A bit of a thread hijack again, but since there doesn't seem to be a thread for Scott's speaker design, I'd like to leave this review/build log here. This is also a more formal "thanks" for Scott's design and build help/suggestions.
See my full build log at this link.
So far, I've built the KT88 amp. Some modifications include a LED lit power switch, headphone output and switch, and bias mod/6CL3 diode mod. I've also added some capacitors as mentioned in post 258 to eliminate hum. To complete the system, I've built some speakers from Scott's design. As far as I'm concerned, this is the best arrangement I've ever had.
Most everyone here should already know how the amp sounds, so I won't try to review that. However, I want to rave about the speakers. (Scott correct me if there's anywhere I've made a mistake) They use a Ciare PT382 as a tweeter and a Eminence Deltalite II 2510 as a woofer tied together with a custom zobel crossover. I sourced the parts from Erse Audio in the States.
The cabinets I've built were the floor standing models, so they are quite hefty. I built them with 18mm Baltic birch. I can stand on them with no bending or creaking. Sourcing the components in Norway was a challenge, but not impossible. Pretty much everything was ordered from abroad. I'm still paying customs/toll bills. The build log goes into more detail, but I'll leave the review here.
I'll preface this by saying that I'm no expert at reviewing speakers. I've had limited access to high end equipment and I'm just a hobbyist that got deep into making something. And since the look is mostly my own doing, I won't touch on that. Anyway, here goes... When compared to my old Infinity Reference 40s, there is simply no comparison. These new speakers are fuller, deeper, brighter, louder and all around better. Every type of song sounds better.
These are sensitive. I have no way of measuring how much, but they are more than adequately loud to get the neighbors knocking at my door when driven with the KT88 amp. The first thing I noticed was the depth of sound, I could clearly distinguish the highs such as voice and cymbals and even feel their location. My worry was that this would produce listening fatigue with sharp highs, especially in the confines of my hard living room, but I have yet to feel that. On the opposite end, the speakers aren't designed for thumping lows, but I feel that kind of thing is unnecessary when it comes to the type of music I listen to and that the low end is covered well enough as it is. If I want to watch movies, I'll get a sub in there.
I feel immersed when I listen with these, in fact I sometimes just get stuck sitting there in front of them. It feels like they aren't even there and the band is in front of me. The sound is coming from the space in front of me. Recommended!!
See my full build log at this link.
So far, I've built the KT88 amp. Some modifications include a LED lit power switch, headphone output and switch, and bias mod/6CL3 diode mod. I've also added some capacitors as mentioned in post 258 to eliminate hum. To complete the system, I've built some speakers from Scott's design. As far as I'm concerned, this is the best arrangement I've ever had.
Most everyone here should already know how the amp sounds, so I won't try to review that. However, I want to rave about the speakers. (Scott correct me if there's anywhere I've made a mistake) They use a Ciare PT382 as a tweeter and a Eminence Deltalite II 2510 as a woofer tied together with a custom zobel crossover. I sourced the parts from Erse Audio in the States.
The cabinets I've built were the floor standing models, so they are quite hefty. I built them with 18mm Baltic birch. I can stand on them with no bending or creaking. Sourcing the components in Norway was a challenge, but not impossible. Pretty much everything was ordered from abroad. I'm still paying customs/toll bills. The build log goes into more detail, but I'll leave the review here.
I'll preface this by saying that I'm no expert at reviewing speakers. I've had limited access to high end equipment and I'm just a hobbyist that got deep into making something. And since the look is mostly my own doing, I won't touch on that. Anyway, here goes... When compared to my old Infinity Reference 40s, there is simply no comparison. These new speakers are fuller, deeper, brighter, louder and all around better. Every type of song sounds better.
These are sensitive. I have no way of measuring how much, but they are more than adequately loud to get the neighbors knocking at my door when driven with the KT88 amp. The first thing I noticed was the depth of sound, I could clearly distinguish the highs such as voice and cymbals and even feel their location. My worry was that this would produce listening fatigue with sharp highs, especially in the confines of my hard living room, but I have yet to feel that. On the opposite end, the speakers aren't designed for thumping lows, but I feel that kind of thing is unnecessary when it comes to the type of music I listen to and that the low end is covered well enough as it is. If I want to watch movies, I'll get a sub in there.
