[G8torbyte]

@JacobLTA , @jamato8
Thank you for the feedback on the questions about the tubes. I'll stick with the 12AT7/AU7 equivalents. I also looked into 12AV7's but they were mentioned as drawing more heat so those don't sound like a good option either. I found a pair of 7062's at a reasonable price and will try those out when they arrive.

Enjoying the music and experimenting with this nice amp

 

[jamato8]

It won't cause any problems to use a 5751 in this circuit but they will not last as long.

Yes but they won't sound optimum.

I follow the curves for a tube and go from there. While the 12AT7, 5751, 12AU7 and 12AX7 will work in the same circuit, it doesn't mean they will sound there best. Will anything go bad, very doubtful and you will have sound and maybe something you like. But as mentioned, I like following the curve for a tube to be the best out of it. I will insert a resistor that is approx. the right value, measure across the resistor for the drop and get the current. From this I know if I am in the right area I want to be for a certain class of tube. I then listen and fine tube. And since we are talking about the best sound possible, for me, it comes down to using a certain tube type in the best setting possible.

Over 150 hours on the Velo now. Excellent sounding. I would say it take 150 to 200 hours for burn in, for all the components to form etc.

 

[Velozity]

Looking forward to getting a Velo sometime later this year. @JacobLTA , in this circuit which affects the overall sound signature the most - the preamp tubes or the power tubes? I've been building quite a collection of rare top-tier NOS tubes to try with this amp.

 

[cats4cans]

Looking forward to getting a Velo sometime later this year. @JacobLTA , in this circuit which affects the overall sound signature the most - the preamp tubes or the power tubes? I've been building quite a collection of rare top-tier NOS tubes to try with this amp.

With the MZ3 I’ve noticed different small tubes have more effect. Not sure how much the Velo’s circuit is different. I think the fundamentals are still the same.

 

[Pharmaboy]

Has anyone used matched Brimar/Footscray CV455s as input tubes?

(sorry if an answer was posted here & I mssed it somehow)

 

[jonathan c]

I have (but in LTA MZ3). Great pairing with
Sylvania 'yellow print' 12SN7 pair !!

 

[jonathan c]

With the MZ3 I’ve noticed different small tubes have more effect. Not sure how much the Velo’s circuit is different. I think the fundamentals are still the same.

I noticed (in MZ3) that 12SN7s were more to my liking than 6SN7s .

 

[Pharmaboy]

I have (but in LTA MZ3). Great pairing with
Sylvania 'yellow print' 12SN7 pair !!

I know about these amazing input tubes only because of you! One of the great audio "finds" of my career.

 

[jonathan c]

I know about these amazing input tubes only because of you! One of the great audio "finds" of my career.

Next step: Brimar CV4033 ... (the $$ version of CV455 )

 

[jamato8]

I noticed (in MZ3) that 12SN7s were more to my liking than 6SN7s .

The 12SN7 is a quieter tube due to the heater being 12.6 volts so you are further from ground. I used to always raise the ground to around 50 volts. A tube then is very quiet. The tube sees the correct heater voltage but a resistor to ground makes it electrically appear much higher.

 

[Pharmaboy]

Next step: Brimar CV4033 ... (the $$ version of CV455 )

Here's how crazy this hobby is: I don't own a Velo yet ... I'm just "interested" in a Velo, mainly because (I'm guessing) its two RCA output pairs can be used simultaneously. Between that & the remote control + stepped pot, it becomes a pretty fascinating preamp possibility.*

...and yet here I am, fanatically googling NOS tubes for this thing!

Results are mixed:

• I already own a matched pair of 1957 CV4033s (currently on WA3 w/adapters); great that I have pairs each of CV455s and 4033s
• But on the downside, I can't find yellow label Sylvania 12SN7s

*Am I insane to think a Velo could be used at a preamp 12 hrs/day without blowing out tubes, causing the tube gods to assassinate me, and so on?

