QuestionI know you get alot of people that write in so hopefully you will remember me I have the Dynako ST 70 ,PS Audio preamp and Sony speakers,I took your advice and finally cleaned the inside of the preamp Saturday,it was filthy,vacuuming didn't help I had to take a thin paint brush and clean it,the volume and other controls operate smoothly now,no scratching,still the preamp dulls the sound a bit,would rather listen with cd player directly hooked up to amp,the thing that is bothering me now is when the volume is turned up musical passages sound congested and loose distinct detail,I am not sure if this is 1.the amp doesn.t have enough power to drive these speakers,it is only 35w per channel,2.the tubes are weakening and need to get replaced.3.it is a limitation of the speakers,4,the accoustics of the room and particularly where the speakers are causing alot of reflected sound,I am considering borrowing a higher powered solid state amp or reciever to check this,what do you think?Also i was considering buying a turntable ,Yes going back to vinyl!,I had lots of albums stored away at my parents and I took thenm home with me at Christmas,Any recommendations for decent turntable/cartridge combo for under $200,Was considering a Denon Pdf29?
AnswerDear Peter,
Good to hear from you again.
It is virtually axiomatic that bypassing a premplifier, if possible--certainly with the Dynaco, will produce a "cleaner" sound than with the preamp engaged. All the factors you mention that indicate your dissatisfaction with the sound quality could prompt an individual treatise. Much has been written about power requirements, tube replacement, room acoustics, and especially speaker accuracy. It's not possible for me to essentially guess which of these factors, or their various combinations (is it 2 and 4? 1 and 3? 1, 3, and 4?), could be contributing. For instance, I have no idea what the power requirements of the Sony speakers are.
However, there are some things I can counsel on. First, despite the rage for lower powered amplifiers (9 watt triodes?) the past few years, unless you have extremely efficient speakers (with an efficiency coefficient of 90dB SPL and preferably much higher), lower powered amplifiers do not have the "guts" or power reserves to drive dynamic peaks, say symphonic tutti passages, much less consistent delivery at moderately high volumes. They simply poop out. Remember, when the Dynaco 70 was king, any amplifier that delivered more than 35-50 WPC RMS was a rarity, and an expensive one at that. Amplifier designs, both solid state and tube, over the last 25+ years have afforded far greater output of raw power at pennies per watt. Even the most modest of Sony's A/V amplifiers puts out 100 watts per channel into a 5.1 array. So, yes, the lower power of your Dynaco could be an issue.
Second, tubed amps and preamps have their own, unique colorations. So removing the PS Audio preamp from the signal chain, besides providing a direct signal path, will also remove the preamp's unique coloration from what you hear. This change should be, and is, audible. When you borrow a solid state amp to "test" the speakers, you're doing two things: (1) presumably using one with more power to see if the Sonys are up to the task, and (2) introducing another variable into your evaluation. Solid state amplifiers generally have no coloration. So the sound you hear is going to be different from that of the Dynaco/PS Audio combination (or the Dynaco alone) simply because you've removed the tubes from the equation. Be careful. Do not jump to the conclusion that the solid state amp is necessarily "better" because the sound has changed. Yes, the power will test the limits of the speakers, but that doesn't mean that the "sound" of the Dynacos is compromised. It will simply be different. It's up to you to decide which you prefer.
There is no ideal (or "Abso!ute") sound. There are only differences.
There is one source that I absolutely trust for an honest evaluation of a Dynaco 70 amplifier. It is Audio by Van Alstine in Minnesota. Frank Van Alstine has been rebuilding them for years and will even build you a new amplifier on a Dynaco 70 chassis. Go to www.avahifi.com to check him out. Then give him a call; his phone number is at the bottom of his home page. Tell him what you have and what your objective is. He'll recommend his best possible solution. He's one of the great guys of audio. You'll learn just by talking with him. I use his Omega Star III EC preamplifier and couldn't be more pleased.
Finally, turntables. These are the most complex machines in audio. Unless you have a to-die-for vinyl collection, I suggest a modest, not necessarily budget, model with a good cartridge. I use a Rotel RP-955 'table and tone arm with a Shure V-15 V xMR cartridge with excellent results. However, with a Japanese 'table like the Denon, Shure's M97XE would probably be sufficient. The largest collection of 'tables and cartridges on line is at www.needledoctor.com. Knock yourself out. No, I haven't heard the Denon DP-29F, but it is one of many budget models Needle Doctor handles. One of its advantages is that it has a built-in phono preamp, so you don't need to have a PHONO input on your preamp. It can connect directly to any line level input. You should also check out Music Hall, Rega, and Rotel.
Good luck.
Kindest regards,
Kevin