I feel immersed when I listen with these, in fact I sometimes just get stuck sitting there in front of them. It feels like they aren't even there and the band is in front of me. The sound is coming from the space in front of me. Recommended!!
That's fantastic Eric. The speakers look great. Excellent job on the veneer.
I'm really glad you like the performance. The last short paragraph of of your post pretty much says it all. I feel the same way.
Concerning the low-end response, the 2510 woofer takes quite "a while" to break in. You will definitely notice a dramatic improvement in the bass response. I put "a while" in quotes because it is linked to the actual time-in-service and the signal level at which they are in service. I promise you will notice the difference after "a while".
The Ciare tweeter part number should be 1.38TW. I was assured that these are available on an ongoing basis from usspeaker.com. The PT382 part number, although it appears to be the same unit, seems to be an interim part number used for the car market. If anyone decides to build these just stay with the 1.38TW number from usspeaker.com. I believe this is what Eric actually ordered. (I have no affiliation with usspeaker.com, however they seem to be the only readily accesible vendor for this product.)
As a side note:
I'm not sure why you had a hum problem after doing the bias/6CL3 mod since you did not change the choke, but I'm glad the capacitor mod took care of the problem. I'll have to look into that. Thanks for the info.
Scott
I'm really glad you like the performance. The last short paragraph of of your post pretty much says it all. I feel the same way.
Concerning the low-end response, the 2510 woofer takes quite "a while" to break in. You will definitely notice a dramatic improvement in the bass response. I put "a while" in quotes because it is linked to the actual time-in-service and the signal level at which they are in service. I promise you will notice the difference after "a while".
The Ciare tweeter part number should be 1.38TW. I was assured that these are available on an ongoing basis from usspeaker.com. The PT382 part number, although it appears to be the same unit, seems to be an interim part number used for the car market. If anyone decides to build these just stay with the 1.38TW number from usspeaker.com. I believe this is what Eric actually ordered. (I have no affiliation with usspeaker.com, however they seem to be the only readily accesible vendor for this product.)
As a side note:
I'm not sure why you had a hum problem after doing the bias/6CL3 mod since you did not change the choke, but I'm glad the capacitor mod took care of the problem. I'll have to look into that. Thanks for the info.
Scott
You're correct: 1.38TW. My mistake, I searched high and low for a source that was closer to me, but I ended up ordering from usspeaker.com and suffering the toll.
I have a really hard time knowing when exactly the hum started, since I did a lot of the modifications all at once. I even went back and checked all the wiring routing and even changed out tubes and nothing helped. I found some polypro caps in the neighborhood and picked them up just to give it a try. It's not vanished, but it's much much more tolerable than before.
Eric,
There must be something else going on with the amp with regards to the hum. The hum should be less than 1mV at the speaker terminals even with the changes. Have you measured the hum voltage? What is the DC filament voltage going to the rectifiers?
Also:
What is the new B+ voltage?
KT88 cathode voltage?
6N1P cathode voltage?
Can you tell if it is 60Hz or 120Hz hum?
There must be something else going on with the amp with regards to the hum. The hum should be less than 1mV at the speaker terminals even with the changes. Have you measured the hum voltage? What is the DC filament voltage going to the rectifiers?
Also:
What is the new B+ voltage?
KT88 cathode voltage?
6N1P cathode voltage?
Can you tell if it is 60Hz or 120Hz hum?
Hi Scott,
I finished all modifications to use 5AR4 rectifier.....
....and installed a switch to change between 39k and 47k anode resistance on the driver.
First impressions seems to a good improvement for the amp.
Music seems to have more body and sounds more relaxed.
But there is even more noise on the speakers.
I didn't try the 6922 yet.....but I will report when I did.
I bought first of all a Ruby 5AR4....the highly recommended NOS GZ34 are incredibly expensive.
Thanks
Gregor
I finished all modifications to use 5AR4 rectifier.....