 

[G8torbyte]

Here's how crazy this hobby is: I don't own a Velo yet ... I'm just "interested" in a Velo, mainly because (I'm guessing) its two RCA output pairs can be used simultaneously. Between that & the remote control + stepped pot, it becomes a pretty fascinating preamp possibility.*

...and yet here I am, fanatically googling NOS tubes for this thing!

Results are mixed:

• I already own a matched pair of 1957 CV4033s (currently on WA3 w/adapters); great that I have pairs each of CV455s and 4033s
• But on the downside, I can't find yellow label Sylvania 12SN7s

*Am I insane to think a Velo could be used at a preamp 12 hrs/day without blowing out tubes, causing the tube gods to assassinate me, and so on?

On the RCA outputs here is the note from the Velo manual:

The two preamplifier outputs are paralleled and will put out the
same amount of power. If you are using both outputs at the same
time, the output voltage of the preamplifier will be shared.
The headphone output is accessible via the TRS (¼" or 6.35mm)
jack. When a headphone plug is inserted, the preamplifier outputs
are muted.

Over the next few weeks I'll be trying out these tubes.

12AT7 and 7062's

6SN7/12SN7/12SX7

Plus I have a couple sets of Sylvania and GE's that I'd been using with the HP8 amp.

 

[jamato8]

Here's how crazy this hobby is: I don't own a Velo yet ... I'm just "interested" in a Velo, mainly because (I'm guessing) its two RCA output pairs can be used simultaneously. Between that & the remote control + stepped pot, it becomes a pretty fascinating preamp possibility.*

...and yet here I am, fanatically googling NOS tubes for this thing!

Results are mixed:

• I already own a matched pair of 1957 CV4033s (currently on WA3 w/adapters); great that I have pairs each of CV455s and 4033s
• But on the downside, I can't find yellow label Sylvania 12SN7s

*Am I insane to think a Velo could be used at a preamp 12 hrs/day without blowing out tubes, causing the tube gods to assassinate me, and so on?

The LTA amps are easy on tubes. The Velo would be easy on tubes and unless the tube is wonky to begin with, it should last a very long time. It is better to have a tube on if you are going to use it over a 12 hour period than off and on, which is harder on a tube and will shorten its life.

 

[Tralfaz]

I've done a little tube rolling recently.

I started with RCA12SN7s and Genalex Gold Lion 12AT7s since they worked well in my MZ2. Great combo with a huge soundstage, image specificity, tonal balance, and dynamics.

But I couldn't leave well enough alone so I replaced this combo with the stock tubes. The stock tubes were solid but unspectacular so I returned the Gold Lions (I don't have any other 12AT7s in the house) and started swapping output tubes.

I have a lot of 6SN7s from other gear and had good experience in the past with Sylvanias and Westinghouses but after a few days they didn't work as well as the RCAs I'd been using so I'm now back where I started: Gold Lion 12AT7s (which are getting pretty pricy these days) and the vintage RCA 12SN7s.

What I've learned from all of this is that sometimes a tube that works magic in one application can be pedestrian in another. I may ftry a few other tubes down the road but really I'm very happy with what I have now. That being said, I love reading what others are using in the Velos, there are some very creative folks out there.

 

[cats4cans]

Has anyone used matched Brimar/Footscray CV455s as input tubes?

(sorry if an answer was posted here & I mssed it somehow)

I noticed (in MZ3) that 12SN7s were more to my liking than 6SN7s .

I recently had the CV455s in my MZ3 and they were great, right up there with some old RCA "Boonton" 6201 that have been my favorite so far. I bought a pair so I could try them in the MZ3, but the plan was to have them around for when an HP8 makes its way home. I probably need to order another pair (or2). It's good to have backups and options.

I've squirreled away enough RCA 12SX7 and 12SN7GT tubes to last a lifetime in my MZ3 ( I hope I live that long). I've been trying some 6SN7 lately (again tube testing for eventual use in the HP8). The price to performance is heavily skewed toward the 12V tubes. I end up spending double (or more) for 6V tubes and I'm not even going for the popular unobtanium types. I'm interested to see how the new production premium tubes fair against NOS now that the prices are closer. It used to be a no brainer to go NOS. I'm not so sure now.