Balancing Act

[morphsci]

The original 307A TTVJ Millett was the reason I decided to go with the 307A with the BA. That amp was/is excellent and certainly showed that the tube was capable of great sound and could create a very neutral amp. The decision to go with the BA was purely based on economics.

[pigmode]

^ Thanks again.

[balderon]

I am very pleased with the BA although I have yet to find a reasonably priced Mullard ECC35. Prior to Craig shipping my amp I sent my EML 300b mesh to him as he was interested in auditioning. I wanted to share Craigs responses.

Here is my take on the tubes. The driver tube makes a huge difference. The output tubes make a more subtle difference when listening with the new production Russian made Tung Sol 6SN7. Listening was referenced to with the Raytheon 6F8G tube. To make this easy on my head I will just list the tubes overall as favorite to least favorite understanding each tube has strengths and weaknesses, and this is just one listeners opinion.

All tubes are new production with 40 hours run time.

KR PX4

Sophia Royal Princess 300B

EML mesh 300B

AVVT 300BLS

KR 842

EH platinum matched 300B

EAT 300B

Full Music mesh 300B

Sophia PX4

Shuguang 300B metal plate

Shuguang 300B carbon plate

A few days layer I received this followup message from Craig.

I had a chance to play around with the EML mesh 300B tubes. With the rear panel bias switch in the PX4 position the EML 300B tubes really come to life. One PX4 owner was over listening, and felt the EML sounded better than the KR PX4. The tubes still operate well below their safe current, and plate power rating so try both settings and see if you agree.

I did notice the difference switching the bias to the PX4 position. It's certainly the way to go with the EML mesh.

[Tari]

Craig is now out of metal - sold out his current BA run.

I talked to him about the 307A option at this point and he said it would be a $100 upcharge because of the different top plate/sockets than the current Current offerings. As it only runs the 307A, the bias switch on the back and the meter on the PS would be useless (except that meters look cool.)

Oh, and turns out he'll have two versions of the Electra at the upcoming meet: One OTL with 4 6SN7's and 4 6SLGT's, and another version which will be SET, using 2 EF86's, a 6SN7, and two KT120's. The pricing he's talking about on the initial run is under 3K on an OTL option, while the custom transformer costs (I assume silver secondary electra-print) on the SE would bring price up to around $3200.

[K.S.]

I didnt know about the 2nd configuration of the electra. Does anybody have any thoughts on what config would be better? Which meet is he bringing them to?

[spritzer]

Single ended fed through a transformer is a novelty act, no more than that. Also, is he using 6SL7's as output tubes in the OTL version?

[Jon L]

Oh, and turns out he'll have two versions of the Electra at the upcoming meet: One OTL with 4 6SN7's and 4 6SLGT's, and another version which will be SET, using 2 EF86's, a 6SN7, and two KT120's. The pricing he's talking about on the initial run is under 3K on an OTL option, while the custom transformer costs (I assume silver secondary electra-print) on the SE would bring price up to around $3200.

Can't wait to listen to both versions!

[Tari]

I didnt know about the 2nd configuration of the electra. Does anybody have any thoughts on what config would be better? Which meet is he bringing them to?

The meet was supposed to be in March but Craig said it should be some time in April for interested parties. I didn't press for for info as I don't plan being in California in the next couple months.

Also, slip of the tongue with the 6SL7 on the OTL as I was just looking for some today. It was actually the 6L6GTB. The OTL was balanced input to output, 40 watts plate power per channel and 1800 peak to peak. I don't know much more about the SE as we discussed it for only a short while. I also believe the OTL would be on a PCB while the SE would be point to point.

[spritzer]

Ahh 6L6 makes a lot more sense. Don't know why he didn't just go with EL34's but then again Craig likes to be a bit different. I do have high hopes for the Electra since the WES is a dud and so is the LL (unless you happen to like a SRM-323 with mosfet output). I just hope Craig has given the assembly monkeys a good thrashing and spent a bit more money for more reliable parts.

As for the SE electrostatic amps, you basically have all the issues of a SE amp plus have to deal with a transformer doing the phase splitting and probably some gain. As such it will never be a contender for a TOTL solution but should be fun none the less.

[Jon L]

As for the SE electrostatic amps, you basically have all the issues of a SE amp plus have to deal with a transformer doing the phase splitting and probably some gain. As such it will never be a contender for a TOTL solution but should be fun none the less.

Hehe, some of us *like* the SE "distortion," and the KT120 is indeed a promising tube, although I haven't seen much use in SE configuration. Audio Research has been switching to KT120 tubes but in push-pull configuration.

[Tari]

He did mention the EL34 as one of the rolling options for the SE but seemed to prefer his current configuration. When I mentioned chassis he thought he could fit the SE in a ZDT chassis as the transformers are about the same size. Can't comment on parts selection except to say I think he hasn't really skimped on them with his dynamic amps relative to his pricing.

While I haven't heard the LL Craig has and said it sounded great. I'm not privy to it's current design, but I am under the impression that it has been changed - certainly since it's early iterations and I believe some changes were made from the prototype at Canjam.

Edit - Just remembered I have heard the LL with a 507 briefly. It was my first time hearing a 507 so I don't really have a frame of comparison.

[pigmode]

I talked to him about the 307A option at this point and he said it would be a $100 upcharge because of the different top plate/sockets than the current Current offerings. As it only runs the 307A, the bias switch on the back and the meter on the PS would be useless (except that meters look cool.)

Cool, I just need to bide my time and see what unfolds with time. I probably need to audition an 009 system before making a decision.

[spritzer]

The KT120 is a promising tube and I'm glad Craig dropped the 300B. I'm building a SE amp with 300B's (or rather I have all the parts but no time) but to me it's just a curiosity. I know it will never work as well as a full push-pull circuit but at least it will never be as bad as the A-10...

He did mention the EL34 as one of the rolling options for the SE but seemed to prefer his current configuration. When I mentioned chassis he thought he could fit the SE in a ZDT chassis as the transformers are about the same size. Can't comment on parts selection except to say I think he hasn't really skimped on them with his dynamic amps relative to his pricing.

While I haven't heard the LL Craig has and said it sounded great. I'm not privy to it's current design, but I am under the impression that it has been changed - certainly since it's early iterations and I believe some changes were made from the prototype at Canjam.

Edit - Just remembered I have heard the LL with a 507 briefly. It was my first time hearing a 507 so I don't really have a frame of comparison.

I don't think anybody who's seen inside the EC amps will ever contest the use of less than optimal parts. I'm all for cheap parts that perform well (as in not spending a fortune on Mundorf caps which are just rebadged F&T units for instance) but some of the parts are too cheap and do not hold up with use. Take the Lorlin/Alpha/"who else makes them this week" switches he uses and all the issues they have caused.

There will be a full circuit analysis of the LL shortly after the first units ship but seeing how hard some people are pushing IXYS parts as some superior beings (which they aren't) I'm guessing mosfets for the output devices. A truly bad idea compared to excellent BJT's such as the 4686/4686A.

[K.S.]

As for the SE electrostatic amps, you basically have all the issues of a SE amp plus have to deal with a transformer doing the phase splitting and probably some gain. As such it will never be a contender for a TOTL solution but should be fun none the less.

From my emails with Craig, this is just a entry level stat amp. He has plans in the future for a TOTL amp.

[spritzer]

From those specs the OTL version of the Electra is far better than the WES so I hope we'll see something crazy.

[luvdunhill]

While its true that F&T makes Mundorf, it's not true that they are rebadged. People ave claimed this, but the measurement do not agree. Welcome to the world of contract manufacturing.

[spritzer]

The large film caps and PSU caps certainly look identical but the smaller silver/gold etc. stuff is probably made for them by F&T. If you are going to use an OEM manufacturer then there are far worse choices than F&T though...

[Anaxilus]

I just hope Craig has given the assembly monkeys a good thrashing..

Some current assembly pics of the BA:

[deepak]

Is there some secret sauce to optimizing the OPTs to sound good with a wide variety of headphone impedances? I am just wondering since there is only a single tap off the Electraprints in the BA, but some other commercial offerings have multiple output taps off their transformers.

[purrin]

Is there some secret sauce to optimizing the OPTs to sound good with a wide variety of headphone impedances? I am just wondering since there is only a single tap off the Electraprints in the BA, but some other commercial offerings have multiple output taps off their transformers.

Silver secondaries and some secret sauce winding? I know it's 5k to 16.

[deepak]

Heh I was actually looking for a more technical answer than just the silver part. I had Colin's spudder which I think had a 32 ohm output off the Electras and sounded great with Grados and LCD-2, but came off muffled with Senns (I mean by no means bad, but comparing it to Dynahi the differences were obvious).

[purrin]

Craig did say he took one of them apart to see what Electraprint did with that particular transformer. I didn't really pay attention, but it was something along the lines of how the secondaries wires lined-up with the primaries. The other thing is I noticed is how thin, tightly packed, and precisely cut the laminations are (you can just barely make out the individual laminations in the photo Mike posted.) Would be a serious pain to put together if the E's and I's alternated with each layer, which I believe could be the case.

But still, the BA does sound more "rounded" or "muffled" in the bass and less clear compared to well implemented solid-state. It really can't be helped given its design (maybe it could use more power.) I do feel where the BA really shines is with sensitive low-impedance headphones (AT's, Grados, etc.), not that they do a bad job with the HD650s or similar.

Edited April 14, 2012 by purrin

[deepak]

Well if KG releases his high frequency AC heater board/power supply I want to try my hand (and probably fail miserably) at a DHT transformer coupled amp with multiple taps in the long distant future. Maybe even venture into the insane territory like Magnequest TL iron

[recstar24]

Doesn't millett have a HF AC heater supply on his DIY page? He may even still have boards.

[morphsci]

Craig did say he took one of them apart to see what Electraprint did with that particular transformer. I didn't really pay attention, but it was something along the lines of how the secondaries wires lined-up with the primaries. The other thing is I noticed is how thin, tightly packed, and precisely cut the laminations are (you can just barely make out the individual laminations in the photo Mike posted.) Would be a serious pain to put together if the E's and I's alternated with each layer, which I believe could be the case.

But still, the BA does sound more "rounded" or "muffled" in the bass and less clear compared to well implemented solid-state. It really can't be helped given its design (maybe it could use more power.) I do feel where the BA really shines is with sensitive low-impedance headphones (AT's, Grados, etc.), not that they do a bad job with the HD650s or similar.

When talking about the BA you really need to specify what flavor BA you are talking about.