Curious_George

I have a Realistic SAF-24 (circa 1961, made in Japan) that is similar to the Pilot SA-232. I've been meaning to restore it for years, but have not yet. Last time I plugged it in it worked great.

I hope you get many years of enjoyment out of the amp Rich. It will take about 50 hours to break-in those 300B's. At least that has been my experience with directly heated triodes. I use to think tube break-in was bogus, but after seeing distortion decrease and gain stabilze as the tubes "broke-in" I was a believer.

If you’re willing to pay for shipping one way, I’ll pay for return shipping and I’ll test the amp for you. I’ll make a video of the testing too.

I bet one of my custom built amps the Crimson 275 cannot meet 20Hz to 20kHz @ 1% THD+N at 75 Watts RMS, 8 Ohm load.

Since this thread has not had any input in awhile, does anybody have more opinions to share? I think the Sovtek 2A3 monoplate is by far the best value and sounds pretty good. I've heard various Chinese variants too, but I like the Sovtek the best. The Sovtek is almost a 300B on its own. It can handle 450V on the plate and power dissipation is 30 Watts. It is no slouch. Physically, the Sovtek 2A3 plate is almost the same size as a 300B. You can get a solid 7.5 Watts out of it and it will smile all the while. This is 300B territory for half the price or more in most cases. I still love 300B's, but if you are on a budget or simply do not want to spend too much on tubes, but invest money in other areas (like transformers), the Sovteks are the way to go. I won't go into much detail about the sound quality of different tubes, because I honestly do not hear too much difference between a lot of components if the equipment is designed well.

Yep. One stop light town, literally, but I love it after living in metro areas most of my life.

My point was that all sources of power will have an impact on noise and ultimately the audio quality of electronic circuits.

Not quite, maybe at absolute zero. Battery Noise.pdf

To rebuild a Type A or Type AA crossover or build an ALK Uniserval, there is plenty of info here on the forum for somebody with basic skills to do it. That is what makes it "easy". If you can't solder, then you can learn if so inclined. If you don't feel comfortable or want to do it, then you pay somebody like Dean or whoever to do it. Building passive crossovers is not difficult, especially when you already have a design to follow.

An excess of upper midrange frequencies around the crossover and passband frequency. Yes, the mass roll off is acoustically decreasing the frequency, but I believe you can still hear the upper mid frequencies (when they are allowed to roll off naturally) which is why (in my opinion) most people who describe the AA versus the ALK Universal say it sounds like the adjectives I used. Is the Universal missing something physically or intangible? Physically meaning it could have been a better or different design? Or intangible meaning it (the crossover) is not performing its job correctly and introducing or not attenuating the frequencies properly?

The most significant difference between the AA and ALK Universal is in the upper midrange to lower tweeter transition (mid / tweeter crossover) point. The AA lets the midrange roll off naturally versus a 12dB roll off of the ALK Universal. I believe what most people hear as a difference between the two crossovers is the excess upper midrange interacting with the lower tweeter frequencies in the crossover region. This might be described as a more "intimate" or "full" or "lush" or "engaging" or any another term for "an excess of something" in a certain area. I personally like the way the ALK Universal sounds, but the AA for how simple it is, works quite well and there is nothing wrong with it.

I'm a Bob Carver fan too, but not all of his products were great. I'm not concerned with the power output or other specs, but what is advertised versus reality. I would like to see (photos and testing) a verified production unit and then judge from there. Bob always had clever ways to demonstrate certain test measurements that were part of his marketing.

Schematic at the end of manual. Crimson-275-Owners-Manual-REV100.pdf

A 19lb tube amp IS NOT going to put out 75 Watts per channel at any acceptable distortion measurements. That is simple physics. I am sure the 15 Watts sounds good, but it’s not an amp I would buy. It’s kinda like a Eico HF87, which I like a lot.

Cornhole. 😂

Yes! Happy Festivus to everyone and whatever you celebrate.

Model number should be “Crummy215”.

Came from this thread...

In most cases, cast is for "bling" unless the extra strength is really needed. I'd rather have a good woofer with the specs I need for a design than a cast frame. If it was cast and price was nominal, I would buy the cast, if not, stamped steel.

In this case, people are right, you can hear a difference in these woofers, but it is not the cast frame.

Here are the enclosure recomendations from the software for the 1526 & 1526C. No tweaking done. Green is 1526C Orange is 1526

If these T/S parameters are accurate, the non-cast frame woofer does much better in a vented enclosure. The higher BL product on the cast frame woofer prefers an enclosure about 1/2 the size of the non-cast. If you could compare a 1526 & 1526C in the same (Cornwall) enclosure, side by side, you would find the 1526 has tigher controlled bass than the 1526C.

With the exception of the BL product, the other specs are very similar and would be considered in tolerance for most woofer drivers. The higher BL product makes the driver sensitivity go up and the QTS go down. The sensitivity difference is what you would hear out of all these variances.

My next amp project is going to be an Eico HF87 clone, but with a CCS for the phase splitter section. I love the topology of the amp, sweet and simple but robust. Instead of using an ECC83 for the front end tube, I’m going to use a 6SL7GT.

What beast is that?