....and installed a switch to change between 39k and 47k anode resistance on the driver.
First impressions seems to a good improvement for the amp.
Music seems to have more body and sounds more relaxed.
But there is even more noise on the speakers.
I didn't try the 6922 yet.....but I will report when I did.
I bought first of all a Ruby 5AR4....the highly recommended NOS GZ34 are incredibly expensive.
Thanks
Gregor
Hi Scott,
I don't know what I heard the first time, but for sure it's not coming from the amp.
In fact it seems to more quiet than before.
My loudest source is expectedly my budgie phono.
Another question.....just to make sure I can#t damage anything.
I've built this passive preamp with DIY ladder attenuator.....
For some reason I liked the idea of switching (isolated) grounds as well as signals.
Switch 2decks2pole per deck 6pos break before make Electroswitch
But I have bad popping noise when switching the inputs obviously from input potencials.
I want to install 1MOhm between all signal/ground on the input RCA.....
Is there any harm for the AMP?!
Thanks
Gregor
I don't know what I heard the first time, but for sure it's not coming from the amp.
In fact it seems to more quiet than before.
My loudest source is expectedly my budgie phono.
Another question.....just to make sure I can#t damage anything.
I've built this passive preamp with DIY ladder attenuator.....
For some reason I liked the idea of switching (isolated) grounds as well as signals.
Switch 2decks2pole per deck 6pos break before make Electroswitch
But I have bad popping noise when switching the inputs obviously from input potencials.
I want to install 1MOhm between all signal/ground on the input RCA.....
Is there any harm for the AMP?!
Thanks
Gregor
Hi Scott,
Is it possible to add a RCA output for the amp?!
Sometimes I want to copy LP's for portable audio and so far I have to use my other SS amp.
Also I try to get together a mouser order for the headphone mod and some other parts
and I need more value ;-)
Thanks
PS:Merry Christmas and successful DIY'er year for all of you here
Gregor
Is it possible to add a RCA output for the amp?!
Sometimes I want to copy LP's for portable audio and so far I have to use my other SS amp.
Also I try to get together a mouser order for the headphone mod and some other parts
and I need more value ;-)
Thanks
PS:Merry Christmas and successful DIY'er year for all of you here
Gregor
Hi Gregor,
The two amplifers are high-impedance input. If your source is a low-impedance output of a few hundred ohms or less, which I assume it is, the way to do this is use a y-cable. Just split the signal from your source and input to both amplifiers.
Merry Christmas and Happy New Year to you and everyone too.
Scott
The two amplifers are high-impedance input. If your source is a low-impedance output of a few hundred ohms or less, which I assume it is, the way to do this is use a y-cable. Just split the signal from your source and input to both amplifiers.
Merry Christmas and Happy New Year to you and everyone too.
Scott
I have this wonderful kit and it sounds just fantastic! I am new to valves so can someone tell please which switch connection selects triode and then of course the other connection would be ultralinear
Thanks
Triode mode: 5+ watt output per channel (with KT88)
Ultralinear mode: 10+ watt output per channel (with KT88)
Thanks
Triode mode: 5+ watt output per channel (with KT88)
Ultralinear mode: 10+ watt output per channel (with KT88)
Great amp choice!
See schematic in post #126 of the other thread
http://www.diyaudio.com/forums/tubes-valves/175786-kt88-se-complete-kit-13.html#post2407908
Also, see picture (top view) in post #44 on this thread
http://www.diyaudio.com/forums/vendors-bazaar/180897-kt88-se-basic-master-kit-5.html#post2612954
The (toggle) switch for Triode/UL can be seen just beyond the 6N1P tube in the (top view) picture. Do NOT switch it when the amp is powered on.
On mine, the switch is in Triode mode with the toggle pushed toward the output transformers. I guess it depends on the orientation of the switch as installed.
It should be easy to verify. The U/L setting should be considerably louder in comparison. Again, don't flip the switch when the amp is powered on.
It should be easy to verify. The U/L setting should be considerably louder in comparison. Again, don't flip the switch when the amp is powered on.
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