[pmillett]

Quote:

Originally Posted by dsavitsk /img/forum/go_quote.gif A single 6H30 will power almost any phones to extreme volumes, for example.

True... I built an amp using a single 6H30pi and a Sowter 9351. It sounded very nice. But it had two issues: The Miller capacitance of a 6H30p is high, so you need a fairly low-Z source to drive it. And the 9351 costs 91 GBP each - given today's worthless dollar, that's $360 worth of OPTs, plus shipping from England.

Pete

 

[pabbi1]

I was exposed to a schematic using 6H30 on psu and 6H30pi on the amp sections (sorry, not literate enough to know which 'stage') but it requires 6 Lundahl transforners at around $1k for the Sweedish iron, unless I was confused about the trannies required for the balanced build.

Still considering this, some day.

dsavitsk: Something like this?

This from the same guy loosely associated with the Raven project.

 

[dsavitsk]

Quote:

Originally Posted by pmillett /img/forum/go_quote.gif True... I built an amp using a single 6H30pi and a Sowter 9351. It sounded very nice. But it had two issues: The Miller capacitance of a 6H30p is high, so you need a fairly low-Z source to drive it. And the 9351 costs 91 GBP each - given today's worthless dollar, that's $360 worth of OPTs, plus shipping from England. Pete

That's a lot. I got a pair of 1W parafeed 5K:32 transformers from electra-print for under $100. I also got a pair of nickel lams to swap into those, also for $100, which means $200 for Nickel parafeed transformers. Or, $200 for Intact Audio's nickel AVC's which can be used as an OPT (I am working on a version right now with 71a's). Or, my single feed 5K:32 electra-prints gapped at 35mA weren't more than $150 or so.

Lundahl has the LL1930 which will work for differential or single ended parafeed at about $120 or so. The Hammond 119DA is decent at $60, though they were more decent when they cost $30 for the pair last year. A pair of power toroids can be had for about $40 and can sound surprisingly good.

Check out my L'espressivo project for more:
Background and ramblings
Actual build instructions

Or my shunt regulated single feed amp

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif dsavitsk: Something like this?

Yeah, but you can get away with way cheaper iron.

Here's the Balanced L'espressivo, which would run you about $180 or so.

 

[Voltron]

Quote:

Originally Posted by pmillett /img/forum/go_quote.gif Hey, if you don't like overkill, go for a (practical and perfectly "adequate") opamp-in-a-box! Besides, it can double as a beverage warmer. I really think this thread needs to be titled "Nate Maher's Menace". Nate did all the work. I only helped because Nate promised to pick up my beer tab at CanJam. He doesn't know what he signed himself up for Or maybe call it Maher's Menace... ...Maher's Millett Menace... ...Menacing Maher's Millett... ...Maher's Mega-Massive Menace... Pete

One vote for Maher's Menacing Millett. Too bad Nate's going to need a second mortgage to cover that bar tab! Talk about menacing.

 

[fierce_freak]

dsavitsk, I've been very interested in both the L'espressivo and the S^3 amps you've put together for quite awhile. I'm looking at putting together a high-end tube amp in the near future, but perhaps I'll start out with a balanced L'espressivo to start (I've never heard a transformer coupled amp, only OTL).

I've been thinking of going more along the line that Nate has gone, though, as all the top tube amps that are easy to get impressions on are, for the most part, overbuilt OTL amps (Wheatfield, Zana Deux, Singlepowers).

 

[n_maher]

Quote:

Originally Posted by Voltron /img/forum/go_quote.gif One vote for Maher's Menacing Millett. Too bad Nate's going to need a second mortgage to cover that bar tab! Talk about menacing.

Al, my plan is to get him started drinking whisky and only later remind him that I agreed to pick up the beer tab. As my West Coast lawyer I may need backup on this...

 

[Voltron]

Quote:

Originally Posted by n_maher /img/forum/go_quote.gif Al, my plan is to get him started drinking whisky and only later remind him that I agreed to pick up the beer tab. As my West Coast lawyer I may need backup on this...

Given that your East Coast counsel is a ball of nerves and and will be rather distracted, I will gladly step in and practice law outside my jurisdiction to back you up on this one. Only problem I foresee is that Pete has been reading this thread, so we had better scrub our posts.

 

[naamanf]

Quote:

Originally Posted by n_maher /img/forum/go_quote.gif I'm going to create a thread for this amp since it is my intention at the end of the build to publish the schematic and any relevant details so that anyone who's crazy enough can build this amp.

Well we have already established I'm crazy......

 

[dsavitsk]

Quote:

Originally Posted by n_maher /img/forum/go_quote.gif Al, my plan is to get him started drinking whisky and only later remind him that I agreed to pick up the beer tab.

TV : Are you stuck in a deadend job?
Homer : May be.
TV : Are you sitting on your couch in front of the tv ...
Homer : What's it to you?
TV : Are you on to your 3rd beer of the evening?
Homer : Does whiskey count as beer?

 

[pmillett]

Quote:

Originally Posted by Voltron /img/forum/go_quote.gif Given that your East Coast counsel is a ball of nerves and and will be rather distracted, I will gladly step in and practice law outside my jurisdiction to back you up on this one. Only problem I foresee is that Pete has been reading this thread, so we had better scrub our posts.

Wait... you owe me beer too, don't you? I sense a conflict of interest...

Pete

 

[amphead]

Dsavitsk, how about 119DA and the Bijou?

 

[pabbi1]

Quote:

Originally Posted by pmillett /img/forum/go_quote.gif Wait... you owe me beer too, don't you? I sense a conflict of interest... Pete

Truth be told, and in a perfect world, half the DIY board owes you (more than) a beer... I'm sure my tab is at five or six, just based on your designs I have enjoyed / built.

 

[dsavitsk]

Quote:

Originally Posted by amphead /img/forum/go_quote.gif Dsavitsk, how about 119DA and the Bijou?

One answer is that I think the Amveco toroids actually sound better for less money. Or, the Lundahl LL1930's also sound better for about $40 extra (these use mu metal rather than amorphous cores and lack the shielding of the other Lundahls which is why they are less expensive. They are still quite good, and probably the best deal in the Lundahl line.) If you have the Hammonds, use them, but otherwise they probably aren't the best deal in the price range.

By the way, here's a post on how to pick your power toroid for output use: HeadWize: View Post [DIY Workshop > Less-pressivo: High performance, low cost, all tube, headphone amp]

The other answer is that the Bijou is not really the ideal platform for transformer coupling. It will work, but the amp uses various features to obtain a low Z out, and my sense is that using those features is an either or with transformers. That is, transformers allow you to build much simpler circuits that use many less components -- less tubes, less capacitors, etc. The trade off, of course, is that you have to spend the extra money on the transformer. But, doing both in the same amp is probably not the best idea from a design perspective as I think it probably compromises both designs. That is to say, I don't think adding a pair of OPTs is going to bring much to the table.

I like to joke about the original L'espressivo being so cheap to build, but honestly, the only reason it ever becomes expensive is if you start adding expensive parts -- the parts list remains pretty constant.

 

[amphead]

Ok, the only reason I brought that up was Lo Z phones(K701) and NFB removed. The lower the impedance load, the closer to a shorted output. Just too large of a current demand that might be tamed with a matched OPT. Nates design here looks good. The Native Menace.

 

[n_maher]

Quote:

Originally Posted by amphead /img/forum/go_quote.gif Nate's implementation of Pete's design here looks good.

FIFY