TubesGlo

I installed 7 or 8 of these in custom home theaters, excellent processor and a great price!

After years of el34's I was surprised to see the blue glow also from my 6p3s-e.

I'm selective of what I'll buy from HF and yes they have stepped up their game as of late. I do own these two floor jacks and both have served well. I own a Snap-On torque wrench and purchased 3 of HF's Icon torque wrenches which are every bet as accurate and well made as the Snap-On. Don't hesitate to go with HF floor jacks, no problems there.

My reference was to the experience we had with certain individual Tecate components, not to Klipsch PCB's or their vendor. Relax, I wasn't on the offensive you can stop playing defense.

Shouldn't have made a blanket statement but all of the ultra c's our engineering team was using at the time were indeed made in Asia.

Tecate is an importer not a manufacturer per se. Their caps are made in Asia and are very inexpensive but spec sheets indicate decent quality. I've used Cornell Dubilier WMF polyester caps for years and that won't change. Some of theirs are now imported also and manufactured to their specs. I do think a good polyester is a great choice in crossovers for horn loaded speakers, not far behind a good quality PIO. That higher ESR with polyester has something to do with balancing the sound we hear helping it to be more pleasant. Still clear but not bright.

How necessary is it to match ESR between each network in the pair, polyester (Mylar) having higher readings than most other types. Is there an acceptable difference that won't effect the speaker audibly and do these caps read close if they're indeed being tested to match?

I listened to my modified Hafler 500 for years with a tube pre using NOS Mullard CV4003'S. I do believe an amplifier's only job is to amplify the level of the input signal faithfully without adding coloration. Of course we love tubes and what they can do to season the sound. That being said I like a tube pre in front of both my solid state and tube amps for how it "seasons" the incoming signal at the amp.

Yup, I agree....except for your last sentence. When I have someone sitting next to me asking to turn it down to talk, I tell them "Shut the f@$k up you're here to listen to the music"

No surprise here. David Hafler and his team engineered with intelligence and produced gear with excellent specs. Simple designs that performed well at a reasonable price. My first real amp was a Hafler 500 I built in '84. I still have it along with a 220 and my ST-70. All of these designs can still compete with and often outperform many high priced modern amps. Refreshing them with updated caps etc is a must and well worth the effort. Your ST-35 is true to the original circuit with modern quality transformers that are spec'd to be just like the originals. The amp is a testament of the enduring design that Hafler and team created over 60 years ago. Congrats on experiencing one of the best values in tube amps available today.

I wouldn't over think the bias set point. Best practice is to stay with manufacturers specs. They've designed, tested and evaluated the amp to perform best at their recommended setting. Lowering the bias too much will increase distortion, increasing it will run the tubes hotter and out of their comfort zone.

I believe any changes made to the original components in a 60 year old circuit be they resistors or capacitors when in the signal path, can and do influence the sound. CC resistors when in spec are going to sound different than metal film...maybe very noticeable, maybe not so much. Depends on your equipment and your ears. For me, I've settled on carbon film for my tube gear. I wouldn't tear into a new solid state amp and change out original metal films though, just for the hell of it.

I completely understand your feelings on this. I'm usually very skeptical with circuit component changes but for me the CF's took a bit of sharpness and edge off the upper highs. All metal film in my tube circuits tilted the sound towards a more sterile and brighter presentation. Yes splitting hairs...but I personally prefer the CF.

In order of preference for best sound in my system: Carbon Film - Carbon Comp (when all are within spec) and lastly metal film. I suppose it goes against conventional wisdom not to use metal film as they are technically more accurate and with tighter tolerance. In my experience and in my system, a high quality carbon film like Takman just sounds sweeter. After spending time with them in my amp I installed them in the signal path of my preamp.

I also have a ST-70 along with two SS amps I have put on the shelf for backup if needed. I completely refreshed the ST-70 with a stock replacement 7199 driver board. I have 3 sets of strong testing RCA and Sylvania driver tubes. I used Takman carbon film resistors and CDE wmf series coupling caps on the board. I first listened with carbon comp and then metal film resistors. Yes they do influence the sound. The condition of the driver board, the components used and the driver tubes have a greater influence on the sound than the output tubes. Get that right first and then roll out EL34's, KT66 , KT77 and fat bottle 6CA7's and decide what sounds best in your system. Give your ST-70 a fighting chance before investing in a completely different amp. When healthy with the right board configuration and tubes it is a very capable and sweet sounding amp. I use a tube preamp and my speakers are home built Cornwall clones at 100db sensitivity. Highs and mids are smooth, rich and detailed. Bass is clean, detailed and strong. BTW I have two strong testing sets of vintage Mullard xf2 power tubes. I couldn't be happier with my system....and won't spend thousands more chasing a unicorn.

