dynaco st-70 or OTL opinion

[tillmbil]

The Dynaco you are looking at has new speaker jacks set at 8 ohms. JUst thought I would point that out. You would have to be able to solder to change it.

[sheltie dave]

Speakerfritz, if you want something newly built and spec'd out that you will soon sell, get the NOSValves ST 70 routed through Craig, and you will have the specs AND a one year warranty to ensure an easy resale. Craig sorts his amps thoroughly, and stands up for his work.

The ST 70 will smoke the Chinese OTL in the bass department, if this is the same set of monos that I recently heard(there are a few cottage factories that churn out multiple types of tube amps.) The OTLs generally have the airy transparent mid/highs to die for, but they are like a lightweight boxer. Fast as all getout, with wonderful transient response, but little punching power. The OTLs are a wonderful match IF your musical preferences align with their strengths.

The ST70, modded properly, is a solid cruiserweight boxer, with power across the board, can mix it up in the bass ring, a little slower, but a very respectable entry into tubes.

I think you already know which ones you want. Just be aware besides the vital speaker fuses, you will also take a financial hit on the Chinese monos. They aren't the same profile as the Futtermans and select American OTLs, so you may be looking at 20-40% off ast resale, coupled with a longer time on market, above and beyond your initial wait.

Good luck with your choice. Either flavor is a respectable example of their genre.

[Guest " "]

Here is a link no one mentioned. this company puts out complete kits to original spec's.

http://www.dynakitparts.com/store/product.aspx?id=2

[sheltie dave]

Speakerfritz, there are actually three or four other "kit" suppliers as well, with numerous threads in the past year about them.

It is difficult to pull the trigger on a new kit that replicates known limitations of the Dyna platforms for that amount of change. With these dang speakers(if the $$$ is there,) you end up jumping in whole hog and getting a modded platform with less(or no) compromises, or you hit the low price entry point platform. Going in for a higher priced 'original' based kit also gets your the inherent 'original' high end breakup at higher volumes.

Mark has modded thousands of Dynas, to the point where he has washed his hands of doing another. Craig has picked up the gauntlet, and has done a legion of Dynaco rebuilds/mods for forum members, and has learned what sounds best on Klipsch speakers. If you are not handy with high voltage and soldering, value for your money often leads to Craig.

Still curious whether you are going with the ballerina, the brick mason, or still window shopping on your amp selection. Your two choices are quite the disparate pair!

[Guest " "]

////////////////////////////insert////////////

Speakerfritz, there are actually three or four other "kit" suppliers as well, with numerous threads in the past year about them.

It is difficult to pull the trigger on a new kit that replicates known limitations of the Dyna platforms for that amount of change. With these dang speakers(if the $$$ is there,) you end up jumping in whole hog and getting a modded platform with less(or no) compromises, or you hit the low price entry point platform. Going in for a higher priced 'original' based kit also gets your the inherent 'original' high end breakup at higher volumes.

Mark has modded thousands of Dynas, to the point where he has washed his hands of doing another. Craig has picked up the gauntlet, and has done a legion of Dynaco rebuilds/mods for forum members, and has learned what sounds best on Klipsch speakers. If you are not handy with high voltage and soldering, value for your money often leads to Craig.

Still curious whether you are going with the ballerina, the brick mason, or still window shopping on your amp selection. Your two choices are quite the disparate pair!

/////////////end of insert////////////////////////////////

looking for new. not intrested at all in used, refurbished, used-modified, used-upgraded, etc.

To evaluate initially, first cut are the technological options (single-ended, push-pull, OTL, hybrid, etc), second cut model/company etc.

Complete kit sounds like an option once the technological path is determined. Since I have built amps from scratch before, taking a new clone down the mod/upgrade road during initial construction sounds like a better approach, than buying something used that has to been checked out and repaired (tube replacement inclusive.).

I am still transversing the technological road to determine the platform, no where near company/model yet.

[SET12]

Speakerfritz,

I have read both of this guys books and I like most of his work with OTL's plus he is concerned about what can be done when fault issues arise, a big issue with OTL's is the bass in my opinion and Bruce Rozenblits as well, he discovered why OTL's have issues with bass and addressed the issue recieving a patent for it! he fixed the issue rather easyly I might add but never the less you might consider his products! Kits to!

http://www.transcendentsound.com/

SET12

[Guest " "]

Speakerfritz,

I have read both of this guys books and I like most of his work with OTL's plus he is concerned about what can be done when fault issues arise, a big issue with OTL's is the bass in my opinion and Bruce Rozenblits as well, he discovered why OTL's have issues with bass and addressed the issue recieving a patent for it! he fixed the issue rather easyly I might add but never the less you might consider his products! Kits to!

http://www.transcendentsound.com/

SET12

thanks, will look into it.

