July 24, 2012
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Sovtek KT88
The review set of eight Sovtek KT88 tubes was purchased from an online vendor but I no longer remember which one or their cost. They are currently available at the Tube Depot for $54.95 a matched pair and at The Tube Store for $63.95, also for a matched pair.
These tubes were all manufactured in 1999 and, as such, may no longer be representative of current production Sovtek KT88s. They are a top getter-only, three-hole, grey plate KT88 and have a chrome colored collar and black base. Unusually, and perhaps uniquely for a KT88, they have an ST-shaped bottle normally only seen on certain 6550 output tubes. Sovteks have a reputation for rugged build quality and good longevity.
The subject tubes had a total time of over 15 hours burn-in on the amp. Although the Sovtek KT88s had all been used previously, they did exhibit some change as they settled in. Specifically, the bass became deeper and their sound smoothed-out to a small degree.
They replaced a well-used set of SED =C= 6550C tubes. The 6550C was the output tube used by conrad-johnson to voice the 140 during its design and was supplied as stock with the unit.
Listening Impressions:
- The Into the Labyrinth CD by Dead Can Dance clearly depicts the reverb used on voices; percussion instruments have a nice pop although they lack some heft and do not reach as far and as cleanly into the bass as the SED 6550C.
- Lower bass response extends almost as deep as the 6550C but is a bit more thuddy and less defined.
- Tolling bells sound reminiscent of the GE 6550A with a nice metallic quality although a bit lighter in weight.
- Massed strings are less edgy than solo violin with a feathery quality that is pleasing and the level of detail is borderline reference quality.
- The Pachelbel: Canon & Gigue CD by Trevor Pinnock and the English Concert reveals plenty of clarity and high frequency energy with massed strings retaining their leading-edge transient snap within a fairly deep and wide sound stage.
In conclusion, although I didn’t dislike the Sovtek KT88s, I also didn’t particularly like them, either. Even though I wouldn’t have previously imagined myself saying so, they make the SED =C= 6550C tubes sound liquid and smooth in comparison. In terms of ranking, these would fall very near the bottom, just above the KT88EH and the 6550EH.
NB: I believe I will be taking a hiatus in reviewing additional output tubes. Based on a comment on the importance of the input tube to the overall sound of the Premier 140 by one of this web log's readers, I have started to compile listening notes on various input tubes that I will use in the Premier 140. Eventually, a comparison of the 6DJ8 family of tubes used for this purpose will be posted. During the interim, look for postings on various tweaks I've made to my system and who knows what else.
Comments (2)
Who would have known that tubes made in the late-90s are now "old stock?"
But I applaud your honesty in giving your true feeling/assessment of the Sovtek KT88. Too bad the "professional" reviews aren't this honest.
@rpghero27 -
It's funny, but I look at the these tubes and they appear to be brand new and I'm just about to blab on about them when I realize if anyone's going to buy them now, these aren't the ones s/he is going to get. So I feel obligated to say something to that effect since current production may, or may not, sound quite like these, or maybe anything at all like these.