I agree 100%. When electrical components such as capacitors, resistors etc. are designed and manufactured to meet a specific value, that component alone should not influence the sound of an amplifier per se. Output coupling caps in my tube preamp have had subtle but notable effect on sound. The PIO crossover caps certainly had a notable effect. When all resistors on my tube amp driver board were updated from old carbon comps to metal films there was certainly a change and not actually for the better. Yes the amp was quieter but it became somewhat sterile, cold almost too clean in an unnatural way. When I replaced them with high quality Takman carbon films I found what I wanted , a more pleasant top end and smoother overall with excellent detail. When components meet spec such as interconnects, speaker cables and power cables, here is where in the audiophile world of boutique offerings things get silly. I use homemade interconnects and speaker cables using Mogami wire, power cables are standard issue. My power is from clean, dedicated circuits. A very lucrative industry exists because some believe that 10,000 dollar speaker cables offer an improvement and they hear the difference and can afford them. I'm just not in that camp. I read the Audiogon forum occasionally just for a good laugh. Lifting cables off the floor improves sound and you heard that improvement? Really?

They're really hard to beat for the money and punch way above their weight. I rotate my 220 in place of my ST-70 once in a while and I'm always impressed. It drives my Cornscalas with authority. With everything in spec they sound great even in stock form.

Before using a tube amp full time my main system was SS with tube preamp. My first amp almost 40 years ago was a Hafler 500 I built from a kit....I still have it along with a 220. Very simple designs with clean, mosfet sound. I've owned a lot of different amps over the years but will never let go of these. I think the right SS amp in your system can offer a great experience with just a different flavor vs tubes. If not a good match with your gear, you'll know it right away and will be hard to get used to.

I'm not sure at what point ESR becomes too high for use in a network cap, maybe .5 ohm? I ordered twice what I needed so I could experiment with different configurations at the same total capacitance. None of these measured higher than .31 and when paralleled that reading came way down. If this type of cap imparts some "coloring" to the sound it does it in a positive way. I say this because the audible difference is notable from the Sonicraft caps. Some may say those caps or other metalized poly types are "transparent" or " neutral" in crossovers of horn loaded speakers. To me the highs sounded somewhat sterile with a bit of bite in the upper frequencies that I didn't care for. With the PIO's in the crossovers everything sounds more natural and correct, 3 dimensional. I don't care how they measure or how my tube amp measures, I'm totally satisfied and enjoying the music like never before.

I recently had a similar experience, replaced Sonicaps with NOS PIO cans imported from Europe, posted about it this morning. Subjective as it may be I do like what I'm hearing much better and it's not a small difference. I lived happily with the Sonicaps for 7 months but after a month with these PIO's I won't be trying anything else, I'm very happy.

You won't be disappointed, performance way above their price!

I was impressed with the "ballpark" test results of these caps. Excellent sounding and one hell of a bargain. of a bargain.

A few months ago I read a post by "thebes" from 2013 regarding his experience with Russian military surplus PIO caps in crossover networks. My Crites Type B's came with Sonicraft caps at 2.5uf and 4uf. This was my first experience with these. I like the old Cornell Dubilier WMF polyester film for coupling use in my tube gear and was going to try them in my networks. Nothing wrong with Sonicraft and they measure very low for ESR but I felt need for change. I ended up ordering a small assortment of the PIO'S to try from two sellers, one in Bulgaria and the other Romania. I got some MBGP, MBGO and KBG..N or M. They all test really well and are right on for capacitance and low in ESR. I know my Peak tester isn't the best but it gives me a pretty good idea of where they're at. I tried a couple different variations with some paralleled and settled on a 2uf and .5uf for the HF input in parallel and a 4uf (KBG) for the tweeter. After these settled in I noticed a definite improvement toward a more natural and realistic overall tone with instruments and voice. I try to be neutral when evaluating any changes in components staying between subjective and objective. The caps have higher ESR (max of .31) than the Sonicrafts but something in the materials used and construction process of thes PIO's made a real and audible change to my speakers sound for the better, much better. Now these are Crites type B that I built last year to get close to the Heritage sound that I just couldn't afford. I know the Cornwal IV sound very well and I will say that I'm extremely pleased with these to the point at 58 years old I feel I've finally assembled my end game system. If you've been on the fence regarding foreign military surplus PIO'S, I would urge you give them a try. My 65.00 investment / experiment is one of the best value changes I've ever made in a sound system. Thank you "thebes" for that post which helped convince me to give them a try!

Sort of a side note question with probably an obvious answer. Wouldn't it be safe to assume that with high sensitivity speakers such as the Cornwall for example, an amplifiers output tubes will be worked less outputting the same dB level vs a speaker with lower sensitivity? Longer tube life over time etc.?