[Guest " "]

Speakerfritz,

I have read both of this guys books and I like most of his work with OTL's plus he is concerned about what can be done when fault issues arise, a big issue with OTL's is the bass in my opinion and Bruce Rozenblits as well, he discovered why OTL's have issues with bass and addressed the issue recieving a patent for it! he fixed the issue rather easyly I might add but never the less you might consider his products! Kits to!

http://www.transcendentsound.com/

SET12

Looks good...best so far....The T16 OTL in kit form looks like a no brainer. the T16 can be used in stereo mode at 15 watts per channel, or built as a mono block 40 watt unit. But two mono blocks will put you at the cost of "THE BEAST". The Beast looks very attractive. I'm on the mailing list. Thanks for the lead.

[Guest " "]

Speakerfritz,

I have read both of this guys books and I like most of his work with OTL's plus he is concerned about what can be done when fault issues arise, a big issue with OTL's is the bass in my opinion and Bruce Rozenblits as well, he discovered why OTL's have issues with bass and addressed the issue recieving a patent for it! he fixed the issue rather easyly I might add but never the less you might consider his products! Kits to!

http://www.transcendentsound.com/

SET12

Looks good...best so far....The T16 OTL in kit form looks like a no brainer. the T16 can be used in stereo mode at 15 watts per channel, or built as a mono block 40 watt unit. But two mono blocks will put you at the cost of "THE BEAST". The Beast looks very attractive. I'm on the mailing list. Thanks for the lead.

[NOSValves]

If you are interested in a Dynaco St70, I have one that I would sell. Its been rebuilt and modded by Craig (NOSVALVES) and is in excellent cosmetic condition. It sounds great!

If you are interested email me. $600.00 plus shipping

What a incredible deal on a wonderful condition ST70. By the way this one has the same front end board as listed in the auction. Save $400 for the missing $2 wood strip on the front.

Craig

[JBryan]

"The Beast looks very attractive. I'm on the mailing list. Thanks for the lead."

In case you're still interested, Bruce sent an email the other day...

"Dear Customers,

The BEAST amplifier in on sale. The next four BEAST kits, RCA version only, will be sold at the super low price of $2495 per pair. This sale is limited to kits only, and to the next four orders. First come, first serve. Assembled amps are not included. This is your chace to own the best of the best at an incredibly low price. When four pair are sold, the sale is over. "

I don't know if he's sold off the kits yet - if not, the price is right.

Have fun, Bryan

[Guest " "]

"The Beast looks very attractive. I'm on the mailing list. Thanks for the lead."

In case you're still interested, Bruce sent an email the other day...

"Dear Customers,

The BEAST amplifier in on sale. The next four BEAST kits, RCA version only, will be sold at the super low price of $2495 per pair. This sale is limited to kits only, and to the next four orders. First come, first serve. Assembled amps are not included. This is your chace to own the best of the best at an incredibly low price. When four pair are sold, the sale is over. "

I don't know if he's sold off the kits yet - if not, the price is right.

Have fun, Bryan

the price is very right.

I am on my way to NH from NY to pick up a car for my youngest son. When I get back, I'll give it my full attention....assuming my youngest leaves me any spending money after his car deal.

[Erik Mandaville]

Speakerfritz:

I would also like to recommend the Transcendent OTLs. Bass response, even from the comparatively low-powered SE OTL is excellent. I have built several Transcendent products for other forum members, and think Rozenblit is an extremely talented and innovative designer.

If you have experience building from scratch, I would absolutely encourage building your own, or as you said, perhaps starting with one of the very nice new Dyna kits (I've looked at those, too), and then modify if so desired from there. There are as many people who are at peace with and enjoy the original Dynaco 'sound' as there are who prefer some of the contemporary modifications of them.

I had a Transcendent T-16 in our system for a few weeks, and I am still kicking myself for not keeping it here. It was an incredibly fine sounding amp, with very balanced frequency response, top-to-bottom.

The Beast looks great, too, but I just don't have the need for that kind of power here. Rozenblit is also comfortable with sharing his designs, and the schematics and circuit descriptions are available in his books if you might be interested with building totally from scratch. The kits are put together well, though, and have a very functional and clean look, IMO.

Good luck, have fun!

Erik

[Erik Mandaville]

Speakerfritz:

YOu have a PM!

Erik

[JBryan]

"I would also like to recommend the Transcendent OTLs. Bass response, even from the comparatively low-powered SE OTL is excellent...."

I second Erik's opinion - I've had a pr of the Transcendent SE-OTL amps in my system for months (off and on) and the bottom-end is wonderful - very tight and by design, the amps do not have transformers to "filter" out the bass. Good transformers that have the transparency and extended range that lesser iron can't offer are expensive. At $800, the SE-OTL amp offers much of the performance and qualities for about the cost of a couple of good transformers alone. Another quality of these amps is that they are quiet - as in its difficult to tell if they are on ('cept for the heat) through horns with 106dB efficiency.

