[rds]

I just looked at my back panel drawing at it seems that switch can be put where the fuse currently is on my build, with a little modification (while keeping the power switch). However, the depth may be an issue. It looks like we have about 20mm available.

Wiatrob what do you think the minimum achievable depth is?

 

[wiatrob]

Quote:

Originally Posted by rds /img/forum/go_quote.gif Wiatrob what do you think the minimum achievable depth is?

I need to measure with the BOM case panel on. I'll try to get a measurement soon.

 

[wiatrob]

A few more pics.

I bent each resistor lead around and soldered it to the next resistor, making a 'ring' of leads. I left the last resistor lead in place, and sleeved it in teflon.

This lead and the wire are soldered into the R3H location. I jumpered the heater switch positions. Not that you can still see my old switch in the case, but it's since been removed.

I did a little more hack woodwork - the switch is mounted 1/4" into my pane so I do have more clearance in this build than a BOM case.

I will do some comparisons with the stock power switch and RDS suggested panel template this week..

 

[smeggy]

Very cool, nice work guys.

 

[Forte]

Oh Great, more tubes to buy!

Nice work guys and neatly done.

 

[rds]

Quote:

Originally Posted by wiatrob /img/forum/go_quote.gif A few more pics. I bent each resistor lead around and soldered it to the next resistor, making a 'ring' of leads. I left the last resistor lead in place, and sleeved it in teflon. This lead and the wire are soldered into the R3H location. I jumpered the heater switch positions. Not that you can still see my old switch in the case, but it's since been removed. I did a little more hack woodwork - the switch is mounted 1/4" into my pane so I do have more clearance in this build than a BOM case. I will do some comparisons with the stock power switch and RDS suggested panel template this week..

You'd have to play a bit with the positioning in my template. If you have autocad I can send you the template.

 

[wiatrob]

Quote:

Originally Posted by rds /img/forum/go_quote.gif You'd have to play a bit with the positioning in my template. If you have autocad I can send you the template.

No Autocad here

However, i do have the template printed out. I will be building up a 'stick' unit this week for a door prize for the next Colorado meet (see sig) -I'll take a look at your template and see how what kind of fit we can get.

 

[cfcubed]

Few things:

1. Did not want rds auricap option & impressions to be lost in this heater switch biz. Sounds like a nice option.
2. cheaper R3Hs on the switch, like Xicon 1/8W metal films @ 3.5mm long, are smaller than VDs & could buy a few MMs in depth.
3. Forte - know you were kidding but instead of more tubes to buy, thinking less expensive ones to buy. Could bring a bunch more $2 tubes to the plate.

Someday we should finish compiling a list of tubes that work in CTH. Although perhaps not optimized for them, the full list w/this 7 heater tweak could be twice as large as the original one.

 

[TimJo]

Nice work guys.

Since I really am happy with my current 'compact' model for it's portability, I can see a second version in my future with all of the heater mods in place - more of a desktop version in a custom enclosure, with a box full of tubes sitting next to it.

 

[TimJo]

So yesterday, I did a mini shootout between two of my favorite 12AU7 variants. Both tubes were made by CBS/Hytron ~ the 7730 & the 7318.

The 7318 has short plates and steel pins, whereas the 7730 has long plates and gold pins, both with halo getters.

Here's a little description of the 7730 off the interweb:

This is a premium version of the 12AU7 made only by CBS/Hytron. This tube has very low noise characteristics and heavily plated gold pins. These were intended for critical test instrument applications, but due to their superior low noise performance, these make excellent choices for audio applications.

There is a lot of similarity between the two tubes. Both produce an enormous amount of detail, with the 7730 winning out a bit, especially with harmonics produced with stringed instruments. It's the only tube I've listened to where you can really hear a lifelike reproduction of the harmonics that are produced from a steel fingerpick breaking contact with a well tuned steel string. It also is able to reproduce the sound of harmonics that are created between the fret and the string with more realism than I have heard elsewhere. That being said, the 7318 does a really good job as well, but not like the 7730 (at least through DT880's).

But, after listening to to several albums with both tubes, my overall favorite ends up being the 7318 because of what my ears perceive to be a flatter response across the entire frequency spectrum. It seems like the 7730 dips a bit somewhere in the lower mids, and doesn't have as much bass extension when compared to the 7318.

Both tubes are amazing though...

