• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

All-Tube Power Amp? (sans pre-amp)

#61
77PBass said:
Tone on the other hand is a different matter. Think of all the songs that have been recorded using a B-15n (with a tube power section) that are the bedrock of popular music.
Click to expand...

Since there are no album credits listing a B-15n I don't believe the stories of how popular this amp was. From just as many credible historical accounts, Bass players did DI more often than not. At the time also was tape recordings, tape saturation, and signal compression - who's to say these don't account more for the tone than whatever amp or mic was used?

In any account. These "classic" recordings get played back on SS amps.

Doesn't matter much, today's music, is selling more than ever. There was a nice reprise of older rock as "Guitar Hero" peaked in sales but that's on the decline. New players, new sounds, less recycled.
 
#62
projectMalamute said:
You will notice that the link you provided calls the KT88 an exact replacement for a 6550.

Also, the 6L6 (and 6550 and KT88) is a beam forming tetrode, the EL34 is a true pentode. They are pretty different tubes, and sound it.

Completely different deal than 6L6 vs EL34.
Click to expand...
See this was what i was trying to get across. He said Bassman123450 they are the same tube but one doesnt have as much gain.......so as i said i think there must be a difference in them it maybe very small though.They sound different too, one giving more distortion then the other.
 
#63
77PBass said:
Funny you should say that as I was going to include that but decided it would muddy the point I was making.

I do think A/D converters have come a long way since the ones in those first machines so I think it was a tech/user learning/improvement curve.
Click to expand...

Thing is, even in the first generation there were good CD releases and good CD masterings of pre-CD releases - along with all the abysmal ones... Ironically, some of the "re-masterings" today of material that was already sounding good in CD media appear by examination of raw data to be mere "hike up the compression and limiting by at least 6 dB" exercises. So not only do the lamented industry-wide Volume Wars continue, but now they are used to re-sell product to people who already own it on CD, a huckster's game with a big splashy REMASTERED campaign behind it.

So you might get some new bonus tracks and some new packaging but you actually end up with further degraded audio quality. Brilliant!
 
#64
So, with all the comments, I looked up the actual data sheets for the 6550 and the KT88 (RCA, GE, and Tung Sol, I believe). Both are beam power tetrodes with very similar characteristics. Both are capable of delivering 100 watts output per pair in a class AB push-pull circuit.

I stand corrected! (There you have it!) The KT88 has higher maximum plate voltages specified for it than the 6550. In a class AB push-pull power amp classification, however, the KT88 is rated for 50 watts nominally for the pair in an ultra-linear application, where the 6550 is rated at 70 watts.

The older SVTs ran 795 VDC on the plate with a plate current for all six tubes at somewhat around or just over 1000 ma (1 amp). Control grid voltages (bias) were set nominally at -55 VDC. This allowed for the amp to put out 100 watts per pair of tubes (300 watts total) with a clean sound and stable environment for the tubes. These values were hard on KT88s. It seems that almost every SVT we had come into our shop with KT88s had some output problems and left with matched pairs of 6550s.
 
#66
Bassman12350 said:
So, with all the comments, I looked up the actual data sheets for the 6550 and the KT88 (RCA, GE, and Tung Sol, I believe). Both are beam power tetrodes with very similar characteristics. Both are capable of delivering 100 watts output per pair in a class AB push-pull circuit.

I stand corrected! (There you have it!) The KT88 has higher maximum plate voltages specified for it than the 6550. In a class AB push-pull power amp classification, however, the KT88 is rated for 50 watts nominally for the pair in an ultra-linear application, where the 6550 is rated at 70 watts.

The older SVTs ran 795 VDC on the plate with a plate current for all six tubes at somewhat around or just over 1000 ma (1 amp). Control grid voltages (bias) were set nominally at -55 VDC. This allowed for the amp to put out 100 watts per pair of tubes (300 watts total) with a clean sound and stable environment for the tubes. These values were hard on KT88s. It seems that almost every SVT we had come into our shop with KT88s had some output problems and left with matched pairs of 6550s.
Click to expand...

you checked the voltage on the plate when its running 100watts a pair?

Newer kt88's are more like 6550's where as older ones are alot more reliable and do more power than the 6550s
 
#69
MAMMOTHvolume said:
you checked the voltage on the plate when its running 100watts a pair?

Newer kt88's are more like 6550's where as older ones are alot more reliable and do more power than the 6550s
Click to expand...
Absolutely! I remember these amps well and have the utmost respect for that power supply. Definitely lethal! Supply volts were 795 - 800 with just under that (perhaps 775 - 780) at full rated output. The best one I remember working on clipped at about 360 watts RMS into 8 ohms.
 
#72
seamonkey said:
Since there are no album credits listing a B-15n I don't believe the stories of how popular this amp was. From just as many credible historical accounts, Bass players did DI more often than not. At the time also was tape recordings, tape saturation, and signal compression - who's to say these don't account more for the tone than whatever amp or mic was used?

In any account. These "classic" recordings get played back on SS amps.

Doesn't matter much, today's music, is selling more than ever. There was a nice reprise of older rock as "Guitar Hero" peaked in sales but that's on the decline. New players, new sounds, less recycled.
Click to expand...

Ok, I give up. the "These "classic" recordings get played back on SS amps." did it for me. :rollno: I'm done.
 
#73
greenboy said:
Thing is, even in the first generation there were good CD releases and good CD masterings of pre-CD releases - along with all the abysmal ones... Ironically, some of the "re-masterings" today of material that was already sounding good in CD media appear by examination of raw data to be mere "hike up the compression and limiting by at least 6 dB" exercises. So not only do the lamented industry-wide Volume Wars continue, but now they are used to re-sell product to people who already own it on CD, a huckster's game with a big splashy REMASTERED campaign behind it.

So you might get some new bonus tracks and some new packaging but you actually end up with further degraded audio quality. Brilliant!
Click to expand...

What, the Recording Industry selling the same old donkey with a new saddle? I am shocked! Shocked I say!
 

Latest posts

Top Bottom
Back