(BTW - Erik, I read your thread on the Transcendent Forum regarding your mod for older SE-OTL amps. When did Bruce start producing the newer version and how can I tell the difference?)

If you don't think the 1.5 watts (or 4 watt monoblocks) of power is enough for your setup, run the bass bins with a 30-50 watt amp (digital amps work very well in this application). You can build a very simple passive filter or better yet, an active xover, like the Marchand will allow you to dial in the best cutoff point(s) and even adjust the frequency response at those points (damping control).

Have fun, Bryan

[Guest " "]

"I would also like to recommend the Transcendent OTLs. Bass response, even from the comparatively low-powered SE OTL is excellent...." I second Erik's opinion - I've had a pr of the Transcendent SE-OTL amps in my system for months (off and on) and the bottom-end is wonderful - very tight and by design, the amps do not have transformers to "filter" out the bass. Good transformers that have the transparency and extended range that lesser iron can't offer are expensive. At $800, the SE-OTL amp offers much of the performance and qualities for about the cost of a couple of good transformers alone. Another quality of these amps is that they are quiet - as in its difficult to tell if they are on ('cept for the heat) through horns with 106dB efficiency. (BTW - Erik, I read your thread on the Transcendent Forum regarding your mod for older SE-OTL amps. When did Bruce start producing the newer version and how can I tell the difference?) If you don't think the 1.5 watts (or 4 watt monoblocks) of power is enough for your setup, run the bass bins with a 30-50 watt amp (digital amps work very well in this application). You can build a very simple passive filter or better yet, an active xover, like the Marchand will allow you to dial in the best cutoff point(s) and even adjust the frequency response at those points (damping control). Have fun, Bryan

Funny you should mention the active xover. I put a post up in 2 channel audio of an active xover tube circut that almost follows the heritage line xover points (500/5000) as well a 70hz sub xover point. Im trying to decide on small wattage tube-amps for tri-amping or one larger one and stay legacy. total cost of one or the other looks about the same.

[Erik Mandaville]

Bryan:

"(BTW - Erik, I read your thread on the Transcendent Forum regarding your mod for older SE-OTL amps. When did Bruce start producing the newer version and how can I tell the difference?)"

This had to do with some experiments I was doing on the grounding scheme, which in my experience has often been more complex a trick to pull off on a single stereo amplifier than with a pair of monoblocks. What Bruce came up with was a variation on what I had proposed and what I found to work well here. The feedback connections were part of the residual noise concern, but for me not the main culprit; which turned out to be ground connections related to the way the shields were used on the input into the amp. A couple of the SE OTLs I made seemed a little more prone than others, but the amps overall are really very quiet. I still want a pair for myself, and his prices are very good.

BTW: I always enjoy the picture of your Oris horns! The Oris 150 system was the main reason I had purchased an older pair of La Scalas a few years ago. I wanted to use the bass bin with the Oris and my PM2A drivers. I told my wife I was planning to very carefully remove the top section of the LSs (by way of my circular saw[]), and then mount the Oris/2A combo on top of that. She was not impressed by my use of the word 'carefully' as it related to the sawing, and mumbled something about what a crazy idea it was (I'm sure she is right). Anyway, I like the sound of the La Scalas so much that the PM2As have remained in the Medallion II cabinet.

Can I ask you somethng, Bryan? How do you find the Oris/K-horn arrangement compared to the stock Klipschorns? I'm still really curious about the Oris Horns!

Erik

[JBryan]

speakerfritz wrote:

"Funny you should mention the active xover. I put a post up in 2 channel audio of an active xover tube circuit that almost follows the heritage line xover points (500/5000) as well a 70hz sub xover point. Im trying to decide on small wattage tube-amps for tri-amping or one larger one and stay legacy. total cost of one or the other looks about the same."

My thoughts on the use of an active xover revolve around its ease of use and adjustability. When Mr. Klipsch & Co. designed a xover for the Khorn, they concerned themselves with the drivers and horns' optimal cut-off points and tested it in their anabolic chamber. The result was a well-designed speaker that worked with most systems and in most rooms (with proper corners, of course). The drawback is that the speaker has been optimized for one environment, therefore in other environments (like say, my living room), it is compromised to varying degrees.

To make matters worse, I couldn't leave well enough alone and ruined a perfectly good pr of Khorns by replacing the mid-horn and tweeter with a horn that PWK most likely never heard nor had an opinion of (thank goodness!). The parameters of the new setup pretty much ruled out the use of the existing xovers (in my case, the AK-2 and then the ALK) so I picked up a Marchand XM9 xover.