 

[Trapper32]

Quote:

Originally Posted by TimJo /img/forum/go_quote.gif So yesterday, I did a mini shootout between two of my favorite 12AU7 variants. Both tubes were made by CBS/Hytron ~ the 7730 & the 7318. The 7318 has short plates and steel pins, whereas the 7730 has long plates and gold pins, both with halo getters. Here's a little description of the 7730 off the interweb: This is a premium version of the 12AU7 made only by CBS/Hytron. This tube has very low noise characteristics and heavily plated gold pins. These were intended for critical test instrument applications, but due to their superior low noise performance, these make excellent choices for audio applications. There is a lot of similarity between the two tubes. Both produce an enormous amount of detail, with the 7730 winning out a bit, especially with harmonics produced with stringed instruments. It's the only tube I've listened to where you can really hear a lifelike reproduction of the harmonics that are produced from a steel fingerpick breaking contact with a well tuned steel string. It also is able to reproduce the sound of harmonics that are created between the fret and the string with more realism than I have heard elsewhere. That being said, the 7318 does a really good job as well, but not like the 7730 (at least through DT880's). But, after listening to to several albums with both tubes, my overall favorite ends up being the 7318 because of what my ears perceive to be a flatter response across the entire frequency spectrum. It seems like the 7730 dips a bit somewhere in the lower mids, and doesn't have as much bass extension when compared to the 7318. Both tubes are amazing though...

Great write up TimJo Being a guitarist myself I really listen for those harmonics you described. Have u listened to the Bugle Boy 6dj8 and if you have i wonder how they compare to the 7318 or 7730.

 

[TimJo]

^^ The only 6DJ8 I have (so far

) is an Amperex made in Holland. It is a great tube with the best low end presence out of all the tubes I have heard so far. If I want to listen to a recording, and focus on the bass player, that's my tube of choice. But in terms of detail, both of the CBS/Hytron tubes win out.

I'm on the look out for some Bugle Boy's though - they get great reviews across the board, and it would be interesting to compare them to the Amperex 6DJ8's.

 

[cfcubed]

Quote:

Originally Posted by TimJo /img/forum/go_quote.gif < snip > I'm on the look out for some Bugle Boy's though - they get great reviews across the board, and it would be interesting to compare them to the Amperex 6DJ8's.

I've 6.3v-heated Amperex (Holland - white label) & Bugle Boy (both 6DJ8 AFAIR) and IIRC the BB may add a bit of detail that the non-BB lacks while retaining it strong bass. Perhaps its my specific tubes but I'd not say the presentation differs greatly IMO.

Those 7NNN CBS/Hytrons are not very common, but from what I'm reading I think a couple types of Siemens tubes might be worth trying, e.g. for midrange detail. Seems keyid feels other Siemens tubes may offer even better detail & slam...

 

[smeggy]

I swapped the caps over to Sonicaps thanks to waitrob and it's going great.

I currently have the CTH and Beta/EHHA wired to the Pico DAC so I can play the same thing through all three amps simultaneously and the CTH can hold it's head high in this company. It really does perform well above it's diminutive size and is extremely good in in t's own right.

It's a great all-rounder and does nothing wrong. The Beta has the most solid sound of the three, with thunderous bass and tight as a drum and very smooth. The EHHA isn't as solid or thundering in the lower regions but has a delightful sense of air and separation with nice atmosphere and the CTH is the more aggressive of them with the 6n6p tube and upgraded caps (tuned that way on purpose).

It's a sparkling amp with great bite and clarity and very appealing all round sound. It's hard for me to say one is better than the other because they each have distinct strengths and there's no way I'd say the CTH was outclassed, just a different flavor depending on what I'm listening to.

Remarkable little amp. After a week of nothing but beta and ehha I thought it might be a bit of a let down going back to the CTH, nope, not a bit of it. Every bit as good as I remembered and it's happily blasting my ears off with some spikey metal and it's a perfect match.

 

[cfcubed]

Quote:

Originally Posted by smeggy /img/forum/go_quote.gif Remarkable little amp. After a week of nothing but beta and ehha I thought it might be a bit of a let down going back to the CTH, nope, not a bit of it. Every bit as good as I remembered and it's happily blasting my ears off with some spikey metal and it's a perfect match.

Thanks smeggy for the little overview of these amps. Good to hear this as the CTH is the one I'm sticking with for quite a while.

Having heard a Beta22 @ a meet plan to build one this winter but w/what people are saying about EHHA & Bijou who knows where things will end