tube caddy?

My ex-wife's dad was a TV service man back in the 50s and 60s and he knew I would value having it. Unfortunately, that was the only useful thing to result from that marriage.

 

[watchnerd]

My ex-wife's dad was a TV service man back in the 50s and 60s and he knew I would value having it. Unfortunately, that was the only useful thing to result from that marriage.

I saw a few on eBay where a few included NOS tubes were enough to cover the asking price of the whole kit.

 

[MakeMineVinyl]

I saw a few on eBay where a few included NOS tubes were enough to cover the asking price of the whole kit.

I took a look - most seem filled with oddball tubes for old TVs but I saw a few useful ones too. My caddy is in pretty good condition compared to most of the ones on eBay - maybe my ex-wife's dad wasn't a particularly successful serviceman and the caddy sat unused most of the time. I especially liked the caddy that included a mirror in the lid so the serviceman could look at the picture tube while adjusting the controls and swapping tubes. Ah, the good old days!

 

[watchnerd]

I took a look - most seem filled with oddball tubes for old TVs but I saw a few useful ones too. My caddy is in pretty good condition compared to most of the ones on eBay - maybe my ex-wife's dad wasn't a particularly successful serviceman and the caddy sat unused most of the time. I especially liked the caddy that included a mirror in the lid so the serviceman could look at the picture tube while adjusting the controls and swapping tubes. Ah, the good old days!

Yeah, I saw one with about 4 x 6SN7GTB

 

[JRS]

Right. It's positive feedback makes an oscillator and it's what happens when you stick a microphone in front of a speaker and you get that feedback squeal. (I once built a preamp that turned-out to be an RF oscillator and I fried one channel in my power amp. There was an "unexpected" phase shift that turned negative feedback into positive feedback at very-high frequencies.)

Negative feedback (CORRECTIVE feedback) is an awesome thing!!! No actual engineer would disagree. It's what allows you to drive straight down the road as you make corrections with the steering wheel. It how airplanes find the airport and how ships find the port. Positive feedback would be turning to the right when you start drifting to the right... That would be a bad thing!

The amp, cabinet, and speaker are "part of the instrument". They are not supposed to be "high fidelity", they are supposed to alter the sound. Usually when a guitar is recorded direct (without an amp, speaker, or cabinet} a "sim" (a simulator effect) is used to simulate the effect of using an amp because the signal directly out of the guitar doesn't "sound right". Every guitar player has their favorite amp and, they often use all kinds of effect pedals, etc.

A high-fidelity amp isn't supposed to alter the sound. It's supposed to accurately reproduce the recording. You wouldn't want to use a guitar amp (or effect pedal) as your hi-fi/stereo amp.

If you like extra distortion from vinyl, or it you like the "warm crackle" of vinyl, or if you like to boost the bass, etc., that's OK but it's not "high fidelity" reproduction.

Negative feedback has another positive--it keeps us alive. Homeostasis, the property of maintaining a far from equilibrium system with many parameters at a more or less steady state--think body temperature, blood pressure, electrolyte and pH in balance, etc relies heavily on negative feedback which at its very essence is measuring the difference between the actual value and the desired value of some variable and directing energy to reduce the difference. Viva la negative feedback.

 

[watchnerd]

Negative feedback has another positive--it keeps us alive. Homeostasis, the property of maintaining a far from equilibrium system with many parameters at a more or less steady state--think body temperature, blood pressure, electrolyte and pH in balance, etc relies heavily on negative feedback which at its very essence is measuring the difference between the actual value and the desired value of some variable and directing energy to reduce the difference. Viva la negative feedback.

Yeah, amps are just a big endocrine system.

/s

 

[JRS]

Yeah, amps are just a big endocrine system.

/s

No not exactly, but if they get your juices flowing, then more power to you and tube enthusiasts everywhere. Actually, just pointing out that negative feedback can be like organic, man.

 

[mhardy6647]

Negative feedback has another positive-

My brain just exploded.

 

[dienson]

Hello all member
I am newbee, I need some help about my McIntosh C8 tube preamp, I want to buy new tubes for C8, but the stock tube have letter A at end of tube modelname ( 12AX7A ), and all tubes on market no letter A on it ( 12AX7 )
question is can I buy tube 12AX7 without letter A and use on C8 ?
Thank you all

 

[watchnerd]

Hello all member
I am newbee, I need some help about my McIntosh C8 tube preamp, I want to buy new tubes for C8, but the stock tube have letter A at end of tube modelname ( 12AX7A ), and all tubes on market no letter A on it ( 12AX7 )
question is can I buy tube 12AX7 without letter A and use on C8 ?
Thank you all

That's a question for McIntosh.

Sticking a regular 12AX7 probably won't hurt anything, but I don't know if they have some kind of support policy that violates the warranty if you don't use the exact right kind of tube.

 

[SIY]

Hello all member
I am newbee, I need some help about my McIntosh C8 tube preamp, I want to buy new tubes for C8, but the stock tube have letter A at end of tube modelname ( 12AX7A ), and all tubes on market no letter A on it ( 12AX7 )
question is can I buy tube 12AX7 without letter A and use on C8 ?
Thank you all

The A is a designator for a controlled hum version. If the amp uses DC heater supplies or properly done AC, there won't be any real difference.

 

[dienson]

The A is a designator for a controlled hum version. If the amp uses DC heater supplies or properly done AC, there won't be any real difference.

Thank for reply
I really don't know about the DC heater or property done AC,

 

[watchnerd]

Thank for reply
I really don't know about the DC heater or property done AC,

Isn't that model pretty new?

I'm a bit surprised you already have a dead tube.

 

[dienson]

That's a question for McIntosh.

Sticking a regular 12AX7 probably won't hurt anything, but I don't know if they have some kind of support policy that violates the warranty if you don't use the exact right kind of tube.

Thank for reply
I had this pre amp one month then one tube dead, still wait the replace from bestbuy,
I just don't want lost money if the tubes not work on C8, all store said no returnable
Thank you bro

 

[dienson]

Isn't that model pretty new?

I'm a bit surprised you already have a dead tube.

yeah one month, just call to bestbuy for get another tube, they'll order another set two for me, then I want to try another not stock tubes