• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

SE KT88 Amp

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
Cassiel

Cassiel

Disabled Account
Joined 2004
Se Kt88 Amp

Hi,

A friend of mine was listening to my tube amp (se pcl86) the other day and now he wants one... done by me. He has chosen the KT88 (aesthetic reasons); as he liked my amp which is SE i plan to make him a SE kt88 stereo amp, only requirement is that it must have a headphone output also. I can look in the net but i received good help from this forum when i did make my own amp so i was wondering if any tube guru knows of a good schematic for a kt88 SE amp...i know about security( have read books) but i wouldn't like to work with 600v so a B+ voltage around 400 would be preferred.


Thanks in advance,


Stalker
 
Cassiel

Cassiel

Disabled Account
Joined 2004
Thanks for the replies, the link given by powertriode was dead a few days ago but i tried again today and it did work. I like the schematic and the page. I will do that one and post the pics in the photo gallery.


Thanks again for the good link ;)

Stalker
 
I

ICARE

Member
Joined 2003
Hello Staker,

I just finish my SE KT88...
tHIS ONE: http://ptsoundlab.com/sectubes/schemas/kt88/classakt886sn7/classa6sn7kt8811w.htm

http://fr.pg.photos.yahoo.com/ph/icarejy/detail?.dir=9e46&.dnm=cbfa.jpg&.src=ph

The HT=450V so is not too much..it depens of the speaker, you have to be carefullbecause it´s only 10W and it should be good to have at least 94dB for the speakers.

and I´m living in Madrid so if you need help or you want listening my amp NO PROBLEMS, enviame un correo electronico.

See you
J-Y
 
Cassiel

Cassiel

Disabled Account
Joined 2004
I have built a wonderful SE KT88-amp
Click to expand...

That one is dead simple Mikael, happy with its sound?


Here are some more SE KT88 links I have found.
Click to expand...

Thanks again powertriode, i will study over the weekend those schematics and choose the best for me(usually the easiest):)

I just finish my SE KT88
Click to expand...

Hello Icare, your amp looks GREAT, cool design in my opinion. About the speakers, i plan to use Fostex 103 which are 93 dB so they should be ok. Only trouble is they don't sell them in Spain, they're only available in Germany. I would like to know which are yours and if you bought them in Madrid.

and I´m living in Madrid so if you need help or you want listening my amp NO PROBLEMS
Click to expand...

It would be nice to listen to it. Your proposal is very kind and if reason wins over shyness i'll send you an e-mail.

Well thanks to everybody, another SE KT88 is on its way.


Cheers,

Stalker
 
I

ICARE

Member
Joined 2003
Fostex is a good choice but I see one problem with this SE, bass-frequencies will be really poor. I think you know than all SE have this problem.

Of course it depends as well if you want make a other amp for the bass and use it for bi-amplification like me !!
I don´t know your purpose.

My speakers are clone of the AUDIONOTE AZ3 but with some modification, I didn´t find what I wanted so I made them. It´s a TQWT: 94 dB you can see them here:

http://fr.pg.photos.yahoo.com/ph/ic...e=http://fr.pg.photos.yahoo.com/ph//my_photos

You can find fostex in Netherland as well and maybe cheaper, I will check if you have a dealer in Spain but I don´t think so.

No problems if you have more question, and if you start your SE, let me know because I have good contact for ordering components like RIKEN..MUNDORF etc..etc... and don´t be shy :)

See you
J-Y
 
M

Mikael Abdellah

Member
Joined 2003
So far it's the sweetest sounding amp I have ever heard in my entire life, but then again, I haven't heard any other tubeamp. About the poor bass, I must say I disagree. The bass I get from my amp is awesome. Deep, smooth and extremely dynamic. My speakers have roughly 88db sensitivity wich is just a tad to low, but it doesnt bother me so much.

About fostex. www.madisound.com have great prices on fostex-drivers. You might wanna check them out.
 
Cassiel

Cassiel

Disabled Account
Joined 2004
Hi again,
i've been kind of busy...thanks for the replies.

Mikael i'm gonna follow your schematic(quite simple) but what about the power supply? Do you use diode or tube rectification?
Diodes are cheaper but some people say they can hear the difference...i dunno.:rolleyes:
Another question. What OT's do you recommend me? It must have 3 taps right? I do use a Hammond but only has 2 primaries not 3 ...is that an ultraliniar connection, the 2nd grid going to the center tap?
Thanks for the link.

Icare, very kind, Letusa don't work with drivers they told me to ask them in Germany. Your speakers are impressive...yes i have heard about bass deficiencies in tube amps...seems they generally lack in that area, my bass is ok in my amp. Right now i'm out of town but i will send you an email when i do get back.
I must listen to those speakers. :eek: :)
 
Cassiel

Cassiel

Disabled Account
Joined 2004
Hi Icare,


Your email address is not available so i cannot email you; as for the OT's ,i agree with you,Hammond's are nothing out of this world but they were here in Spain so i went for them. Hurry sometimes matters.

Out of town again so no problems about not getting your email, but please do change the configuration or else....i won't hear anything.;)


Cheers,


Stalker
 
K

Kashmire

Member
Joined 2003
I'm currently building a KT88 amp. Picture attached in following posts.

I'm using a schematic from Andrea Ciuffoli below. This is a push-pull idea, but I'm using a similar idea. I replaced the E182CC with a 6c45pi, running at 10mA with the LL1660, with similar plate voltages.

On the secondary side of the LL1660, I don't use push-pull. Instead, I use SE. Refer to the other schematic from Ciuffoli for a SE circuit on the secondary side of the LL1660. You can easily replace the KT90 with a KT88 with very minor modes (if any at all). I have Plitron transformers.
 

Attachments

  • amp_kt88_cf1.gif
    amp_kt88_cf1.gif
    15.6 KB · Views: 1,633
K

Kashmire

Member
Joined 2003
I also tried putting the tube BELOW the output transformer. You can do it either way. By putting the tube below the output transformer, you have the option of running Triode, Pentode, or UL (if your transformer has a UL tap). I also played with using the output transformer's secondary as cathode feedback on the KT88.

Putting the tube on TOP (cathode follower), you are required to run the KT88 in Triode mode (this can be good). You also get the benefit of cathode feedback via action of the output transformer's primary (which can also be good). The drawback is the input signal to the KT88's grid must be HUGE to compensate for (1) the KT88's triode mode, and (2) the gigantic cathode feedback action of the transformer's primary.

What works for you, works against you. Here's the paradox: the output stage is more linear in this configuration, but the driver stage is pushed harder, creating distortion in the driver stage. By making the output stage more linear, it's forced more of the work onto the driver!
 
S

Sherman

Member
Joined 2004
Mikael Abdellah said:
I have built a wonderful SE KT88-amp.

http://213.67.45.220/se_kt88.gif

It's REALLY simple to build. I'm unsure how it would work with headphones, but maybe someone else can answer that for you.
Click to expand...


Amazing. In looking for an amp to build this winter I had decided to go with a simple ECL82 design. Then I saw this one! Just as simple as the ECL82 (well, almost, two tubes here) and I think it would be a nicer sounding amp as well.

I think this may be my project for the winter! Thanks for posting it Mikael!
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom