I've been a member, of this forum, for a little while but haven't done much.
I've built a Dynaco ST35 and a pair of Mk IVs. I'm very happy with both.
The Mk IVs are powering a pair of Rectilinear IIIs. They were built using Mundorf Silver in Oil coupling caps. (As was the ST35.) The Mk IVs have been in the system for only a few days and I'm waiting for the amps to blossom into their full potential.
This makes me wonder about a pair of Mk IIIs with a VTA Driver board and Mundorf Silver/Gold in Oil coupling caps.
The thing is, the Mk III output transformers don't seem to have some of diyAudio members full respect. Some think that they are "good" but others have a lower opinion.
The question is, should I order the full kit, with Dynaco output transformers or acquire parts and sub the outputs? If I choose to use transformers of a different manufacture, What would you suggest?
Thanks so much. Steve
I've built a Dynaco ST35 and a pair of Mk IVs. I'm very happy with both.
The Mk IVs are powering a pair of Rectilinear IIIs. They were built using Mundorf Silver in Oil coupling caps. (As was the ST35.) The Mk IVs have been in the system for only a few days and I'm waiting for the amps to blossom into their full potential.
This makes me wonder about a pair of Mk IIIs with a VTA Driver board and Mundorf Silver/Gold in Oil coupling caps.
The thing is, the Mk III output transformers don't seem to have some of diyAudio members full respect. Some think that they are "good" but others have a lower opinion.
The question is, should I order the full kit, with Dynaco output transformers or acquire parts and sub the outputs? If I choose to use transformers of a different manufacture, What would you suggest?
Thanks so much. Steve
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That's the thing, I don't know. I'm not familiar with anything other than Dyna, Hammond or Edcor.
I'm building a second ST35 using a "Tubesforhifi" main board, Edcor transformers and Mundorf Silver/Gold in Oil output caps but it is far from completion. This is the "high end" of my current knowledge.
I'd consider using currently manufactured Mk III output transformers from Triode or Dynakitparts as I have not yet reached the limits of the transformers that I have used so far. Some of you, however, think that there is better to be had.
I have a lot of time to listen to varied opinions. Maybe the standard current production Dynas are good enough. Where should I be looking for an alternative?
I'm building a second ST35 using a "Tubesforhifi" main board, Edcor transformers and Mundorf Silver/Gold in Oil output caps but it is far from completion. This is the "high end" of my current knowledge.
I'd consider using currently manufactured Mk III output transformers from Triode or Dynakitparts as I have not yet reached the limits of the transformers that I have used so far. Some of you, however, think that there is better to be had.
I have a lot of time to listen to varied opinions. Maybe the standard current production Dynas are good enough. Where should I be looking for an alternative?
There are a lot of "Dyna" transformers. For a Mk3, basically you want something at 4k3 plate to plate with 43% ultralinear taps, irrespective of how it's branded. Put your money there- it will make much more difference than boutique capacitors will.
No reason you can't adapt the Mullard circuit for the input stage- that's basically what the Marantz amps were.
No reason you can't adapt the Mullard circuit for the input stage- that's basically what the Marantz amps were.
About ten years ago I built a stock ST-70 reissue kit as offered from dynakitparts. While I was happy with the quality of the kit itself, the amplifier's performance left me wanting. I wasn't until I installed the low-gain iteration of the tubesforhifi driver board (using 6BH7 preamp tubes and 6CA7 output tubes) that I was satisfied with the sound quality. I eventually upgraded to the K&K Audio board (w/ KT-88s) and have more than happy with that for the last seven years.
I didn't know tubesforhifi offered a driver board for the ST-35 and I don't see one on the website. Perhaps you meant diytube.com? Regardless, my understanding is that the original dynaco Z-565 output transformers were the best-measuring output transformers of the original dynaco lineup.
I have purchased a lot from Shannon Parks (diytube.com) and he is a great guy to deal with. Here's a thread that might interest you: diytube.com • View topic - Monoblock versions of Dynaco ST35 - anyone done it?
I didn't know tubesforhifi offered a driver board for the ST-35 and I don't see one on the website. Perhaps you meant diytube.com? Regardless, my understanding is that the original dynaco Z-565 output transformers were the best-measuring output transformers of the original dynaco lineup.
I have purchased a lot from Shannon Parks (diytube.com) and he is a great guy to deal with. Here's a thread that might interest you: diytube.com • View topic - Monoblock versions of Dynaco ST35 - anyone done it?
You are correct, Brinkman. The board is marked DIYtube Stereo 35 rev C. My apologies.
My interest, at present, is in gathering information on suitable output transformers for the Mk III. I was hoping to coax suitable transformer sources from the vast knowledge of the members of this forum
My interest, at present, is in gathering information on suitable output transformers for the Mk III. I was hoping to coax suitable transformer sources from the vast knowledge of the members of this forum
Fair enough. I have ordered custom iron from ElectraPrint and was happy with it. If you wanted something off the shelf, you might consider this offering from Edcor: EDCOR - CXPP60-4.2K
Thanks, Brinkman, that is the sort of information that I need.
By the way, I was not unhappy with the Z-565 transformers. They sound exceptional in my little ST-35. I want to bi-amp a pair of JBL 8 ohm 130As and 16 ohm 2420 compression drivers with 2345 radial horns, crossing over to 2404 tweeter horns at 7000 cps. I chose the Edcor CXPP25-8k 23%, for the DIYtube ST-35, as it can be ordered with 4-8-16 ohm taps. Old JBL literature shows a plan for an 8 cubic foot ported cabinet for the 130As. As of now, I have not yet decided to include the horns in the cab or in a separate cabinet on top. That's probably more information than you needed to know, but that's just me.
By the way, I was not unhappy with the Z-565 transformers. They sound exceptional in my little ST-35. I want to bi-amp a pair of JBL 8 ohm 130As and 16 ohm 2420 compression drivers with 2345 radial horns, crossing over to 2404 tweeter horns at 7000 cps. I chose the Edcor CXPP25-8k 23%, for the DIYtube ST-35, as it can be ordered with 4-8-16 ohm taps. Old JBL literature shows a plan for an 8 cubic foot ported cabinet for the 130As. As of now, I have not yet decided to include the horns in the cab or in a separate cabinet on top. That's probably more information than you needed to know, but that's just me.
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Sounds great Steve. Not unlike the setup I'm building.
If I follow, your plan is to use the Mk.3s to drive your 130As and your ST-35 to drive your mid & tweeter horns. I'm also assuming you'll use a passive network to divide the mid & hi horns. I'm curious how you're going to handle the active crossover upstream. Are you thinking crossing over to the dark side (DSP)? There's also this that looks interesting: The Acheron: Electronic Crossover Design
If I follow, your plan is to use the Mk.3s to drive your 130As and your ST-35 to drive your mid & tweeter horns. I'm also assuming you'll use a passive network to divide the mid & hi horns. I'm curious how you're going to handle the active crossover upstream. Are you thinking crossing over to the dark side (DSP)? There's also this that looks interesting: The Acheron: Electronic Crossover Design
At that point there are many options. The JBL 130As (8 ohm) are very efficient (101db @1m w/ 1 watt input). They could be driven to ear splitting levels with the Dyna ST-35. I could move the Mk IVs and use the, yet to be constructed, Mk IIIs on the Rectilinears.
The problem is the pre-amp. Most tube pre-amps require a higher input impedance than the 25k which is the input impedance on my DBX 223XL 2 way electronic crossover. Even the McIntosh C-24 requires a 250K ohm load. That means that I will need to use a modern SS pre-amp, unless...
I am also in the middle of gathering parts for a PAS-3 with an Aikido main board and PH10 phono board. I only need to source the power supply and then I can begin the build. Tubes for hifi says that the output impedance of the Aikido board is less than 1k, so it should be OK with the 223XL crossover.
The passive crossover, between the 2420s and 2404 tweeters, are a pair of 7000cps JBL Pro units that I've been hiding.
Lucky me, I just scored (E-bay) a JBL 2220B 15" woofer. Now, I have a pair. The 2220 is the Pro version of the 130A. However, it is a 16 ohm speaker, so it rules out the Dyna ST-35 which only has 4 and 8 ohm outputs.
The problem is the pre-amp. Most tube pre-amps require a higher input impedance than the 25k which is the input impedance on my DBX 223XL 2 way electronic crossover. Even the McIntosh C-24 requires a 250K ohm load. That means that I will need to use a modern SS pre-amp, unless...
I am also in the middle of gathering parts for a PAS-3 with an Aikido main board and PH10 phono board. I only need to source the power supply and then I can begin the build. Tubes for hifi says that the output impedance of the Aikido board is less than 1k, so it should be OK with the 223XL crossover.
The passive crossover, between the 2420s and 2404 tweeters, are a pair of 7000cps JBL Pro units that I've been hiding.
Lucky me, I just scored (E-bay) a JBL 2220B 15" woofer. Now, I have a pair. The 2220 is the Pro version of the 130A. However, it is a 16 ohm speaker, so it rules out the Dyna ST-35 which only has 4 and 8 ohm outputs.
No, Brinkman, no digital in the system. Well, maybe WAV files recorded with Sony Audio Studio and transferred to my Notebook or tablet and played back through a good DA converter. Same as listening to CDs. I still prefer vinyl records.
You mentioned the setup that you are building. I would, most certainly, be interested in hearing more.
I miss-spoke in my last post. The output impedance required by the C-24 pre-amp is 47Kohms. it's the impedance of the hi-level inputs that are 250k.
You mentioned the setup that you are building. I would, most certainly, be interested in hearing more.
I miss-spoke in my last post. The output impedance required by the C-24 pre-amp is 47Kohms. it's the impedance of the hi-level inputs that are 250k.
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Now that I've given it some thought, I think you should consider a pair of custom output transformers from Jack Elliano at ElectraPrint. He's a real character. He's more than capable of winding you a pair of quality 4.3K::16 push pull output transformers with a 33% screen tap (and a 8 ohm tap if you want it). Just don't tell him it's for a Dynakit unless you want more lipstick on a pig remarks. He wound some parafeed output transformers for a tube headphone amplifier I built (hagerman Castanet) and they are very transparent.
My setup is in transition at the moment. I am trying to develop and hone woodworking skills for chassis work and speaker cabinet construction. Nearly every components in my setup - from the turntable to the loudspeakers - is getting an upgrade. I have lots of unstuffed PCBs, horns, and speaker drivers. Feel free to PM me so I don't clutter up the thread. But since you asked, my eventual speaker build will be using a pair of SEOS-18 waveguides with the Denovo-360 CD and a pair of Acoustic Elegance TD15Ms. LF bass with be via a distributed sub arrangement (ala Welti, Geddes & Lejune). What I *really* want is an oblate spheroid synergy horn that holds pattern down to 250Hz and with a .75" throat entrance. Initially, the loudspeakers will be driven with a pair of K&K Audio Push-Pull mono blocks. After that I plan to bi-amp the loudspeakers via DSP.
My setup is in transition at the moment. I am trying to develop and hone woodworking skills for chassis work and speaker cabinet construction. Nearly every components in my setup - from the turntable to the loudspeakers - is getting an upgrade. I have lots of unstuffed PCBs, horns, and speaker drivers. Feel free to PM me so I don't clutter up the thread. But since you asked, my eventual speaker build will be using a pair of SEOS-18 waveguides with the Denovo-360 CD and a pair of Acoustic Elegance TD15Ms. LF bass with be via a distributed sub arrangement (ala Welti, Geddes & Lejune). What I *really* want is an oblate spheroid synergy horn that holds pattern down to 250Hz and with a .75" throat entrance. Initially, the loudspeakers will be driven with a pair of K&K Audio Push-Pull mono blocks. After that I plan to bi-amp the loudspeakers via DSP.
I wouldn't worry about cluttering up the thread, Brinkman. Any speaker that I consider building will very likely be powered by some version of Mk III transformer, custom wound or not.
"Oblate spheroid synergy 250Hz horn with a .75 throat"? You have piqued my curiosity on that one.
You should have seen some of the directions my AudioKarma threads have taken.
"Oblate spheroid synergy 250Hz horn with a .75 throat"? You have piqued my curiosity on that one.
You should have seen some of the directions my AudioKarma threads have taken.
I am not convinced that MkIII transformers consider all diyAudio members
deserves their respect!
Get the kit "as is " and enjoy the Music. Trust Your Ears and ignore all
undocumented rumors.
Oblate spheroid describes the transition from the throat of the horn to the mouth. Beyond the throat, it is most similar in contour to a straight-walled conical horn, which is the typical contour with which Synergy horns are built. A Synergy horn is a co-entrant horn developed by Tom Danley. In a Synergy horn, multiple drivers are coupled to the same horn, with a crossover network dividing up the bandpass of the horn amongst the drivers (like your typical two- or three-way loudspeaker). The trick with a synergy horn is getting the drivers' acoustic centers within 1/4 wavelength of each subsequent driver. The crossover network is no walk in the park either. Done right and the result is a horn with multiple drivers that acoustically behaves as a point source.
Since the compression driver in a synergy horn doesn't need to be high passed at as low as it would in a conventional horn, you can elect to use a compression driver with a smaller exit diameter, which usually also entails a smaller diaphragm. This in turn provides two benefits: you can narrow the diameter of the horn throat and extend pattern holding to a slightly higher frequency (above 10kHz) and due to a smaller CD diaphragm, the breakup frequency of the CD is also pushed up a bit without resorting to exotic materials such as beryllium.
So, Brinkman, could this synergy horn combine a regular cone type lower mid-range with a compression driver for the highs? Instead of a straight walled conical horn, could it use a straight walled exponential horn? A horn with flat walls would be very easy to construct.
I did a search on Bing and it revealed a section on Wikipedia that includes the synergy horn. I must further investigate.
I find this concept difficult to grasp, being stuck in the 60s. You know what they say about the 60s. "Anyone who remembers the 60s, wasn't there".
Thanks Petertub, that was also part of my question. Are there, also, forum members that have a fondness for the currently manufactured Mk III output transformers?
I did a search on Bing and it revealed a section on Wikipedia that includes the synergy horn. I must further investigate.
I find this concept difficult to grasp, being stuck in the 60s. You know what they say about the 60s. "Anyone who remembers the 60s, wasn't there".
Thanks Petertub, that was also part of my question. Are there, also, forum members that have a fondness for the currently manufactured Mk III output transformers?
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Hmmm, a 2245h woofer crossed over to a synergy horn using a 2123h lower mid and 2420 compression driver with a 2405 tweeter. It sends my mind into psychedelic frenzy.
Kind of a, mostly horn loaded, JBL 4345. Should be very efficient.
All pushed by Mk III transformers, of course.
Is my house big enough to hold these things?
Please don't misunderstand, Brinkman, I am not being facetious, I'm just exploring the boundries of the concept. I need to go back to "Bing" and do some real research.
Kind of a, mostly horn loaded, JBL 4345. Should be very efficient.
All pushed by Mk III transformers, of course.
Is my house big enough to hold these things?
Please don't misunderstand, Brinkman, I am not being facetious, I'm just exploring the boundries of the concept. I need to go back to "Bing" and do some real research.
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