In most cases. I would prefer a passive xover as it doesn't impact the system's sound as much as an active one. On the other hand, active xovers tend to maintain the gain/output (passives reduce the output noticeably with low-power amps - especially with the woofer) and offer more on-the-fly adjustments. I was able to use an active xover to mesh the new horn with the Khorn's bass bin pretty easily (I only had to read the instructions twice). It also allows me to adjust each horn's output enabling the use of low-power amps on the mid/high horn and higher-power amps on the woofer. Using the active xover to bi-amp is just as necessary for me as mixing the drivers and horns. Another benefit is the ability to dial in the system to my environment. I can run freq. response curves and adjust the xover to flatten the signal out as much as possible.

If I ever decide on components that I will keep around for awhile, I will most likely measure the optimal cut-offs and settings on the active xover and build a passive xover to those parameters. Until then, the active xover suits my needs very well.

Have fun, Bryan

[JBryan]

Erik,

Thanks for the explanation. I had a slight hum coming for one of the amps that I spent a great deal of time tracking it down. I was able to reduce the hum to the background and I was pretty much resigned to it. I was bothered that I had heard these amps in another system and they were silent and I kept remembering that and Bruce's claim that they are the "quietest amps on the planet - bar none!" When I read the thread regarding your modification, I thought I may have found the culprit. At the time, I was running the Oris horns fullrange directly from the SE-OTL amps, then passing the signal to the digital amps through a passive xover and on to the bass bins. As I said, the hum was slight but noticeable and bothersome. I then bi-wired directly from the amps to the Oris horn and xover/digital amp/bass bin thus eliminating the Oris-to-xover connection. The change resulted in more articulated bass but the hum remained.

Next, I replaced the passive with the active xover to adjust the woofers' cut-off at 160hz as explained in an earlier post. There was significant improvement but I could still hear a distant hum. Recently, I decided to run both the Oris horn and bass bin through the active xover so simplify the wiring and allow me to use the Marchand's damping feature more effectively. The results are mixed. The digital amps no longer receive the signal from the SE-OTL amps so I think I lost a bit of the coherence I got from the SE-OTLs' signal characteristics. On the positive, the bass is as deep, responsive and articulate as I've heard from these bins and I have plenty of control now and can play with the mix a lot more. Eventually, I think this will work out as the better setup for my system - I just have to keep at it.

A totally unexpected benefit of running both horns' signal through the xover is that the hum finally vanished. My TIVO is now louder than the system (something else to deal with - does it ever end?!).

Since I've spent so much time futzing around trying to eliminate noise in various systems over the years, I'm developing a Balanced Noise Theory which states something to the effect that every variation in current (or voltage) caused by the movement of electrons must have an equal reaction in the opposing polarity. If the variation is not offset, the electrons' movements become unchecked. These random current fluctuations result in the release of increased thermal energy or Thermal Noise (or Johnson-Nyquist noise) which manifests as hum and hiss in acoustic applications. I'm still ripping off...er, developing the wording but I'm hoping some electronic genius out there finds some inspiration while dismantling my theory and builds the penultimate circuit to forever eliminate hum for the electronic vocabulary.

Sorry for the rant - Have fun, Bryan

[JBryan]

First of all, I have no idea how what this has to do with Dynaco ST-70 amps and I apologize to speakerfritz for hijacking his thread.

Erik,

I originally bought a Oris 200 kit as I read that its cut-off (200Hz) and dispersion was a better match for the Khorn bass bin. As it happened, a friend was building a Prometheus (Open-Baffle) kit and suggested that I use his Oris 150's as a trial until he decide which speaker he liked best. It took all of 10 minutes to remove the Khorns' mid/tweeter section and install the 150's. I was using a pr of 45 monos at the time and the difference in sound was revelatory. The Oris's extra efficiency suited the 45 amps really well and the improvement was across the board in my opinion. Clarity, extension, coherence, image all come to mind but then, there had to be significant improvement to justify the extra cost of the horns and drivers. As it turned out, my friend ended up with Tannoy coaxials driven by Hypex amps and no longer needed the horns so he offered to sell me his Oris' setup at a very good price. Being the lazy person I am, I bought the 150's and the Oris 200's are still in the box. I did have to close in the bass bins by adding a top and bottom to the existing false corners) but that made a big improvement as well and I am delighted with the result so far.

"I wanted to use the bass bin with the Oris and my PM2A drivers. I told my wife I was planning to very carefully remove the top section of the LSs (by way of my circular saw), and then mount the Oris/2A combo on top of that."

I think you can easily try the Oris setup without permanently damaging your LaScalas. I've seen plenty of folks coupling Oris' with the LS with great results and without alterning the cabinets. I'm not even sure that they went to the trouble of removing the K-33s. The Oris horns may actually benefit from the extra height. You can either mount the new horns on top, overlapping the K-33 or remove the K-33, flip the cabinets over and add ports in the new space....

Have fun, Bryan